Patent Application
20240130224
The present invention relates to an organic electroluminescence device and an electronic device.
An organic electroluminescence device (hereinafter, occasionally referred to as “organic EL device”.) has found its application in a full-color display for mobile phones, televisions, and the like. When voltage is applied to an organic EL device, holes are injected from an anode and electrons are injected from a cathode into an emitting layer. The injected holes and electrons are recombined in the emitting layer to form excitons. Specifically, according to the electron spin statistics theory, singlet excitons and triplet excitons are generated at a ratio of 25%:75%.
In Patent Literatures 1 to 6, for instance, studies have been made to improve performance of organic EL devices. The performance of the organic EL device is evaluable in terms of, for instance, luminance, emission wavelength, chromaticity, luminous efficiency, drive voltage, and lifetime.
In Patent Literatures 1 to 6, an organic EL device in which a hole transporting zone includes a plurality of layers is disclosed.
An object of the invention is to provide an organic electroluminescence device excellent in luminous efficiency and an electronic device including the organic electroluminescence device.
According to an aspect of the invention, there is provided an organic electroluminescence device including: a cathode; an anode; an emitting region disposed between the cathode and the anode; and a hole transporting zone disposed between the anode and the emitting region, in which the emitting region includes at least one emitting layer, the at least one emitting layer includes a first emitting layer, the hole transporting zone includes a first anode side organic layer and a second anode side organic layer, the first anode side organic layer is in direct contact with the second anode side organic layer, the first anode side organic layer and the second anode side organic layer are disposed between the anode and the emitting region in this order from a side close to the anode, the first anode side organic layer contains a first organic material and a second organic material, the first organic material and the second organic material are mutually different, a content of the first organic material in the first anode side organic layer is less than 50 mass %, the second organic material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof, the second anode side organic layer contains a second hole transporting zone material, the second hole transporting zone material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof, the second hole transporting zone material and the first organic material are mutually different, the second hole transporting zone material and the second organic material are mutually the same or different, the first emitting layer is an emitting layer that emits fluorescence, and a refractive index NM1 of the constituent materials contained in the first anode side organic layer and a refractive index NM2 of the constituent material contained in the second anode side organic layer satisfy a relationship of a numerical formula below (Numerical Formula NM).
NM
1
>NM
2 (Numerical Formula NM)
According to an aspect of the invention, there is provided an organic electroluminescence device, including: a cathode; an anode; an emitting region disposed between the cathode and the anode; a hole transporting zone disposed between the anode and the emitting region; and an electron transporting zone disposed between the cathode and the emitting region, in which the emitting region includes at least one emitting layer, the at least one emitting layer includes a first emitting layer, the electron transporting zone includes at least one electron transporting layer, the hole transporting zone includes a first anode side organic layer and a second anode side organic layer, the first anode side organic layer is in direct contact with the second anode side organic layer, the first anode side organic layer and the second anode side organic layer are disposed between the anode and the emitting region in this order from a side close to the anode, the first anode side organic layer contains a first organic material and a second organic material, the first organic material and the second organic material are mutually different, a content of the first organic material in the first anode side organic layer is less than 50 mass %, the second organic material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof, the second anode side organic layer contains a second hole transporting zone material, the second hole transporting zone material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof, the second hole transporting zone material and the first organic material are mutually different, the second hole transporting zone material and the second organic material are mutually the same or different, the at least one electron transporting layer in the electron transporting zone contains a phenanthroline compound having a phenanthroline skeleton, the phenanthroline compound is a compound that has at least one group represented by a formula (21) below and is represented by a formula (20) below, the first emitting layer is an emitting layer that emits fluorescence, and a refractive index NM1 of the constituent materials contained in the first anode side organic layer and a refractive index NM2 of the constituent material contained in the second anode side organic layer satisfy a relationship of a numerical formula below (Numerical Formula NM).
NM
1
>NM
2 (Numerical Formula NM)
In the formula (20):
In the formula (21):
According to an aspect of the invention, there is provided an organic electroluminescence device including: a cathode; an anode; an emitting region disposed between the cathode and the anode; and a hole transporting zone disposed between the anode and the emitting region, in which the emitting region includes at least one emitting layer, the at least one emitting layer includes a first emitting layer, the first emitting layer contains a first host material and a first emitting compound, the first host material is a compound represented by a formula (H1) below, the compound represented by the formula (H1) has at least one deuterium atom, the hole transporting zone includes a first anode side organic layer and a second anode side organic layer, the first anode side organic layer is in direct contact with the second anode side organic layer, the first anode side organic layer and the second anode side organic layer are disposed between the anode and the emitting region in this order from a side close to the anode, the first anode side organic layer contains a first organic material and a second organic material, the first organic material and the second organic material are mutually different, a content of the first organic material in the first anode side organic layer is less than 50 mass %, the second organic material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof, the second anode side organic layer contains a second hole transporting zone material, the second hole transporting zone material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof, the second hole transporting zone material and the first organic material are mutually different, the second hole transporting zone material and the second organic material are mutually the same or different, the first emitting layer is an emitting layer that emits fluorescence, and a refractive index NM1 of the constituent materials contained in the first anode side organic layer and a refractive index NM2 of the constituent material contained in the second anode side organic layer satisfy a relationship of a numerical formula below (Numerical Formula NM).
NM
1
>NM
2 (Numerical Formula NM)
In the formula (H1):
In the compound represented by the formula (H1), R901, R902, R903, R904, R905, R906, R907, R801 and R802 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms;
According to an aspect of the invention, an electronic device including the organic electroluminescence device according to an aspect of the invention is provided.
According to an aspect of the invention, an organic electroluminescence device excellent in luminous efficiency and an electronic device including the organic electroluminescence device can be provided.
Herein, a hydrogen atom includes isotope having different numbers of neutrons, specifically, protium, deuterium and tritium.
In chemical formulae herein, it is assumed that a hydrogen atom (i.e. protium, deuterium and tritium) is bonded to each of bondable positions that are not annexed with signs “R” or the like or “D” representing a deuterium.
Herein, the ring carbon atoms refer to the number of carbon atoms among atoms forming a ring of a compound (e.g., a monocyclic compound, fused-ring compound, cross-linking compound, carbon ring compound, and heterocyclic compound) in which the atoms are bonded to each other to form the ring. When the ring is substituted by a substituent(s), carbon atom(s) contained in the substituent(s) is not counted in the ring carbon atoms. Unless otherwise specified, the same applies to the “ring carbon atoms” described later. For instance, a benzene ring has 6 ring carbon atoms, a naphthalene ring has 10 ring carbon atoms, a pyridine ring has 5 ring carbon atoms, and a furan ring has 4 ring carbon atoms. Further, for instance, 9,9-diphenylfluorenyl group has 13 ring carbon atoms and 9,9′-spirobifluorenyl group has 25 ring carbon atoms.
When a benzene ring is substituted by a substituent in a form of, for instance, an alkyl group, the number of carbon atoms of the alkyl group is not counted in the number of the ring carbon atoms of the benzene ring. Accordingly, the benzene ring substituted by an alkyl group has 6 ring carbon atoms. When a naphthalene ring is substituted by a substituent in a form of, for instance, an alkyl group, the number of carbon atoms of the alkyl group is not counted in the number of the ring carbon atoms of the naphthalene ring. Accordingly, the naphthalene ring substituted by an alkyl group has 10 ring carbon atoms.
Herein, the ring atoms refer to the number of atoms forming a ring of a compound (e.g., a monocyclic compound, fused-ring compound, cross-linking compound, carbon ring compound, and heterocyclic compound) in which the atoms are bonded to each other to form the ring (e.g., monocyclic ring, fused ring, and ring assembly). Atom(s) not forming the ring (e.g., hydrogen atom(s) for saturating the valence of the atom which forms the ring) and atom(s) in a substituent by which the ring is substituted are not counted as the ring atoms. Unless otherwise specified, the same applies to the “ring atoms” described later. For instance, a pyridine ring has 6 ring atoms, a quinazoline ring has 10 ring atoms, and a furan ring has 5 ring atoms. For instance, the number of hydrogen atom(s) bonded to a pyridine ring or the number of atoms forming a substituent is not counted as the pyridine ring atoms. Accordingly, a pyridine ring bonded to a hydrogen atom(s) or a substituent(s) has 6 ring atoms. For instance, the hydrogen atom(s) bonded to carbon atom(s) of a quinazoline ring or the atoms forming a substituent are not counted as the quinazoline ring atoms. Accordingly, a quinazoline ring bonded to hydrogen atom(s) or a substituent(s) has 10 ring atoms.
Herein, “XX to YY carbon atoms” in the description of “substituted or unsubstituted ZZ group having XX to YY carbon atoms” represent carbon atoms of an unsubstituted ZZ group and do not include carbon atoms of a substituent(s) of the substituted ZZ group. Herein, “YY” is larger than “XX,” “XX” representing an integer of 1 or more and “YY” representing an integer of 2 or more.
Herein, “XX to YY atoms” in the description of “substituted or unsubstituted ZZ group having XX to YY atoms” represent atoms of an unsubstituted ZZ group and does not include atoms of a substituent(s) of the substituted ZZ group. Herein, “YY” is larger than “XX,” “XX” representing an integer of 1 or more and “YY” representing an integer of 2 or more.
Herein, an unsubstituted ZZ group refers to an “unsubstituted ZZ group” in a “substituted or unsubstituted ZZ group,” and a substituted ZZ group refers to a “substituted ZZ group” in a “substituted or unsubstituted ZZ group.”
Herein, the term “unsubstituted” used in a “substituted or unsubstituted ZZ group” means that a hydrogen atom(s) in the ZZ group is not substituted with a substituent(s). The hydrogen atom(s) in the “unsubstituted ZZ group” is protium, deuterium, or tritium.
Herein, the term “substituted” used in a “substituted or unsubstituted ZZ group” means that at least one hydrogen atom in the ZZ group is substituted with a substituent. Similarly, the term “substituted” used in a “BB group substituted by AA group” means that at least one hydrogen atom in the BB group is substituted with the AA group.
Substituent Mentioned Herein Substituent mentioned herein will be described below.
An “unsubstituted aryl group” mentioned herein has, unless otherwise specified herein, 6 to 50, preferably 6 to 30, more preferably 6 to 18 ring carbon atoms.
An “unsubstituted heterocyclic group” mentioned herein has, unless otherwise specified herein, 5 to 50, preferably 5 to 30, more preferably 5 to 18 ring atoms.
An “unsubstituted alkyl group” mentioned herein has, unless otherwise specified herein, 1 to 50, preferably 1 to 20, more preferably 1 to 6 carbon atoms.
An “unsubstituted alkenyl group” mentioned herein has, unless otherwise specified herein, 2 to 50, preferably 2 to 20, more preferably 2 to 6 carbon atoms.
An “unsubstituted alkynyl group” mentioned herein has, unless otherwise specified herein, 2 to 50, preferably 2 to 20, more preferably 2 to 6 carbon atoms.
An “unsubstituted cycloalkyl group” mentioned herein has, unless otherwise specified herein, 3 to 50, preferably 3 to 20, more preferably 3 to 6 ring carbon atoms.
An “unsubstituted arylene group” mentioned herein has, unless otherwise specified herein, 6 to 50, preferably 6 to 30, more preferably 6 to 18 ring carbon atoms.
An “unsubstituted divalent heterocyclic group” mentioned herein has, unless otherwise specified herein, 5 to 50, preferably 5 to 30, more preferably 5 to 18 ring atoms.
An “unsubstituted alkylene group” mentioned herein has, unless otherwise specified herein, 1 to 50, preferably 1 to 20, more preferably 1 to 6 carbon atoms.
Specific examples (specific example group G1) of the “substituted or unsubstituted aryl group” mentioned herein include unsubstituted aryl groups (specific example group G1A) below and substituted aryl groups (specific example group G11B). (Herein, an unsubstituted aryl group refers to an “unsubstituted aryl group” in a “substituted or unsubstituted aryl group”, and a substituted aryl group refers to a “substituted aryl group” in a “substituted or unsubstituted aryl group.”) A simply termed “aryl group” herein includes both of an “unsubstituted aryl group” and a “substituted aryl group”.
The “substituted aryl group” refers to a group derived by substituting at least one hydrogen atom in an “unsubstituted aryl group” with a substituent. Examples of the “substituted aryl group” include a group derived by substituting at least one hydrogen atom in the “unsubstituted aryl group” in the specific example group G1A below with a substituent, and examples of the substituted aryl group in the specific example group G1B below. It should be noted that the examples of the “unsubstituted aryl group” and the “substituted aryl group” mentioned herein are merely exemplary, and the “substituted aryl group” mentioned herein includes a group derived by further substituting a hydrogen atom bonded to a carbon atom of a skeleton of a “substituted aryl group” in the specific example group G1B below, and a group derived by further substituting a hydrogen atom of a substituent of the “substituted aryl group” in the specific example group G1B below.
a phenyl group, p-biphenyl group, m-biphenyl group, o-biphenyl group, p-terphenyl-4-yl group, p-terphenyl-3-yl group, p-terphenyl-2-yl group, m-terphenyl-4-yl group, m-terphenyl-3-yl group, m-terphenyl-2-yl group, o-terphenyl-4-yl group, o-terphenyl-3-yl group, o-terphenyl-2-yl group, 1-naphthyl group, 2-naphthyl group, anthryl group, benzanthryl group, phenanthryl group, benzophenanthryl group, phenalenyl group, pyrenyl group, chrysenyl group, benzochrysenyl group, triphenylenyl group, benzotriphenylenyl group, tetracenyl group, pentacenyl group, fluorenyl group, 9,9′-spirobifluorenyl group, benzofluorenyl group, dibenzofluorenyl group, fluoranthenyl group, benzofluoranthenyl group, perylenyl group, and monovalent aryl group derived by removing one hydrogen atom from cyclic structures represented by formulae (TEMP-1) to (TEMP-15) below.
The “heterocyclic group” mentioned herein refers to a cyclic group having at least one hetero atom in the ring atoms. Specific examples of the hetero atom include a nitrogen atom, oxygen atom, sulfur atom, silicon atom, phosphorus atom, and boron atom.
The “heterocyclic group” mentioned herein is a monocyclic group or a fused-ring group.
The “heterocyclic group” mentioned herein is an aromatic heterocyclic group or a non-aromatic heterocyclic group.
Specific examples (specific example group G2) of the “substituted or unsubstituted heterocyclic group” mentioned herein include unsubstituted heterocyclic groups (specific example group G2A) and substituted heterocyclic groups (specific example group G2B). (Herein, an unsubstituted heterocyclic group refers to an “unsubstituted heterocyclic group” in a “substituted or unsubstituted heterocyclic group,” and a substituted heterocyclic group refers to a “substituted heterocyclic group” in a “substituted or unsubstituted heterocyclic group.”) A simply termed “heterocyclic group” herein includes both of an “unsubstituted heterocyclic group” and a “substituted heterocyclic group.”
The “substituted heterocyclic group” refers to a group derived by substituting at least one hydrogen atom in an “unsubstituted heterocyclic group” with a substituent. Specific examples of the “substituted heterocyclic group” include a group derived by substituting at least one hydrogen atom in the “unsubstituted heterocyclic group” in the specific example group G2A below with a substituent, and examples of the substituted heterocyclic group in the specific example group G2B below. It should be noted that the examples of the “unsubstituted heterocyclic group” and the “substituted heterocyclic group” mentioned herein are merely exemplary, and the “substituted heterocyclic group” mentioned herein includes a group derived by further substituting a hydrogen atom bonded to a ring atom of a skeleton of a “substituted heterocyclic group” in the specific example group G2B below, and a group derived by further substituting a hydrogen atom of a substituent of the “substituted heterocyclic group” in the specific example group G2B below.
The specific example group G2A includes, for instance, unsubstituted heterocyclic groups including a nitrogen atom (specific example group G2A1) below, unsubstituted heterocyclic groups including an oxygen atom (specific example group G2A2) below, unsubstituted heterocyclic groups including a sulfur atom (specific example group G2A3) below, and monovalent heterocyclic groups (specific example group G2A4) derived by removing a hydrogen atom from cyclic structures represented by formulae (TEMP-16) to (TEMP-33) below.
The specific example group G2B includes, for instance, substituted heterocyclic groups including a nitrogen atom (specific example group G2B1) below, substituted heterocyclic groups including an oxygen atom (specific example group G2B2) below, substituted heterocyclic groups including a sulfur atom (specific example group G2B3) below, and groups derived by substituting at least one hydrogen atom of the monovalent heterocyclic groups (specific example group G2B4) derived from the cyclic structures represented by formulae (TEMP-16) to (TEMP-33) below.
In the formulae (TEMP-16) to (TEMP-33), XA and YA are each independently an oxygen atom, a sulfur atom, NH or CH2, with a proviso that at least one of XA or YA is an oxygen atom, a sulfur atom, or NH.
When at least one of XA or YA in the formulae (TEMP-16) to (TEMP-33) is NH or CH2, the monovalent heterocyclic groups derived from the cyclic structures represented by the formulae (TEMP-16) to (TEMP-33) include a monovalent group derived by removing one hydrogen atom from NH or CH2.
The “at least one hydrogen atom of a monovalent heterocyclic group” means at least one hydrogen atom selected from a hydrogen atom bonded to a ring carbon atom of the monovalent heterocyclic group, a hydrogen atom bonded to a nitrogen atom of at least one of XA or YA in a form of NH, and a hydrogen atom of one of XA and YA in a form of a methylene group (CH2).
Specific examples (specific example group G3) of the “substituted or unsubstituted alkyl group” mentioned herein include unsubstituted alkyl groups (specific example group G3A) and substituted alkyl groups (specific example group G3B) below. (Herein, an unsubstituted alkyl group refers to an “unsubstituted alkyl group” in a “substituted or unsubstituted alkyl group,” and a substituted alkyl group refers to a “substituted alkyl group” in a “substituted or unsubstituted alkyl group.”) A simply termed “alkyl group” herein includes both of an “unsubstituted alkyl group” and a “substituted alkyl group”.
The “substituted alkyl group” refers to a group derived by substituting at least one hydrogen atom in an “unsubstituted alkyl group” with a substituent. Specific examples of the “substituted alkyl group” include a group derived by substituting at least one hydrogen atom of an “unsubstituted alkyl group” (specific example group G3A) below with a substituent, and examples of the substituted alkyl group (specific example group G3B) below. Herein, the alkyl group for the “unsubstituted alkyl group” refers to a chain alkyl group. Accordingly, the “unsubstituted alkyl group” include linear “unsubstituted alkyl group” and branched “unsubstituted alkyl group.” It should be noted that the examples of the “unsubstituted alkyl group” and the “substituted alkyl group” mentioned herein are merely exemplary, and the “substituted alkyl group” mentioned herein includes a group derived by further substituting a hydrogen atom of a skeleton of the “substituted alkyl group” in the specific example group G3B, and a group derived by further substituting a hydrogen atom of a substituent of the “substituted alkyl group” in the specific example group G3B.
Specific examples (specific example group G4) of the “substituted or unsubstituted alkenyl group” mentioned herein include unsubstituted alkenyl groups (specific example group G4A) and substituted alkenyl groups (specific example group G4B). (Herein, an unsubstituted alkenyl group refers to an “unsubstituted alkenyl group” in a “substituted or unsubstituted alkenyl group,” and a substituted alkenyl group refers to a “substituted alkenyl group” in a “substituted or unsubstituted alkenyl group.”) A simply termed “alkenyl group” herein includes both of an “unsubstituted alkenyl group” and a “substituted alkenyl group”.
The “substituted alkenyl group” refers to a group derived by substituting at least one hydrogen atom in an “unsubstituted alkenyl group” with a substituent. Specific examples of the “substituted alkenyl group” include an “unsubstituted alkenyl group” (specific example group G4A) substituted by a substituent, and examples of the substituted alkenyl group (specific example group G4B) below. It should be noted that the examples of the “unsubstituted alkenyl group” and the “substituted alkenyl group” mentioned herein are merely exemplary, and the “substituted alkenyl group” mentioned herein includes a group derived by further substituting a hydrogen atom of a skeleton of the “substituted alkenyl group” in the specific example group G4B with a substituent, and a group derived by further substituting a hydrogen atom of a substituent of the “substituted alkenyl group” in the specific example group G4B with a substituent.
Specific examples (specific example group G5) of the “substituted or unsubstituted alkynyl group” mentioned herein include unsubstituted alkynyl groups (specific example group G5A) below. (Herein, an unsubstituted alkynyl group refers to an “unsubstituted alkynyl group” in a “substituted or unsubstituted alkynyl group.”) A simply termed “alkynyl group” herein includes both of “unsubstituted alkynyl group” and “substituted alkynyl group”.
The “substituted alkynyl group” refers to a group derived by substituting at least one hydrogen atom in an “unsubstituted alkynyl group” with a substituent. Specific examples of the “substituted alkynyl group” include a group derived by substituting at least one hydrogen atom of the “unsubstituted alkynyl group” (specific example group G5A) below with a substituent.
Unsubstituted Alkynyl Group (Specific Example Group G5A): ethynyl group
Specific examples (specific example group G6) of the “substituted or unsubstituted cycloalkyl group” mentioned herein include unsubstituted cycloalkyl groups (specific example group G6A) and substituted cycloalkyl groups (specific example group G6B). (Herein, an unsubstituted cycloalkyl group refers to an “unsubstituted cycloalkyl group” in a “substituted or unsubstituted cycloalkyl group,” and a substituted cycloalkyl group refers to a “substituted cycloalkyl group” in a “substituted or unsubstituted cycloalkyl group.”) A simply termed “cycloalkyl group” herein includes both of “unsubstituted cycloalkyl group” and “substituted cycloalkyl group”.
The “substituted cycloalkyl group” refers to a group derived by substituting at least one hydrogen atom of an “unsubstituted cycloalkyl group” with a substituent. Specific examples of the “substituted cycloalkyl group” include a group derived by substituting at least one hydrogen atom of the “unsubstituted cycloalkyl group” (specific example group G6A) below with a substituent, and examples of the substituted cycloalkyl group (specific example group G6B) below. It should be noted that the examples of the “unsubstituted cycloalkyl group” and the “substituted cycloalkyl group” mentioned herein are merely exemplary, and the “substituted cycloalkyl group” mentioned herein includes a group derived by substituting at least one hydrogen atom bonded to a carbon atom of a skeleton of the “substituted cycloalkyl group” in the specific example group G6B with a substituent, and a group derived by further substituting a hydrogen atom of a substituent of the “substituted cycloalkyl group” in the specific example group G6B with a substituent.
Specific examples (specific example group G7) of the group represented herein by —Si(R901)(R902)(R903) include:
Specific examples (specific example group G8) of a group represented by —O—(R904) herein include: —O(G1); —O(G2); —O(G3); and —O(G6);
Specific examples (specific example group G9) of a group represented herein by —S—(R905) include: —S(G1); —S(G2); —S(G3); and —S(G6);
Specific examples (specific example group G10) of a group represented herein by —N(R906)(R907) include: —N(G1)(G1); —N(G2)(G2); —N(G1)(G2); —N(G3)(G3); and —N(G6)(G6),
Specific examples (specific example group G11) of “halogen atom” mentioned herein include a fluorine atom, chlorine atom, bromine atom, and iodine atom.
The “substituted or unsubstituted fluoroalkyl group” mentioned herein refers to a group derived by substituting at least one hydrogen atom bonded to at least one of carbon atoms forming an alkyl group in the “substituted or unsubstituted alkyl group” with a fluorine atom, and also includes a group (perfluoro group) derived by substituting all of hydrogen atoms bonded to carbon atoms forming the alkyl group in the “substituted or unsubstituted alkyl group” with fluorine atoms. An “unsubstituted fluoroalkyl group” has, unless otherwise specified herein, 1 to 50, preferably 1 to 30, more preferably 1 to 18 carbon atoms. The “substituted fluoroalkyl group” refers to a group derived by substituting at least one hydrogen atom in a “fluoroalkyl group” with a substituent. It should be noted that the examples of the “substituted fluoroalkyl group” mentioned herein include a group derived by further substituting at least one hydrogen atom bonded to a carbon atom of an alkyl chain of a “substituted fluoroalkyl group” with a substituent, and a group derived by further substituting at least one hydrogen atom of a substituent of the “substituted fluoroalkyl group” with a substituent. Specific examples of the “unsubstituted fluoroalkyl group” include a group derived by substituting at least one hydrogen atom of the “alkyl group” (specific example group G3) with a fluorine atom.
The “substituted or unsubstituted haloalkyl group” mentioned herein refers to a group derived by substituting at least one hydrogen atom bonded to carbon atoms forming the alkyl group in the “substituted or unsubstituted alkyl group” with a halogen atom, and also includes a group derived by substituting all hydrogen atoms bonded to carbon atoms forming the alkyl group in the “substituted or unsubstituted alkyl group” with halogen atoms. An “unsubstituted haloalkyl group” has, unless otherwise specified herein, 1 to 50, preferably 1 to 30, and more preferably 1 to 18 carbon atoms. The “substituted haloalkyl group” refers to a group derived by substituting at least one hydrogen atom in a “haloalkyl group” with a substituent. It should be noted that the examples of the “substituted haloalkyl group” mentioned herein include a group derived by further substituting at least one hydrogen atom bonded to a carbon atom of an alkyl chain of a “substituted haloalkyl group” with a substituent, and a group derived by further substituting at least one hydrogen atom of a substituent of the “substituted haloalkyl group” with a substituent. Specific examples of the “unsubstituted haloalkyl group” include a group derived by substituting at least one hydrogen atom of the “alkyl group” (specific example group G3) with a halogen atom. The haloalkyl group is sometimes referred to as a halogenated alkyl group.
Specific examples of a “substituted or unsubstituted alkoxy group” mentioned herein include a group represented by —O(G3), G3 being the “substituted or unsubstituted alkyl group” in the specific example group G3. An “unsubstituted alkoxy group” has, unless otherwise specified herein, 1 to 50, preferably 1 to 30, more preferably 1 to 18 carbon atoms.
Specific examples of a “substituted or unsubstituted alkylthio group” mentioned herein include a group represented by —S(G3), G3 being the “substituted or unsubstituted alkyl group” in the specific example group G3. An “unsubstituted alkylthio group” has, unless otherwise specified herein, 1 to 50, preferably 1 to 30, more preferably 1 to 18 carbon atoms.
Specific examples of a “substituted or unsubstituted aryloxy group” mentioned herein include a group represented by —O(G1), G1 being the “substituted or unsubstituted aryl group” in the specific example group G1. An “unsubstituted aryloxy group” has, unless otherwise specified herein, 6 to 50, preferably 6 to 30, more preferably 6 to 18 ring carbon atoms.
Specific examples of a “substituted or unsubstituted arylthio group” mentioned herein include a group represented by —S(G1), G1 being the “substituted or unsubstituted aryl group” in the specific example group G1. An “unsubstituted arylthio group” has, unless otherwise specified herein, 6 to 50, preferably 6 to 30, more preferably 6 to 18 ring carbon atoms.
Specific examples of a “trialkylsilyl group” mentioned herein include a group represented by —Si(G3)(G3)(G3), G3 being the “substituted or unsubstituted alkyl group” in the specific example group G3. The plurality of G3 in —Si(G3)(G3)(G3) are mutually the same or different. Each of the alkyl groups in the “trialkylsilyl group” has, unless otherwise specified herein, 1 to 50, preferably 1 to 20, more preferably 1 to 6 carbon atoms.
Specific examples of a “substituted or unsubstituted aralkyl group” mentioned herein include a group represented by -(G3)-(G1), G3 being the “substituted or unsubstituted alkyl group” in the specific example group G3, G1 being the “substituted or unsubstituted aryl group” in the specific example group G1. Accordingly, the “aralkyl group” is a group derived by substituting a hydrogen atom of the “alkyl group” with a substituent in a form of the “aryl group,” which is an example of the “substituted alkyl group.” An “unsubstituted aralkyl group,” which is an “unsubstituted alkyl group” substituted by an “unsubstituted aryl group,” has, unless otherwise specified herein, 7 to 50 carbon atoms, preferably 7 to 30 carbon atoms, more preferably 7 to 18 carbon atoms.
Specific examples of the “substituted or unsubstituted aralkyl group” include a benzyl group, 1-phenylethyl group, 2-phenylethyl group, 1-phenylisopropyl group, 2-phenylisopropyl group, phenyl-t-butyl group, a-naphthylmethyl group, 1-a-naphthylethyl group, 2-a-naphthylethyl group, 1-a-naphthylisopropyl group, 2-α-naphthylisopropyl group, β-naphthylmethyl group, 1-β-naphthylethyl group, 2-β-naphthylethyl group, 1-β-naphthylisopropyl group, and 2-β-naphthylisopropyl group.
Preferable examples of the substituted or unsubstituted aryl group mentioned herein include, unless otherwise specified herein, a phenyl group, p-biphenyl group, m-biphenyl group, o-biphenyl group, p-terphenyl-4-yl group, p-terphenyl-3-yl group, p-terphenyl-2-yl group, m-terphenyl-4-yl group, m-terphenyl-3-yl group, m-terphenyl-2-yl group, o-terphenyl-4-yl group, o-terphenyl-3-yl group, o-terphenyl-2-yl group, 1-naphthyl group, 2-naphthyl group, anthryl group, phenanthryl group, pyrenyl group, chrysenyl group, triphenylenyl group, fluorenyl group, 9,9′-spirobifluorenyl group, 9,9-dimethylfluorenyl group, and 9,9-diphenylfluorenyl group.
Preferable examples of the substituted or unsubstituted heterocyclic group mentioned herein include, unless otherwise specified herein, a pyridyl group, pyrimidinyl group, triazinyl group, quinolyl group, isoquinolyl group, quinazolinyl group, benzimidazolyl group, phenanthrolinyl group, carbazolyl group (1-carbazolyl group, 2-carbazolyl group, 3-carbazolyl group, 4-carbazolyl group, or 9-carbazolyl group), benzocarbazolyl group, azacarbazolyl group, diazacarbazolyl group, dibenzofuranyl group, naphthobenzofuranyl group, azadibenzofuranyl group, diazadibenzofuranyl group, dibenzothiophenyl group, naphthobenzothiophenyl group, azadibenzothiophenyl group, diazadibenzothiophenyl group, (9-phenyl)carbazolyl group ((9-phenyl)carbazole-1-yl group, (9-phenyl)carbazole-2-yl group, (9-phenyl)carbazole-3-yl group, or (9-phenyl)carbazole-4-yl group), (9-biphenylyl)carbazolyl group, (9-phenyl)phenylcarbazolyl group, diphenylcarbazole-9-yl group, phenylcarbazole-9-yl group, phenyltriazinyl group, biphenylyltriazinyl group, diphenyltriazinyl group, phenyldibenzofuranyl group, and phenyldibenzothiophenyl group.
The carbazolyl group mentioned herein is, unless otherwise specified herein, specifically a group represented by one of formulae below.
The (9-phenyl)carbazolyl group mentioned herein is, unless otherwise specified herein, specifically a group represented by one of formulae below.
In the formulae (TEMP-Cz1) to (TEMP-Cz9), * represents a bonding position.
The dibenzofuranyl group and dibenzothiophenyl group mentioned herein are, unless otherwise specified herein, each specifically represented by one of formulae below.
In the formulae (TEMP-34) to (TEMP-41), * represents a bonding position.
Preferable examples of the substituted or unsubstituted alkyl group mentioned herein include, unless otherwise specified herein, a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, and t-butyl group.
The “substituted or unsubstituted arylene group” mentioned herein is, unless otherwise specified herein, a divalent group derived by removing one hydrogen atom on an aryl ring of the “substituted or unsubstituted aryl group.” Specific examples of the “substituted or unsubstituted arylene group” (specific example group G12) include a divalent group derived by removing one hydrogen atom on an aryl ring of the “substituted or unsubstituted aryl group” in the specific example group G1.
The “substituted or unsubstituted divalent heterocyclic group” mentioned herein is, unless otherwise specified herein, a divalent group derived by removing one hydrogen atom on a heterocycle of the “substituted or unsubstituted heterocyclic group.” Specific examples of the “substituted or unsubstituted divalent heterocyclic group” (specific example group G13) include a divalent group derived by removing one hydrogen atom on a heterocyclic ring of the “substituted or unsubstituted heterocyclic group” in the specific example group G2.
The “substituted or unsubstituted alkylene group” mentioned herein is, unless otherwise specified herein, a divalent group derived by removing one hydrogen atom on an alkyl chain of the “substituted or unsubstituted alkyl group.” Specific examples of the “substituted or unsubstituted alkylene group” (specific example group G14) include a divalent group derived by removing one hydrogen atom on an alkyl chain of the “substituted or unsubstituted alkyl group” in the specific example group G3.
The substituted or unsubstituted arylene group mentioned herein is, unless otherwise specified herein, preferably any one of groups represented by formulae (TEMP-42) to (TEMP-68) below.
In the formulae (TEMP-42) to (TEMP-52), Q1 to Q10 are each independently a hydrogen atom or a substituent.
In the formulae (TEMP-42) to (TEMP-52), * represents a bonding position.
In the formulae (TEMP-53) to (TEMP-62), Q1 to Q10 are each independently a hydrogen atom or a substituent.
In the formulae, Qs and Q10 may be mutually bonded through a single bond to form a ring.
In the formulae (TEMP-53) to (TEMP-62), * represents a bonding position.
In the formulae (TEMP-63) to (TEMP-68), Q1 to Q8 are each independently a hydrogen atom or a substituent.
In the formulae (TEMP-63) to (TEMP-68), * represents a bonding position.
The substituted or unsubstituted divalent heterocyclic group mentioned herein is, unless otherwise specified herein, preferably a group represented by any one of formulae (TEMP-69) to (TEMP-102) below.
In the formulae (TEMP-69) to (TEMP-82), Q1 to Q9 are each independently a hydrogen atom or a substituent.
In the formulae (TEMP-83) to (TEMP-102), Q1 to Q8 are each independently a hydrogen atom or a substituent.
The substituent mentioned herein has been described above.
Instances where “at least one combination of adjacent two or more (of . . . ) are mutually bonded to form a substituted or unsubstituted monocyclic ring, mutually bonded to form a substituted or unsubstituted fused ring, or not mutually bonded” mentioned herein refer to instances where “at least one combination of adjacent two or more (of . . . ) are mutually bonded to form a substituted or unsubstituted monocyclic ring, “at least one combination of adjacent two or more (of . . . ) are mutually bonded to form a substituted or unsubstituted fused ring,” and “at least one combination of adjacent two or more (of . . . ) are not mutually bonded.”
Instances where “at least one combination of adjacent two or more (of . . . ) are mutually bonded to form a substituted or unsubstituted monocyclic ring” and “at least one combination of adjacent two or more (of . . . ) are mutually bonded to form a substituted or unsubstituted fused ring” mentioned herein (these instances will be sometimes collectively referred to as an instance of “bonded to form a ring” hereinafter) will be described below. An anthracene compound having a basic skeleton in a form of an anthracene ring and represented by a formula (TEMP-103) below will be used as an example for the description.
For instance, when “at least one combination of adjacent two or more of R921 to R930 are mutually bonded to form a ring,” the combination of adjacent ones of R921 to R930 (i.e. the combination at issue) is a combination of R921 and R922, a combination of R922 and R923, a combination of R923 and R924, a combination of R924 and R930, a combination of R930 and R925, a combination of R925 and R926, a combination of R926 and R927, a combination of R927 and R928, a combination of R928 and R929, or a combination of R929 and R921.
The term “at least one combination” means that two or more of the above combinations of adjacent two or more of R921 to R930 may simultaneously form rings. For instance, when R921 and R922 are mutually bonded to form a ring QA and R925 and R926 are simultaneously mutually bonded to form a ring QB, the anthracene compound represented by the formula (TEMP-103) is represented by a formula (TEMP-104) below.
The instance where the “combination of adjacent two or more” form a ring means not only an instance where the “two” adjacent components are bonded but also an instance where adjacent “three or more” are bonded. For instance, R921 and R922 are mutually bonded to form a ring QA and R922 and R923 are mutually bonded to form a ring QC, and mutually adjacent three components (R921, R922 and R923) are mutually bonded to form a ring fused to the anthracene basic skeleton. In this case, the anthracene compound represented by the formula (TEMP-103) is represented by a formula (TEMP-105) below. In the formula (TEMP-105) below, the ring QA and the ring QC share R922.
The formed “monocyclic ring” or “fused ring” may be, in terms of the formed ring in itself, a saturated ring or an unsaturated ring. When the “combination of adjacent two” form a “monocyclic ring” or a “fused ring,” the “monocyclic ring” or “fused ring” may be a saturated ring or an unsaturated ring. For instance, the ring QA and the ring QB formed in the formula (TEMP-104) are each independently a “monocyclic ring” or a “fused ring.” Further, the ring QA and the ring QC formed in the formula (TEMP-105) are each a “fused ring.” The ring QA and the ring QC in the formula (TEMP-105) are fused to form a fused ring. When the ring QA in the formula (TEMP-104) is a benzene ring, the ring QA is a monocyclic ring. When the ring QA in the formula (TEMP-104) is a naphthalene ring, the ring QA is a fused ring.
The “unsaturated ring” represents an aromatic hydrocarbon ring or an aromatic heterocycle. The “saturated ring” represents an aliphatic hydrocarbon ring or a non-aromatic heterocycle.
Specific examples of the aromatic hydrocarbon ring include a ring formed by terminating a bond of a group in the specific example of the specific example group G1 with a hydrogen atom.
Specific examples of the aromatic heterocycle include a ring formed by terminating a bond of an aromatic heterocyclic group in the specific example of the specific example group G2 with a hydrogen atom.
Specific examples of the aliphatic hydrocarbon ring include a ring formed by terminating a bond of a group in the specific example of the specific example group G6 with a hydrogen atom.
The phrase “to form a ring” herein means that a ring is formed only by a plurality of atoms of a basic skeleton, or by a combination of a plurality of atoms of the basic skeleton and one or more optional atoms. For instance, the ring QA formed by mutually bonding R921 and R922 shown in the formula (TEMP-104) is a ring formed by a carbon atom of the anthracene skeleton bonded to R921, a carbon atom of the anthracene skeleton bonded to R922, and one or more optional atoms. Specifically, when the ring QA is a monocyclic unsaturated ring formed by R921 and R922, the ring formed by a carbon atom of the anthracene skeleton bonded to R921, a carbon atom of the anthracene skeleton bonded to R922, and four carbon atoms is a benzene ring.
The “optional atom” is, unless otherwise specified herein, preferably at least one atom selected from the group consisting of a carbon atom, nitrogen atom, oxygen atom, and sulfur atom. A bond of the optional atom (e.g. a carbon atom and a nitrogen atom) not forming a ring may be terminated by a hydrogen atom or the like or may be substituted by an “optional substituent” described later. When the ring includes an optional element other than carbon atom, the resultant ring is a heterocycle.
The number of “one or more optional atoms” forming the monocyclic ring or fused ring is, unless otherwise specified herein, preferably in a range from 2 to 15, more preferably in a range from 3 to 12, further preferably in a range from 3 to 5.
Unless otherwise specified herein, the ring, which may be a “monocyclic ring” or “fused ring,” is preferably a “monocyclic ring.”
Unless otherwise specified herein, the ring, which may be a “saturated ring” or “unsaturated ring,” is preferably an “unsaturated ring.”
Unless otherwise specified herein, the “monocyclic ring” is preferably a benzene ring.
Unless otherwise specified herein, the “unsaturated ring” is preferably a benzene ring.
When “at least one combination of adjacent two or more” (of . . . ) are “mutually bonded to form a substituted or unsubstituted monocyclic ring” or “mutually bonded to form a substituted or unsubstituted fused ring,” unless otherwise specified herein, at least one combination of adjacent two or more of components are preferably mutually bonded to form a substituted or unsubstituted “unsaturated ring” formed of a plurality of atoms of the basic skeleton, and 1 to 15 atoms of at least one element selected from the group consisting of carbon, nitrogen, oxygen and sulfur.
When the “monocyclic ring” or the “fused ring” has a substituent, the substituent is the substituent described in later-described “optional substituent.” When the “monocyclic ring” or the “fused ring” has a substituent, specific examples of the substituent are the substituents described in the above under the subtitle “Substituent Mentioned Herein.”
When the “saturated ring” or the “unsaturated ring” has a substituent, the substituent is the substituent described in later-described “optional substituent.” When the “monocyclic ring” or the “fused ring” has a substituent, specific examples of the substituent are the substituents described in the above under the subtitle “Substituent Mentioned Herein.”
The above is the description for the instances where “at least one combination of adjacent two or more (of . . . ) are mutually bonded to form a substituted or unsubstituted monocyclic ring” and “at least one combination of adjacent two or more (of . . . ) are mutually bonded to form a substituted or unsubstituted fused ring” mentioned herein (sometimes referred to as an instance of “bonded to form a ring”).
In an exemplary embodiment herein, the substituent for the substituted or unsubstituted group (hereinafter sometimes referred to as an “optional substituent”), is for instance, a group selected from the group consisting of an unsubstituted alkyl group having 1 to 50 carbon atoms, an unsubstituted alkenyl group having 2 to 50 carbon atoms, an unsubstituted alkynyl group having 2 to 50 carbon atoms, an unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, —Si(R901)(R902)(R903), —O—(R904), —S—(R905), —N(R906)(R907), a halogen atom, a cyano group, a nitro group, an unsubstituted aryl group having 6 to 50 ring carbon atoms, and an unsubstituted heterocyclic group having 5 to 50 ring atoms,
In an exemplary embodiment, the substituent for the substituted or unsubstituted group is a group selected from the group consisting of an alkyl group having 1 to 50 carbon atoms, an aryl group having 6 to 50 ring carbon atoms, and a heterocyclic group having 5 to 50 ring atoms.
In an exemplary embodiment, the substituent for the substituted or unsubstituted group is a group selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 18 ring carbon atoms, and a heterocyclic group having 5 to 18 ring atoms.
Specific examples of the above optional substituent are the same as the specific examples of the substituent described in the above under the subtitle “Substituent Mentioned Herein.”
Unless otherwise specified herein, adjacent ones of the optional substituents may form a “saturated ring” or an “unsaturated ring,” preferably a substituted or unsubstituted saturated five-membered ring, a substituted or unsubstituted saturated six-membered ring, a substituted or unsubstituted unsaturated five-membered ring, or a substituted or unsubstituted unsaturated six-membered ring, more preferably a benzene ring.
Unless otherwise specified herein, the optional substituent may further include a substituent. Examples of the substituent for the optional substituent are the same as the examples of the optional substituent.
Herein, numerical ranges represented by “AA to BB” represent a range whose lower limit is the value (AA) recited before “to” and whose upper limit is the value (BB) recited after “to.”
Herein, a numerical formula represented by “A B” means that the value A is equal to the value B, or the value A is larger than the value B.
Herein, a numerical formula represented by “A s B” means that the value A is equal to the value B, or the value A is smaller than the value B.
An organic electroluminescence device of the exemplary embodiment includes: a cathode; an anode; an emitting region disposed between the cathode and the anode; and a hole transporting zone disposed between the anode and the emitting region, in which the emitting region includes at least one emitting layer, the at least one emitting layer includes a first emitting layer, the hole transporting zone includes a first anode side organic layer and a second anode side organic layer, the first anode side organic layer is in direct contact with the second anode side organic layer, the first anode side organic layer and the second anode side organic layer are disposed between the anode and the emitting region in this order from a side close to the anode, the first anode side organic layer contains a first organic material and a second organic material, the first organic material and the second organic material are mutually different, a content of the first organic material in the first anode side organic layer is less than 50 mass %, the second organic material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof, the second anode side organic layer contains a second hole transporting zone material, the second hole transporting zone material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof, the second hole transporting zone material and the first organic material are mutually different, the second hole transporting zone material and the second organic material are mutually the same or different, the first emitting layer is an emitting layer that emits fluorescence, and a refractive index NM1 of the constituent materials contained in the first anode side organic layer and a refractive index NM2 of the constituent material contained in the second anode side organic layer satisfy a relationship of a numerical formula below (Numerical Formula NM).
NM
1
>NM
2 (Numerical Formula NM)
According to the exemplary embodiment, the organic EL device has improved device performance. In an exemplary arrangement according to the exemplary embodiment, the organic EL device has improved luminous efficiency. In an exemplary arrangement according to the exemplary embodiment, the organic EL device has a longer lifetime.
Herein, a zone disposed between an anode and an emitting region and formed by a plurality of organic layers is referred to as a hole transporting zone.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the anode is in direct contact with the hole transporting zone, and the emitting region is in direct contact with the hole transporting zone.
The hole transporting zone includes at least a first anode side organic layer and a second anode side organic layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, when the refractive index NM1 of the constituent materials contained in the first anode side organic layer and the refractive index NM2 of the constituent material contained in the second anode side organic layer satisfy the relationship of the numerical formula (Numerical Formula NM), the organic EL device has improved light-extraction efficiency.
The refractive index NM1 of the constituent materials contained in the first anode side organic layer corresponds to a refractive index of a mixture of compounds contained in the first anode side organic layer (i.e., at least the first organic material and the second organic material). When the second anode side organic layer contains a single type of compound, the refractive index NM2 of the constituent material contained in the second anode side organic layer corresponds to a refractive index of the single type of compound. When the second anode side organic layer contains a plurality of types of compounds, the refractive index NM2 of the constituent material contained in the second anode side organic layer corresponds to a refractive index of a mixture containing the plurality types of compounds. Refractive indices of constituent material(s) contained in the other organic layers are also defined in the same way as described above. The refractive index can be measured by a measurement method described in Examples below.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, a difference NM1−NM2 between a refractive index NM1 of the constituent materials contained in the first anode side organic layer and a refractive index NM2 of the constituent material contained in the second anode side organic layer satisfies a relationship of a numerical formula (Numerical Formula NM1) below.
NM
1
−NM
2≥0.01 (Numerical Formula NM1)
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the difference NM1−NM2 between the refractive index NM1 of the constituent materials contained in the first anode side organic layer and the refractive index NM2 of the constituent material contained in the second anode side organic layer satisfies a relationship of a numerical formula (Numerical Formula NM2), a numerical formula (Numerical Formula NM3), or a numerical formula (Numerical Formula NM4) below.
NM
1
−NM
2≥0.05 (Numerical Formula NM2)
NM
1
−NM
2≥0.075 (Numerical Formula NM3)
NM
1
−NM
2≥0.10 (Numerical Formula NM4)
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the refractive index NM1 of the constituent materials contained in the first anode side organic layer is 1.90 or more.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the refractive index of the second organic material contained in the first anode side organic layer is 1.90 or more.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the refractive index NM1 of the constituent materials contained in the first anode side organic layer is 1.94 or more.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the refractive index of the second organic material contained in the first anode side organic layer is 1.94 or more.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the refractive index NM2 of the constituent material contained in the second anode side organic layer is 1.89 or less.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the refractive index of the second hole transporting zone material contained in the second anode side organic layer is 1.89 or less.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the hole transporting zone consists of the first anode side organic layer and the second anode side organic layer. In this case, the total film thickness of the hole transporting zone corresponds to a total of a film thickness of the first anode side organic layer and a film thickness of the second anode side organic layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer has a film thickness of 20 nm or less.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second anode side organic layer has a film thickness in a range from 30 nm to 150 nm.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second anode side organic layer has a film thickness in a range from 30 nm to 80 nm.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second anode side organic layer has a film thickness in a range from 80 nm to 150 nm.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the ratio of a film thickness of the second anode side organic layer to a film thickness of the first anode side organic layer preferably satisfies a relationship of a numerical formula (Numerical Formula A1), more preferably a numerical formula (Numerical Formula A2) below.
2.0<TL2/TL1<30 (Numerical Formula A1)
8.0<TL2/TL1<16 (Numerical Formula A2)
where TL1 is a film thickness of the first anode side organic layer, TL2 is a film thickness of the second anode side organic layer, and a unit of the film thickness is denoted by nm.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer is in direct contact with the anode.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, when the hole transporting zone consists of the first anode side organic layer and the second anode side organic layer, the second anode side organic layer is in direct contact with the emitting region.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer does not contain any compounds contained in the second anode side organic layer. An arrangement satisfying the above condition is, for instance, an arrangement as follows: when a compound CA, a compound CB and a compound AA are different compounds, the first anode side organic layer contains two types of compounds (the compound CA as the first organic material and the compound CB as the second organic material) and the second anode side organic layer contains a single type of compound (the compound AA). The above condition is satisfied because both the compounds CA and CB contained in the first anode side organic layer are different from the compound AA.
On the other hand, for instance, the above condition is not satisfied when the first anode side organic layer contains two types of compounds (compound CA and compound CB) and the second anode side organic layer contains a single type of compound (compound CB), because the first anode side organic layer and the second anode side organic layer contain the same compound (compound CB).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, all the compound(s) contained in the first anode side organic layer is/are different from all the compound(s) contained in the second anode side organic layer.
An arrangement satisfying the above condition is, for instance, an arrangement as follows: when a compound CA, a compound CB, a compound AA and a compound AB are different compounds, the second anode side organic layer contains a single type of compound (the compound AA) and the first anode side organic layer contains two types of compounds (the compound CA and the compound CB). Further, the above condition is also satisfied when the second anode side organic layer contains two types of compounds (the compound AA and the compound AB) and the first anode side organic layer contains two types of compounds (the compound CA and the compound CB). On the other hand, the above condition is not satisfied, for instance, when the second anode side organic layer contains a single type of compound (the compound AA) and the first anode side organic layer contains two types of compounds (the compound CA and the compound AA), because the first anode side organic layer and the second anode side organic layer contain the same compound (the compound AA).
In the organic EL device according to the exemplary embodiment, the second organic material contained in the first anode side organic layer is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof.
In the monoamine compound and the diamine compound, a nitrogen atom of an amino group is not a ring atom. When a nitrogen atom is a ring atom in a carbazole ring, an azine ring and the like, the nitrogen atom is not a nitrogen atom as an amino group.
For instance, a compound HT-X below has two nitrogen atoms in a molecule: one nitrogen atom in the compound HT-X is a ring atom of a carbazole ring and the other nitrogen atom is not a ring atom but a nitrogen atom as an amino group. The compound HT-X is a compound having a structure in which 9-phenyl-3-carbazolyl group is bonded to a nitrogen atom of an amino group via a linking group, that is, a monoamine compound.
A compound HT-Y below is also a compound having a structure in which 9-carbazolyl group is bonded to a nitrogen atom of an amino group via a linking group, that is, a monoamine compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material contained in the first anode side organic layer is at least one compound selected from the group consisting of a compound represented by a formula (cHT2-1), a compound represented by a formula (cHT2-2), and a compound represented by a formula (cHT2-3) below.
In the formulae (cHT2-1), (cHT2-2), and (cHT2-3):
In an exemplary arrangement of the organic EL device of the exemplary embodiment, a first amino group represented by a formula (c21) below and a second amino group represented by a formula (c22) below in the compound represented by the formula (cHT2-3) are an identical group or different groups.
In the formulae (c21) and (c22), each * represents a bonding position to LB5.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, in the compounds represented by the formulae (cHT2-1), (cHT2-2), and (cHT2-3), the substituent for the “substituted or unsubstituted” group is not a group represented by —N(RC6)(RC7).
In the exemplary embodiment, RC6 and RC7 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms. A plurality of RC6 are mutually the same or different, and a plurality of RC7 are mutually the same or different.
When the substituent for the “substituted or unsubstituted” group is not a group represented by —N(RC6)(RC7), the compounds represented by the formulae (cHT2-1) and (cHT2-2) are each a monoamine compound.
When the substituent for the “substituted or unsubstituted” group is not a group represented by —N(RC6)(RC7), the compound represented by the formula (cHT2-3) is a diamine compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound represented by the formula (cHT2-1) and the compound represented by the formula (cHT2-2) are each a monoamine compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material as the compound contained in the first anode side organic layer is a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound represented by the formula (cHT2-3) is a diamine compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material is a triamine compound having three substituted or unsubstituted amino groups in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material is a tetraamine compound having four substituted or unsubstituted amino groups in a molecule thereof.
When the compounds represented by the formulae (cHT2-1) and (cHT2-2) are each a triamine compound, the compounds represented by the formulae (cHT2-1) and (cHT2-2) each have two groups represented by —N(RC6)(RC7) as the substituents for the “substituted or unsubstituted” group.
When the compounds represented by the formulae (cHT2-1) and (cHT2-2) are each a tetraamine compound, the compound represented by the formula (cHT2-1) has three groups represented by —N(RC6)(RC7) as the substituents for the “substituted or unsubstituted” group.
When the compound represented by the formula (cHT2-3) is a triamine compound, the compound represented by the formula (cHT2-3) has one group represented by —N(RC6)(RC7) as the substituent for the “substituted or unsubstituted” group.
When the compound represented by the formula (cHT2-3) is a tetraamine compound, the compound represented by the formula (cHT2-1) has two groups represented by —N(RC6)(RC7) as the substituents for the “substituted or unsubstituted” group.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material is at least one compound selected from the group consisting of a compound represented by the formula (cHT2-1), a compound represented by the formula (cHT2-2), and a compound represented by the formula (cHT2-3).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material has at least one group selected from the group consisting of a group represented by a formula (2-a), a group represented by a formula (2-b), a group represented by a formula (2-c), a group represented by a formula (2-d), a group represented by a formula (2-e), and a group represented by a formula (2-f) below.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material is at least one compound selected from the group consisting of a compound represented by the formula (cHT2-1), a compound represented by the formula (cHT2-2), and a compound represented by the formula (cHT2-3), and at least one of Ar112, Ar113, Ar121, Ar122, Ar123 or Ar124 in the formulae (cHT2-1), (cHT2-2) and (cHT2-3) has at least one group selected from the group consisting of a group represented by a formula (2-a), a group represented by a formula (2-b), a group represented by a formula (2-c), a group represented by a formula (2-d), a group represented by a formula (2-e), and a group represented by a formula (2-f) below.
In the formula (2-a):
In the formula (2-b):
In the formula (2-c):
In the formula (2-d):
For instance, ** may be a bonding position of a bond with at least one of Ar112, Ar113, Ar121, Ar122, Ar123 or Ar124 in the formulae (cHT2-1), (cHT2-2) and (cHT2-3).
In the formula (2-e):
In the formula (2-f):
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, and the group represented by the formula (2-a), the group represented by the formula (2-b), the group represented by the formula (2-c), the group represented by the formula (2-d), the group represented by the formula (2-e), and the group represented by the formula (2-f) are each independently bonded directly, through a phenylene group, or through a biphenylene group to a nitrogen atom of an amino group of the monoamine compound.
In the organic EL device of the exemplary embodiment, when Z3 is NR319, R312 or R317 is preferably a single bond with *e.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the group represented by the formula (2-e) is a group represented by a formula (2-e7) below.
In the formula (2-e7), R311 to R316, R318 and R319 respectively represent the same as R311 to R316, R318 and R319 in the formula (2-e); and ** represents a bonding position.
In the organic EL device of the exemplary embodiment, when Z3 is NR319, R315, R316, or R318 is also preferably a single bond with *e.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the group represented by the formula (2-e) is a group represented by a formula (2-e4), a formula (2-e5), or a formula (2-e6) below.
In the formulae (2-e4), (2-e5), and (2-e6), R311 to R319 respectively represent the same as R311 to R319 in the formula (2-e); and ** represents a bonding position.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the group represented by the formula (2-e) is a group represented by a formula (2-e1), a formula (2-e2), or a formula (2-e3) below.
In the formulae (2-e1), (2-e2), and (2-e3):
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound contained in the first anode side organic layer (second organic material) is a compound having no thiophene ring in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material as the compound contained in the first anode side organic layer is sometimes referred to as a first hole transporting zone material.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the content of the first organic material contained in the first anode side organic layer is less than 50 mass %.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the content of the first organic material contained in the first anode side organic layer is 15 mass % or less.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the content of the first organic material contained in the first anode side organic layer is 5 mass % or more.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the content of the first organic material contained in the first anode side organic layer is 30 mass % or less, 20 mass % or less, or 15 mass % or less.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the content of the second organic material contained in the first anode side organic layer is more than 50 mass %, 70 mass % or more, 80 mass % or more, or 85 mass % or more.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the content of the second organic material contained in the first anode side organic layer is 95 mass % or less.
The total of the content of the first organic material and the content of the second organic material in the first anode side organic layer is 100 mass % or less.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer contains a doped compound as the first organic material and a first hole transporting zone material as the second organic material.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the doped compound has at least one of a first cyclic structure represented by a formula (P11) below or a second cyclic structure represented by a formula (P12) below.
The first cyclic structure represented by the formula (P11) is fused to at least one cyclic structure of a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 50 ring carbon atoms or a substituted or unsubstituted heterocycle having 5 to 50 ring atoms in a molecule of the doped compound, and a structure represented by ═Z10 is represented by a formula (11a), (11b), (11c), (11d), (11e), (11f), (11g), (11h), (11i), (11j), (11k) or (11m) below.
In the formula (11a), (11 b), (11c), (11 d), (11e), (11f), (11 g), (11 h), (11i), (11j), (11k) or (11 m), R11 to R14 and R1101 to R1110 are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkyl halide group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a group represented by —Si(R901)(R902)(R903), a group represented by —O—(R904), a group represented by —S—(R905), a group represented by —N(R906)(R907), a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms. In the formula (P12), Z1 to Z5 are each independently a nitrogen atom, a carbon atom bonded to R15, or a carbon atom bonded to another atom in a molecule of the doped compound;
In the doped compound, R901 to R907 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms;
An ester group herein is at least one group selected from the group consisting of an alkyl ester group and an aryl ester group.
An alkyl ester group herein is represented, for instance, by —C(═O)ORE. RE is exemplified by a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms (preferably 1 to 10 carbon atoms).
An aryl ester group herein is represented, for instance, by —C(═O)ORAr. RAr is exemplified by a substituted or unsubstituted aryl group having 6 to 30 ring carbon atoms.
A siloxanyl group herein, which is a silicon compound group through an ether bond, is exemplified by a trimethylsiloxanyl group.
A carbamoyl group herein is represented by —CONH2.
A substituted carbamoyl group herein is represented, for instance, by —CONH—ArC or —CONH—RC. ArC is, for instance, at least one group selected from the group consisting of a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms (preferably 6 to 10 ring carbon atoms) and a heterocyclic group having 5 to 50 ring atoms (preferably 5 to 14 ring atoms). ArC may be a group in which a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms is bonded to a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
RC is exemplified by a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms (preferably 1 to 6 carbon atoms).
In the doped compound, all groups specified as “substituted or unsubstituted” groups are preferably “unsubstituted” groups.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material is a monoamine compound having only one substituted or unsubstituted amino group in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material is at least one compound selected from the group consisting of a compound represented by the formula (cHT2-1) and a compound represented by the formula (cHT2-2).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound represented by the formula (cHT2-1) and the compound represented by the formula (cHT2-2), as the second organic material, are each a monoamine compound.
In the organic EL device according to the exemplary embodiment, the second hole transporting zone material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof, or a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second hole transporting zone material is a monoamine compound having one substituted or unsubstituted amino group in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second hole transporting zone material is at least one compound selected from the group consisting of a compound represented by a formula (C1) and a compound represented by a formula (C3) below.
In the formula (C1):
In the formula (C3):
In the formulae (C3-1) and (C3-2), each * represents a bonding position to LC5.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the substituent for the “substituted or unsubstituted” group in the compound represented by the formula (C3) is not a group represented by —N(RC6)(RC7).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the substituent for the “substituted or unsubstituted” group in the compound represented by the formula (C1) is not a group represented by —N(RC6)(RC7).
In the exemplary embodiment, RC6 and RC7 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms. A plurality of RC6 are mutually the same or different, and a plurality of RC7 are mutually the same or different.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound represented by the formula (C1) is at least one compound selected from the group consisting of a compound represented by a formula (cHT3-1), a compound represented by a formula (cHT3-2), a compound represented by a formula (cHT3-3), and a compound represented by the formula (cHT3-4) below.
In the formulae (cHT3-1), (cHT3-2), (cHT3-3), and (cHT3-4):
In the formula (1-a):
In the formula (1-b):
In the formula (1-c):
In the formula (1-d):
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the substituent for the “substituted or unsubstituted” group in the compounds represented by the formulae (cHT3-1), (cHT3-2), (cHT3-3) and (cHT3-4) is not a group represented by —N(RC6)(RC7).
In the exemplary embodiment, RC6 and RC7 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms. A plurality of RC6 are mutually the same or different, and a plurality of RC7 are mutually the same or different.
When the substituent for the “substituted or unsubstituted” group is not a group represented by —N(RC6)(RC7), the compounds represented by the formulae (cHT3-1), (cHT3-2), (cHT3-3) and (cHT3-4) are each a monoamine compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound contained in the second anode side organic layer (second hole transporting zone material) is a diamine compound having two substituted or unsubstituted amino groups in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound contained in the second anode side organic layer is a triamine compound having three substituted or unsubstituted amino groups in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound contained in the second anode side organic layer is a tetraamine compound having four substituted or unsubstituted amino groups in a molecule thereof.
When the compounds represented by the formulae (cHT3-1), (cHT3-2), (cHT3-3) and (cHT3-4) are each a diamine compound, the compounds represented by the formulae (cHT3-1), (cHT3-2), (cHT3-3) and (cHT3-4) each have one group represented by —N(RC6)(RC7) as the substituent for the “substituted or unsubstituted” group.
When the compounds represented by the formulae (cHT3-1), (cHT3-2), (cHT3-3) and (cHT3-4) are each a triamine compound, the compounds represented by the formulae (cHT3-1), (cHT3-2), (cHT3-3) and (cHT3-4) each have two groups represented by —N(RC6)(RC7) as the substituents for the “substituted or unsubstituted” group.
When the compounds represented by the formulae (cHT3-1), (cHT3-2), (cHT3-3) and (cHT3-4) are each a tetraamine compound, the compounds represented by the formulae (cHT3-1), (cHT3-2), (cHT3-3) and (cHT3-4) each have three groups represented by —N(RC6)(RC7) as the substituents for the “substituted or unsubstituted” group.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer contains at least one compound selected from the group consisting of a compound represented by the formula (cHT2-1), a compound represented by the formula (cHT2-2), and a compound represented by the formula (cHT2-3), and the second anode side organic layer contains at least one compound selected from the group consisting of a compound represented by the formula (cHT3-1), a compound represented by the formula (cHT3-2), a compound represented by the formula (cHT3-3), and a compound represented by the formula (cHT3-4).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound contained in the second anode side organic layer is sometimes referred to as a second hole transporting zone material.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second hole transporting zone material is at least one compound selected from the group consisting of a compound represented by the formula (cHT3-1), a compound represented by the formula (cHT3-2), a compound represented by the formula (cHT3-3), and a compound represented by the formula (cHT3-4).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second hole transporting zone material is a monoamine compound, a diamine compound, a triamine compound, or a tetraamine compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the hole transporting zone further includes a third anode side organic layer disposed between the second anode side organic layer and the emitting region.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second anode side organic layer is in direct contact with the third anode side organic layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the third anode side organic layer is in direct contact with the emitting region.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the hole transporting zone consists of the first anode side organic layer, the second anode side organic layer and the third anode side organic layer. In this case, the total film thickness of the hole transporting zone corresponds to a total of a film thickness of the first anode side organic layer, a film thickness of the second anode side organic layer and a film thickness of the third anode side organic layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, all the compound(s) contained in the second anode side organic layer is/are different from all the compound(s) contained in the third anode side organic layer.
An arrangement satisfying the above condition is, for instance, an arrangement as follows: when a compound AA, a compound AB and a compound BB are different compounds, the second anode side organic layer contains a single type of compound (the compound AA) and the third anode side organic layer contains a single type of compound (the compound BB). Further, for instance, the above condition is satisfied also when the second anode side organic layer contains two types of compounds (the compound AA and the compound AB) and the third anode side organic layer contains a single type of compound (the compound BB), because both the compounds AA and AB are different from the compound BB.
On the other hand, for instance, the above condition is not satisfied when the second anode side organic layer contains two types of compounds (the compound AA and the compound AB) and the third anode side organic layer contains a single type of compound (the compound AB), because the second anode side organic layer and the third anode side organic layer contain the same compound (the compound AB).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the third anode side organic layer does not contain any compounds contained in the first anode side organic layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the third anode side organic layer contains at least one compound selected from the group consisting of a compound represented by the formula (cHT3-1), a compound represented by the formula (cHT3-2), a compound represented by the formula (cHT3-3), and a compound represented by the formula (cHT3-4).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer, the second anode side organic layer, and the third anode side organic layer each contain a monoamine compound having only one substituted or unsubstituted amino group in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer, the second anode side organic layer, and the third anode side organic layer each contain no diamine compounds.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, at least one of the first anode side organic layer, the second anode side organic layer, or the third anode side organic layer may also contain a diamine compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound contained in the third anode side organic layer is sometimes referred to as a third hole transporting zone material.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the third hole transporting zone material is at least one compound selected from the group consisting of a compound represented by the formula (cHT3-1), a compound represented by the formula (cHT3-2), a compound represented by the formula (cHT3-3), and a compound represented by the formula (cHT3-4).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the third hole transporting zone material is a monoamine compound, a diamine compound, a triamine compound, or a tetraamine compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the hole transporting zone further includes a fourth anode side organic layer disposed between the third anode side organic layer and the emitting region.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the fourth anode side organic layer is in direct contact with the emitting region.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the fourth anode side organic layer is in direct contact with the third anode side organic layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer, the second anode side organic layer, the third anode side organic layer, and the fourth anode side organic layer are disposed in this order from a side close to the anode.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the fourth anode side organic layer is a blocking layer. For instance, when the blocking layer is disposed close to the anode with respect to the first emitting layer, the blocking layer permits transport of holes and blocks electrons from reaching each organic layer in the hole transporting zone provided closer to the anode beyond the blocking layer. Alternatively, the blocking layer may be provided in direct contact with the first emitting layer so that excitation energy does not leak out from the first emitting layer toward neighboring layer(s). The blocking layer disposed close to the anode with respect to the first emitting layer blocks excitons generated in the first emitting layer from transferring to each organic layer in the hole transporting zone. The first emitting layer is preferably in direct contact with the blocking layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the fourth anode side organic layer contains a fourth hole transporting zone material.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the fourth hole transporting zone material and the third hole transporting zone material are different compounds.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the fourth hole transporting zone material, the third hole transporting zone material, and the second hole transporting zone material are different compounds.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the fourth anode side organic layer contains at least one compound selected from the group consisting of a compound represented by the formula (cHT3-1), a compound represented by the formula (cHT3-2), a compound represented by the formula (cHT3-3), and a compound represented by the formula (cHT3-4). In an exemplary arrangement of the organic EL device of the exemplary embodiment, although the third anode side organic layer and the fourth anode side organic layer may each contain a compound represented by the formula (cHT3-1), the compound contained in the third anode side organic layer and the compound contained in the fourth anode side organic layer are mutually different in a molecular structure.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer, the second anode side organic layer, the third anode side organic layer, and the fourth anode side organic layer each contain a monoamine compound having only one substituted or unsubstituted amino group in a molecule thereof.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the first anode side organic layer, the second anode side organic layer, the third anode side organic layer, and the fourth anode side organic layer contain no diamine compounds.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, at least one of the first anode side organic layer, the second anode side organic layer, the third anode side organic layer, or the fourth anode side organic layer may also contain a diamine compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the fourth hole transporting zone material is at least one compound selected from the group consisting of a compound represented by the formula (cHT3-1), a compound represented by the formula (cHT3-2), a compound represented by the formula (cHT3-3), and a compound represented by the formula (cHT3-4).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the fourth hole transporting zone material is a monoamine compound, a diamine compound, a triamine compound, or a tetraamine compound.
In the exemplary embodiment, all groups specified as “substituted or unsubstituted” groups are preferably “unsubstituted” groups.
In the exemplary embodiment, the first hole transporting zone material, the second hole transporting zone material, the third hole transporting zone material, and the fourth hole transporting zone material each may be occasionally referred to as a hole transporting zone material.
The hole transporting zone material according to the exemplary embodiment can be produced by a known method or through a known alternative reaction using a known material(s) tailored for the target compound in accordance with the known method.
Specific examples of the hole transporting zone material according to the exemplary embodiment include the following compounds. However, the invention is by no means limited to the specific examples.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second organic material contained in the first anode side organic layer (the first hole transporting zone material) is preferably at least one compound selected from compounds below.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound contained in the second anode side organic layer (the second hole transporting zone material) is preferably at least one compound selected from compounds below.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the compound contained in the third anode side organic layer (the third hole transporting zone material) is preferably at least one compound selected from compounds below.
It should be noted that compounds shown as examples of compounds contained in the first anode side organic layer, the second anode side organic layer and the third anode side organic layer may overlap with each other; however, in the exemplary embodiment, different compounds can be appropriately selected from among these shown compounds, as compounds usable in the first anode side organic layer, the second anode side organic layer and the third anode side organic layer.
Specific examples of the doped compound as the first organic material include the following compounds. It should however be noted that the invention is not limited to the specific examples of the doped compound.
The emitting region includes at least one emitting layer. The at least one emitting layer includes a first emitting layer.
In an arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer contains a first host material. Although the first host material is not particularly limited, for instance, a compound selected from the group consisting of a compound represented by a formula (H1) described below and a first compound described below may be used.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer contains a first emitting compound. Although the first emitting compound is not particularly limited, for instance, a compound selected from the group consisting of a compound represented by a formula (6) described below, a third compound described below and a fourth compound described below may be used.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer contains the first host material and the first emitting compound.
The first emitting compound is preferably a compound that emits light having a maximum peak wavelength of 500 nm or less, more preferably a compound that emits light having a maximum peak wavelength in a range from 430 nm to 480 nm. The first emitting compound is preferably a fluorescent compound that emits fluorescence having a maximum peak wavelength of 500 nm or less, more preferably a fluorescent compound that emits fluorescence having a maximum peak wavelength in a range from 430 nm to 480 nm.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer contains the first host material and the first emitting compound having a maximum peak wavelength of 500 nm or less.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, a half bandwidth of a maximum peak of the first emitting compound is in a range from 1 nm to 30 nm.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting compound is a compound containing no azine ring structure in a molecule thereof.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting compound is preferably not a boron-containing complex, more preferably not a complex.
As a fluorescent compound that emits blue fluorescence and is usable for the first emitting layer, for instance, compounds such as a pyrene derivative, a styrylamine derivative, a chrysene derivative, a fluoranthene derivative, a fluorene derivative, a diamine derivative, and a triarylamine derivative may be used.
Herein, the blue light emission refers to a light emission in which a maximum peak wavelength of emission spectrum is in a range from 430 nm to 500 nm.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, when the emitting region includes two or more emitting layers, the two or more emitting layers are each an emitting layer that emits fluorescence.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, one or more emitting layers contained in the emitting region are each an emitting layer that emits fluorescence.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer does not contain a metal complex. Moreover, in an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer does not contain a boron-containing complex.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer does not contain a phosphorescent material (dopant material).
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer does not contain a heavy-metal complex or a phosphorescent rare earth metal complex. Examples of the heavy-metal complex herein include iridium complex, osmium complex, and platinum complex.
A measurement method of the maximum peak wavelength of a compound is as follows. A toluene solution of a measurement target compound at a concentration of 5 μmol/L was prepared and put in a quartz cell. An emission spectrum (ordinate axis: luminous intensity, abscissa axis: wavelength) of each of the samples was measured at a normal temperature (300K). The emission spectrum can be measured using a spectrophotometer (machine name: F-7000) produced by Hitachi High-Tech Science Corporation. It should be noted that the machine for measuring the emission spectrum is not limited to the machine used herein.
A peak wavelength of the emission spectrum exhibiting the maximum luminous intensity is defined as the maximum peak wavelength. Herein, the maximum peak wavelength of fluorescence is occasionally referred to as a maximum fluorescence peak wavelength (FL-peak).
In an emission spectrum of the first emitting compound, where a peak exhibiting a maximum luminous intensity is defined as a maximum peak and a height of the maximum peak is defined as 1, heights of other peaks appearing in the emission spectrum are preferably less than 0.6. It should be noted that the peaks in the emission spectrum are defined as local maximum values.
Moreover, in the emission spectrum of the first emitting compound, the number of peaks is preferably less than three.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer contains 0.5 mass % or more of the first emitting compound with respect to a total mass of the first emitting layer.
The first emitting layer contains the first emitting compound preferably at 10 mass % or less, more preferably at 7 mass % or less, and still more preferably at 5 mass % less with respect to the total mass of the first emitting layer.
Herein, the “host material” refers to, for instance, a material that accounts for “50 mass % or more of the layer.”
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer preferably contains the first host material at 60 mass % or more, more preferably at 70 mass % or more, still more preferably at 80 mass % or more, still further more preferably at 90 mass % or more, and yet still further more preferably at 95 mass % or more, with respect to the total mass of the first emitting layer.
The first emitting layer preferably contains the first host material at 99.5 mass % or less with respect to the total mass of the first emitting layer.
When the first emitting layer contains the first host material and the first emitting compound, the upper limit of a total of the content ratios of the first host material and the first emitting compound is 100 mass %.
In the organic EL device according to the exemplary embodiment, the first emitting layer may further contain any other material than the first host material and the first emitting compound.
The first emitting layer may contain a single type of the first host material or may contain two or more types of the first host material. The first emitting layer may contain a single type of the first emitting compound or may contain two or more types of the first emitting compound.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first host material has at least one deuterium atom.
Moreover, in an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first host material does not have a deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first host material is a compound represented by a formula (H1) below.
In the formula (H1):
In the compound represented by the formula (H1):
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, Ar301 and Ar302 are each independently a phenyl group, naphthyl group, phenanthryl group, biphenyl group, terphenyl group, diphenylfluorenyl group, dimethylfluorenyl group, benzodiphenylfluorenyl group, benzodimethylfluorenyl group, dibenzofuranyl group, dibenzothienyl group, naphthobenzofuranyl group, or naphthobenzothienyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L301 is a single bond, or an unsubstituted arylene group having 6 to 22 ring carbon atoms; and
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, R301 to R308 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, or a group represented by —Si(R901)(R902)(R903).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, R301 to R308 are each a hydrogen atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L302 is a single bond, and Ar302 is an unsubstituted phenyl group.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, L302 is a single bond, and Ar302 is an unsubstituted 2-naphthyl group.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, L302 is a single bond, and Ar302 is an unsubstituted 1-naphthyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L302 is an unsubstituted p-phenylene group, and Ar302 is an unsubstituted phenyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L302 is an unsubstituted m-phenylene group, and Ar302 is an unsubstituted phenyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L302 is an unsubstituted o-phenylene group, and Ar302 is an unsubstituted phenyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L302 is an unsubstituted p-phenylene group, and Ar302 is an unsubstituted 1-naphthyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L302 is an unsubstituted p-phenylene group, and Ar302 is an unsubstituted 2-naphthyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L302 is an unsubstituted 1,4-naphthalenediyl group, and Ar302 is an unsubstituted phenyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L302 is an unsubstituted m-phenylene group, and Ar302 is an unsubstituted 2-naphthyl group.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, R301 to R308 each independently have at least one deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L301, L302, Ar301 and Ar302 each independently have at least one deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first host material is a compound represented by a formula (H10) below.
In the formula (H10), Ar301, R301 to R308, L301, and L302 each independently represent the same as Ar301, R301 to R308, L301 and L302 in the formula (H1);
In the compound represented by the formula (H10), R901, R902, R903, R904, R905, R906 and R907 each independently represent the same as R901, R902, R903, R904, R905, R906 and R907 in the formula (H1).
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, at least one combination of adjacent two or more of R311 to R314 in the formula (H10) are mutually bonded to form a substituted or unsubstituted benzene ring.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, R301 to R308 each independently have at least one deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L301, L302, Ar301 and R310 to R314 each independently have at least one deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first host material is a compound represented by a formula (H31), (H32) or (H33) below.
In the formulae (H31), (H32) and (H33), X3, R301 to R308, R310 to R314, L301, L302 and Ar301 each independently represent the same as X3, R301 to R308, R310 to R314, L301, L302 and Ar301 in the formula (H10); and
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first host material is a compound represented by a formula (H301) or (H302) below.
In the formulae (H301) and (H302),
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first host material is a compound represented by a formula (H311), (H312), (H321), (H322), (H331) or (H332) below.
In the formulae (H311), (H312), (H321), (H322), (H331) and (H332),
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L301 and L302 of the first host material are each independently a single bond or a substituted or unsubstituted arylene group having 6 to 14 ring carbon atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L301 and L302 of the first host material are each independently a single bond, a substituted or unsubstituted phenylene group or a substituted or unsubstituted naphthylene group.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, L301 and L302 of the first host material are each a single bond.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first host material is a compound represented by a formula (H313), (H314), (H323), (H324), (H333) or (H334) below.
In the formulae (H313), (H314), (H323), (H324), (H333) and (H334),
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, R311 to R317 and R321 to R324 of the first host material are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, R311 to R317 and R321 to R324 of the first host material are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, Ar301 of the first host material is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, Ar301 of the first host material is a group represented by a formula (a1), (a2), (a3) or (a4) below.
In the formulae (a1), (a2), (a3), and (a4):
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, Ar301 of the first host material is a group represented by the formula (a1) or (a2).
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, R330 to R335 and R341 to R348 of the first host material are each a hydrogen atom.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, X3 of the first host material is an oxygen atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, R301 to R308 of the first host material are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, or a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, R301 to R308 of the first host material are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, R301 to R308 of the first host material are each a hydrogen atom.
Compound Represented by Formula (H20) In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first host material is a compound represented by a formula (H20) below.
In the formula (H20):
[Formula 213]
-L203-Ar203 (H21)
In the formulae (H20) and (H21):
In the formula (H20), R901, R902, R903, R904, R905, R906, and R907 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms;
In an arrangement of the organic EL device according to the exemplary embodiment, Ar201, Ar202 and Ar203 are each independently a phenyl group, a naphthyl group, a phenanthryl group, a biphenyl group, a terphenyl group, a diphenylfluorenyl group, a dimethylfluorenyl group, a benzodiphenylfluorenyl group, a benzodimethylfluorenyl group, a dibenzofuranyl group, a dibenzothienyl group, a naphthobenzofuranyl group, or a naphthobenzothienyl group.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, R201 to R208 each independently have at least one deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, L201, L202, L203, Ar201, Ar202 and Ar203 each independently have at least one deuterium atom.
In an arrangement of the organic EL device according to the exemplary embodiment, the compound represented by the formula (H20) is a compound represented by a formula (201), a formula (202), a formula (203), a formula (204), a formula (205), a formula (206), a formula (207), a formula (208), or a formula (209) below.
In the formulae (201) to (209), L201 and Ar201 respectively represent the same as L201 and Ar201 in the formula (H20); and R201 to R208 each independently represent the same as R201 to R208 in the formula (H20).
In an arrangement of the organic EL device according to the exemplary embodiment, the compound represented by the formula (H20) is a compound represented by a formula (221), a formula (222), a formula (223), a formula (224), a formula (225), a formula (226), a formula (227), a formula (228), or a formula (229) below.
In the formulae (221), (222), (223), (224), (225), (226), (227), (228) and (229):
In an arrangement of the organic EL device according to the exemplary embodiment, the compound represented by the formula (H20) is a compound represented by a formula (241), a formula (242), a formula (243), a formula (244), a formula (245), a formula (246), a formula (247), a formula (248), or a formula (249) below.
In the formulae (241), (242), (243), (244), (245), (246), (247), (248) and (249):
In an arrangement of the organic EL device according to the exemplary embodiment, R201 to R208 in the formula (H20) are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, or a group represented by —Si(R901)(R902)(R903).
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, in the formula (H20), L101 is a single bond or an unsubstituted arylene group having 6 to 22 ring carbon atoms; and Ar101 is a substituted or unsubstituted aryl group having 6 to 22 ring carbon atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, R201 to R208 that are substituents of an anthracene skeleton in the formula (H20) are each preferably a hydrogen atom in terms of preventing inhibition of intermolecular interaction and inhibiting decrease in electron mobility. However, R201 to R208 each may be a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, when the emitting region includes at least the first emitting layer containing the first host material and the second emitting layer containing the second host material, R301 to R308 that are substituents of an anthracene skeleton in the compound represented by the formula (H1) are each preferably a hydrogen atom in terms of preventing inhibition of intermolecular interaction and inhibiting decrease in electron mobility. However, R301 to R308 each may be a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the anode, the second emitting layer, the first emitting layer, and the cathode may be provided in this order. Alternatively, the anode, the first emitting layer, the second emitting layer, and the cathode may be provided in this order.
When the second emitting layer and the first emitting layer are layered in this order from the side close to the anode and the first host material contained in the first emitting layer is the compound represented by the formula (H1), the following phenomenon may occur. It is thus preferable that R301 to R308 in the formula (H1) are each not a bulky substituent.
Assuming that R301 to R308 in the formula (H1) are each a bulky substituent such as an alkyl group and a cycloalkyl group, intermolecular interaction may be inhibited to decrease the electron mobility of the first host material relative to that of the second host material, so that a relationship of μe(H1)>μe(H2) shown by a numerical formula (Numerical Formula 3) below may not be satisfied. When the compound represented by the formula (H1) is used as the first host material in the first emitting layer, it can be expected that satisfying the relationship of μe(H1)>μe(H2) inhibits a decrease in a recombination ability between holes and electrons in the second emitting layer and a decrease in luminous efficiency. It should be noted that substituents, namely, a haloalkyl group, alkenyl group, alkynyl group, group represented by —Si(R901)(R902)(R903), group represented by —O—(R904), group represented by —S—(R905), group represented by —N(R906)(R907), aralkyl group, group represented by —C(═O)R801, group represented by —COOR802, halogen atom, cyano group, and nitro group are likely to be bulky, and an alkyl group and cycloalkyl group are likely to be further bulky.
In the compound represented by the formula (H1), R301 to R308, which are the substituents on the anthracene skeleton, are each preferably not a bulky substituent and preferably not an alkyl group and cycloalkyl group. More preferably, R301 to R308 are each not an alkyl group, cycloalkyl group, haloalkyl group, alkenyl group, alkynyl group, group represented by —Si(R901)(R902)(R903), group represented by —O—(R904), group represented by —S—(R905), group represented by —N(R906)(R907), aralkyl group, group represented by —C(═O)R801, group represented by —COOR802, halogen atom, cyano group, and nitro group.
In the formula (H1), examples of the substituent for the “substituted or unsubstituted” group on R301 to R308 also preferably do not include the above-described substituent that is likely to be bulky, especially a substituted or unsubstituted alkyl group and a substituted or unsubstituted cycloalkyl group. When examples of the substituent for the “substituted or unsubstituted” group on R301 to R308 do not include a substituted or unsubstituted alkyl group and a substituted or unsubstituted cycloalkyl group, inhibition of intermolecular interaction to be caused by presence of a bulky substituent such as an alkyl group and a cycloalkyl group can be prevented, thereby preventing a decrease in the electron mobility. Moreover, when the compound described above is used as the first host material in the first emitting layer, a decrease in a recombination ability between holes and electrons in the second emitting layer and a decrease in the luminous efficiency can be inhibited.
Further preferably, R301 to R308 that are the substituents on the anthracene skeleton are not bulky substituents and R301 to R308 as substituents are unsubstituted. Assuming that R301 to R308 that are the substituents on the anthracene skeleton are not bulky substituents and substituents are bonded to R301 to R308 that are not bulky substituents, the substituents bonded to R301 to R308 are preferably not bulky substituents; and the substituents bonded to R201 to R208 serving as substituents are preferably not an alkyl group and cycloalkyl group, more preferably not an alkyl group, cycloalkyl group, haloalkyl group, alkenyl group, alkynyl group, group represented by —Si(R901)(R902)(R903), group represented by —O—(R904), group represented by —S—(R905), group represented by —N(R906)(R907), aralkyl group, group represented by —C(═O)R801, group represented by —COOR802, halogen atom, cyano group, and nitro group.
In the first host material, the groups specified to be “substituted or unsubstituted” are each preferably an “unsubstituted” group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the emitting layer contains a compound represented by the formula (H10) as the first host material. The compound represented by the formula (H10) has at least one deuterium atom or does not have a deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the emitting layer contains a compound represented by the formula (H20) as the first host material. The compound represented by the formula (H20) has at least one deuterium atom or does not have a deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the emitting layer contains, as the first host material, a compound represented by the formula (H10) and a compound represented by the formula (H20). In this arrangement, it is preferable that at least one of the compound represented by the formula (H10) or the compound represented by the formula (H20) has at least one deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, when the emitting layer contains, as the first host material, a compound represented by the formula (H10) and a compound represented by the formula (H20), the compound represented by the formula (H10) substantially does not contain a deuterium atom and the compound represented by the formula (H20) contains at least one deuterium atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, when the emitting layer contains, as the first host material, a compound represented by the formula (H10) and a compound represented by the formula (H20), the compound represented by the formula (H20) substantially does not contain a deuterium atom and the compound represented by the formula (H10) does not contain at least one deuterium atom.
Here, “the compound substantially does not contain a compound having a deuterium atom” means that the compound contains no deuterium atom or that the compound is allowed to contain a deuterium atom approximately at the natural abundance ratio. The natural abundance ratio of deuterium atoms is, for example, 0.015% or less.
The first host material can be produced by a known method. The first host material can also be produced based on a known method through a known alternative reaction using a known material(s) tailored for the target compound.
Specific examples of the first host material include the following compounds. It should however be noted that the invention is not limited to the specific examples of the first host material.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting compound is a compound represented by the formula (6) below.
In the formula (6):
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the ring a, ring b and ring c are each a ring (a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocycle having 5 to 50 ring atoms) fused with a fused bicyclic structure formed of a boron atom and two nitrogen atoms at the center of the formula (6).
The “aromatic hydrocarbon ring” for the rings a, b, and c has the same structure as a compound formed by introducing a hydrogen atom to the “aryl group”.
Ring atoms of the “aromatic hydrocarbon ring” for the ring a include three carbon atoms on the fused bicyclic structure at the center of the formula (6).
Ring atoms of the “aromatic hydrocarbon ring” for the rings b and c include two carbon atoms on the fused bicyclic structure at the center of the formula (6).
Specific examples of the “substituted or unsubstituted aromatic hydrocarbon ring having 6 to 50 ring carbon atoms” include a compound formed by introducing a hydrogen atom to the “aryl group” described in the specific example group G1.
The “heterocycle” for the rings a, b, and c has the same structure as a compound formed by introducing a hydrogen atom to the “heterocyclic group” described above.
Ring atoms of the “heterocycle” for the ring a include three carbon atoms on the fused bicyclic structure at the center of the formula (6). Ring atoms of the “heterocycle” for the rings b and c include two carbon atoms on the fused bicyclic structure at the center of the formula (6). Specific examples of the “substituted or unsubstituted heterocycle having 5 to 50 ring atoms” include a compound formed by introducing a hydrogen atom to the “heterocyclic group” described in the specific example group G2.
R601 and R602 may be each independently bonded with the ring a, ring b, or ring c to form a substituted or unsubstituted heterocycle. The “heterocycle” in this arrangement includes a nitrogen atom on the fused bicyclic structure at the center of the formula (6). The heterocycle in the above arrangement optionally includes a hetero atom other than the nitrogen atom. R601 and R602 being bonded with the ring a, ring b, or ring c specifically means that atoms forming R601 and R602 are bonded with atoms forming the ring a, ring b, or ring c. For instance, R601 may be bonded with the ring a to form a bicyclic (or tri-or-more cyclic) fused nitrogen-containing heterocycle, in which the ring including R601 and the ring a are fused. Specific examples of the nitrogen-containing heterocycle include a compound corresponding to the nitrogen-containing bi(or-more)cyclic fused heterocyclic group in the specific example group G2.
The same applies to R601 bonded with the ring b, R602 bonded with the ring a, and R602 bonded with the ring c.
R601 and R602 each independently may not be bonded with the ring a, ring b, or ring c.
In an exemplary embodiment, the ring a, ring b and ring c in the formula (6) are each independently a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 50 ring carbon atoms.
In an exemplary embodiment, the ring a, ring b and ring c in the formula (6) are each independently a substituted or unsubstituted benzene ring or a substituted or unsubstituted naphthalene ring.
In an exemplary embodiment, R601 and R602 in the formula (6) are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms,
In an exemplary embodiment, the compound represented by the formula (6) is a compound represented by a formula (62) below.
In the formula (62):
R601A and R602A in the formula (62) are groups corresponding to R601 and R602 in the formula (6), respectively.
For instance, R601A and R611 are optionally bonded with each other to form a bicyclic (or tri-or-more cyclic) fused nitrogen-containing heterocycle, in which the ring including R601A and R611 and a benzene ring corresponding to the ring a are fused. Specific examples of the nitrogen-containing heterocycle include a compound corresponding to the nitrogen-containing bi(or-more)cyclic fused heterocyclic group in the specific example group G2. The same applies to R601A bonded with R621, R602A bonded with R613, and R602A bonded with R614.
At least one combination of adjacent two or more of R611 to R621 are mutually bonded to form a substituted or unsubstituted monocyclic ring, or mutually bonded to form a substituted or unsubstituted fused ring.
For instance, R611 and R612 are optionally mutually bonded to form a structure in which a benzene ring, indole ring, pyrrole ring, benzofuran ring, benzothiophene ring or the like is fused to the six-membered ring bonded with R611 and R612, the resultant fused ring forming a naphthalene ring, carbazole ring, indole ring, dibenzofuran ring, or dibenzothiophene ring, respectively.
In an exemplary embodiment, R611 to R621 not contributing to ring formation are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary embodiment, R611 to R621 not contributing to ring formation are each independently a hydrogen atom, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary embodiment, R611 to R621 not contributing to ring formation are each independently a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms.
In an exemplary embodiment, R611 to R621 not contributing to ring formation are each independently a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms; and at least one of R611 to R621 is a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms.
In an exemplary embodiment, the compound represented by the formula (62) is a compound represented by a formula (63) below.
In the formula (63):
R631 is optionally bonded with R646 to form a substituted or unsubstituted heterocycle. For instance, R631 and R646 are optionally bonded with each other to form a tri-or-more cyclic fused nitrogen-containing heterocycle, in which a benzene ring bonded with R646, a ring including a nitrogen atom, and a benzene ring corresponding to the ring a are fused. Specific examples of the nitrogen-containing heterocycle include a compound corresponding to a nitrogen-containing tri(-or-more)cyclic fused heterocyclic group in the specific example group G2. The same applies to R633 bonded with R647, R634 bonded with R651, and R641 bonded with R642.
In an exemplary embodiment, R631 to R651 not contributing to ring formation are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary embodiment, R631 to R651 not contributing to ring formation are each independently a hydrogen atom, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary embodiment, R631 to R651 not contributing to ring formation are each independently a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms.
In an exemplary embodiment, R631 to R651 not contributing to ring formation are each independently a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms; and
In an exemplary embodiment, the compound represented by the formula (63) is a compound represented by a formula (63A) below.
In the formula (63A):
In an exemplary embodiment, R661 to R665 are each independently a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary embodiment, R661 to R665 are each independently a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms.
In an exemplary embodiment, the compound represented by the formula (63) is a compound represented by a formula (63B) below.
In the formula (63B):
In an exemplary embodiment, the compound represented by the formula (63) is a compound represented by a formula (63B′) below.
In the formula (63B′), R672 to R675 each independently represent the same as R672 to R675 in the formula (63B).
In an exemplary embodiment, at least one of R671 to R675 is a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a group represented by —N(R906)(R907), or a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary embodiment:
In an exemplary embodiment, the compound represented by the formula (63) is a compound represented by a formula (63C) below.
In the formula (63C):
In an exemplary embodiment, the compound represented by the formula (63) is a compound represented by a formula (63C′) below.
In the formula (63C′), R683 to R686 each independently represent the same as R683 to R686 in the formula (63C).
In an exemplary embodiment, R681 to R686 are each independently a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, or a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary embodiment, R681 to R686 are each independently a substituted or unsubstituted aryl group having 6 to 50 carbon atoms.
The compound represented by the formula (6) is producible by initially bonding the ring a, ring b and ring c with linking groups (a group including N—R601 and a group including N—R602) to form an intermediate (first reaction), and bonding the ring a, ring b and ring c with a linking group (a group including a boron atom) to form a final product (second reaction). In the first reaction, an amination reaction (e.g. Buchwald-Hartwig reaction) is applicable. In the second reaction, Tandem Hetero-Friedel-Crafts Reactions or the like is applicable.
In an exemplary embodiment, the compound represented by the formula (6) is a compound represented by a formula (42-2) below.
In the formula (42-2),
In the formula (42-2), R901, R902, R903, R904, R905, R906 and R907 each independently represent the same as R901, R902, R903, R904, R905, R906 and R907 in the formula (62).
Specific examples of the compound represented by the formula (6) are shown below. It should however be noted that these specific examples are merely exemplary and do not limit the compound represented by the formula (6).
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the emitting region consists of the first emitting layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the emitting region includes the first emitting layer and further includes the second emitting layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the emitting region consists of the first emitting layer and the second emitting layer.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the emitting region includes at least the first emitting layer containing the first host material and the second emitting layer containing the second host material. The first host material and the second host material are different from each other.
When the emitting region includes at least the first emitting layer and the second emitting layer, the luminous efficiency is improved by utilizing Tripret-Tripret-Annhilation (sometimes referred to as TTA).
TTA is a mechanism in which triplet excitons collide with one another to generate singlet excitons. It should be noted that the TTA mechanism is also occasionally referred to as a TTF mechanism as described in WO2010/134350.
The TTF phenomenon will be described. Holes injected from an anode and electrons injected from a cathode are recombined in an emitting layer to generate excitons. As for the spin state, as is conventionally known, singlet excitons account for 25% and triplet excitons account for 75%. In a conventionally known fluorescent device, light is emitted when singlet excitons of 25% are relaxed to the ground state. The remaining triplet excitons of 75% are returned to the ground state without emitting light through a thermal deactivation process. Accordingly, the theoretical limit value of the internal quantum efficiency of the conventional fluorescent device is believed to be 25%.
The behavior of triplet excitons generated within an organic substance has been theoretically examined. According to S. M. Bachilo et al. (J. Phys. Chem. A, 104, 7711 (2000)), assuming that high-order excitons such as quintet excitons are quickly returned to triplet excitons, triplet excitons (hereinafter abbreviated as 3A*) collide with one another with an increase in density thereof, whereby a reaction shown by the following formula occurs. In the formula, 1A represents the ground state and 1A* represents the lowest singlet excitons.
3A*+3A*→(4/9)1A+(1/9)1A*+(13/9)3A*
In other words, 53A*→41A+1A* is satisfied, and it is expected that, among triplet excitons initially generated, which account for 75%, one fifth thereof (i.e., 20%) is changed to singlet excitons. Accordingly, the amount of singlet excitons which contribute to emission is 40%, which is a value obtained by adding 15% (75%×(1/5)=15%) to 25%, which is the amount ratio of initially generated singlet excitons. At this time, a ratio of luminous intensity derived from TTF (TTF ratio) relative to the total luminous intensity is 15/40, i.e., 37.5%. Assuming that singlet excitons are generated by collision of initially generated triplet excitons accounting for 75% (i.e., one singlet exciton is generated from two triplet excitons), a significantly high internal quantum efficiency of 62.5% is obtained, which is a value obtained by adding 37.5% (75%×(1/2)=37.5%) to 25% (the amount ratio of initially generated singlet excitons). At this time, the TTF ratio is 37.5/62.5=60%.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, in terms of expressing the TTF mechanism, a triplet energy of the first host material T1(H1) and a triplet energy of the second host material T1(H2) preferably satisfy a relationship of a numerical formula (Numerical Formula 1) below, more preferably satisfy a relationship of a numerical formula (Numerical Formula 2) below.
T
1(H2)>T1(H1) (Numerical Formula 1)
T
1(H2)−T1(H1)>0.03 eV (Numerical Formula 2)
When an exemplary arrangement of the organic EL device according to the exemplary embodiment includes the first emitting layer and the second emitting layer satisfying the relationship of the above numerical formula (Numerical Formula 1), luminous efficiency of the device is improved.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, it is considered that since the relationship of the numerical formula (Numerical Formula 1) is satisfied, triplet excitons generated by recombination of holes and electrons in the second emitting layer and present on an interface between the second emitting layer and organic layer(s) in direct contact therewith are not likely to be quenched even under the presence of excessive carriers on the interface between the second emitting layer and the organic layer(s). For instance, the presence of a recombination region locally on an interface between the second emitting layer and a hole transporting layer or an electron blocking layer is considered to cause quenching by excessive electrons. Meanwhile, the presence of a recombination region locally on an interface between the second emitting layer and an electron transporting layer or a hole blocking layer is considered to cause quenching by excessive holes.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, by including the first emitting layer and the second emitting layer so as to satisfy the relationship of the numerical formula (Numerical Formula 1), triplet excitons generated in the second emitting layer can transfer to the first emitting layer without being quenched by excessive carriers and be inhibited from back-transferring from the first emitting layer to the second emitting layer. Consequently, the first emitting layer exhibits the TTF mechanism to effectively generate singlet excitons, thereby improving the luminous efficiency.
Accordingly, the organic EL device includes, as different regions, the second emitting layer mainly generating triplet excitons and the first emitting layer mainly exhibiting the TTF mechanism using triplet excitons having transferred from the second emitting layer, and a difference in triplet energy is provided by using a compound having a smaller triplet energy than that of the second host material in the second emitting layer as the first host material in the first emitting layer, thereby improving the luminous efficiency.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first emitting layer and the second emitting layer are in direct contact with each other.
Herein, a layer structure in which the first emitting layer and the second emitting layer are in direct contact with each other can include one of arrangements (LS1), (LS2) and (LS3) below.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer contains the second host material. Although the second host material is not particularly limited, for instance, a compound selected from the group consisting of first compounds described below and a compound represented by the formula (H1) may be used.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer contains a second emitting compound. Although the second emitting compound is not particularly limited, for instance, a compound selected from the group consisting of a compound represented by the formula (6), a third compound described below and a fourth compound described below may be used.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer contains the second host material and the second emitting compound.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second emitting compound is a compound that is the same as or different from the first emitting compound contained in the first emitting layer.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the second host material and the first host material contained in the first emitting layer are mutually different compounds.
The second emitting compound is preferably a compound that emits light having a maximum peak wavelength of 500 nm or less, more preferably a compound that emits light having a maximum peak wavelength in a range from 430 nm to 480 nm. The second emitting compound is preferably a fluorescent compound that emits fluorescence having a maximum peak wavelength of 500 nm or less, more preferably a fluorescent compound that emits fluorescence having a maximum peak wavelength in a range from 430 nm to 480 nm.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer contains the second host material and the second emitting compound having a maximum peak wavelength of 500 nm or less.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, a half bandwidth of a maximum peak of the second emitting compound is in a range from 1 nm to 30 nm.
A measurement method of the maximum peak wavelength of compounds is as follows.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, a triplet energy of the first emitting compound T1(D1) and a triplet energy of the first host material T1(H1) preferably satisfy a relationship of a numerical formula (Numerical Formula 4A) below.
T
1(D1)>T1(H1) (Numerical Formula 4A)
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, when the first emitting compound and the first host material satisfy the relationship of the numerical formula (Numerical Formula 4A), in transfer of triplet excitons generated in the second emitting layer to the first emitting layer, the triplet excitons energy-transfer not onto the first emitting compound having higher triplet energy but onto molecules of the first host material. In addition, triplet excitons generated by recombination of holes and electrons on the first host material do not transfer to the first emitting compound having higher triplet energy. Triplet excitons generated by recombination on molecules of the first emitting compound quickly energy-transfer to molecules of the first host material.
Triplet excitons in the first host material do not transfer to the first emitting compound but efficiently collide with one another on the first host material to generate singlet excitons by the TTF phenomenon.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, a singlet energy Si(H1) of the first host material and a singlet energy Si(D1) of the first emitting compound preferably satisfy a relationship of a numerical formula (Numerical Formula 4) below.
S
1(H1)>S1(D1) (Numerical Formula 4)
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, when the first emitting compound and the first host material satisfy the relationship of the numerical formula (Numerical Formula 4), due to the singlet energy of the first emitting compound being smaller than the singlet energy of the first host material, singlet excitons generated by the TTF phenomenon energy-transfer from the first host material to the first emitting compound, thereby contributing to emission (preferably fluorescence) of the first emitting compound.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, when the second emitting layer and the first emitting layer are layered in this order from a side close to the anode, it is preferable that an electron mobility of the second host material μe(H2) and an electron mobility of the first host material μe(H1) satisfy a relationship of a formula (Numerical Formula 3) below. When the first host material and the second host material satisfy the relationship of the numerical formula (Numerical Formula 3) below, a recombination ability between holes and electrons in the second emitting layer is improved.
μe(H1)>μe(H2) (Numerical Formula 3)
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, when the second emitting layer and the first emitting layer are layered in this order from a side close to the anode, it is also preferable that a hole mobility of the second host material μh(H2) and a hole mobility of the first host material μh(H1) satisfy a relationship of a formula (Numerical Formula 31) below.
μh(H2)>μh(H1) (Numerical Formula 31)
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, when the second emitting layer and the first emitting layer are layered in this order from a side close to the anode, it is also preferable that the hole mobility μh(H2) of the second host material, the electron mobility μe(H2) of the second host material, the hole mobility μh(H1) of the first host material, and the electron mobility μe(H1) of the first host material satisfy a relationship of a numerical formula (Numerical Formula 32) below.
(μe(H1)/μh(H1))>(μe(H2)/μh(H2)) (Numerical Formula 32)
In an exemplary arrangement of the organic EL device of the exemplary embodiment, it is preferable that a singlet energy of the second host material Si(H2) and a singlet energy of the second emitting compound Si(D2) satisfy a relationship of a numerical formula (Numerical Formula 20) below.
S
1(H2)>S1(D2) (Numerical Formula 20)
When the second host material and the second emitting compound satisfy the relationship of the numerical formula (Numerical Formula 20), singlet excitons generated on the second host material easily energy-transfer from the second host material to a second dopant material, thereby contributing to emission (preferably, fluorescence) of the second emitting compound.
In the organic EL device according to the second exemplary embodiment, the triplet energy of the second host material T1(H2) and a triplet energy of the second emitting compound T1(D2) preferably satisfy a relationship of a numerical formula (Numerical Formula 20A) below.
T
1(D2)>T1(H2) (Numerical Formula 20A)
When the second host material and the second emitting compound satisfy the relationship of the numerical formula (Numerical Formula 20A), triplet excitons generated in the second emitting layer are transferred not onto the second emitting compound having higher triplet energy but onto the second host material, thereby being easily transferred to the first emitting layer.
Methods of measuring the triplet energy T1, the singlet energy S1, the hole mobility and the electron mobility will be described below.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting compound is a compound containing no azine ring structure in a molecule thereof.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting compound is preferably not a boron-containing complex, more preferably not a complex.
As a fluorescent compound that emits blue fluorescence and is usable for the second emitting layer, for instance, compounds such as a pyrene derivative, a styrylamine derivative, a chrysene derivative, a fluoranthene derivative, a fluorene derivative, a diamine derivative, and a triarylamine derivative may be used.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer does not contain a metal complex. Moreover, in an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer does not contain a boron-containing complex.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer does not contain a phosphorescent material (dopant material).
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer does not contain a heavy-metal complex or a phosphorescent rare earth metal complex.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer contains 0.5 mass % or more of the emitting compound with respect to a total mass of the second emitting layer. The second emitting layer contains the emitting compound preferably at 10 mass % or less, more preferably at 7 mass % or less, and still more preferably at 5 mass % less with respect to the total mass of the second emitting layer.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the second emitting layer preferably contains the second host material at 60 mass % or more, more preferably at 70 mass % or more, still more preferably at 80 mass % or more, still further more preferably at 90 mass % or more, and yet still further more preferably at 95 mass % or more, with respect to the total mass of the second emitting layer.
The second emitting layer preferably contains the second host material at 99.5 mass % or less with respect to the total mass of the second emitting layer. When the second emitting layer contains the second host material and the second emitting compound, the upper limit of a total of the content ratios of the second host material and the second emitting compound is 100 mass %.
In the organic EL device according to the exemplary embodiment, the second emitting layer may further contain any other material than the second host material and the second emitting compound.
The second emitting layer may contain a single type of the second host material or may contain two or more types of the second host material. The second emitting layer may contain a single type of the second emitting compound or may contain two or more types of the second emitting compound.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the film thickness of the first emitting layer is preferably 5 nm or more, more preferably 15 nm or more. When the film thickness of the first emitting layer is 5 nm or more, in an arrangement in which the emitting region includes the second emitting layer, triplet excitons having transferred from the second emitting layer to the first emitting layer are easily inhibited from returning to the second emitting layer Further, when the film thickness of the first emitting layer is 5 nm or more, triplet excitons can be sufficiently separated from the recombination portion in the second emitting layer.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the film thickness of the first emitting layer is preferably 20 nm or less. When the film thickness of the first emitting layer is 20 nm or less, a density of the triplet excitons in the first emitting layer is improved to cause the TTF phenomenon more easily.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the film thickness of the first emitting layer is preferably in a range from 5 nm to 20 nm.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the film thickness of the second emitting layer is preferably 3 nm or more, more preferably 5 nm or more. When the film thickness of the second emitting layer is 3 nm or more, the film thickness is sufficiently large to cause recombination of holes and electrons in the second emitting layer.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the film thickness of the second emitting layer is preferably 15 nm or less, more preferably 10 nm or less. When the film thickness of the second emitting layer is 15 nm or less, the film thickness is sufficiently thin to allow for transfer of triplet excitons to the first emitting layer.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the film thickness of the second emitting layer is more preferably in a range from 3 nm to 15 nm.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, it is also preferable that the first host material, in adding to being any of the examples of the compound above (such as the compound represented by the formula (H1)), is, for instance, a compound selected from the group consisting of first compounds represented by a formula (1), a formula (1X), a formula (12X), a formula (13X), a formula (14X), a formula (15X), a formula (16X), a formula (1000B), a formula (16X), a formula (17X-1), a formula (17X-2), a formula (17X-3) and a formula (18) below.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, it is also preferable that the second host material is, for instance, a compound selected from the group consisting of first compounds represented by the formula (1), the formula (1X), the formula (12X), the formula (13X), the formula (14X), the formula (15X), the formula (16X), the formula (1000B), the formula (16X), the formula (17X-1), the formula (17X-2), the formula (17X-3) and the formula (18) below and a compound represented by the formula (H1).
The first compound may also be used as the first host material and the second host material.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by the formula (1) below. The first compound represented by the formula (1) has at least one group represented by a formula (11) below.
In the formula (1):
In the first compound represented by the formula (1), R901, R902, R903, R904, R905, R906, R907, R801 and R802 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms;
In an exemplary embodiment, Ar101 is preferably a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary embodiment, Ar101 is a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, a substituted or unsubstituted pyrenyl group, a substituted or unsubstituted phenanthryl group, or a substituted or unsubstituted fluorenyl group.
In an exemplary embodiment, the first compound is preferably represented by a formula (101) below.
In the formula (101):
In an exemplary embodiment, L101 is preferably a single bond or a substituted or unsubstituted arylene group having 6 to 50 ring carbon atoms.
In an exemplary embodiment, two or more of R101 to R110 are each preferably a group represented by the formula (11).
In an exemplary embodiment, it is preferable that two or more of R101 to R110 are each a group represented by the formula (11) and Ar101 is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary embodiment, it is preferable that: Ar101 is not a substituted or unsubstituted pyrenyl group, L101 is not a substituted or unsubstituted pyrenylene group, and the substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms for R101 to R110 not being the group represented by the formula (11) is not a substituted or unsubstituted pyrenyl group.
In an exemplary embodiment: R101 to R110 not being the group represented by the formula (11) are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary embodiment: R101 to R110 not being the group represented by the formula (11) are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms.
In an exemplary embodiment, R101 to R110 not being the group represented by the formula (11) are each preferably a hydrogen atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by the formula (1X) below.
In the formula (1X):
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the group represented by the formula (11X) is a group represented by a formula (111X) below.
In the formula (111X):
Among positions *1 to *8 of carbon atoms in a cyclic structure represented by a formula (111aX) below in the group represented by the formula (111X), L111 is bonded to one of the positions *1 to *4, R141 is bonded to each of three positions of the rest of *1 to *4, L112 is bonded to one of the positions *5 to *8, and R142 is bonded to each of three positions of the rest of *5 to *8.
For instance, in the group represented by the formula (111X), when L111 is bonded to a carbon atom at *2 in the cyclic structure represented by the formula (111aX) and L112 is bonded to a carbon atom at *7 in the cyclic structure represented by the formula (111aX), the group represented by the formula (111X) is represented by a formula (111bX) below.
In the formula (111 bX):
In the organic EL device according to the exemplary embodiment, the group represented by the formula (111X) is preferably a group represented by the formula (111bX).
In the compound represented by the formula (1X), preferably, ma is 1 or 2 and mb is 1 or 2.
In the compound represented by the formula (1X), preferably, ma is 1 and mb is 1.
In the compound represented by the formula (1X), Ar101 is preferably a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In the compound represented by the formula (1X), Ar101 is preferably a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, a substituted or unsubstituted benz[a]anthryl group; a substituted or unsubstituted pyrenyl group, a substituted or unsubstituted phenanthryl group, or a substituted or unsubstituted fluorenyl group.
The compound represented by the formula (1X) is also preferably represented by a formula (101X) below.
In the formula (101X):
In the compound represented by the formula (1X), L101 is preferably a single bond, or a substituted or unsubstituted arylene group having 6 to 50 ring carbon atoms.
The compound represented by the formula (1X) is also preferably represented by a formula (102X) below.
In the formula (102X):
In the compound represented by the formula (1X), preferably, ma is 1 or 2 and mb is 1 or 2 in the formula (102X).
In the compound represented by the formula (1X), preferably, ma is 1 and mb is 1 in the formula (102X).
In the compound represented by the formula (1X), the group represented by the formula (11X) is also preferably a group represented by a formula (11AX) or a group represented by a formula (11 BX) below.
In the formulae (11 AX) and (11 BX):
The compound represented by the formula (1X) is also preferably represented by a formula (103X) below.
In the formula (103X):
In the compound represented by the formula (1X), L131 is also preferably a substituted or unsubstituted arylene group having 6 to 50 ring carbon atoms.
In the compound represented by the formula (1X), L132 is also preferably a substituted or unsubstituted arylene group having 6 to 50 ring carbon atoms.
In the compound represented by the formula (1X), two or more of R101 to R112 are each also preferably a group represented by the formula (11).
In the compound represented by the formula (1X), it is preferable that two or more of R101 to R112 are each a group represented by the formula (11X) and Ar101 in the formula (11X) is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In the compound represented by the formula (1X), it is also preferable that Ar101 is not a substituted or unsubstituted benz[a]anthryl group, L101 is not a substituted or unsubstituted benz[a]anthrylene group, and, the substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms for R101 to R110 not being the group represented by the formula (11X) is not a substituted or unsubstituted benz[a]anthryl group.
In the compound represented by the formula (1X), R101 to R112 not being the group represented by the formula (11X) are preferably each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In the compound represented by the formula (1X), R101 to R112 not being the group represented by the formula (11X) are each preferably a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms.
In the compound represented by the formula (1X), R101 to R112 not being the group represented by the formula (11X) are each preferably a hydrogen atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by the formula (12X) below.
In the formula (12X):
In the formula (12X), combinations of adjacent two of R1201 to R1210 refer to a combination of R1201 and R1202, a combination of R1202 and R1203, a combination of R1203 and R1204, a combination of R1204 and R1205, a combination of R1205 and R1206, a combination of R1207 and R1208, a combination of R1208 and R1209, and a combination of R1209 and R1210.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by the formula (13X) below.
In the formula (13X):
In the organic EL device according to the exemplary embodiment, none of combinations of adjacent two or more of R1301 to R1310 not being the group represented by the formula (131) are bonded to each other. Combinations of adjacent two of R1301 to R1310 in the formula (13X) refer to a combination of R1301 and R1302, a combination of R1302 and R1303, a combination of R1303 and R1304, a combination of R1304 and R1305, a combination of R1305 and R1306, a combination of R1307 and R1308, a combination of R1308 and R1309, and a combination of R1309 and R1310.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by the formula (14X) below.
In the formula (14X):
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by the formula (15X) below.
In the formula (15X):
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by the formula (16X) below.
In the formula (16X):
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by the formula (1000B) below.
In the formula (1000B):
In the formula (1000B), X is preferably an oxygen atom.
The compound represented by the formula (1000B) is preferably a compound that has at least one group represented by the formula (110) and is represented by a formula (100) below.
In the formula (100): R10 to R19 each independently represent the same as R10 to R19 in the formula (1000B); and Ar100, L100 and mx respectively represent the same as Ar100, L100 and mx in the formula (110).
The compound represented by the formula (1000B) is also preferably a compound represented by a formula (101) or (102) below.
In the formulae (101) and (102): R10 to R19 each independently represent the same as R10 to R19 in the formula (1000B), and Ar100, L100 and mx respectively represent the same as Ar100, L100 and mx in the formula (110).
In the formula (1000B), R10 to R19 not being the group represented by the formula (110) are preferably each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, or a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In the formula (1000B), R10 to R19 not being the group represented by the formula (110) are each preferably a hydrogen atom.
In the formula (1000B), L100 is preferably a single bond or an arylene group having at most three substituted or unsubstituted benzene rings.
In the formula (1000B), L1n is preferably not a substituted or unsubstituted anthrylene group.
In the formula (1000B), L1n is also preferably a single bond.
In the formula (1000B), the group represented by -(L100)mx- in the formula (110) is also preferably a group represented by any one of formulae (111) to (120) below.
In the formulae (111) to (120), * represents a bonding position.
The group represented by -(L100)mx- in the formula (110) is preferably a group represented by the formula (111) or (112).
In the formula (1000B), Ar100 is preferably an aryl group in which at least four substituted or unsubstituted benzene rings are fused.
In the formula (1000B), Ar100 is preferably an aryl group in which substituted or unsubstituted four benzene rings are fused or an aryl group in which substituted or unsubstituted five benzene rings are fused.
In the formula (1000B): Ar100 is preferably a group represented by a formula (1100), a formula (1200), a formula (1300), a formula (1400), a formula (1500), a formula (1600), a formula (1700) or a formula (1800) below.
In the formula (1100), one of R111 to R120 is a bond;
A group represented by the formula (1100) in which R111 is a bond is represented by a formula (1112) below. A group represented by the formula (1100) in which R120 is a bond is represented by a formula (1113) below. A group represented by the formula (1100) in which R119 is a bond is represented by a formula (1114) below.
In the formulae (1112), (1113), and (1114):
In the formulae (1100), (1200), (1300), (1400), (1500), (1600), (1700) and (1800), R111 to R120 not being a bond, R1201 to R1212 not being a bond, R1301 to R1314 not being a bond, R1401 to R1414 not being a bond, R1501 to R1514 not being a bond, R1601 to R1612 not being a bond, R1701 to R1710 not being a bond, and R1801 to R1812 not being a bond are preferably each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, or a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In the formulae (1100), (1200), (1300), (1400), (1500), (1600), (1700) and (1800), R111 to R120 not being a bond, R1201 to R1212 not being a bond, R1301 to R1314 not being a bond, R1401 to R1414 not being a bond, R1501 to R1514 not being a bond, R1601 to R1612 not being a bond, R1701 to R1710 not being a bond, and R1801 to R1812 not being a bond are preferably each a hydrogen atom.
The compound represented by the formula (1000B) preferably includes only one benzoxanthene ring in a molecule thereof.
The compounds represented by the formulae (100), (101) and (102) in which a benzoxanthene ring is substituted by a benzothioxanthene ring are also preferable.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by a formula (17X-1) below.
In the formula (17X-1):
In the formula (17X-2),
In the formula (17X-3),
In the formulae (17X-1), (17X-2) and (17X-3), X14 is preferably an oxygen atom.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the first compound is a compound represented by the formula (18) below.
In the formula (18):
In the formula (18), X18 is preferably an oxygen atom.
In the first compound, the groups specified to be “substituted or unsubstituted” are each preferably an “unsubstituted” group.
In the organic EL device according to the exemplary embodiment, it is also preferable that the second host material has, in a molecule, a linking structure including a benzene ring and a naphthalene ring that are linked with a single bond, in which the benzene ring and the naphthalene ring in the linking structure are each independently fused or not fused with a further monocyclic ring or fused ring, and the benzene ring and the naphthalene ring in the linking structure are further linked to each other by cross-linking at at least one site other than the single bond.
When the second host material has the linking structure including such cross-linking, deterioration in the chromaticity of the organic EL device is expected to be inhibited.
The second host material in the above case is only required to have a linking structure as the minimum unit in a molecule, the linking structure including a benzene ring and a naphthalene ring linked to each other with a single bond (occasionally referred to as a benzene-naphthalene linking structure), the linking structure being as represented by a formula (X1) or a formula (X2) below. The benzene ring may be fused with a further monocyclic ring or fused ring, and the naphthalene ring may be fused with a further monocyclic ring or fused ring. For instance, also in a case where the second host material has, in a molecule, a linking structure including a naphthalene ring and a naphthalene ring linked to each other with a single bond (occasionally referred to as a naphthalene-naphthalene linking structure) and being as represented by a formula (X3), a formula (X4), or a formula (X5) below, the naphthalene-naphthalene linking structure is regarded as including the benzene-naphthalene linking structure since one of the naphthalene rings includes a benzene ring.
In the organic EL device according to the above exemplary embodiment, the cross-linking also preferably includes a double bond. Specifically, the second host material also preferably has a structure in which the benzene ring and the naphthalene ring are further linked to each other at any other site than the single bond by the cross-linking structure including a double bond.
Assuming that the benzene ring and the naphthalene ring in the benzene-naphthalene linking structure are further linked to each other at at least one site other than the single bond by cross-linking, for instance, a linking structure (fused ring) represented by a formula (X11) below is obtained in a case of the formula (X1), and a linking structure (fused ring) represented by a formula (X31) below is obtained in a case of the formula (X3).
Assuming that the benzene ring and the naphthalene ring in the benzene-naphthalene linking structure are further linked to each other at any other site than the single bond by cross-linking including a double bond, for instance, a linking structure (fused ring) represented by a formula (X12) below is obtained in a case of the formula (X1), a linking structure (fused ring) represented by a formula (X21) or formula (X22) below is obtained in a case of the formula (X2), a linking structure (fused ring) represented by a formula (X41) below is obtained in a case of the formula (X4), and a linking structure (fused ring) represented by a formula (X51) below is obtained in a case of the formula (X5).
Assuming that the benzene ring and the naphthalene ring in the benzene-naphthalene linking structure are further linked to each other at at least one site other than the single bond by cross-linking including a hetero atom (e.g., an oxygen atom), for instance, a linking structure (fused ring) represented by a formula (X13) below is obtained in a case of the formula (X1).
In the organic EL device according to the exemplary embodiment, also preferably, the second host material has, in a molecule, a biphenyl structure including a first benzene ring and a second benzene ring linked to each other with a single bond, and the first benzene ring and the second benzene ring in the biphenyl structure are further linked to each other by cross-linking at at least one site other than the single bond.
In the organic EL device according to the above exemplary embodiment, also preferably, the first benzene ring and the second benzene ring in the biphenyl structure are further linked to each other by the cross-linking at one site other than the single bond. When the second host material has the biphenyl structure including such cross-linking, deterioration in the chromaticity of the organic EL device is expected to be inhibited.
In the organic EL device according to the above exemplary embodiment, the cross-linking also preferably includes a double bond.
In the organic EL device according to the above exemplary embodiment, the cross-linking also preferably includes no double bond.
Also preferably, the first benzene ring and the second benzene ring in the biphenyl structure are further linked to each other by the cross-linking at two sites other than the single bond.
In the organic EL device according to the exemplary embodiment, also preferably, the first benzene ring and the second benzene ring in the biphenyl structure are further linked to each other by the cross-linking at two sites other than the single bond, and the cross-linking includes no double bond. When the second host material has the biphenyl structure including such cross-linking, deterioration in the chromaticity of the organic EL device is expected to be inhibited.
For instance, assuming that the first benzene ring and the second benzene ring in the biphenyl structure represented by a formula (BP1) below are further linked to each other by cross-linking at at least one site other than the single bond, the biphenyl structure is exemplified by linking structures (fused rings) represented by formulae (BP11) to (BP15) below.
The formula (BP11) represents a linking structure in which the first benzene ring and the second benzene ring are linked to each other at one site other than the single bond by cross-linking including no double bond.
The formula (BP12) represents a linking structure in which the first benzene ring and the second benzene ring are linked to each other at one site other than the single bond by cross-linking including a double bond.
The formula (BP13) represents a linking structure in which the first benzene ring and the second benzene ring are linked to each other at two sites other than the single bond by cross-linking including no double bond.
The formula (BP14) represents a linking structure in which the first benzene ring and the second benzene ring are linked to each other by cross-linking including no double bond at one of two sites other than the single bond, and the first benzene ring and the second benzene ring are linked to each other by cross-linking including a double bond at the other of the two sites other than the single bond.
The formula (BP15) represents a linking structure in which the first benzene ring and the second benzene ring are linked to each other at two sites other than the single bond by cross-linking including a double bond.
In the first compound, the groups specified to be “substituted or unsubstituted” are each preferably an “unsubstituted” group.
The first compound usable in the organic EL device according to the exemplary embodiment can be produced by a known method. The first compound can also be produced based on a known method through a known alternative reaction using a known material(s) tailored for the target compound.
Specific examples of the first compound usable in the organic EL device according to the exemplary embodiment include the following compounds. It should however be noted that the invention is not limited to the specific examples of the first compound.
In the specific examples of the compound herein, D represents a deuterium atom, Me represents a methyl group, and tBu represents a tert-butyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, examples of the first emitting compound and the second emitting compound, in addition to being the examples of the compounds above (such as the compound represented by the formula (6)), are a third compound below and a fourth compound below.
The third compound and the fourth compound are each independently at least one compound selected from the group consisting of a compound represented by a formula (3), a compound represented by a formula (4), a compound represented by a formula (5), a compound represented by a formula (7), a compound represented by a formula (8), a compound represented by a formula (9), and a compound represented by the formula (10) below.
The compound represented by the formula (3) will be described below.
In the formula (3):
In the formula (31):
In the third and fourth compounds, R901, R902, R903, R904, R905, R906, and R907 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms;
In the formula (3), two of R301 to R310 are each preferably a group represented by the formula (31).
In an exemplary embodiment, the compound represented by the formula (3) is a compound represented by a formula (33) below.
In the formula (33):
In the formula (31), L301 is preferably a single bond, and L302 and L303 are each preferably a single bond.
In an exemplary embodiment, the compound represented by the formula (3) is represented by a formula (34) or a formula (35) below.
In the formula (34):
In the formula (35):
In the formula (31), at least one of Ar301 or Ar302 is preferably a group represented by a formula (36) below.
In the formulae (33) to (35), at least one of Ar312 or Ar313 is preferably a group represented by the formula (36).
In the formulae (33) to (35), at least one of Ar315 or Ar316 is preferably a group represented by the formula (36).
In the formula (36):
X3 is preferably an oxygen atom.
At least one of R321 to R327 is preferably a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In the formula (31), preferably, Ar301 is a group represented by the formula (36) and Ar302 is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In the formulae (33) to (35), preferably, Ar312 is a group represented by the formula (36) and Ar313 is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In the formulae (33) to (35), preferably, Ar315 is a group represented by the formula (36) and Ar316 is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary embodiment, the compound represented by the formula (3) is represented by a formula (37) below.
In the formula (37):
Specific examples of the compound represented by the formula (3) include compounds shown below.
The compound represented by the formula (4) will be described below.
In the formula (4):
The “aromatic hydrocarbon ring” for the A1 ring and A2 ring has the same structure as a compound formed by introducing a hydrogen atom to the “aryl group” described above.
Ring atoms of the “aromatic hydrocarbon ring” for the A1 ring and A2 ring include two carbon atoms on a fused bicyclic structure at the center of the formula (4).
Specific examples of the “substituted or unsubstituted aromatic hydrocarbon ring having 6 to 50 ring carbon atoms” include a compound formed by introducing a hydrogen atom to the “aryl group” described in the specific example group G1.
The “heterocycle” for the A1 ring and A2 ring has the same structure as a compound formed by introducing a hydrogen atom to the “heterocyclic group” described above.
Ring atoms of the “heterocycle” for the A1 ring and A2 ring include two carbon atoms on a fused bicyclic structure at the center of the formula (4).
Specific examples of the “substituted or unsubstituted heterocycle having 5 to 50 ring atoms” include a compound formed by introducing a hydrogen atom to the “heterocyclic group” described in the specific example group G2.
Rb is bonded to any one of carbon atoms forming the aromatic hydrocarbon ring as the A1 ring or any one of atoms forming the heterocycle as the A1 ring.
Rc is bonded to any one of carbon atoms forming the aromatic hydrocarbon ring as the A2 ring or any one of atoms forming the heterocycle as the A2 ring.
At least one of Ra, Rb, or Rc is preferably a group represented by a formula (4a) below. More preferably, at least two of Ra, Rb, or Rc are each a group represented by the formula (4a).
[Formula 352]
*-L401-Ar401 (4a)
In the formula (4a):
In the formula (4b):
In an exemplary embodiment, the compound represented by the formula (4) is represented by a formula (42) below.
In the formula (42):
At least one of R401 to R411 is preferably a group represented by the formula (4a). More preferably, at least two of R401 to R411 are each a group represented by the formula (4a).
R404 and R411 are each preferably a group represented by the formula (4a).
In an exemplary embodiment, the compound represented by the formula (4) is a compound formed by bonding a structure represented by a formula (4-1) or a formula (4-2) below to the A1 ring.
Further, in an exemplary embodiment, the compound represented by the formula (42) is a compound formed by bonding a structure represented by the formula (4-1) or the formula (4-2) to a ring bonded to R404 to R407.
In the formula (4-1), two * are each independently bonded to a ring-forming carbon atom of the aromatic hydrocarbon ring or a ring atom of the heterocycle as the A1 ring in the formula (4) or bonded to one of R404 to R407 in the formula (42);
In an exemplary embodiment, the compound represented by the formula (4) is a compound represented by a formula (41-3), a formula (41-4) or a formula (41-5) below.
In the formulae (41-3), (41-4), and (41-5):
In an exemplary embodiment, a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 50 ring carbon atoms as the A1 ring in the formula (41-5) is a substituted or unsubstituted naphthalene ring, or a substituted or unsubstituted fluorene ring.
In an exemplary embodiment, a substituted or unsubstituted heterocycle having 5 to 50 ring atoms as the A1 ring in the formula (41-5) is a substituted or unsubstituted dibenzofuran ring, a substituted or unsubstituted carbazole ring, or a substituted or unsubstituted dibenzothiophene ring.
In an exemplary embodiment, the compound represented by the formula (4) or the formula (42) is selected from the group consisting of compounds represented by formulae (461) to (467) below.
In the formulae (461), (462), (463), (464), (465), (466), and (467):
In an exemplary embodiment, at least one combination of adjacent two or more of R401 to R411 in the compound represented by the formula (42) are mutually bonded to form a substituted or unsubstituted monocyclic ring, or mutually bonded to form a substituted or unsubstituted fused ring. This exemplary embodiment will be described in detail below as a compound represented by a formula (45) below.
The compound represented by the formula (45) will be described below.
In the formula (45):
In the formula (45), Rn and Rn+1 (n being an integer selected from 461, 462, 464 to 466, and 468 to 470) are mutually bonded to form a substituted or unsubstituted monocyclic ring or fused ring together with two ring-forming carbon atoms bonded to Rn and Rn+1. The ring is preferably formed of atoms selected from the group consisting of a carbon atom, an oxygen atom, a sulfur atom, and a nitrogen atom, and is made of preferably 3 to 7 atoms, more preferably 5 or 6 atoms.
The number of the above cyclic structures in the compound represented by the formula (45) is, for instance, 2, 3, or 4. The two or more of the cyclic structures may be present on the same benzene ring on the basic skeleton represented by the formula (45) or may be present on different benzene rings. For instance, when three cyclic structures are present, each of the cyclic structures may be present on the corresponding one of the three benzene rings of the formula (45).
Examples of the above cyclic structures in the compound represented by the formula (45) include structures represented by formulae (451) to (460) below.
In the formulae (451) to (457):
In the formulae (458) to (460):
In the formula (45), preferably, at least one of R462, R464, R465, R470 or R471 (preferably, at least one of R462, R465 or R470, more preferably R462) is a group forming no cyclic structure.
(i) A substituent, if present, for a cyclic structure formed by Rn and Rn+1 in the formula (45), (ii) R461 to R471 forming no cyclic structure in the formula (45), and (iii) R4501 to R4514, R4515 to R4525 in the formulae (451) to (460) are preferably each independently a group selected from the group consisting of a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a group represented by —N(R906)(R907), a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms, or groups represented by formulae (461) to (464) below.
In the formulae (461) to (464):
R901 to R907 in the third compound and the fourth compound are as defined above.
In an exemplary embodiment, the compound represented by the formula (45) is represented by any one of formulae (45-1) to (45-6) below.
In the formulae (45-1) to (45-6):
In an exemplary embodiment, the compound represented by the formula (45) is represented by any one of formulae (45-7) to (45-12) below.
In the formulae (45-7) to (45-12):
In an exemplary embodiment, the compound represented by the formula (45) is represented by any one of formulae (45-13) to (45-21) below.
In the formulae (45-13) to (45-21):
When the ring g or the ring h further has a substituent, examples of the substituent include a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, a group represented by the formula (461), a group represented by the formula (463), and a group represented by the formula (464).
In an exemplary embodiment, the compound represented by the formula (45) is represented by any one of formulae (45-22) to (45-25) below.
In the formulae (45-22) to (45-25):
In an exemplary embodiment, the compound represented by the formula (45) is represented by a formula (45-26) below.
In the formula (45-26):
Specific examples of the compound represented by the formula (4) include compounds shown below. In the specific examples below, Ph represents a phenyl group, and D represents a deuterium atom.
The compound represented by the formula (5) will be described below. The compound represented by the formula (5) corresponds to a compound represented by the formula (41-3) described above.
In the formula (5):
R521 and R522 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a group represented by —Si(R901)(R902)(R903), a group represented by —O—(R904), a group represented by —S—(R905), a group represented by —N(R906)(R907), a halogen atom, a cyano group, a nitro group, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
“A combination of adjacent two or more of R501 to R507 and R511 to R517” refers to, for instance, a combination of R501 and R502, a combination of R502 and R503, a combination of R503 and R504, a combination of R505 and R506, a combination of R506 and R507, and a combination of R501, R502, and R503.
In an exemplary embodiment, at least one, preferably two of R501 to R507 or R511 to R517 are each a group represented by —N(R906)(R907).
In an exemplary embodiment, R501 to R507 and R511 to R517 are each independently a hydrogen atom, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary embodiment, the compound represented by the formula (5) is a compound represented by a formula (52) below.
In the formula (52):
In an exemplary embodiment, the compound represented by the formula (5) is a compound represented by a formula (53) below.
In the formula (53), R551, R552 and R561 to R564 each independently represent the same as R551, R552 and R561 to R564 in the formula (52).
In an exemplary embodiment, R561 to R564 in the formulae (52) and (53) are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms (preferably a phenyl group).
In an exemplary embodiment, R521 and R522 in the formula (5) and R551 and R552 in the formulae (52) and (53) are each a hydrogen atom.
In an exemplary embodiment, the substituent for the “substituted or unsubstituted” group in the formulae (5), (52) and (53) is a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
Specific examples of the compound represented by the formula (5) include compounds shown below.
The compound represented by the formula (7) will be described below.
In the formula (7):
In the formula (7), each of the ring p, ring q, ring r, ring s, and ring t is fused with an adjacent ring(s) sharing two carbon atoms. The fused position and orientation are not limited but may be defined as required.
In an exemplary embodiment, in the formula (72) or the formula (73) representing the ring r, m1=0 or m2=0 is satisfied.
In an exemplary embodiment, the compound represented by the formula (7) is represented by any one of formulae (71-1) to (71-6) below.
In the formulae (71-1) to (71-6), R701, X7, Ar701, Ar702, L701, m1 and m3 respectively represent the same as R701, X7, Ar701, Ar702, L701, m1 and m3 in the formula (7).
In an exemplary embodiment, the compound represented by the formula (7) is represented by any one of formulae (71-11) to (71-13) below.
In the formulae (71-11) to (71-13), R701, X7, Ar701, Ar702, L701, m1, m3 and m4 respectively represent the same as R701, X7, Ar701, Ar702, L701, m1, m3 and m4 in the formula (7).
In an exemplary embodiment, the compound represented by the formula (7) is represented by any one of formulae (71-21) to (71-25) below.
In the formulae (71-21) to (71-25), R701, X7, Ar701, Ar702, L701, m1 and m4 respectively represent the same as R701, X7, Ar701, Ar702, L701, m1 and m4 in the formula (7).
In an exemplary embodiment, the compound represented by the formula (7) is represented by any one of formulae (71-31) to (71-33) below.
In the formulae (71-31) to (71-33), R701, X7, Ar701, Ar702, L701, and m2 to m4 respectively represent the same as R701, X7, Ar701, Ar702, L701, and m2 to m4 in the formula (7).
In an exemplary embodiment, Ar701 and Ar702 are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary embodiment, one of Ar701 and Ar702 is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, and the other of Ar701 and Ar702 is a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
Specific Examples of Compound Represented by Formula (7) Specific examples of the compound represented by the formula (7) include compounds shown below.
The compound represented by the formula (8) will be described below.
In the formula (8):
At least one of R801 to R804 not forming the divalent group represented by the formula (82) or R11 to R814 is a monovalent group represented by a formula (84) below;
In the formula (84):
In the formula (8), the positions for the divalent group represented by the formula (82) and the divalent group represented by the formula (83) to be formed are not specifically limited but the divalent groups may be formed at any possible positions on R801 to R808.
In an exemplary embodiment, the compound represented by the formula (8) is represented by any one of formulae (81-1) to (81-6) below.
In the formulae (81-1) to (81-6):
In an exemplary embodiment, the compound represented by the formula (8) is represented by any one of formulae (81-7) to (81-18) below.
In the formulae (81-7) to (81-18):
R801 to R808 not forming the divalent group represented by the formula (82) or (83) and not being the monovalent group represented by the formula (84), and R811 to R814 and R821 to R824 not being the monovalent group represented by the formula (84) are preferably each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 50 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms.
The monovalent group represented by the formula (84) is preferably represented by a formula (85) or (86) below.
In the formula (85):
In the formula (86):
In the formula (87):
Specific examples of the compound represented by the formula (8) include compounds shown below as well as the compounds disclosed in WO 2014/104144.
The compound represented by the formula (9) will be described below.
In the formula (9):
In the formula (92):
At least one of A91 ring or A92 ring is bonded to * in a structure represented by the formula (92). In other words, the ring-forming carbon atoms of the aromatic hydrocarbon ring or the ring atoms of the heterocycle of A91 ring in an exemplary embodiment are bonded to * in a structure represented by the formula (92). Further, the ring-forming carbon atoms of the aromatic hydrocarbon ring or the ring atoms of the heterocycle of A92 ring in an exemplary embodiment are bonded to * in a structure represented by the formula (92).
In an exemplary embodiment, a group represented by a formula (93) below is bonded to one or both of A91 ring and A92 ring.
In the formula (93):
In an exemplary embodiment, in addition to A91 ring, the ring-forming carbon atoms of the aromatic hydrocarbon ring or the ring atoms of the heterocycle of A92 ring are bonded to * in the structures represented by the formula (92). In this case, the structures represented by the formula (92) may be mutually the same or different.
In an exemplary embodiment, R91 and R92 are each independently a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary embodiment, R91 and R92 are mutually bonded to form a fluorene structure.
In an exemplary embodiment, A91 ring and A92 ring are each independently a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 50 ring carbon atoms, example of which is a substituted or unsubstituted benzene ring.
In an exemplary embodiment, A93 ring is a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 50 ring carbon atoms, example of which is a substituted or unsubstituted benzene ring.
In an exemplary embodiment, X9 is an oxygen atom or a sulfur atom.
Specific examples of the compound represented by the formula (9) include compounds shown below.
In the formula (10):
In an exemplary embodiment, Ar1001 is a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms.
In an exemplary embodiment, Ax3 ring is a substituted or unsubstituted aromatic hydrocarbon ring having 6 to 50 ring carbon atoms, example of which is a substituted or unsubstituted benzene ring, a substituted or unsubstituted naphthalene ring, or a substituted or unsubstituted anthracene ring.
In an exemplary embodiment, R1003 and R1004 are each independently a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms.
In an exemplary embodiment, ax is 1.
Specific examples of the compound represented by the formula (10) include compounds shown below.
In an exemplary embodiment, the substituent for “the substituted or unsubstituted” group in each of the formulae is an unsubstituted alkyl group having 1 5 to 50 carbon atoms, an unsubstituted aryl group having 6 to 50 ring carbon atoms, or an unsubstituted heterocyclic group having 5 to 50 ring atoms.
In an exemplary embodiment, the substituent for “the substituted or unsubstituted” group in each of the formulae is an unsubstituted alkyl group having 1 to 18 carbon atoms, an unsubstituted aryl group having 6 to 18 ring carbon atoms, or an unsubstituted heterocyclic group having 5 to 18 ring atoms.
An exemplary arrangement of the organic EL device according to the exemplary embodiment further includes an electron transporting zone disposed between the cathode and the emitting region. The electron transporting zone includes at least one electron transporting layer. The at least one electron transporting layer in the electron transporting zone contains a nitrogen-containing compound having at least one of a five-membered ring containing a nitrogen atom or a six-membered ring containing a nitrogen atom.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, at least one electron transporting layer in the electron transporting zone contains, as a nitrogen-containing compound, at least one compound selected from the group consisting of an imidazole derivative, a benzimidazole derivative, an azine derivative, a carbazole derivative and a phenanthroline derivative.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, at least one electron transporting layer in the electron transporting zone contains, as a nitrogen-containing compound, a phenanthroline derivative.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, the phenanthroline derivative (phenanthroline compound) contained in the electron transporting layer is a compound that has at least one group represented by a formula (21) below and is represented by a formula (20) below.
In the formula (20):
In the formula (21):
In the phenanthroline compound, R901, R902, R903, R904, R905, R906, R907, R931, R932, R933, R934, R935, R936 and R937 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms;
A group represented by —O—(R904) herein in which R904 is a hydrogen atom is a hydroxy group.
A group represented by —O—(R905) herein in which R905 is a hydrogen atom is a thiol group.
A group represented by —S(═O)2R933 herein in which R933 is a substituent is a substituted sulfo group.
A group represented by —B(R934)(R935) herein in which R934 and R935 are each a substituent is a substituted boryl group.
A group represented by —P(═O)(R936)(R937) herein is a substituted phosphine oxide group when R936 and R937 are each a substituent, and an aryl phosphoryl group when R936 and R937 are each an aryl group.
An “unsubstituted polyvalent linear, branched or cyclic aliphatic hydrocarbon group” mentioned herein has, unless otherwise specified herein, 1 to 50, preferably 1 to 20, more preferably 1 to 6 carbon atoms.
An “unsubstituted polyvalent aromatic hydrocarbon group” mentioned herein has, unless otherwise specified herein, 6 to 50, preferably 6 to 30, more preferably 6 to 18 ring carbon atoms.
An “unsubstituted polyvalent heterocyclic group” mentioned herein has, unless otherwise specified herein, 5 to 50, preferably 5 to 30, more preferably 5 to 18 ring atoms.
In an exemplary embodiment, a heterocyclic group having 5 to 50 ring atoms in Ar2 of the formula (21) contains a substituted or unsubstituted group derived from the ring structure represented by the formula (20).
In an exemplary embodiment, X21 and X28 of the formula (20) are each a carbon atom bonded to the group represented by the formula (21).
In an exemplary embodiment, one of X21 and X28 of the formula (20) is a carbon atom bonded to the group represented by the formula (21), and the other of X21 and X28 of the formula (20) is a carbon atom bonded to a hydrogen atom.
In an exemplary embodiment, X21 to X28 of the formula (20) are each independently CR21 or a carbon atom bonded to the group represented by the formula (21).
In an exemplary embodiment, X21 to X28 of the formula (20) not being a carbon atom bonded to the group represented by the formula (21) are each CR21. In other words, in an exemplary embodiment, the compound represented by the formula (20) is a 1,10-phenanthroline derivative.
In an exemplary embodiment, Ar2 of the formula (21) is a substituted or unsubstituted fused aromatic hydrocarbon group having 8 to 20 ring carbon atoms.
In an exemplary embodiment, the fused aromatic hydrocarbon group having 8 to 20 ring carbon atoms is, for instance, a group derived from any one of aromatic hydrocarbons selected from the group consisting of naphthalene, anthracene, acephenanthrylene, aceanthrylene, benzoanthracene, triphenylene, pyrene, chrysene, naphthacene, fluorene, phenanthrene, fluoranthene and benzofluoranthene.
In an exemplary embodiment, Ar2 of the formula (21) is a substituted or unsubstituted anthryl group.
In an exemplary embodiment, Ar2 of the formula (21) is a substituted or unsubstituted heterocyclic group having 5 to 40 ring carbon atoms.
In an exemplary embodiment, Ar2 of the formula (21) is a substituted or unsubstituted group derived from the ring structure represented by the formula (20).
In an exemplary embodiment, Ar21 of the formula (21) is a group represented by a formula (23) below.
In the formula (23):
In the formula of the phenanthroline compound:
In an exemplary embodiment, X21 to X28 in the formula (23) are preferably each independently a nitrogen atom, CR21, or a carbon atom bonded to L22 or L23, more preferably CR21 or a carbon atom bonded to L22 or L23.
In an exemplary embodiment, the phenanthroline compound is a compound represented by a formula (24) below.
In the formula (24):
In an exemplary embodiment, the phenanthroline compound is a compound represented by a formula (24A) below.
In the formula (24A):
In an exemplary embodiment, the phenanthroline compound is a compound represented by a formula (24B) below.
In the formula (24B):
In an exemplary embodiment, the phenanthroline compound is a compound represented by a formula (25) below.
In the formula (25):
In an exemplary embodiment, the phenanthroline compound is a compound represented by a formula (25A) below.
In the formula (25A):
In an exemplary embodiment, L2 in the formulae (24), (24A), (24B), (25) and (25A) is a single bond, a substituted or unsubstituted arylene group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted divalent heterocyclic group having 5 to 50 ring atoms.
In an exemplary embodiment, the phenanthroline compound is a compound represented by a formula (25B) below.
In the formula (25B):
In an exemplary embodiment, the phenanthroline compound is a compound represented by a formula (25C) below.
In the formula (25C):
In an exemplary embodiment, the phenanthroline compound is a compound represented by a formula (25D) below.
In the formula (25D):
In an exemplary embodiment, the phenanthroline compound is a compound represented by a formula (25E) below.
In the formula (25E):
L3 in the formulae (25B), (25C), (25D) and (25E) is also preferably a substituted or unsubstituted arylene group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted divalent heterocyclic group having 5 to 50 ring atoms.
The phenanthroline compound can be produced by a known method. The phenanthroline compound also can be produced based on a known method through a known alternative reaction using a known material(s) tailored for the target compound.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, at least one electron transporting layer in the electron transporting zone contains, as a nitrogen-containing compound, an azine derivative.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the azine derivative contained in the electron transporting layer is a compound represented by a formula (E42) below.
In the formula (E42):
R901 to R907 in the azine derivative are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms;
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the azine derivative contained in the electron transporting layer is a compound represented by a formula (E421) below.
In the formula (E421):
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the azine derivative contained in the electron transporting layer is a compound represented by a formula (E422) and a compound represented by a formula (E423) below.
In the formula (E422):
In the formula (E423):
In the formulae (E422) and (E423), R901 to R907 each independently represent the same as R901 to R907 in the azine derivative.
When n4 is 1 in the formula (E421), for instance, the group represented by (Ar421)n4-L421-* in the formula (E421) is represented by a formula (E421-1) below. In this arrangement, L421 is a divalent linking group. * represents a bonding position with a six-membered ring in the formula (E421).
When n4 is 2 in the formula (E421), the group represented by (Ar421)n4-L421-* in the formula (E421) is represented by a formula (E421-2) below. Ar421 are mutually the same or different. In this arrangement, L421 is a trivalent linking group.
When n4 is 3 in the formula (E421), the group represented by (Ar421)n4-L421-* in the formula (E421) is represented by a formula (E421-3) below. Ar421 are mutually the same or different. In this arrangement, L421 is a tetravalent linking group.
The same applies to the group represented by (Ar422)n4-L421-* in the formula (E422).
In the formulae (E421-1), (E421-2) and (E421-3), * represents a bonding position with a six-membered ring in the formula (E421).
In the formulae (E421) and (E422), L421 as the linking group is preferably a divalent or trivalent group derived from any of benzene, biphenyl, terphenyl, naphthalene and phenanthrene.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the substituent for “the substituted or unsubstituted” group in the azine derivative is a group selected from the group consisting of an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 18 ring carbon atoms and a heterocyclic group having 5 to 18 ring atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the substituent for “the substituted or unsubstituted” group in the azine derivative is an alkyl group having 1 to 5 carbon atoms.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the groups specified to be “substituted or unsubstituted” in the azine derivative are each an “unsubstituted” group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, at least one electron transporting layer in the electron transporting zone contains, as a nitrogen-containing compound, a benzimidazole derivative.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the benzimidazole derivative contained in the electron transporting layer is a compound represented by a formula (E41) below.
In the formula (E41):
In the formula (E41), Z901 to Z907 are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 50 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 50 ring carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 ring carbon atoms, or a substituted or unsubstituted heterocyclic group having 5 to 50 ring atoms;
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the benzimidazole derivative contained in the electron transporting layer is a compound represented by a formula (E41A), (E41B), (E41C), (E41D) or (E41E) below.
In the formulae (E41A), (E41B), (E41C), (E41D) and (E41E):
In an exemplary arrangement of the organic EL device of the exemplary embodiment, in the formulae (E41A), (E41B), (E41C), (E41D) and (E41E), Ar41 is a group represented by a formula (E412) below.
In the formula (E412):
In the formula (E412), R901 to R907 each independently represent the same as R901 to R907 in the benzimidazole derivative.
In the formulae (E41A), (E41B), (E41C), (E41D) and (E41E): L41 is preferably a substituted or unsubstituted phenylene group, a substituted or unsubstituted biphenylene group, a substituted or unsubstituted naphthylene group, a substituted or unsubstituted pyridinylene group, or a substituted or unsubstituted 9,9′-spirobifluorenylene group.
In the formulae (E41A), (E41B), (E41C), (E41D) and (E41E): L41 is more preferably an unsubstituted phenylene group, an unsubstituted biphenylene group, an unsubstituted naphthylene group, an unsubstituted pyridinylene group, or an unsubstituted 9,9′-spirobifluorenylene group.
In the formulae (E41A), (E41B), (E41C), (E41D) and (E41E): Ar41 is preferably a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted phenanthryl group, a substituted or unsubstituted fluoranthenyl group, a substituted or unsubstituted pyrenyl group, or a substituted or unsubstituted fluorenyl group.
In the formulae (E41A), (E41B), (E41C), (E41D) and (E41E): Ar41 is more preferably an unsubstituted phenyl group, an unsubstituted biphenyl group, an unsubstituted terphenyl group, an unsubstituted naphthyl group, an unsubstituted phenanthryl group, an unsubstituted fluoranthenyl group, an unsubstituted pyrenyl group, or an unsubstituted 9,9-dimethylfluorenyl group.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the benzimidazole derivative contained in the electron transporting layer is a compound represented by a formula (E413) below.
In the formula (E413):
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the groups specified to be “substituted or unsubstituted” in the benzimidazole derivative are each an “unsubstituted” group.
Specific examples of the nitrogen-containing compound include the following compounds. However, the invention is by no means limited to the specifically listed nitrogen-containing compounds.
A second exemplary embodiment and a third exemplary embodiment of the invention will be described below.
An organic EL device according to each of the second and third exemplary embodiments is one arrangement of the organic EL device according to the first exemplary embodiment.
Thus, elements that may be contained in the organic EL device of the second exemplary embodiment are similar to the elements that may be contained in the organic EL device described in the first exemplary embodiment. Likewise, elements that may be contained in the organic EL device of the third exemplary embodiment are similar to the elements that may be contained in the organic EL device described in the first exemplary embodiment.
The organic EL device according to the second exemplary embodiment includes:
NM
1
>NM
2 (Numerical Formula NM)
According to the second exemplary embodiment, the organic EL device has improved device performance. In an exemplary arrangement according to the second exemplary embodiment, the organic EL device has improved luminous efficiency. In an exemplary arrangement according to the second exemplary embodiment, the organic EL device has a longer lifetime.
The organic EL device according to the third exemplary embodiment includes:
NM
1
>NM
2 (Numerical Formula NM)
According to the third exemplary embodiment, the organic EL device has improved device performance. In an exemplary arrangement according to the third exemplary embodiment, the organic EL device has improved luminous efficiency. In an exemplary arrangement according to the third exemplary embodiment, the organic EL device has a longer lifetime.
The organic EL devices according to the first to third exemplary embodiments each may further include one or more organic layer(s) in addition to the first anode side organic layer, the second anode side organic layer and the first emitting layer. Those organic layers include, for instance, at least one layer selected from the group consisting of an electron injecting layer, a hole blocking layer and an electron blocking layer, in addition to the third anode side organic layer, the fourth anode side organic layer, the second emitting layer and the electron transporting layer.
In the organic EL devices according to the first to third exemplary embodiments, the arrangement of the organic layers may consist of the first anode side organic layer, the second anode side organic layer, and the first emitting layer. Alternatively, the arrangement of the organic layers may further include, for instance, at least one layer selected from the group consisting of the third anode side organic Layer, the fourth anode side organic layer, the second emitting layer, the electron injecting layer, the electron transporting layer, the hole blocking layer and other layers.
An organic EL device 1D includes a substrate 2, an anode 3, a cathode 4, and organic layers 14 disposed between the anode 3 and the cathode 4. The organic layers 14 include a first anode side organic layer 61, a second anode side organic layer 62, a first emitting layer 51, an electron transporting layer 8, and an electron injecting layer 9, which are layered in this order from a side close to the anode 3.
An organic EL device 1 includes a substrate 2, an anode 3, a cathode 4, and organic layers 10 disposed between the anode 3 and the cathode 4. The organic layers 10 include a first anode side organic layer 61, a second anode side organic layer 62, a third anode side organic layer 63, a first emitting layer 51, an electron transporting layer 8, and an electron injecting layer 9, which are layered in this order from a side close to the anode 3.
An organic EL device 1A includes a substrate 2, an anode 3, a cathode 4, and organic layers 11 disposed between the anode 3 and the cathode 4. The organic layers 11 include a first anode side organic layer 61, a second anode side organic layer 62, a third anode side organic layer 63, a fourth anode side organic layer 64, a first emitting layer 51, an electron transporting layer 8, and an electron injecting layer 9, which are layered in this order from a side close to the anode 3.
An organic EL device 1E includes a substrate 2, an anode 3, a cathode 4, and organic layers 15 disposed between the anode 3 and the cathode 4. The organic layers 15 include a first anode side organic layer 61, a second anode side organic layer 62, a second emitting layer 52, a first emitting layer 51, an electron transporting layer 8, and an electron injecting layer 9, which are layered in this order from a side close to the anode 3.
An organic EL device 1B includes a substrate 2, an anode 3, a cathode 4, and organic layers 12 disposed between the anode 3 and the cathode 4. The organic layers 12 include a first anode side organic layer 61, a second anode side organic layer 62, a third anode side organic layer 63, a second emitting layer 52, a first emitting layer 51, an electron transporting layer 8, and an electron injecting layer 9, which are layered in this order from a side close to the anode 3.
An organic EL device 1C includes a substrate 2, an anode 3, a cathode 4, and organic layers 13 disposed between the anode 3 and the cathode 4. The organic layers 13 include a first anode side organic layer 61, a second anode side organic layer 62, a third anode side organic layer 63, a fourth anode side organic layer 64, a second emitting layer 52, a first emitting layer 51, an electron transporting layer 8, and an electron injecting layer 9, which are layered in this order from a side close to the anode 3.
In the organic EL device 1D of
In the organic EL device 1E of
In the organic EL device 1D of
In the organic EL device 1 of
In the organic EL device 1A of
The arrangements of the organic EL devices depicted in
The invention is not limited to the exemplary arrangements of the organic EL devices depicted in
An exemplary arrangement of the organic EL device according to the exemplary embodiment, when the emitting region includes the first emitting layer and the second emitting layer, may include an interposed layer as an organic layer disposed between the first emitting layer and the second emitting layer.
In an exemplary embodiment, in order to inhibit an overlap between a Singlet emitting region and a TTF emitting region, the interposed layer contains no emitting compound or may contain an emitting compound in an insubstantial amount provided that the overlap can be inhibited.
For instance, the interposed layer contains 0 mass % of an emitting compound. Alternatively, for instance, the interposed layer may contain an emitting compound provided that the emitting compound contained is a component accidentally mixed in a producing process or a component contained as impurities in a material.
For instance, when the interposed layer consists of a material A, a material
B, and a material C, the content ratios of the materials A, B, and C in the interposed layer are each 10 mass % or more, and the total of the content ratios of the materials A, B, and C is 100 mass %.
In the following, the interposed layer is occasionally referred to as a “non-doped layer”. A layer containing an emitting compound is occasionally referred to as a “doped layer”.
It is considered that luminous efficiency is improvable in an arrangement including layered emitting layers because the Singlet emitting region and the TTF emitting region are typically likely to be separated from each other.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, when the interposed layer (non-doped layer) is disposed between the first emitting layer and the second emitting layer in the emitting region, it is expected that a region where the Singlet emitting region and the TTF emitting region overlap with each other is reduced to inhibit a decrease in TTF efficiency caused by collision between triplet excitons and carriers. That is, it is considered that providing the interposed layer (non-doped layer) between the emitting layers contributes to the improvement in the efficiency of TTF emission.
The interposed layer is the non-doped layer.
The interposed layer contains no metal atom. The interposed layer thus contains no metal complex.
The interposed layer contains an interposed layer material. The interposed layer material is not an emitting compound.
The interposed layer material may be any material except for the emitting compound.
Examples of the interposed layer material include: 1) a heterocyclic compound such as an oxadiazole derivative, benzimidazole derivative, or phenanthroline derivative; 2) a fused aromatic compound such as a carbazole derivative, anthracene derivative, phenanthrene derivative, pyrene derivative or chrysene derivative; and 3) an aromatic amine compound such as a triarylamine derivative or a fused polycyclic aromatic amine derivative.
One or both of the first host material and the second host material may be used as the interposed layer material. The interposed layer material may be any material provided that the Singlet emitting region and the TTF emitting region are separated from each other and the Singlet emission and the TTF emission are not hindered.
In an exemplary arrangement of the organic EL device according to the exemplary embodiment, the respective content ratios of all the materials forming the interposed layer in the interposed layer are 10 mass % or more.
The interposed layer contains the interposed layer material as a material forming the interposed layer.
The interposed layer preferably contains 60 mass % or more of the interposed layer material, more preferably contains 70 mass % or more of the interposed layer material, still more preferably contains 80 mass % or more of the interposed layer material, still further more preferably 90 mass % or more of the interposed layer material, and yet still further more preferably 95 mass % or more of the interposed layer material, with respect to the total mass of the interposed layer.
The interposed layer may contain a single type of the interposed layer material or may contain two or more types of the interposed layer material.
When the interposed layer contains two or more types of the interposed layer material, an upper limit of the total of the content ratios of the two or more types of the interposed layer material is 100 mass %.
It should be noted that the interposed layer of the exemplary embodiment may further contain any other material than the interposed layer material.
The interposed layer may be provided in the form of a single layer or a laminate of two or more layers.
As long as the overlap between the Singlet emitting region and the TTF emitting region is inhibited, a film thickness of the interposed layer is not particularly limited but each layer in the interposed layer is preferably in a range from 3 nm to 15 nm, more preferably in a range from 5 nm to 10 nm.
The interposed layer having a film thickness of 3 nm or more easily separates the Singlet emitting region from the emitting region derived from TTF.
The interposed layer having a film thickness of 15 nm or less easily inhibits a phenomenon where the host material of the interposed layer emits light.
It is preferable that the interposed layer contains the interposed layer material as a material forming the interposed layer and the triplet energy of the first host material T1(H1), the triplet energy of the second host material T1(H2), and a triplet energy of at least one interposed layer material T1(Mmid) satisfy a relationship of a numerical formula (Numerical Formula 21) below.
T
1(H2)≥T1(Mmid)≥T1(H1) (Numerical Formula 21)
When the interposed layer contains two or more interposed layer materials as a material forming the interposed layer, the triplet energy of the first host material T1(H1), the triplet energy of the second host material T1(H2), and a triplet energy of each interposed layer material T1(MEA) more preferably satisfy a relationship of a numerical formula (Numerical Formula 21A) below.
T
1(H2)≥T1(MEA)≥T1(H1) (Numerical Formula 21A)
An exemplary arrangement of the organic EL device according to the exemplary embodiment may further include a diffusion layer.
When an exemplary arrangement of the organic EL device according to the exemplary embodiment includes the diffusion layer, the diffusion layer is preferably disposed between the first emitting layer and the second emitting layer.
An arrangement of the organic EL device will be further described below. It should be noted that the reference numerals are occasionally omitted below.
The substrate is used as a support for the organic EL device. For instance, glass, quartz, plastics and the like are usable for the substrate. A flexible substrate is also usable. The flexible substrate is a bendable substrate, which is exemplified by a plastic substrate. Examples of the material for the plastic substrate include polycarbonate, polyarylate, polyethersulfone, polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, polyimide, and polyethylene naphthalate. Further, an inorganic vapor deposition film is also usable.
Metal, an alloy, an electrically conductive compound, a mixture thereof, or the like having a large work function (specifically, 4.0 eV or more) is preferably used as the anode formed on the substrate. Specific examples of the material include indium tin oxide (ITO), indium oxide-tin oxide containing silicon or silicon oxide, indium oxide-zinc oxide, indium oxide containing tungsten oxide and zinc oxide, and graphene. In addition, gold (Au), platinum (Pt), nickel (Ni), tungsten (W), chrome (Cr), molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), titanium (Ti), and nitrides of a metal material (e.g., titanium nitride) are usable.
The material is typically formed into a film by a sputtering method. For instance, the indium oxide-zinc oxide can be formed into a film by the sputtering method using a target in which zinc oxide in a range from 1 mass % to 10 mass % is added to indium oxide. Moreover, for instance, the indium oxide containing tungsten oxide and zinc oxide can be formed by the sputtering method using a target in which tungsten oxide in a range from 0.5 mass % to 5 mass % and zinc oxide in a range from 0.1 mass % to 1 mass % are added to indium oxide. In addition, the anode may be formed by a vacuum deposition method, a coating method, an inkjet method, a spin coating method or the like.
Among the EL layers formed on the anode, since the hole injecting layer adjacent to the anode is formed of a composite material into which holes are easily injectable irrespective of the work function of the anode, a material usable as an electrode material (e.g., metal, an alloy, an electroconductive compound, a mixture thereof, and the elements belonging to the group 1 or 2 of the periodic table) is also usable for the anode.
A material having a small work function such as elements belonging to Groups 1 and 2 in the periodic table of the elements, specifically, an alkali metal such as lithium (Li) and cesium (Cs), an alkaline earth metal such as magnesium (Mg), calcium (Ca) and strontium (Sr), alloys (e.g., MgAg and AlLi) including the alkali metal or the alkaline earth metal, a rare earth metal such as europium (Eu) and ytterbium (Yb), alloys including the rare earth metal are also usable for the anode. It should be noted that the vacuum deposition method and the sputtering method are usable for forming the anode using the alkali metal, alkaline earth metal and the alloy thereof. Further, when a silver paste is used for the anode, the coating method and the inkjet method are usable.
It is preferable to use metal, an alloy, an electroconductive compound, a mixture thereof, or the like having a small work function (specifically, 3.8 eV or less) for the cathode. Examples of the material for the cathode include elements belonging to Groups 1 and 2 in the periodic table of the elements, specifically, an alkali metal such as lithium (Li) and cesium (Cs), an alkaline earth metal such as magnesium (Mg), calcium (Ca) and strontium (Sr), alloys (e.g., MgAg and AlLi) including the alkali metal or the alkaline earth metal, a rare earth metal such as europium (Eu) and ytterbium (Yb), and alloys including the rare earth metal.
It should be noted that the vacuum deposition method and the sputtering method are usable for forming the cathode using the alkali metal, alkaline earth metal and the alloy thereof. Further, when a silver paste is used for the cathode, the coating method and the inkjet method are usable.
By providing the electron injecting layer, various conductive materials such as Al, Ag, ITO, graphene, and indium oxide-tin oxide containing silicon or silicon oxide may be used for forming the cathode regardless of the work function. The conductive materials can be formed into a film using the sputtering method, inkjet method, spin coating method and the like.
In an exemplary arrangement of the organic EL device of the exemplary embodiment, an electron transporting layer is disposed between the emitting region and the cathode.
The electron transporting layer is a layer containing a highly electron-transporting substance. For the electron transporting layer, 1) a metal complex such as an aluminum complex, beryllium complex, and zinc complex, 2) a hetero aromatic compound such as imidazole derivative, benzimidazole derivative, azine derivative, carbazole derivative, and phenanthroline derivative, and 3) a high polymer compound are usable. Specifically, as a low-molecule organic compound, a metal complex such as Alq, tris(4-methyl-8-quinolinolato)aluminum (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato)beryllium (abbreviation: BeBq2), BAlq, Znq, ZnPBO and ZnBTZ is usable. In addition to the metal complex, a heteroaromatic compound such as 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(ptert-butylphenyl)-1,3,4-oxadiazole-2-yl]benzene (abbreviation: OXD-7), 3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), and 4,4′-bis(5-methylbenzoxazole-2-yl)stilbene (abbreviation: BzOs) is usable. In the exemplary embodiment of the exemplary embodiment, the nitrogen-containing compound (preferably, a benzimidazole compound) is preferably usable. The above-described substances mostly have an electron mobility of 10−6 cm2V·s or more. It should be noted that any substance other than the above substance may be used for the electron transporting layer as long as the substance exhibits a higher electron transportability than the hole transportability. The electron transporting layer may be provided in the form of a single layer or a laminate of two or more layers of the above substance(s).
Further, a high polymer compound is usable for the electron transporting layer. For instance, poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)](abbreviation: PF-Py), poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)](abbreviation: PF-BPy) and the like are usable.
The electron injecting layer is a layer containing a highly electron-injectable substance. Examples of a material for the electron injecting layer include an alkali metal, alkaline earth metal and a compound thereof, examples of which include lithium (Li), cesium (Cs), calcium (Ca), lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), and lithium oxide (LiOx). In addition, the alkali metal, alkaline earth metal or the compound thereof may be added to the substance exhibiting the electron transportability in use. Specifically, for instance, magnesium (Mg) added to Alq may be used. In this case, the electrons can be more efficiently injected from the cathode.
Alternatively, the electron injecting layer may be provided by a composite material in a form of a mixture of the organic compound and the electron donor. Such a composite material exhibits excellent electron injectability and electron transportability since electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material excellent in transporting the generated electrons. Specifically, the above examples (e.g., the metal complex and the hetero aromatic compound) of the substance forming the electron transporting layer are usable. As the electron donor, any substance exhibiting electron donating property to the organic compound is usable. Specifically, the electron donor is preferably alkali metal, alkaline earth metal and rare earth metal such as lithium, cesium, magnesium, calcium, erbium and ytterbium. The electron donor is also preferably alkali metal oxide and alkaline earth metal oxide such as lithium oxide, calcium oxide, and barium oxide. Moreover, a Lewis base such as magnesium oxide is usable. Further, the organic compound such as tetrathiafulvalene (abbreviation: TTF) is usable.
An exemplary arrangement of the organic EL devices according to the first to third exemplary embodiments may be a so-called tandem organic EL device, in which a plurality of emitting regions are layered via a charge generating layer (occasionally also referred to as an intermediate layer and the like). The tandem organic EL device is exemplified by an organic EL device below.
The organic EL device according to an exemplary arrangement of the first to third exemplary embodiments includes a first emitting unit including the hole transporting zone as a first hole transporting zone and the emitting region as a first emitting region;
NL
1
>NL
2 (Numerical Formula L)
The tandem organic EL devices according to the first to third exemplary embodiments have an improved luminous efficiency.
In an exemplary arrangement of the tandem organic EL devices of the first to third exemplary embodiments, a maximum peak wavelength of the first emitting compound and a maximum peak wavelength of the third emitting compound are different from each other.
In an exemplary arrangement of the tandem organic EL device of the first to third exemplary embodiments, the maximum peak wavelength of the first emitting compound is shorter than the maximum peak wavelength of the third emitting compound.
In an exemplary arrangement of the tandem organic EL devices of the first to third exemplary embodiments, one or more maximum peak wavelengths of one or more of the emitting compounds contained in one or more of the emitting layers in the first emitting region are each shorter than one or more maximum peak wavelengths of one or more of the emitting compounds contained in one or more of the emitting layers in the second emitting region.
In an exemplary arrangement of the tandem organic EL devices of the first to third exemplary embodiments, the second hole transporting zone further includes a third cathode side organic layer,
In an exemplary arrangement of the first to third exemplary embodiments, the tandem organic EL device further includes a third emitting unit and a second charge generating layer. The third emitting unit is disposed between the second emitting unit and the cathode, and the second charge generating layer is disposed between the third emitting unit and the second emitting unit.
In an exemplary arrangement of the tandem organic EL devices of the first to third exemplary embodiments, the third emitting unit includes a third emitting region and a third hole transporting zone.
In an exemplary arrangement of the tandem organic EL devices of the first to third exemplary embodiments, the third emitting region includes at least one emitting layer. The emitting layer(s) included in the third emitting region, the first emitting layer included in the first emitting region and the third emitting layer included in the second emitting region may be the same as or different from each other.
In an exemplary arrangement of the tandem organic EL devices of the first to third exemplary embodiments, the third hole transporting zone includes at least one organic layer. The organic layers included in the third hole transporting zone, the first emitting region and the second emitting region may be the same as or different from each other.
In the tandem organic EL device according to each of the first to third exemplary embodiments, the first charge generating layer and the second charge generating layer each mean a layer in which holes and electrons are generated when a voltage is applied. For instance, when the first charge generating layer includes a plurality of layers, the first charge generating layer preferably includes an N layer disposed close to the anode and through which electrons are injected into the first emitting unit, and a P layer disposed close to the cathode and through which holes are injected into the second emitting unit. For instance, when the second charge generating layer includes a plurality of layers, the second charge generating layer preferably includes an N layer disposed close to the anode and through which electrons are injected into the second emitting unit, and a P layer disposed close to the cathode and through which holes are injected into the third emitting unit. Examples of a material usable for the first charge generating layer and the second charge generating layer include a known material(s) usable for the charge generating layer in the tandem organic EL device.
In an exemplary embodiment, the third emitting layer contained in the second emitting region and the emitting layer contained in the third emitting region each contain a host material and an emitting compound. Examples of the host material may be the host materials described in the first exemplary embodiment. Examples of the emitting compound may be the emitting compounds described in the first exemplary embodiment.
In an exemplary arrangement of the organic EL device of each of the first to third exemplary embodiments, the tandem organic EL device is used for a light-emitting apparatus.
In the organic EL device 10A, the first emitting unit 51B and the second emitting unit 52B are connected in series through the first charge generating layer 70.
The organic EL device 10A includes, as two emitting units, the first emitting unit 51B and the second emitting unit 52B.
The first emitting unit 51B includes a first emitting layer 51 and an anode side electron transporting layer 8, which are layered in this order from a side close to the anode 3. The anode side electron transporting layer 8 corresponds to the electron transporting layer 8 in
The second emitting unit 52B includes a first cathode side organic layer 611, a second cathode side organic layer 612, a third emitting layer 600, a cathode side electron transporting layer 631, and an electron injecting layer 641, which are layered in this order from a side close to the first charge generating layer 70.
The emitting region 5 of the first emitting unit 51B includes the first emitting layer 51, and an emitting region 621 of the second emitting unit 52B includes the third emitting layer 600.
The hole transporting zone included between the anode 3 and the first emitting layer 51 includes a first anode side organic layer 61 and a second anode side organic layer 62.
The hole transporting zone included between the first charge generating layer 70 and the third emitting layer 600 includes the first cathode side organic layer 611 and the second cathode side organic layer 612.
The organic EL device 10B differs from the organic EL device 10A of
The arrangements of the tandem organic EL devices depicted in
The organic EL device according to any of the above exemplary embodiments may be a bottom emission type organic EL device.
The organic EL device according to any of the above exemplary embodiments may be a top emission type organic EL device.
A method for forming each layer of the organic EL device according to any of the above exemplary embodiments is subject to no limitation except for the above particular description. However, known methods of dry film-forming such as vacuum deposition, sputtering, plasma or ion plating and wet film-forming such as spin coating, dipping, flow coating or ink-jet are applicable.
The film thickness of each of the organic layers of the organic EL device according to any of the above exemplary embodiments is not limited unless otherwise specified in the above. In general, the thickness preferably ranges from several nanometers to 1 μm because an excessively small film thickness is likely to cause defects (e.g. pin holes) and an excessively large thickness leads to the necessity of applying high voltage and consequent reduction in efficiency.
The organic electroluminescence device according to an exemplary arrangement of any of the exemplary embodiments emits light having a maximum peak wavelength of 500 nm or less when the organic electroluminescence device is driven.
The organic electroluminescence device according to an exemplary arrangement of any of the exemplary embodiments emits light having a maximum peak wavelength in a range from 430 nm to 480 nm when the organic electroluminescence device is driven.
The maximum peak wavelength of the light emitted from the organic EL device when being driven is measured as follows.
Voltage is applied to the organic EL device such that a current density becomes 10 mA/cm2, where spectral radiance spectrum is measured by a spectroradiometer CS-2000 (produced by Konica Minolta, Inc.). A peak wavelength of an emission spectrum, at which the luminous intensity of the obtained spectral radiance spectrum is at the maximum, is measured and defined as a maximum peak wavelength (unit: nm).
A method of measuring triplet energy T1 is exemplified by a method below.
A measurement target compound is dissolved in EPA (diethylether:isopentane:ethanol=5:5:2 in volume ratio) so as to fall within a range from 10−5 mol/L to 10−4 mol/L, and the obtained solution is encapsulated in a quartz cell to provide a measurement sample. A phosphorescence spectrum (ordinate axis: phosphorescent luminous intensity, abscissa axis: wavelength) of the measurement sample is measured at a low temperature (77K). A tangent is drawn to the rise of the phosphorescence spectrum close to the short-wavelength region. An energy amount is calculated by a conversion equation (F1) below on a basis of a wavelength value λedge [nm] at an intersection of the tangent and the abscissa axis. The calculated energy amount is defined as triplet energy T1.
T
1 [eV]=1239.85/λedge Conversion Equation (F1):
The tangent to the rise of the phosphorescence spectrum close to the short-wavelength region is drawn as follows. While moving on a curve of the phosphorescence spectrum from the short-wavelength region to the local maximum value closest to the short-wavelength region among the local maximum values of the phosphorescence spectrum, a tangent is checked at each point on the curve toward the long-wavelength of the phosphorescence spectrum. An inclination of the tangent is increased along the rise of the curve (i.e., a value of the ordinate axis is increased). A tangent drawn at a point of the local maximum inclination (i.e., a tangent at an inflection point) is defined as the tangent to the rise of the phosphorescence spectrum close to the short-wavelength region.
A local maximum point where a peak intensity is 15% or less of the maximum peak intensity of the spectrum is not counted as the above-mentioned local maximum peak intensity closest to the short-wavelength region. The tangent drawn at a point that is closest to the local maximum peak intensity closest to the short-wavelength region and where the inclination of the curve is the local maximum is defined as a tangent to the rise of the phosphorescence spectrum close to the short-wavelength region.
For phosphorescence measurement, a spectrophotofluorometer body F-4500 (manufactured by Hitachi High-Technologies Corporation) is usable. Any device for phosphorescence measurement is usable. A combination of a cooling unit, a low temperature container, an excitation light source and a light-receiving unit may be used for phosphorescence measurement.
A method of measuring the singlet energy S1 with use of a solution (occasionally referred to as a solution method) is exemplified by a method below.
A toluene solution of a measurement target compound at a concentration ranging from 10−5 mol/L to 10−4 mol/L is prepared and put in a quartz cell. An absorption spectrum (ordinate axis: absorption intensity, abscissa axis: wavelength) of the thus-obtained sample is measured at a normal temperature (300K). A tangent is drawn to the fall of the absorption spectrum close to the long-wavelength region, and a wavelength value λedge (nm) at an intersection of the tangent and the abscissa axis is assigned to a conversion equation (F2) below to calculate singlet energy.
S
1 [eV]=1239.85/λedge Conversion Equation (F2):
Any device for measuring absorption spectrum is usable. For instance, a spectrophotometer (U3310 manufactured by Hitachi, Ltd.) is usable.
The tangent to the fall of the absorption spectrum close to the long-wavelength region is drawn as follows. While moving on a curve of the absorption spectrum from the local maximum value closest to the long-wavelength region, among the local maximum values of the absorption spectrum, in a long-wavelength direction, a tangent at each point on the curve is checked. An inclination of the tangent is decreased and increased in a repeated manner as the curve falls (i.e., a value of the ordinate axis is decreased). A tangent drawn at a point where the inclination of the curve is the local minimum closest to the long-wavelength region (except when absorbance is 0.1 or less) is defined as the tangent to the fall of the absorption spectrum close to the long-wavelength region.
The local maximum absorbance of 0.2 or less is not counted as the above-mentioned local maximum absorbance closest to the long-wavelength region.
The electron mobility can be measured according to an impedance measurement using a mobility evaluation device produced by the following steps. The mobility evaluation device is, for instance, produced by the following steps.
A compound Target, which is to be measured for an electron mobility, is vapor-deposited on a glass substrate having an aluminum electrode (anode) so as to cover the aluminum electrode, thereby forming a measurement target layer. A compound ET-A below is vapor-deposited on this measurement target layer to form an electron transporting layer. LiF is vapor-deposited on this formed electron transporting layer to form an electron injecting layer. Metal aluminum (Al) is vapor-deposited on this formed electron injecting layer to form a metal cathode.
An arrangement of the mobility evaluation device above is roughly shown as follows.
Numerals in parentheses represent a film thickness (nm).
The mobility evaluation device for the electron mobility is set in an impedance measurement device to perform an impedance measurement. In the impedance measurement, a measurement frequency is swept from 1 Hz to 1 MHz. At this time, an alternating current amplitude of 0.1 V and a direct current voltage V are applied to the device. A modulus M is calculated from a measured impedance Z using a relationship of a calculation formula (C1) below.
M=jωZ Calculation formula (C1):
In the calculation formula (C1), j is an imaginary unit whose square is −1 and ω is an angular frequency [rad/s].
In a bode plot in which an imaginary part of the modulus M is represented by an ordinate axis and the frequency [Hz] is represented by an abscissa axis, an electrical time constant τ of the mobility evaluation device is obtained from a frequency fmax showing a peak using a calculation formula (C2) below.
τ=1/(2πfmax) Calculation formula (C2):
π in the calculation formula (C2) is a symbol representing a circumference ratio.
An electron mobility μe is calculated from a relationship of a calculation formula (C3-1) below using τ.
μe=d2/(Vτ) Calculation formula (C3-1):
d in the calculation formula (C3-1) is a total film thickness of organic thin film(s) forming the device. In a case of the arrangement of the mobility evaluation device for the electron mobility, d=210 [nm] is satisfied.
The hole mobility can be measured according to an impedance measurement using a mobility evaluation device produced by the following steps. The device for mobility evaluation is produced, for instance, according to the following steps.
A compound HA-2 below is vapor-deposited on a glass substrate having an ITO transparent electrode (anode) so as to cover the transparent electrode, thereby forming a hole injecting layer. A compound HT-A below is vapor-deposited on this formed hole injecting layer to form a hole transporting layer. Subsequently, a compound Target, which is to be measured for a hole mobility, is vapor-deposited to form a measurement target layer. Metal aluminum (Al) is vapor-deposited on this measurement target layer to form a metal cathode.
An arrangement of the mobility evaluation device above is roughly shown as follows.
Numerals in parentheses represent a film thickness (nm).
The mobility evaluation device for the hole mobility is set in an impedance measurement device to perform an impedance measurement. In the impedance measurement, a measurement frequency is swept from 1 Hz to 1 MHz. At this time, an alternating current amplitude of 0.1 V and a direct current voltage V are applied to the device. A modulus M is calculated from a measured impedance Z using the relationship of the calculation formula (C1).
In a bode plot in which an imaginary part of the modulus M is represented by an ordinate axis and the frequency [Hz] is represented by an abscissa axis, an electrical time constant T of the mobility evaluation device is obtained from a frequency fmax showing a peak using the calculation formula (C2).
A hole mobility μh is calculated from a relationship of a calculation formula (C3-2) below using T obtained from the calculation formula (C2).
μh=d2/(Vτ) Calculation formula (C3-2):
d in the calculation formula (C3-2) is a total film thickness of organic thin film(s) forming the device. In a case of the arrangement of the mobility evaluation device for the hole mobility, d=215 [nm] is satisfied.
The electron mobility and the hole mobility herein are each a value obtained in a case where a square root of an electric field intensity meets E1/2=500 [V1/2/cm1/2]. The square root of the electric field intensity, E1/2, can be calculated from a relationship of a calculation formula (C4) below.
E
1/2
=V
1/2
/d
1/2 Calculation formula (C4):
For the impedance measurement, a 1260 type by Solartron Analytical is used as the impedance measurement device, and for a higher accuracy, a 1296 type dielectric constant measurement interface by Solartron Analytical can be used together therewith.
An organic EL device according to an additional exemplary embodiment 1 will be described below.
In the organic EL device of the additional exemplary embodiment 1, the “first emitting layer” corresponds to the “second emitting layer” described in the first exemplary embodiment, and the “second emitting layer” corresponds to the “first emitting layer” described in the first exemplary embodiment.
For the rest of the arrangement, elements that may be contained in the organic EL device of the additional exemplary embodiment 1 are similar to the elements that may be contained in the organic EL device described in the first exemplary embodiment.
The organic EL device according to the additional exemplary embodiment 1 includes:
According to the additional exemplary embodiment 1, a luminous efficiency of the organic EL device is improvable.
An organic EL display device according to additional exemplary embodiment 2 will be described below.
In the organic EL display device of the additional exemplary embodiment 2, the “blue-emitting organic EL device as a blue pixel” corresponds to the organic EL device of the additional exemplary embodiment 1.
Thus, elements that may be contained in the organic EL display device of the additional exemplary embodiment 2 are similar to the elements that may be contained in the organic EL device of the additional exemplary embodiment 1.
An organic EL display device of the additional exemplary embodiment 2 includes:
An electronic device according to a fourth exemplary embodiment is installed with the organic EL device according to any of the above exemplary embodiments. Examples of the electronic device include a display device and a light-emitting apparatus. Examples of the display device include a display component (e.g., an organic EL panel module), TV, mobile phone, tablet and personal computer. Examples of the light-emitting apparatus include an illuminator and a vehicle light.
In an exemplary arrangement of the electronic device according to the fourth exemplary embodiment, the light-emitting apparatus is installed with the tandem organic EL device according to the above exemplary embodiment. In an exemplary arrangement of the electronic device according to the fourth exemplary embodiment, the light-emitting apparatus preferably includes the tandem organic EL device according to the above exemplary embodiments and a color conversion layer. The light-emitting apparatus preferably includes a color filter. The color conversion layer is preferably disposed between the tandem organic EL device and the color filter. The color conversion layer preferably contains a substance that emits light by absorbing light. The substance that emits light by absorbing light is preferably a quantum dot. In the light-emitting apparatus, the color conversion layer is preferably disposed to be irradiated with light emission from the tandem organic EL device.
In an exemplary arrangement of the electronic device according to the fourth exemplary embodiment, the display device is installed with the light-emitting apparatus. The light-emitting apparatus also can be used for a display device, for instance, as a backlight of the display device.
The scope of the invention is not limited by the above-described exemplary embodiments but includes any modification and improvement as long as such modification and improvement are compatible with the invention.
For instance, the number of emitting layers is not limited to one or two, and more than two emitting layers may be layered. For instance, the rest of the emitting layers may be a fluorescent emitting layer or a phosphorescent emitting layer with use of emission caused by electron transfer from the triplet excited state directly to the ground state.
Further, for instance, a blocking layer is optionally provided adjacent to a side of the emitting layer close to the cathode. The blocking layer provided in direct contact with the side of the emitting layer close to the cathode preferably blocks at least one of holes or excitons.
For instance, when the blocking layer is provided in contact with the side of the emitting layer close to the cathode, the blocking layer permits transport of electrons, and blocks holes from reaching a layer provided closer to the cathode (e.g., the electron transporting layer) beyond the blocking layer. When the organic EL device includes the electron transporting layer, the blocking layer may be disposed between the emitting layer and the electron transporting layer.
Alternatively, the blocking layer may be provided adjacent to the emitting layer so that the excitation energy does not leak out from the emitting layer toward neighboring layer(s). The blocking layer blocks excitons generated in the emitting layer from being transferred to a layer(s) (e.g., the electron transporting layer and the like) closer to the electrode(s) than the blocking layer. The emitting layer is preferably in direct contact with the blocking layer.
Specific structure, shape and the like of the components in the invention may be designed in any manner as long as an object of the invention can be achieved.
The invention will be described in further detail with reference to Examples. The scope of the invention is by no means limited to Examples.
Structures of compounds as the first organic material used for producing organic EL devices in Examples are shown below.
Structures of compounds as the second organic material, the second hole transporting zone material and the third hole transporting zone material used for producing organic EL devices in Examples are shown below.
Structures of the other compounds used for producing organic EL devices in Examples are shown below.
The organic EL devices were produced and evaluated as follows.
A glass substrate (size: 25 mm×75 mm×1.1 mm thick, produced by Geomatec Co., Ltd.) having an ITO transparent electrode (anode) was ultrasonic-cleaned in isopropyl alcohol for five minutes, and then UV-ozone-cleaned for 30 minutes. The film thickness of the ITO transparent electrode was 130 nm.
After the glass substrate having the transparent electrode line was cleaned, the glass substrate was mounted on a substrate holder of a vacuum deposition apparatus. First, a compound HT-1-1 (second organic material) and a compound HA (first organic material) were co-deposited on a surface of the glass substrate, where the transparent electrode line was provided, to cover the transparent electrode, thereby forming a 10-nm-thick first anode side organic layer (occasionally also referred to as a hole injecting layer). The ratios of the compound HT-1-1 and the compound HA in the first anode side organic layer were 97 mass % and 3 mass %, respectively.
A compound HT-2-1 (second hole transporting material) was vapor-deposited on the first anode side organic layer to form a 40-nm-thick second anode side organic layer (occasionally also referred to as a first hole transporting layer).
A compound BH-1 (first host material) and a compound BD-1 (first emitting compound) were co-deposited on the second anode side organic layer, thereby forming a 25-nm-thick first emitting layer. The ratios of the compound BH-1 and the compound BD-1 in the first emitting layer were 97 mass % and 3 mass %, respectively.
A compound ET-1 was vapor-deposited on the first emitting layer to form a 10-nm-thick first electron transporting layer (occasionally also referred to as a hole blocking layer (HBL)).
A compound ET-2 was vapor-deposited on the first electron transporting layer to form a 15-nm-thick second electron transporting layer (ET).
A compound LiF was vapor-deposited on the second electron transporting layer to form a 1-nm-thick electron injecting layer.
Metal (A1) was vapor-deposited on the electron injecting layer to form an 80-nm-thick cathode.
A device arrangement of the organic EL device in Example 1-1 is roughly shown as follows.
Numerals in parentheses represent a film thickness (unit: nm).
The numerals (97%:3%) represented by percentage in the same parentheses indicate a ratio (mass %) between the compound HT-1-1 and the compound HA in the first anode side organic layer. The numerals (97%:3%) represented by percentage in the same parentheses indicate a ratio (mass %) between the first host material (compound BH-1) and the first emitting compound (compound BD-1) in the first emitting layer.
Organic EL devices of Examples 1-2 to 1-3 were each produced in the same manner as in Example 1-1 except that the compound BD-1 contained in the first emitting layer was changed to a compound shown in Table 1.
An organic EL device of Comparative Example 1-1 was produced in the same manner as in Example 1-1 except that the compound HT-2-1 contained in the second anode side organic layer was changed to a compound shown in Table 1 and that the compound BD-1 contained in the first emitting layer was changed to a compound shown in Table 1.
An organic EL device of Comparative Example 1-2 was produced in the same manner as in Example 1-2 except that the compound HT-2-1 contained in the second anode side organic layer was changed to a compound shown in Table 1.
The produced organic EL devices were evaluated as follows. Tables 1 to 4 show evaluation results.
A voltage (unit: V) was measured when current was applied between the anode and the cathode such that a current density was 10 mA/cm2.
Voltage was applied to the organic EL devices such that a current density was 10 mA/cm2, where spectral radiance spectrum was measured by a spectroradiometer CS-2000 (produced by Konica Minolta, Inc.). The external quantum efficiency EQE (unit: %) was calculated based on the obtained spectral radiance spectra, assuming that the spectra were provided under a Lambertian radiation.
Voltage was applied to the produced organic EL devices so that a current density was 50 mA/cm2, where a time (LT95 (unit: hr)) elapsed before a luminance intensity was reduced to 95% of the initial luminance intensity was measured. The luminance intensity was measured by a spectroradiometer CS-2000 (produced by Konica Minolta, Inc.).
Examples 1-1 to 1-3, in which the refractive index NM1 of the constituent materials contained in the first anode side organic layer and the refractive index NM2 of the constituent material contained in the second anode side organic layer satisfied the relationship of the numerical formula (Numerical Formula NM) (NM1>NM2), emitted light with higher efficiency and had a longer life compared to Comparative Examples 1-1 and 1-2, in which the relationship of the numerical formula (Numerical Formula NM) was not satisfied.
A glass substrate (size: 25 mm×75 mm×1.1 mm thick, produced by Geomatec Co., Ltd.) having an ITO transparent electrode (anode) was ultrasonic-cleaned in isopropyl alcohol for five minutes, and then UV-ozone-cleaned for 30 minutes. The film thickness of the ITO transparent electrode was 130 nm.
After the glass substrate having the transparent electrode line was cleaned, the glass substrate was mounted on a substrate holder of a vacuum deposition apparatus. First, a compound HT-1-3 and a compound HA were co-deposited on a surface of the glass substrate, where the transparent electrode line was provided, to cover the transparent electrode, thereby forming a 10-nm-thick first anode side organic layer (occasionally also referred to as a hole injecting layer). The ratios of the compound HT-1-3 and the compound HA in the first anode side organic layer were 97 mass % and 3 mass %, respectively.
A compound HT-2-3 was vapor-deposited on the first anode side organic layer to form a 40-nm-thick second anode side organic layer (occasionally also referred to as a first hole transporting layer).
A compound BH-2 (first host material), a compound BH-4 (first additional host material) and a compound BD-4 (first emitting compound) were co-deposited on the second anode side organic layer, thereby forming a 25-nm-thick first emitting layer. The ratios of the compound BH-2, the compound BH-4 and the compound BD-4 in the first emitting layer were 50 mass %, 47 mass %, 3 mass %, respectively.
A compound ET-1 was vapor-deposited on the first emitting layer to form a 5-nm-thick first electron transporting layer (occasionally also referred to as a hole blocking layer (HBL)).
A compound ET-4 and a compound Liq were co-deposited on the first electron transporting layer such that the ratio of the compound ET4 was 50 mass % and the ratio of the compound Liq was 50 mass % to form a 20-nm-thick second electron transporting layer (ET).
A compound LiF was vapor-deposited on the second electron transporting layer to form a 1-nm-thick electron injecting layer.
Metal (A1) was vapor-deposited on the electron injecting layer to form an 80-nm-thick cathode.
A device arrangement of the organic EL device in Example 2-1 is roughly shown as follows.
Numerals in parentheses represent a film thickness (unit: nm).
The numerals (97%:3%) represented by percentage in the same parentheses indicate a ratio (mass %) between the compound HT-1-3 and the compound HA in the first anode side organic layer, the numerals (50%: 47%:3%) represented by percentage in the same parentheses indicate a ratio (mass %) between the first host material (compound BH-2), the first additional host material (compound BH-4), and the first emitting compound (compound BD-4) in the first emitting layer, and the numerals (50%:50%) represented by percentage in the same parentheses indicate a ratio (mass %) between the compound ET-4 and the compound Liq in the second electron transporting layer.
An organic EL device of Example 2-2 was produced in the same manner as in Example 2-1 except that the compound BH-4 and the compound BD-4 were co-deposited on the second anode side organic layer to form the first emitting layer. The ratios of the compound BH-4 and the compound BD-4 in the first emitting layer were 97 mass % and 3 mass %, respectively.
An organic EL device of Example 2-3 was produced in the same manner as in Example 2-1 except that the compound BH-2 and the compound BD-4 were co-deposited on the second anode side organic layer to form the first emitting layer. The ratios of the compound BH-2 and the compound BD-4 in the first emitting layer were 97 mass % and 3 mass %, respectively.
An organic EL device of Comparative Example 2-1 was produced in the same manner as in Example 2-1 except that the compound HT-1-3 was vapor-deposited on the first anode side organic layer to form a 35-nm-thick second anode side organic layer, that the compound HT-2-3 was vapor-deposited on this second anode side organic layer to form a 5-nm-thick third anode side organic layer, and that the first emitting layer was formed on this third anode side organic layer.
An organic EL device of Comparative Example 2-2 was produced in the same manner as in Example 2-2 except that the compound HT-1-3 was vapor-deposited on the first anode side organic layer to form a 35-nm-thick second anode side organic layer, that the compound HT-2-3 was vapor-deposited on this second anode side organic layer to form a 5-nm-thick third anode side organic layer, and that the first emitting layer was formed on this third anode side organic layer.
An organic EL device of Comparative Example 2-3 was produced in the same manner as in Example 2-3 except that the compound HT-1-3 was vapor-deposited on the first anode side organic layer to form a 35-nm-thick second anodic organic layer, that the compound HT-2-3 was vapor-deposited on this second anode side organic layer to form a 5-nm-thick third anode side organic layer, and that the first emitting layer was formed on this third anode side organic layer.
Example 2-1, in which the refractive index NM1 of the constituent materials contained in the first anode side organic layer and the refractive index NM2 of the constituent material contained in the second anode side organic layer satisfied the relationship of the numerical formula (Numerical Formula NM) (NM1>NM2), emitted light with higher efficiency and had a longer life compared to Comparative Example 2-1, in which the relationship of the numerical formula (Numerical Formula NM) was not satisfied.
Example 2-2, in which the refractive index NM1 of the constituent materials contained in the first anode side organic layer and the refractive index NM2 of the constituent material contained in the second anode side organic layer satisfied the relationship of the numerical formula (Numerical Formula NM) (NM1>NM2), emitted light with higher efficiency compared to Comparative Example 2-2, in which the relationship of the numerical formula (Numerical Formula NM) was not satisfied. Similarly, Example 2-3 emitted light with higher efficiency than Comparative Example 2-3.
A glass substrate (size: 25 mm×75 mm×1.1 mm thick, produced by Geomatec Co., Ltd.) having an ITO transparent electrode (anode) was ultrasonic-cleaned in isopropyl alcohol for five minutes, and then UV-ozone-cleaned for 30 minutes. The film thickness of the ITO transparent electrode was 130 nm.
After the glass substrate having the transparent electrode line was cleaned, the glass substrate was mounted on a substrate holder of a vacuum deposition apparatus. First, a compound HT-1-2 and a compound HA were co-deposited on a surface of the glass substrate, where the transparent electrode line was provided, to cover the transparent electrode, thereby forming a 10-nm-thick first anode side organic layer (occasionally also referred to as a hole injecting layer). The ratios of the compound HT-1-2 and the compound HA in the first anode side organic layer were 97 mass % and 3 mass %, respectively.
A compound HT-2-2 was vapor-deposited on the first anode side organic layer to form a 40-nm-thick second anode side organic layer (occasionally also referred to as a first hole transporting layer).
A compound HT-3-1 was vapor-deposited on the second anode side organic layer to form a 5-nm-thick third anode side organic layer (occasionally also referred to as a second hole transporting layer or an electron blocking layer).
A compound BH-2 (first host material) and a compound BD-4 (first emitting compound) were co-deposited on the third anode side organic layer, thereby forming a 25-nm-thick first emitting layer. The ratios of the compound BH-2 and the compound BD-4 in the first emitting layer were 97 mass % and 3 mass %, respectively.
A compound ET-1 was vapor-deposited on the first emitting layer to form a 5-nm-thick first electron transporting layer (occasionally also referred to as a hole blocking layer (HBL)).
A compound ET-2 was vapor-deposited on the first electron transporting layer to form a 20-nm-thick second electron transporting layer (ET).
A compound LiF was vapor-deposited on the second electron transporting layer to form a 1-nm-thick electron injecting layer.
Metal (A1) was vapor-deposited on the electron injecting layer to form an 80-nm-thick cathode.
A device arrangement of the organic EL device in Example 3-1 is roughly shown as follows.
Numerals in parentheses represent a film thickness (unit: nm).
The numerals (97%:3%) represented by percentage in the same parentheses indicate a ratio (mass %) between the compound HT-1-2 and the compound HA in the first anode side organic layer. The numerals (97%:3%) represented by percentage in the same parentheses indicate a ratio (mass %) between the first host material (compound BH-2) and the first emitting compound (compound BD-4) in the first emitting layer.
Organic EL devices of Examples 3-2, 3-3, 3-5 and 3-6 were each produced in the same manner as in Example 3-1, except that the compound contained in the first electron transporting layer, the compound contained in the second electron transporting layer, the film thickness of the first electron transporting layer and the film thickness of the second electron transporting layer were changed to compounds and film thicknesses shown in Table 3.
In Table 3, the numerals (70%:30%) represented by percentage indicate a ratio (mass %) between the compound ET-4 and the compound Liq in the second electron transporting layer; and the numerals (50%:50%) represented by percentage indicate a ratio (mass %) between the compound ET-6 and the compound Liq in the second electron transporting layer or a ratio (mass %) between the compound ET-9 and the compound Liq in the second electron transporting layer.
An organic EL device of Examples to 3-4 was produced in the same manner as in Example 3-1 except that the compound contained in the first electron transporting layer and the film thickness of the first electron transporting layer were respectively changed to a compound and a film thickness shown in Table 3, and that the second electron transporting layer was not formed.
In Table 3, the numerals (50%:50%) represented by percentage indicate a ratio (mass %) between the compound ET-2 and the compound ET7 in the second electron transporting layer.
An organic EL device of Comparative Example 3-1 was produced in the same manner as in Example 3-1 except that the second hole transporting zone material was changed to a compound shown in Table 3, that the compound contained in the first electron transporting layer and the film thickness of the first electron transporting layer were respectively changed to a compound and a film thickness shown in Table 3, and that the second electron transporting layer was not formed. In Table 3, Alq3 represents tris(8-quinolinolato)aluminum.
Examples 3-1 to 3-6, in which the refractive index NM1 of the constituent materials contained in the first anode side organic layer and the refractive index NM2 of the constituent material contained in the second anode side organic layer satisfied the relationship of the numerical formula (Numerical Formula NM) (NM1>NM2), emitted light with higher efficiency and had a longer life compared to Comparative Example 3-1, in which the relationship of the numerical formula (Numerical Formula NM) was not satisfied. Examples 3-1 to 3-6 were driven at a lower voltage compared to Comparative Example 3-1.
A glass substrate (size: 25 mm×75 mm×1.1 mm thick, produced by Geomatec Co., Ltd.) having an ITO transparent electrode (anode) was ultrasonic-cleaned in isopropyl alcohol for five minutes, and then UV-ozone-cleaned for 30 minutes. The film thickness of the ITO transparent electrode was 130 nm.
After the glass substrate having the transparent electrode line was cleaned, the glass substrate was mounted on a substrate holder of a vacuum deposition apparatus. First, a compound HT-1-2 and a compound HA were co-deposited on a surface of the glass substrate, where the transparent electrode line was provided, to cover the transparent electrode, thereby forming a 10-nm-thick first anode side organic layer (occasionally also referred to as a hole injecting layer). The ratios of the compound HT-1-2 and the compound HA in the first anode side organic layer were 97 mass % and 3 mass %, respectively.
A compound HT-2-4 was vapor-deposited on the first anode side organic layer to form a 40-nm-thick second anode side organic layer (occasionally also referred to as a first hole transporting layer).
A compound HT-3-2 was vapor-deposited on the second anode side organic layer to form a 5-nm-thick third anode side organic layer (occasionally also referred to as a second hole transporting layer or an electron blocking layer).
A compound BH-1 (first host material) and a compound BD-5 (first emitting compound) were co-deposited on the third anode side organic layer, thereby forming a 25-nm-thick first emitting layer. The ratios of the compound BH-1 and the compound BD-5 in the first emitting layer were 99 mass % and 1 mass %, respectively.
A compound ET-12 was vapor-deposited on the first emitting layer to form a 10-nm-thick first electron transporting layer (occasionally also referred to as a hole blocking layer (HBL)).
A compound ET-2 was vapor-deposited on the first electron transporting layer to form a 15-nm-thick second electron transporting layer (ET).
A compound LiF was vapor-deposited on the second electron transporting layer to form a 1-nm-thick electron injecting layer.
Metal (A1) was vapor-deposited on the electron injecting layer to form an 80-nm-thick cathode.
A device arrangement of the organic EL device in Example 4-1 is roughly shown as follows.
Numerals in parentheses represent a film thickness (unit: nm).
The numerals (97%:3%) represented by percentage in the same parentheses indicate a ratio (mass %) between the compound HT-1-2 and the compound HA in the first anode side organic layer. The numerals (99%:1%) represented by percentage in the same parentheses indicate a ratio (mass %) between the first host material (compound BH-1) and the first emitting compound (compound BD-5) in the first emitting layer.
An organic EL device of Comparative Example 4-1 was produced in the same manner as in Example 4-1 except that the compound HT-2-4 contained in the second anode side organic layer was changed to a compound shown in Table 4 and that the compound BD-5 contained in the first emitting layer was changed to a compound shown in Table 4.
Example 4-1, in which the refractive index NM1 of the constituent materials contained in the first anode side organic layer and the refractive index NM2 of the constituent material contained in the second anode side organic layer satisfied the relationship of the numerical formula (Numerical Formula NM) (NM1>NM2), emitted light with higher efficiency and had a longer life compared to Comparative Example 4-1, in which the relationship of the numerical formula (Numerical Formula NM) was not satisfied.
A toluene solution of a measurement target compound at a concentration of 10 μmol/L was prepared and put in a quartz cell. An absorption spectrum (ordinate axis: absorption intensity, abscissa axis: wavelength) of the thus-obtained sample was measured at a normal temperature (300K). A tangent was drawn to the fall of the absorption spectrum close to the long-wavelength region, and a wavelength value λedge (nm) at an intersection of the tangent and the abscissa axis was assigned to a conversion equation (F2) below to calculate singlet energy.
S
1 [eV]=1239.85/λedge Conversion Equation (F2):
A spectrophotometer (U3310 produced by Hitachi, Ltd.) was used for measuring absorption spectrum.
The tangent to the fall of the absorption spectrum close to the long-wavelength region is drawn as follows. While moving on a curve of the absorption spectrum from the local maximum value closest to the long-wavelength region, among the local maximum values of the absorption spectrum, in a long-wavelength direction, a tangent at each point on the curve is checked. An inclination of the tangent is decreased and increased in a repeated manner as the curve falls (i.e., a value of the ordinate axis is decreased). A tangent drawn at a point where the inclination of the curve is the local minimum closest to the long-wavelength region (except when absorbance is 0.1 or less) is defined as the tangent to the fall of the absorption spectrum close to the long-wavelength region.
The local maximum absorbance of 0.2 or less is not counted as the above-mentioned local maximum absorbance closest to the long-wavelength region.
A measurement target compound was dissolved in EPA (diethylether:isopentane:ethanol=5:5:2 in volume ratio) at a concentration of 10 μmol/L to prepare a solution, and the solution was put in a quartz cell to provide a measurement sample. A phosphorescence spectrum (ordinate axis: phosphorescent luminous intensity, abscissa axis: wavelength) of the measurement sample was measured at a low temperature (77K). A tangent was drawn to the rise of the phosphorescence spectrum close to the short-wavelength region. An energy amount was calculated by a conversion equation (F1) below on a basis of a wavelength value λedge [nm] at an intersection of the tangent and the abscissa axis. The calculated energy amount was defined as triplet energy T1. It should be noted that the triplet energy T1 may have an error of about plus or minus 0.02 eV depending on measurement conditions.
T
1 [eV]=1239.85/λedge Conversion Equation (F1):
The tangent to the rise of the phosphorescence spectrum close to the short-wavelength region is drawn as follows. While moving on a curve of the phosphorescence spectrum from the short-wavelength region to the local maximum value closest to the short-wavelength region among the local maximum values of the phosphorescence spectrum, a tangent is checked at each point on the curve toward the long-wavelength of the phosphorescence spectrum. An inclination of the tangent is increased along the rise of the curve (i.e., a value of the ordinate axis is increased). A tangent drawn at a point of the local maximum inclination (i.e., a tangent at an inflection point) is defined as the tangent to the rise of the phosphorescence spectrum close to the short-wavelength region.
A local maximum point where a peak intensity is 15% or less of the maximum peak intensity of the spectrum is not counted as the above-mentioned local maximum peak intensity closest to the short-wavelength region. The tangent drawn at a point that is closest to the local maximum peak intensity closest to the short-wavelength region and where the inclination of the curve is the local maximum is defined as a tangent to the rise of the phosphorescence spectrum close to the short-wavelength region.
For phosphorescence measurement, a spectrophotofluorometer body F-4500 produced by Hitachi High-Technologies Corporation was used.
A measurement target compound was dissolved in toluene at a concentration of 4.9×10−6 mol/L to prepare a toluene solution thereof. Using a fluorescence spectrometer (spectrophotofluorometer F-7000 manufactured by Hitachi High-Tech Science Corporation), the toluene solution of the measurement target compound was excited at 390 nm, where a maximum fluorescence peak wavelength A (unit: nm) was measured.
Table 5 shows measurement values of the singlet energy S1, the triplet energy T1 and the maximum fluorescence peak wavelength A of the compounds used for the preparation of the organic EL devices.
The refractive index of the constituent materials (compounds) forming the organic layer was measured as follows.
A measurement target material was vacuum-deposited on a glass substrate to form a film having an approximately 50 nm thickness. Using a spectroscopic ellipsometer (M-2000U1, produced by J. A. Woollam Co., Inc. (US)), the obtained sample film was irradiated with incident light (from ultraviolet light through visible light to near-infrared light) every 5 degrees in a measurement angle range of 45 degrees to 75 degrees to measure change in a deflection state of the light reflected on the sample surface. In order to improve the measurement accuracy of the extinction coefficient, a transmission spectrum in a substrate normal direction (direction perpendicular to a surface of the substrate of the organic EL device) was also measured by M-2000U1. Similarly, the same measurement was performed also on the glass substrate on which no measurement target material was vapor-deposited. The obtained measurement information was fitted using analysis software (Complete EASE) produced by J. A. Woollam Co., Inc.
Refractive indices in an in-plane direction and a normal direction, extinction coefficients in the in-plane direction and the normal direction, and an order parameter of an organic film formed on the substrate were calculated under fitting conditions of using an anisotropic model rotationally symmetric about one axis and setting a parameter MSE indicating a mean square error in said analysis software to be 3.0 or less. A peak close to the long-wavelength region of the extinction coefficient (in-plane direction) was defined as S1, and the order parameter was calculated by a peak wavelength of S1. As fitting conditions for the glass substrate, an isotropic model was used.
Typically, a film formed by vacuum-depositing a low molecular material on the substrate is rotationally symmetric about one axis extending along the substrate normal direction. When an angle formed by the substrate normal direction and a molecular axis in a thin film formed on the substrate is defined as 6 and the extinction coefficients in a substrate parallel direction (Ordinary direction) and a substrate perpendicular direction (Extra-Ordinary direction) obtained by performing the variable-angle spectroscopic ellipsometry measurement on the thin film are respectively defined as ko and ke, S′ represented by a formula below is the order parameter.
S′=1−<cos 2θ>=2ko/(ke+2ko)=2/3(1−S)
S=(1/2)<3 cos 2θ−1>=(ke−ko)/(ke+2ko)
An evaluation method of the molecular orientation is a publicly known method, and details thereof are described in Organic Electronics, volume 10, page 127 (2009). Further, the method for forming the thin film is a vacuum deposition method.
The order parameter S′ obtained by the variable-angle spectroscopic ellipsometry measurement is 1.0 when all molecules are oriented in parallel with the substrate. When molecules are random without being oriented, the order parameter S′ is 0.66.
Herein, a value at 2.7 eV in the substrate parallel direction (Ordinary direction), from among the values measured above, is defined as a refractive index of the measurement target material.
When a layer was formed by a constituent material containing a plurality of compounds, a refractive index of the constituent material of the layer, the layer being a film formed by co-depositing the plurality of compounds as the measurement target material on the glass substrate or a film formed by vapor-depositing a mixture containing the plurality of compounds, was measured using a spectroscopic ellipsometer in the same manner as above.
Tables 1 to 4 show constituent materials of the first and second anode side organic layers, refractive indices of the constituent materials (compounds) of the individual layers, and the differences in refractive index NM1−NM2.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-217949 | Dec 2020 | JP | national |
| 2021-074498 | Apr 2021 | JP | national |
| 2021-106108 | Jun 2021 | JP | national |
| 2021-106127 | Jun 2021 | JP | national |
| 2021-163146 | Oct 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/048350 | 12/24/2021 | WO |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17511495 | Oct 2021 | US |
| Child | 18259254 | US | |
| Parent | 17511495 | Oct 2021 | US |
| Child | 17511495 | US |
