Patent Grant
11424418
The present invention relates to the field of organic electroluminescent devices. More particularly, the present invention relates to an organic electroluminescent device comprising a mixture of at least two materials.
The structures of organic electroluminescent devices in which an organic semiconductor is used as a functional material are described in U.S. Pat. Nos. 4,539,507, 5,151,629, EP 0676461, and WO 9827136, for example. Luminescent materials used here more tend to be organometallic complexes that exhibit phosphorescence rather than fluorescence (M. A. Baldo et al., Appl. Phys. Lett. 1999, 75, 4-6). For quantum mechanical reasons, the use of an organometallic compound as a phosphorescence emitter can achieve up to a four-fold increase in energy and power efficiency. However, in general, triplet-emitting organic electroluminescent devices still need to be improved, for example, they still need to be improved in terms of efficiency, operating voltage, lifetime etc. This applies in particular to OLEDs that emit light in relatively long wave regions, such as red light.
The properties of phosphorescent OLEDs are not only determined by triplet light emitters used, other materials used, particularly matrix materials, are also particularly important here.
Therefore, it is an urgent problem to find an organic luminescent material with improved luminous efficiency, operating voltage, lifetime etc. achieved by a good synergy between a doping material and a matrix.
In order to solve one of the problems present in the prior art, the inventors have found after intensive research that by using the organic electroluminescent material of the present invention, which contains at least one organic compound A with 3.0 eV>ET≥2.0 eV and compound B represented by formula M(LA)x(LB)y(LC)z, in an organic electroluminescent device, an organic electroluminescent device with an improved lifetime and/or a reduced operating voltage can be obtained.
The absolute value of ET[B]−ET[A] is ≤0.5 eV, in which ET[B] represents the triplet energy level of the compound B, and ET[A] represents the triplet energy level of the organic compound A;
in the formula M(LA)x(LB)y(LC)z,
M represents a metal element with an atomic weight greater than 40;
x represents an integer of 1, 2 or 3, y represents an integer of 0, 1 or 2, z represents an integer of 0, 1 or 2, and the sum of x, y and z is equal to the oxidation state of metal M;
LA is LA1 or LA2:
R1 is selected from the group consisting of C(Ra)3, trans-cyclohexyl having a 1-8 carbon atom substituent, and a 1,1′-bis(trans-cyclohexyl)-4-substituent having a 1-8 carbon atom substituent;
R4 and R5 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, an alkyl group, a cycloalkyl group, a heteroalkyl group, an aralkyl group, an alkoxy group, an aryloxy group, an amino group, a silyl group, an alkenyl group, a cycloalkenyl group, a heteroalkenyl group, an alkynyl group, an aryl group, and a heterocyclic aryl group;
there is one or two or more substituents R1;
there is one or two or more substituents R4 on ring A and ring B;
there is one or two or more substituents R5 on ring C;
X1, X2, X3 and X4 are each independently carbon or nitrogen, and X1, X2 and X3 are not nitrogen at the same time;
n represents an integer ≥0;
each Ra is independently selected from the group consisting of a C1-C40 linear alkyl group, a C1-C40 linear heteroalkyl group, a C3-C40 branched or cyclic alkyl group, a C3-C40 branched or cyclic heteroalkyl group, and a C2-C40 alkenyl or alkynyl group, with these groups being optionally substituted with one or more R6, one or more non-adjacent —CH2— groups being optionally replaced by —R6C═CR6—, —C≡C—, —Si(R6)2—, —Ge(R6)2—, —Sn(R6)2—, —C(═O)—, —C(═S)—, —C(═Se)—, —C(═NR6)—, —P(═O)(R6)—, —S(O)—, —S(O2)—, —N(R6)—, —O—, —S— or —C(ONR6)—, and one or more hydrogen atoms in Ra being optionally replaced by a deuterium atom, a halogen atom, a nitrile group or a nitro group, wherein two or more adjacent substituents Ra are optionally joined or fused to form a monocyclic or polycyclic aliphatic, aromatic or heteroaromatic ring system optionally substituted with one or more groups R6;
each R6 is independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, a nitrile group, a nitro group, a C1-C40 linear alkyl group, a C1-C40 linear heteroalkyl group, a C3-C40 branched or cyclic alkyl group, a C3-C40 branched or cyclic heteroalkyl group, a C2-C40 alkenyl group, and an alkynyl group, with the R6 being optionally substituted with one or more groups Rm, one or more non-adjacent —CH2— groups in R6 being optionally replaced by —RmC≡CRm—, —C≡C—, —Si(Rm)2—, —Ge(Rm)2—, —Sn(Rm)2—, —C(═O)—, —C(═S)—, —C(═Se)—, —C(═NRm)—, —P(═O)(Rm)—, —S(O)—, —S(O2)—, —N(Rm)—, O, S or CONRm, and one or more hydrogen atoms in R6 being optionally replaced by a deuterium atom, a halogen atom, a nitrile group or a nitro group, wherein two or more adjacent substituents R6 are optionally joined or fused to form a monocyclic or polycyclic aliphatic, aromatic or heteroaromatic ring system optionally substituted with one or more groups Rm;
Rm is selected from the group consisting of a hydrogen atom, a deuterium atom, a fluorine atom, a nitrile group, and a C1-C20 aliphatic hydrocarbon group, wherein one or more hydrogen atoms can be replaced by a deuterium atom, a halogen atom, or a nitrile group, and two or more adjacent substituents Rm optionally form a monocyclic or polycyclic aliphatic, aromatic or heteroaromatic ring system with each other;
Ar1 is selected from the group consisting of the following groups:
R2, R3 and Rx are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, an alkyl group with a total carbon atom number of 1-40, a cycloalkyl group with a total carbon atom number of 3-40, an alkoxy group with a total carbon atom number of 1-40, a linear alkenyl group with a total carbon atom number of 2-40, a heteroalkyl group with a total carbon atom number of 1-40, and a cycloalkenyl group with a total carbon atom number of 2-40;
LB is:
wherein R7 and R8 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, an alkyl group, a cycloalkyl group, a heteroalkyl group, an aralkyl group, an alkoxy group, an aryloxy group, an amino group, a silyl group, an alkenyl group, a cycloalkenyl group, a heteroalkenyl group, an alkynyl group, an aryl group, and a heterocyclic aryl group; adjacent groups in R7 and R8 are optionally joined or fused to form a five-membered ring, a six-membered ring or a fused polycyclic ring; and independently for each of R7 and R8, there is one or two or more such groups;
ring D and ring E are each independently selected from the group consisting of a five-membered carbocyclic ring, a five-membered heterocyclic ring, a six-membered carbocyclic ring, and a six-membered heterocyclic ring;
X5 is nitrogen or carbon; and
LC is:
wherein R9, R10 and R11 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, an alkyl group, a cycloalkyl group, heteroalkyl group, an aralkyl group, an alkoxy group, an aryloxy group, an amino group, a silyl group, an alkenyl group, a cycloalkenyl group, a heteroalkenyl group, an alkynyl group, an aryl group, and a heterocyclic aryl group; and adjacent groups in R9, R10 and R11 are optionally joined or fused to form a five-membered ring, a six-membered ring, or a fused polycyclic ring.
The present invention has the following beneficial effects:
Due to comprising an organic compound A with 3.0 eV>ET≥2.0 eV and a compound B of M(LA)x(LB)y(LC)z, the organic electroluminescent material of the present invention has the advantages of an increased luminescence lifetime and/or a reduced operating voltage on the basis of maintaining other electronic properties at a certain level. The organic electroluminescent device of the present invention which is obtained by using the organic electroluminescent material of the present invention thus also has the advantages of an increased luminescence lifetime and/or a reduced operating voltage.
The specific embodiments of the present invention will be further described in detail below in conjunction with the drawings.
In
In order to illustrate the present invention more clearly, the present invention is further described below in conjunction with preferred examples and the drawings. Like parts are indicated by like reference signs throughout the drawings. A person skilled in the art should understand that the content specifically described below is illustrative and not restrictive, and is not intended to limit the scope of protection of the present invention.
Numerical ranges in the present invention should be understood as specifically disclosing the upper and lower limits of the ranges and each intermediate value therebetween. Each smaller range between any stated values or intermediate values within a stated range and any other stated values or intermediate values within that stated range is also included in the present invention. The upper and lower limits of such smaller ranges may be independently included in or excluded from a range.
Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention belongs. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in the description are incorporated by reference to disclose and describe methods and/or materials associated with the documents. In case of conflict with any incorporated document, the content of the description shall prevail. Unless otherwise indicated, “%” is a percentage based on weight.
[Organic Electroluminescent Material]
The organic electroluminescent material of the present invention comprises the following compounds:
1) at least one organic compound A with 3.0 eV>ET≥2.0 eV; and
2) at least one compound B represented by M(LA)x(LB)y(LC)z, with the absolute value of ET[B]−ET[A]≤0.5 eV, in which ET[B] is the triplet energy level of the compound B, and ET[A] represents the triplet energy level of the compound A.
The following apply to the symbols and signs used:
M represents a metal element with an atomic weight greater than 40;
x represents an integer of 1, 2 or 3, y represents an integer of 0, 1 or 2, z represents an integer of 0, 1 or 2, and the sum of x, y and z is equal to the oxidation state of metal M;
LA is LA1 or LA2:
R1 is selected from the group consisting of C(Ra)3, trans-cyclohexyl having a 1-8 carbon atom substituent, and a 1,1′-bis(trans-cyclohexyl)-4-substituent having a 1-8 carbon atom substituent;
R4 and R5 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, an alkyl group, a cycloalkyl group, a heteroalkyl group, an aralkyl group, an alkoxy group, an aryloxy group, an amino group, a silyl group, an alkenyl group, a cycloalkenyl group, a heteroalkenyl group, an alkynyl group, an aryl group, and a heterocyclic aryl group;
there is one or two or more substituents R1;
there is one or two or more substituents R4 on ring A and ring B;
there is one or two or more substituents R5 on ring C;
X1, X2, X3 and X4 are each independently carbon or nitrogen, and X1, X2 and X3 are not nitrogen at the same time;
n represents an integer ≥0;
each Ra is independently selected from the group consisting of a C1-C40 linear alkyl group, a C1-C40 linear heteroalkyl group, a C3-C40 branched or cyclic alkyl group, a C3-C40 branched or cyclic heteroalkyl group, and a C2-C40 alkenyl or alkynyl group, with these groups being optionally substituted with one or more R6, one or more non-adjacent —CH2— groups being optionally replaced by —R6C═CR6—, —C≡C—, —Si(R6)2—, —Ge(R6)2—, —Sn(R6)2—, —C(═O)—, —C(═S)—, —C(═Se)—, —C(═NR6)—, —P(═O)(R6)—, —S(O)—, —S(O2)—, —N(R6)—, —O—, —S— or —C(ONR6)—, and one or more hydrogen atoms in Ra being optionally replaced by a deuterium atom, a halogen atom, a nitrile group or a nitro group, wherein two or more adjacent substituents Ra are optionally joined or fused to form a monocyclic or polycyclic aliphatic, aromatic or heteroaromatic ring system optionally substituted with one or more groups R6;
each R6 is independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, a nitrile group, a nitro group, a C1-C40 linear alkyl group, a C1-C40 linear heteroalkyl group, a C3-C40 branched or cyclic alkyl group, a C3-C40 branched or cyclic heteroalkyl group, a C2-C40 alkenyl group, and an alkynyl group, with the R6 being optionally substituted with one or more groups Rm, one or more non-adjacent —CH2— groups in R6 being optionally replaced by —RmC═CRm—, —C≡C—, —Si(Rm)2—, —Ge(Rm)2—, —Sn(Rm)2—, —C(═O)—, —C(═S)—, —C(═Se)—, —C(═NRm)—, —P(═O)(Rm)—, —S(O)—, —S(O2)—, —N(Rm)—, O, S or CONRm, and one or more hydrogen atoms in R6 being optionally replaced by a deuterium atom, a halogen atom, a nitrile group or a nitro group, wherein two or more adjacent substituents R6 are optionally joined or fused to form a monocyclic or polycyclic aliphatic, aromatic or heteroaromatic ring system optionally substituted with one or more groups Rm;
Rm is selected from the group consisting of a hydrogen atom, a deuterium atom, a fluorine atom, a nitrile group, and a C1-C20 aliphatic hydrocarbon group, wherein one or more hydrogen atoms can be replaced by a deuterium atom, a halogen atom, or a nitrile group, and two or more adjacent substituents Rm optionally form a monocyclic or polycyclic aliphatic, aromatic or heteroaromatic ring system with each other;
Ar1 is selected from any of the following groups:
R2, R3 and Rx are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, an alkyl group with a total carbon atom number of 1-40, a cycloalkyl group with a total carbon atom number of 3-40, an alkoxy group with a total carbon atom number of 1-40, a linear alkenyl group with a total carbon atom number of 2-40, a heteroalkyl group with a total carbon atom number of 1-40, and a cycloalkenyl group with a total carbon atom number of 2-40;
LB is:
wherein R7 and R8 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, an alkyl group, a cycloalkyl group, a heteroalkyl group, an aralkyl group, an alkoxy group, an aryloxy group, an amino group, a silyl group, an alkenyl group, a cycloalkenyl group, a heteroalkenyl group, an alkynyl group, an aryl group, and a heterocyclic aryl group; adjacent groups in R7 and R8 are optionally joined or fused to form a five-membered ring, a six-membered ring or a fused polycyclic ring; and independently for each of R7 and R8, there is one or two or more such groups;
ring D and ring E are each independently selected from the group consisting of a five-membered carbocyclic ring, a five-membered heterocyclic ring, a six-membered carbocyclic ring, and a six-membered heterocyclic ring;
X5 is nitrogen or carbon; and
LC is:
wherein R9, R10 and R11 are each independently selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, an alkyl group, a cycloalkyl group, heteroalkyl group, an aralkyl group, an alkoxy group, an aryloxy group, an amino group, a silyl group, an alkenyl group, a cycloalkenyl group, a heteroalkenyl group, an alkynyl group, an aryl group, and a heterocyclic aryl group; and adjacent groups in R9, R10 and R11 are optionally joined or fused to form a five-membered ring, a six-membered ring, or a fused polycyclic ring.
In the case of an aryl group among the groups in the present invention, it contains 6 to 60 carbon atoms. The heteroaryl group in the present invention is an aromatic group containing 2-60 carbon atoms and at least one heteroatom with the total of carbon atoms and heteroatoms being at least 5. The heteroatom is preferably selected from N, O or S. The aryl or heteroaryl group here is considered to refer to a simple aromatic ring, i.e., benzene, naphthalene, etc., or a simple heteroaromatic ring, such as pyridine, pyrimidine or thiophene, or a fused aryl or heteroaryl group, such as anthracene, phenanthrene, quinoline or isoquinoline. Aromatic rings connected to each other via a single bond, such as biphenyl, on the contrary, are not within the scope of the aryl or heteroaryl group of the present invention, but belong to the aromatic ring systems of the present invention.
In the present invention, an aromatic ring system or a heteroaromatic ring system refers to a ring system group in which a plurality of aryl or heteroaryl groups and optionally a non-aromatic unit such as C, N, O, or S are connected. For example, a system in which two or more aryl groups are connected by, for example, a short alkyl group. In addition, systems such as fluorene, 9,9′-spirobifluorene, 9,9-diarylfluorene, triarylamine and diaryl ethers are also considered as aromatic ring systems in the sense of the present invention.
Examples of aliphatic hydrocarbon groups or alkyl groups or alkenyl groups or alkynyl groups in the sense of the present invention, which contain 1-40 carbon atoms and in which an individual hydrogen atom or —CH2— group is optionally substituted with a substituent, include, for example, the following groups: methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, 2-methylbutyl, n-pentyl, sec-pentyl, neopentyl, cyclopentyl, n-hexyl, neohexyl, cyclohexyl, n-heptyl, cycloheptyl, n-octyl, cyclooctyl, 2-ethylhexyl, cyclohexenyl, heptenyl, cycloheptenyl, octenyl, cyclooctenyl, ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl or octynyl. As alkoxy groups, preference is given to alkoxy groups having 1-40 carbon atoms, and examples of such a group include methoxy, trifluoromethoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, sec-pentyloxy, 2-methylbutoxy, n-hexyloxy, cyclohexyloxy, n-heptyloxy, cycloheptyloxy, n-octyloxy, cyclooctyloxy, 2-ethylhexyloxy, pentafluoroethoxy 2,2,2-trifluoroethoxy etc. As heteroalkyl groups, preference is given to alkyl groups having 1-40 carbon atoms, in which an individual hydrogen atom or —CH2— group is optionally substituted with an oxygen, sulfur, or halogen atom, and examples of such a group include an alkoxy group, an alkylthio group, a fluorinated alkoxy group, and a fluorinated alkylthio group. Among these groups, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, t-butoxy, methylthio, ethylthio, n-propylthio, isopropylthio, n-butylthio, isobutylthio, sec-butylthio, tert-butylthio, trifluoromethylthio, trifluoromethoxy, pentafluoroethoxy, pentafluoroethylthio, 2,2,2-trifluoroethoxy, 2,2,2-trifluoroethylthio, ethyleneoxy, ethylenethio, propyleneoxy, propylenethio, butenethio, butenyloxy, pentenyloxy, pentenylthio, cyclopentenyloxy, cyclopentenylthio, hexenyloxy, hexenylthio, cyclohexenyloxy, cyclohexenethio, ethynyloxy, ethynylthio, propynyloxy, propynylthio, butynyloxy, butynylthio, pentynyloxy, pentynylthio, hexynyloxy, and hexynylthio are preferred.
As the cycloalkyl group of the present invention, examples include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl; and as the cycloalkenyl group of the present invention, examples include cyclobutenyl, cyclopentenyl, and cyclohexenyl, cycloheptyl, and cycloheptenyl, wherein one or more —CH2— groups are optionally replaced by the above-mentioned groups; moreover, one or more hydrogen atoms are optionally replaced by a deuterium atom, a halogen atom or a nitrile group.
The aromatic or heteroaromatic ring system of the present invention, in which an aromatic or heteroaromatic ring atom may in each case also be substituted with the above-mentioned groups R1, R4 or R5, refers in particular to groups derived from the following substances: benzene, naphthalene, anthracene, benzoanthracene, phenanthrene, pyrene, chrysene, perylene, fluoranthene, tetracene, pentacene, benzopyrene, biphenyl, diphenyl, terphenyl, trimeric benzene, fluorene, spirobifluorene, dihydrophenanthrene, dihydropyrene, tetrahydropyrene, cis- or trans-indenofluorene, cis- or trans-indenocarbazole, cis- or trans-indolocarbazole, trimeric indene, trimeric indene, spirotrimeric indene, spiroisotrimeric indene, furan, benzofuran, isobenzofuran, dibenzofuran, thiophene, benzothiophene, isobenzothiophene, dibenzothiophene, pyrrole, indole, isoindole, carbazole, pyridine, quinoline, isoquinoline, acridine, phenanthridine, benzo[5,6]quinoline, benzo[6,7]quinoline, benzo[7,8]quinoline, phenothiazine, phenoxazine, pyrazole, indazole, imidazole, benzimidazole, naphthoimidazole, phenanthroimidazole, pyridoimidazole, pyrazinoimidazole, quinoxalinoimidazole, oxazole, benzoxazole, naphthoxazole, anthraxazole, phenanthroxazole, isoxazole, 1,2-thiazole, 1,3-thiazole, benzothiazole, pyridazine, hexaazabenzophenanthrene, benzopyridazine, pyrimidine, benzopyrimidine, quinoxaline, 1,5-diazaanthracene, 2,7-diazapyrene, 2,3-diazapyrene, 1,6-diazapyrene, 1,8-diazapyrene, 4,5-diazapyrene, 4,5,9,10-tetraazaperylene, pyrazine, phenazine, phenoxazine, phenothiazine, fluorubin, naphthyridine, azacarbazole, benzocarboline, carboline, phenanthroline, 1,2,3-triazole, 1,2,4-triazole, benzotriazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 1,3,5-triazine, 1,2,4-triazine, 1,2,3-triazine, tetrazole, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine, 1,2,3,5-tetrazine, purine, pteridine, indolizine and benzothiadiazole or groups derived from a combination of these systems.
For the organic compound A with 3.0 eV>ET≥2.0 eV in the present invention, ET refers to the triplet energy level of the compound. The ET value of the compound is determined by quantum chemical calculation as described in the examples section below.
[Compound B represented by M(LA)x(LB)y(LC)z] Preferred embodiments of the compound B represented by the formula M(LA)x(LB)y(LC)z are described below.
In a preferred embodiment of the present invention, the metal M is preferably Ir or Pt, that is, the compound B represented by M(LA)x(LB)y(LC)z is preferably Ir(LA)(LB)(LC), Ir(LA)2(LB), Ir(LA)(LB)2, Ir(LA)2(LC), Ir(LA)3, Pt(LA)(LB) or Pt(LA)(LC).
The LA is preferably selected from the group consisting of LA-1 to LA-17:
wherein R1, R2, R4, R5 and Ar1 used have the meanings given above, and R1, R2, R4, R5 and Ar1 are the same or different from each other.
In a preferred embodiment of the present invention, the LA is particularly preferably selected from the group consisting of the following compounds represented by L1 to L104:
wherein R1, R2, R3 and Rx used herein have the meanings given above, and the above-mentioned R1, R2, R3 and Rx are the same or different from each other.
In a preferred embodiment of the present invention, the LB is selected from the group consisting of the following compounds represented by LB1 to LB44:
In a preferred embodiment of the present invention, the LC is selected from the group consisting of the following compounds represented by LC1 to LC48:
Examples of the preferred compounds M(LA)x(LB)y(LC)z according to the above-mentioned embodiment are compounds shown in the following table:
[Organic compound A with 3.0 eV>ET≥2.0 eV]
Embodiments of the organic compound A with 3.0 eV>ET≥2.0 eV according to the present invention are described below.
In the present invention, it is preferable that the organic compound A with 3.0 eV>ET≥2.0 eV contains at least one from the group consisting of groups of formulas X-1 to X-13.
wherein
Z1 and Z2 each independently represent one selected from the group consisting of deuterium, a halogen atom, a hydroxy group, a nitrile group, a nitro group, an amino group, an amidine group, a hydrazine group, a hydrazone group, a carboxy group, a carboxylate group, a sulfonic acid group, a sulfonate group, a phosphoric acid group, a phosphate group, a C1-C60 alkyl group, a C2-C60 alkenyl group, a C2-C60 alkynyl group, a C1-C60 alkoxy group, a C3-C60 cycloalkyl group, a C3-C60 cycloalkenyl group, a C6-C60 aryl group, a C6-C60 fused ring aryl group, a C6-C60 aryloxy group, a C6-C60 arylsulfide group, and a C2-C60 heterocyclic aryl group;
x1 represents an integer of 1-4, x2 represents an integer of 1-3, x3 represents 1 or 2, x4 represents an integer of 1-6, and x5 represents an integer of 1-5;
T1 is selected from —B(R′)—, —N(R′)—, —P(R′)—, —O—, —S—, —Se—, —S(═O)—, —S(O2)—, —C(R′R″)—, —Si(R′R″)— or —Ge(R′R″)—, wherein R′ and R″ are each independently selected from the group consisting of a C1-C60 alkyl group, a C2-C60 alkenyl group, a C2-C60 alkynyl group, a C1-C60 alkoxy group, a C3-C60 cycloalkyl group, a C3-C60 cycloalkenyl group, a C6-C60 aryl group, a C1-C10 alkyl-containing C6-C60 aryl group, a C1-C10 alkyl-containing C6-C60 aryloxy group, and a C1-C10 alkyl-containing C6-C60 arylthio group; and R′ and R″ are optionally fused or joined to form a ring; and
represents the connection of a substituent to the main structure.
In a preferred embodiment of the present invention, the organic compound A with 3.0 eV>ET≥2.0 eV contains a group formed by bonding at least one group selected from the group consisting of the groups represented by formulas X-1 to X-13 to an indenocarbazolyl group, an indolocarbazolyl group or a carbazolyl group directly or via a bridging group, wherein the indenocarbazolyl group or indolocarbazolyl group or carbazolyl group is optionally substituted with one or more Ar1 groups, with the Ar1 having the meaning as defined above;
the indenocarbazolyl group, indolocarbazolyl group or carbazolyl group is preferably selected from the group consisting of the following structures represented by formulas X-14 to X-21:
wherein each R4 is independently selected from the group consisting of a hydrogen atom, a deuterium atom, an alkyl group, a cycloalkyl group, a heteroalkyl group, an aralkyl group, an alkoxy group, an aryloxy group, an amino group, a silyl group, an alkenyl group, a cycloalkenyl group, a heteroalkenyl group, an alkynyl group, an aryl group, and a heterocyclic aryl group. R represents a bridge bond or bridging group connected to X-1 to X-13, and the bridge bond or bridging group is connected to the X-1 to X-13; and
T1 has the same meaning as that given above.
Examples of the organic compound A with 3.0 eV>ET≥2.0 eV include the following compounds represented by P205 to P380.
The organic electroluminescent material comprising an organic compound A with 3.0 eV>ET≥2.0 eV and a compound B represented by M(LA)x(LB)y(LC)z of the present invention may be used as, for example, a hole injection material, a hole transport material, or a packaging layer material in an organic electroluminescent device, and is preferably used as a light-emitting layer in an organic electroluminescent device. In the case of serving as a light-emitting layer, preference is given to a phosphorescent light-emitting layer, wherein the organic compound A with 3.0 eV>ET≥2.0 eV is used as a matrix material, the compound B represented by M(LA)x(LB)y(LC)z is used as a doping material, and with the joint participation of both, phosphorescence is emitted.
In the case where the compound B represented by M(LA)x(LB)y(LC)z as a doping material and the organic compound A with 3.0 eV>ET≥2.0 eV as a matrix material work together as a phosphorescent light-emitting layer, the triplet energy level of the organic compound A with 3.0 eV>ET≥2.0 eV is preferably not significantly lower than or greater than the triplet energy level of the compound of M(LA)x(LB)y(LC)z, and the absolute value of the triplet energy levels ET[A]−ET[B] is preferably ≤0.2 eV, particularly preferably ≤0.15 eV, very particularly preferably ≤0.1 eV. The ET[B] is the triplet energy level of the metal complex of M(LA)x(LB)y(LC)z, and the ET[A] is the triplet energy level of the compound with 3.0 eV>ET≥2.0 eV as the matrix material. If more than two matrix materials are contained in the light-emitting layer, the above-mentioned relationship is preferably also applicable to other matrix materials.
With regard to the ratio between the organic compound A with 3.0 eV>ET≥2.0 eV and the compound B represented by M(LA)x(LB)y(LC)z, the ratio of the organic compound A with 3.0 eV>ET≥2.0 eV to the compound represented by M(LA)x(LB)y(LC)z is preferably between 99:1 and 80:20, preferably between 99:1 and 90:10, particularly preferably between 99:1 and 95:5.
The organic electroluminescent device comprises a cathode, an anode, and at least one light-emitting layer. In addition to these layers, it may further comprise other layers, for example, in one embodiment, it may comprise one or more hole injection layers, hole transport layers, hole blocking layers, electron transport layers, electron injection layers, exciton blocking layers, electron blocking layers and/or charge generation layers. An intermediate layer having, for example, an exciton blocking function may also be introduced between two light-emitting layers. However, it should be noted that the presence of all these layers is not necessary. The organic electroluminescent device here may comprise one light-emitting layer, or may comprise a plurality of light-emitting layers. That is, a plurality of luminescent compounds capable of emitting phosphorescence are used in the light-emitting layers. A system having three light-emitting layers is particularly preferred, wherein the three layers respectively emit blue light, green light, and red light. If more than one light-emitting layer is present, according to the invention, at least one of these layers comprises the organic electroluminescent material containing an organic compound A with 3.0 eV>ET≥2.0 eV and a compound represented by the formula M(LA)x(LB)y(LC)z of the present invention.
In another embodiment of the present invention, the organic electroluminescent device of the present invention does not comprise an individual hole injection layer and/or hole transport layer and/or hole blocking layer and/or electron transport layer, i.e. the case where the light-emitting layer is directly adjacent to the hole injection layer or anode, and/or the light-emitting layer is directly adjacent to the electron transport layer or electron injection layer or cathode, as described in, for example, WO 2005053051.
In the other layers of organic electroluminescent device of the present invention, particularly in the hole injection and hole transport layers and in the electron injection and electron transport layers, all materials can be used in a manner generally used according to the prior art. A person of ordinary skill in the art will therefore be able to use all materials known for organic electroluminescent devices in combination with the light-emitting layer according to the present invention without involving any inventive effort.
Furthermore, preference is given to the following organic electroluminescent device in which one or more layers are applied by means of a sublimation method, wherein the material is applied by means of vapor deposition in a vacuum sublimation device at an initial pressure below 10−5 mbar, preferably below 10−6 mbar. The initial pressure may also be even lower, for example below 10−7 mbar.
Furthermore, preference is given to the following organic electroluminescent device in which one or more layers are applied by means of an organic vapor deposition method or by means of carrier gas sublimation, wherein the material is applied at a pressure between 10−5 mbar and 1 bar. A particular example of this method is an organic vapor jet printing method, in which the material is applied directly through a nozzle and is therefore structured.
Furthermore, preference is given to the following organic electroluminescent device in which one or more layers are produced by using a solution by means of, for example, spin coating, or by means of any desired printing method such as screen printing, flexography, lithography, photo-initiated thermal imaging, heat transfer printing, inkjet printing, or nozzle printing. Soluble compounds are obtained, for example, by means of appropriate substitution. These methods are also particularly suitable for oligomers, dendrimers and polymers. In addition, a hybrid method is feasible, in which for example one or more layers are applied from a solution and one or more additional layers are applied by means of vapor deposition.
These methods are generally known to a person of ordinary skill in the art, and they can be applied to an organic electroluminescent device containing the compound according to the present invention without involving any inventive effort.
The present invention also relates to a method for manufacturing the organic electroluminescent device according to the present invention, in which at least one layer is applied by means of a sublimation method, and/or at least one layer is applied by means of an organic vapor deposition method or carrier gas sublimation, and/or at least one layer is applied from a solution by means of spin coating or by means of a printing method.
The organic electroluminescent material of the present invention may further optionally comprise other compounds. The organic electroluminescent material of the present invention may be, for example, a liquid phase, which is processed by means of spin coating or by means of a printing method. As such a liquid phase, it may be in the form of, for example, a solution, a dispersion, or an emulsion. As the solvent used for forming the liquid phase, a mixture of two or more solvents may be preferably used. Suitable and preferred solvents are, for example, toluene, anisole, o-xylene, m-xylene or p-xylene, methyl benzoate, mesitylene, tetralin, o-dimethoxybenzene, tetrahydrofuran, methyl tetrahydrofuran, tetrahydropyran, chlorobenzene, dioxane, phenoxytoluene, especially 3-phenoxytoluene, (−)-fenchone, 1,2,3,5-tetramethylbenzene, 1,2,4,5-tetramethylbenzene, 1-methylnaphthalene, 2-methylbenzothiazole, 2-phenoxyethanol, 2-pyrrolidone, 3-methylanisole, 4-methylanisole, 3,4-dimethylanisole, 3,5-dimethylanisole, acetophenone, α-terpineol, benzothiazole, butyl benzoate, cumene, cyclohexanol, cyclohexanone, cyclohexylbenzene, decalin, dodecylbenzene, ethyl benzoate, indan, methyl benzoate, 1-methylpyrrolidone, p-methylisopropylbenzene, phenetole, 1,4-diisopropylbenzene, dibenzyl ether, diethylene glycol butyl methyl ether, triethylene glycol butyl methyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, tripropylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 2-isopropylnaphthalene, pentylbenzene, hexylbenzene, heptylbenzene, octylbenzene, 1,1-bis(3,4-dimethylphenyl)ethane, or mixtures of these solvents, etc.
The test instrument and method for testing the performances of OLED materials and elements in the following examples are as follows:
OLED element performance testing conditions:
Luminance and chromaticity coordinates: tested using spectral scanner PhotoResearch PR-715;
Current density and lighting voltage: tested using digital source meter Keithley 2420;
Power efficiency: tested using NEWPORT 1931-C;
Lifetime test: using LTS-1004AC lifetime test device.
Method for determining the triplet energy level ET of a compound
The triplet energy level of the material is determined via quantum chemical calculation. To do this, “Gaussian09W” software is used. In order to calculate the ET of the organic compound A with 3.0 eV>ET≥2.0 eV, geometric structure optimization is first carried out using a “ground state/semi-empirical/default spin/AM1/charge 0/spin singlet” method, an energy calculation is subsequently carried out on the basis of the ground state-optimized geometry. A method of “TD-SCF/DFT/default spin/B3LYP with a 6-31G(d) base set” (charge 0, spin singlet) is used here. For the compound B represented by M(LA)x(LB)y(LC)z, geometric structure optimization is carried out via a “ground state/Hartree-Fock/default spin/LanL2 MB/charge 0/spin singlet” method. An energy calculation is carried out analogously to the method described above for matrix organic substances, with the difference that a “LanL2DZ” base set is used for the metal atom and the “6-31G(d)” base set is used for the ligands. The triplet energy level T1 of the material obtained by the energy calculation is defined as the energy of the lowest energy triplet as generated by quantum chemical calculation. The triplet energy level ET value of the compound is thus determined. For the purposes of the present application, this value is regarded as the ET value of the material.
Table 1 below lists the triplet energy levels ET(A) of some compounds A as shown with 3.0 eV>ET≥2.0 eV:
Table 2 below lists the triplet energy levels ET(B) of some compounds represented by M(LA)x(LB)y(LC)z:
OLED Device Manufacturing:
Pretreatment of Examples R1 to R25: In order to improve the processing, a clean glass plate coated with structured ITO with a thickness of 50 nm is coated with PEDOT:PSS at 20 nm, which is applied from an aqueous solution by means of spin coating. The sample is then dried by means of heating at 180° C. for 10 minutes. These coated glass plates form substrates to which an OLED is applied.
Pretreatment of Examples R26 to R63: A clean glass plate coated with structured ITO with a thickness of 50 nm is treated with an oxygen plasma for 130 seconds. These plasma-treated glass plates form substrates to which an OLED is applied. The substrate is kept under vacuum before coating. Coating is started within 10 minutes after the plasma treatment.
Pretreatment of Examples R64 to R101: A clean glass plate coated with structured ITO with a thickness of 50 nm is treated with an oxygen plasma for 130 seconds and subsequently with an argon plasma for 150 seconds. These plasma-treated glass plates form substrates to which an OLED is applied. The substrate is kept under vacuum before coating. Coating is started within 10 minutes after the plasma treatment.
The OLED basically has a structure of the following layers: a substrate/a hole transport layer (HTL)/an optional intermediate layer (IL)/an electron blocking layer (EBL)/a light-emitting layer (EML)/an optional hole blocking layer (HBL)/an electron transport layer (ETL)/an optional electron injection layer (EIL) and a final cathode. The cathode is formed of an aluminum layer having a thickness of 100 nm. The exact structure of the OLED is shown in Table 3. Materials required for manufacturing the OLED are shown in Table 5.
All the materials are applied by means of thermal vapor deposition in a vacuum chamber. The light-emitting layer here is composed of at least one matrix material (host material) formed of organic compound A with 3.0 eV>ET≥2.0 eV and compound B (luminous dopant) represented by M(LA)x(LB)y(LC)z, wherein the luminous dopant and the one or more host materials are mixed at a specific mass ratio by means of co-evaporation. For example, the expression of P323:P01 (95%:5%) here means that the material P323 is present in this layer at a mass proportion of 95%, and P01 is present in this layer at a mass proportion of 5%. Similarly, the electron transport layer may also be composed of a mixture of two materials.
The OLED is characterized by standard methods. For this purpose, the electroluminescence spectrum, current efficiency (cd/A), power efficiency (lm/W), external quantum efficiency (EQE, %) calculated as a luminous density function according to a current/voltage/luminous density profile (I-V-L) exhibiting Lambertian emission characteristics, and lifetime are determined. The electroluminescence spectrum is measured at a luminous density of 1000 cd/m2, and the color coordinates CIE (1931) x and y values are calculated. The expression T95 in Table 3 refers to the time in the lifetime of a luminescent device, which corresponds to the luminosity having been reduced to 95% of the initial value thereof.
Data for various OLEDs are summarized in Table 4. Examples R1 to R101 show the data of the OLED of the present invention.
Some examples are explained in more detail below to illustrate the advantages of the OLED of the present invention.
With regard to the use of the organic electroluminescent material of the present invention in a light-emitting layer of a phosphorescent OLED, the combined use of the composition according to the present invention can achieve a good external quantum efficiency. In addition, an excellent improvement of more than twice is obtained in terms of lifetime. In particular, an excellent lifetime is obtained using a combination of compounds P242 and P02 (Example R65), and an excellent efficiency is obtained using P323 and P11 (Example R70).
In addition, excellent performance data is obtained using various compositions of a compound with 3.0 eV>ET≥2.0 eV and a phosphorescence emitter of M(LA)x(LB)y(LC)z, which indicates the broad applicability of the layer according to the present invention.
The performance test results of red light devices obtained are listed in Table 4.
It can be known from the above that a red light element manufactured by means of a combination of a compound having a triplet energy level of 3.0 eV>ET≥2.0 eV and a phosphorescence emitter of M(LA)x(LB)y(LC)z, which are appropriately selected, has a low driving voltage and improved external quantum efficiency and current efficiency under the condition of an element luminous brightness of initially 1000 nits, and thus has a reduced power consumption and improved element lifetime.
Obviously, the above-mentioned examples of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the embodiments of the present invention. For a person of ordinary skill in the art, it would also be possible to make other different forms of changes or variations on the basis of the above description, and it is not possible to exhaust all embodiments here. Any obvious changes or variations derived from the technical solution of the present invention are still within the scope of protection of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201910470842.6 | May 2019 | CN | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 4539507 | VanSlyke et al. | Sep 1985 | A |
| 5151629 | VanSlyke | Sep 1992 | A |
| 20060097227 | Okajima | May 2006 | A1 |
| 20070020237 | Yoon | Jan 2007 | A1 |
| 20070290610 | Park | Dec 2007 | A1 |
| Number | Date | Country |
|---|---|---|
| 0676461 | Oct 1995 | EP |
| WO9827136 | Jun 1998 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20200381633 A1 | Dec 2020 | US |
