Patent Application
20210098714
This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0121391, filed on Oct. 1, 2019, the entire content of which is hereby incorporated by reference.
One or more aspects of embodiments of the present disclosure relate to an organic electroluminescence device, and more particularly, to an organic electroluminescence device including a plurality of light-emitting materials in an emission layer.
Organic electroluminescence displays are being actively developed as image displays. An organic electroluminescence display differs from a liquid crystal display in that it is a so-called a self-luminescent display, in which holes and electrons respectively injected from a first electrode and a second electrode recombine in an emission layer, and a light-emitting material including an organic compound in the emission layer emits light to attain display.
In the application of an organic electroluminescence device to a display, decreases in driving voltage, and increases in emission efficiency and/or lifespan of the organic electroluminescence device are desired, and development of materials for an organic electroluminescence device capable of stably attaining the above requirements is also desired.
Recently, in order to achieve an organic electroluminescence device with high efficiency, materials capable of phosphorescence emission (which uses energy in a triplet state) or delayed fluorescence emission (which uses the generating phenomenon of singlet excitons by the collision of triplet excitons (triplet-triplet annihilation, TTA)) are being developed, and materials capable of thermally activated delayed fluorescence (TADF) using delayed fluorescence are being developed.
One or more aspects of embodiments of the present disclosure are directed toward an organic electroluminescence device showing excellent lifespan (lifetime) characteristics and emission efficiency.
One or more example embodiments of the present disclosure provide an organic electroluminescence device including a first electrode, a second electrode opposite the first electrode, and an emission layer disposed between the first electrode and the second electrode. The emission layer includes a host having a first luminescent onset wavelength, a first dopant having a second luminescent onset wavelength, and a second dopant different from the first dopant and having a third luminescent onset wavelength. The third luminescent onset wavelength is greater than the first luminescent onset wavelength and the second luminescent onset wavelength.
In an embodiment, a normalized light intensity at a cross point of a normalized light absorption spectrum and a normalized light emission spectrum of the second dopant may be about 0.5 or more.
In an embodiment, a distance between a peak of the normalized light absorption spectrum and a peak of the normalized light emission spectrum of the second dopant may be about 50 nm or less.
In an embodiment the second dopant may have a smaller (e.g., may be smaller in) lowest triplet excitation energy level than each of the host and the first dopant.
In an embodiment, the host may include a first host and a second host, the second host being different from the first host.
In an embodiment, the first host may be represented by Formula H-1:
In Formula H-1, L1 may be a direct linkage, a substituted or unsubstituted arylene group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroarylene group of 2 to 30 carbon atoms for forming a ring; Ar1 may be a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring; “a” and “b” may each independently be an integer of 0 to 4; and R1 and R2 may each independently be a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring.
In an embodiment, the second host may be represented by Formula H-2:
In Formula H-2, Z1 to Z3 may each independently be CRy or N; and Ry and R11 to R13 may each independently be a hydrogen atom, a deuterium atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring.
In an embodiment, the first dopant may include an organometallic complex including iridium (Ir), ruthenium (Ru), rhodium (Rh), platinum (Pt), palladium (Pd), copper (Cu), or osmium (Os) as a central metal element.
In an embodiment, the first dopant may be represented by Formula D-1:
In Formula D-1, M may be Pt, Pd, Cu, Os, Ir, Ru, or Rh; Q1 to Q4 may each independently be C or N; C1 to C4 may each independently be a substituted or unsubstituted hydrocarbon ring of 5 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heterocycle of 2 to 30 carbon atoms for forming a ring; L21 to L23 may each independently be a direct linkage, *—O—*, *—S—*,
a substituted or unsubstituted divalent alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted arylene group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroarylene group of 2 to 30 carbon atoms for forming a ring; e1 to e3 may each independently be 0 or 1; R21 to R26 may each independently be a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted amine group, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 1 to 30 carbon atoms for forming a ring, or may be combined with an adjacent group to form a ring; d1 to d4 may each independently be an integer of 0 to 4; and when M is Pt, Pd, Cu, or Os, “m” may be 1, and when M is Ir, Ru, or Rh, “m” may be 2, and e2 may be 0.
In an embodiment, the second dopant may be represented by Formula D-2a:
In Formulae D-2a, X1 and X2 may each independently be NRm or O; Rm may be a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring; and R31 to R41 may each independently be a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted amine group, a substituted or unsubstituted boryl group, a substituted or unsubstituted oxy group, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring, or may be combined with an adjacent group to form a ring.
In an embodiment, the second dopant may be represented by Formula D-2b:
D1-L2-A1 [Formula D-2b]
In Formula D-2b, L2 may be a direct linkage, a substituted or unsubstituted arylene group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroarylene group of 2 to 30 carbon atoms for forming a ring; and D1 may be represented by Formula D-2-1 or Formula D-2-2:
In Formulae D-2-1 and D-2-2, L3 and L4 may each independently be a direct linkage, or a substituted or unsubstituted arylene group of 6 to 30 carbon atoms for forming a ring; R42 to R59 may each independently be a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted silyl group, a substituted or unsubstituted alkyl group of 1 to 15 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring; Y1 may be a direct linkage, CRaRb, SiRcRd, GeReRf, NRg, O or S; Ra to Rg may each independently be a substituted or unsubstituted alkyl group of 1 to 15 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring; Ra and Rb, Rc and Rd, and/or Re and Rf may be combined with each other to form a ring; and A1 may be represented by one of Formulae D-2-3 to D-2-10:
Y2 may be C═O or S(═O)2; Y3 may be C═O, or O; Y4 and Y5 may each independently be O or S; Y6 and Y7 may each independently be N or CQ12, Y8 may be O or NQ13; Q1 to Q13 may each independently be a substituted or unsubstituted alkyl group of 1 to 15 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring; n1, n4, and n6 may each independently be 0 to 4; n3, n5, n7, n8, and n10 may each independently be an integer of 0 to 3; n2 may bean integer of 0 to 5; and n9 may be an integer of 0 to 2.
In an embodiment, the first host and the second host may be in a weight ratio of about 7:3 to about 3:7.
In an embodiment, an amount of the first dopant may be about 10 wt % to about 15 wt %, and an amount of the second dopant may be about 1 wt % to about 5 wt % based on a total weight of the first host, the second host, the first dopant, and the second dopant.
One or more example embodiments of the present disclosure provide an organic electroluminescence device including a first electrode, a second electrode on the first electrode, and an emission layer between the first electrode and the second electrode. The emission layer includes a first host, a second host that is different from the first host, a first dopant having a second onset wavelength, and a second dopant different from the first dopant and having a third onset wavelength. The third onset wavelength may be greater than the second onset wavelength, and a normalized light intensity at a cross point of a normalized light absorption spectrum and a normalized light emission spectrum of the second dopant may be about 0.5 or more.
One or more example embodiments of the present disclosure provide an organic electroluminescence device including a first electrode, a second electrode on the first electrode, and an emission layer between the first electrode and the second electrode. The emission layer includes a first host including a hole transport moiety, a second host different from the first host and including an electron transport moiety, a first dopant having a second onset wavelength and including an organometallic complex including Ir, Ru, Rh, Pt, Pd, Cu, or Os as a central metal element, and a second dopant having a third onset wavelength and being a delayed fluorescence emitting body. The third onset wavelength may be greater than the second onset wavelength.
The accompanying drawings are included to provide a further understanding of the present disclosure and are incorporated in and constitute a part of this specification. The drawings illustrate example embodiments of the present disclosure and, together with the description, serve to explain principles of the present disclosure. In the drawings:
The present disclosure may have various modifications and may be embodied in different forms, and example embodiments will be explained in more detail with reference to the accompany drawings. The present disclosure may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, all modifications, equivalents, and substituents which are included in the spirit and technical scope of the present disclosure should be included in the present disclosure.
It will be understood that when an element (or region, layer, part, etc.) is referred to as being “on”, “connected to” or “coupled to” another element, it can be directly on, connected or coupled to the other element, or a third intervening element may be present.
Like reference numerals refer to like elements throughout, and duplicative descriptions thereof may not be provided. In addition, in the drawings, the thickness, the ratio, and the dimensions of constituent elements may be exaggerated for effective explanation of technical contents.
The term “and/or” includes one or more combinations which may be defined by relevant elements. As used herein, the terms “substantially”, “about”, and similar terms are used as terms of approximation and not as terms of degree, and are intended to account for the inherent deviations in measured or calculated values that would be recognized by those of ordinary skill in the art.
It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element could be termed a second element without departing from the teachings of the present disclosure. Similarly, a second element could be termed a first element. As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.
In addition, the terms “below”, “beneath”, “on” and “above” are used for explaining the relation of elements shown in the drawings. The terms are relative concept and are explained based on the direction shown in the drawing.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, numerals, steps, operations, elements, parts, or the combination thereof, but do not preclude the presence or addition of one or more other features, numerals, steps, operations, elements, parts, or the combination thereof.
Hereinafter, the organic electroluminescence device according to an embodiment of the present disclosure will be explained with reference to attached drawings.
In addition, the organic electroluminescence device 10 of an embodiment may further include a plurality of functional layers between the first electrode EL1 and the second electrode EL2, in addition to the emission layer EML. The plurality of the functional layers may include a hole transport region HTR and an electron transport region ETR. For example, the organic electroluminescence device 10 according to an embodiment may include a first electrode EL1, a hole transport region HTR, an emission layer EML, an electron transport region ETR, and a second electrode EL2, stacked in this stated order. In some embodiments, the organic electroluminescence device 10 of an embodiment may include a capping layer CPL disposed on the second electrode EL2.
The organic electroluminescence device 10 of an embodiment may include a compound of an embodiment, which will be explained later, in the emission layer EML disposed between the first electrode EL1 and the second electrode EL2. However, an embodiment of the present disclosure is not limited thereto, and in some embodiments the organic electroluminescence device 10 of an embodiment may include a compound of an embodiment, which will be explained later, in the hole transport region HTR or the electron transport region ETR (which are included in the plurality of the functional layers disposed between the first electrode EL1 and the second electrode EL2, in addition to the emission layer EML), or in the capping layer CPL disposed on the second electrode.
The first electrode EL1 has conductivity (e.g., may be conductive). The first electrode EL1 may be formed using a metal alloy or a conductive compound. The first electrode EL1 may be an anode. In some embodiments, the first electrode EU may be a pixel electrode. The first electrode EL1 may be a transmissive electrode, a transflective electrode, or a reflective electrode. If the first electrode EU is a transmissive electrode, the first electrode EL1 may include a transparent metal oxide (such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and/or indium tin zinc oxide (ITZO)). If the first electrode EL1 is a transflective electrode or the reflective electrode, the first electrode EU may include silver (Ag), magnesium (Mg), copper (Cu), aluminum (Al), platinum (Pt), palladium (Pd), gold (Au), nickel (Ni), neodymium (Nd), iridium (Ir), chromium (Cr), lithium (Li), calcium (Ca), LiF/Ca, LiF/AI, molybdenum (Mo), titanium (Ti), a compound thereof, or a mixture thereof (for example, a mixture of Ag and Mg). In some embodiments, the first electrode EU may have a structure including a plurality of layers including a reflective layer or a transflective layer formed using the above materials, and a transmissive conductive layer formed using ITO, IZO, ZnO, or ITZO. For example, the first electrode EL1 may include a three-layer structure of ITO/Ag/ITO. However, an embodiment of the present disclosure is not limited thereto. The thickness of the first electrode EL1 may be about 1,000 A to about 10,000 Å, for example, about 1,000 Å to about 3,000 Å.
The hole transport region HTR is provided on the first electrode EL1. The hole transport region HTR may include at least one of a hole injection layer HIL, a hole transport layer HTL, a hole buffer layer, or an electron blocking layer EBL. The thickness of the hole transport region HTR may be about 50 Å to about 1,500 Å.
The hole transport region HTR may have a single layer formed using a single material, a single layer formed using a plurality of different materials, or a multilayer structure including a plurality of layers formed using a plurality of different materials.
For example, the hole transport region HTR may have a single layer structure including a hole injection layer HIL or a hole transport layer HTL, or may have a single layer structure including a hole injection material and a hole transport material (e.g., simultaneously or as a mixture). In some embodiments, the hole transport region HTR may have a structure of a plurality of layers formed using a plurality of different materials, such as a structure including a hole injection layer HIL/hole transport layer HTL, a hole injection layer HIL/hole transport layer HTL/hole buffer layer, a hole injection layer HIL/hole buffer layer, a hole transport layer HTL/hole buffer layer, or a hole injection layer HIL/hole transport layer HTL/electron blocking layer EBL, without limitation, each being stacked on the first electrode EL1.
The hole transport region HTR may be formed using various suitable methods (such as a vacuum deposition method, a spin coating method, a cast method, a Langmuir-Blodgett (LB) method, an inkjet printing method, a laser printing method, and/or a laser induced thermal imaging (LITI) method).
The hole injection layer HIL may include, for example, a phthalocyanine compound such as copper phthalocyanine, N,N′-diphenyl-N,N′-bis-[4-(phenyl-m-tolyl-amino)-phenyl]-phenyl-4,4′-diamine (DNTPD), 4,4′,4″-[tris(3-methylphenyl)phenylamino] triphenylamine (m-MTDATA), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine (TDATA), 4,4′,4″-tris{N,-2-naphthyl)-N-phenylamino}-triphenylamine (2-TNATA), poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS), polyaniline/dodecylbenzenesulfonic acid (PANI/DBSA), polyaniline/camphor sulfonic acid (PANI/CSA), polyaniline/poly(4-styrenesulfonate) (PANI/PSS), N,N′-di(1-naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), triphenylamine-containing polyether ketone (TPAPEK), 4-isopropyl-4′-methyldiphenyliodonium [tetrakis(pentafluorophenyl)borate], and/or dipyrazino[2,3-f:2′,3′-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN).
The hole transport layer HTL may include, for example, carbazole derivatives such as N-phenyl carbazole and polyvinyl carbazole, fluorine-based derivatives, N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine (TPD), triphenylamine-based derivatives such as 4,4′,4″-tris(N-carbazolyl)triphenylamine (TCTA), N,N′-di(1-naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), 4,4′-cyclohexylidene bis[N,N-bis(4-methylphenyl)benzeneamine (TAPC), 4,4′-bis[N,N′-(3-tolyl)amino]-3,3′-dimethylbiphenyl (HMTPD), 1,3-bis(N-carbazolyl)benzene (mCP), etc.
The thickness of the hole transport region HTR may be about 50 Å to about 10,000 Å, for example, about 100 Å to about 5,000 Å. The thickness of the hole injection region HIL may be, for example, about 30 Å to about 1,000 Å, and the thickness of the hole transport layer HTL may be about 30 Å to about 1,000 Å. For example, the thickness of the electron blocking layer EBL may be about 10 Å to about 1,000 Å. If the thicknesses of the hole transport region HTR, the hole injection layer HIL, the hole transport layer HTL and the electron blocking layer EBL satisfy the above-described ranges, satisfactory hole transport properties may be achieved without a substantial increase in driving voltage.
The hole transport region HTR may further include a charge generating material in addition to the above-described materials to increase conductivity. The charge generating material may be dispersed substantially uniformly or non-uniformly in the hole transport region HTR. The charge generating material may be, for example, a p-dopant. The p-dopant may be a quinone derivative, a metal oxide, or a cyano group-containing compound, without limitation. For example, non-limiting examples of the p-dopant include quinone derivatives (such as tetracyanoquinodimethane (TCNQ) and/or 2,3,5,6-tetrafluoro-7,7′,8,8′-tetracyanoquinodimethane (F4-TCNQ)), metal oxides (such as tungsten oxide and/or molybdenum oxide), and inorganic metal compounds (such as CuI and/or RbI), without limitation.
As described above, the hole transport region HTR may further include at least one of a hole buffer layer or an electron blocking layer EBL in addition to the hole injection layer HIL and the hole transport layer HTL. The hole buffer layer may compensate for an optical resonance distance according to the wavelength of light emitted from the emission layer EML, and may thereby increase light emission efficiency. The hole transport region HTR and the hole buffer layer may include the same materials. The electron blocking layer EBL may prevent or reduce electron injection from the electron transport region ETR to the hole transport region HTR.
The emission layer EML is provided on the hole transport region HTR. The emission layer EML may have a thickness of, for example, about 100 Å to about 1,000 Å or about 100 Å to about 300 Å. The emission layer EML may have a single layer formed using a single material, a single layer formed using a plurality of different materials, or a multilayer structure having a plurality of layers formed using a plurality of different materials.
In the organic electroluminescence device 10 of an embodiment, the emission layer EML may include a plurality of different kinds (e.g., classes) of light-emitting materials. The organic electroluminescence device 10 of an embodiment may include a first host and a second host, which are different from each other, and a first dopant and a second dopant, which are different from each other.
In the description, the term “substituted or unsubstituted” refers to a state of being substituted, or unsubstituted with at least one substituent selected from the group consisting of a deuterium atom, a halogen atom, a cyano group, a nitro group, an amino group, a silyl group, an oxy group, a thio group, a sulfinyl group, a sulfonyl group, a carbonyl group, a boron group, a phosphine oxide group, a phosphine sulfide group, an alkyl group, an alkenyl group, an alkoxy group, a hydrocarbon ring group, an aryl group, and a heterocyclic group. Each of the exemplified substituents may be further substituted or unsubstituted. For example, in some embodiments a biphenyl group may be interpreted as a named aryl group, or in some embodiments may be interpreted as a phenyl group substituted with a phenyl group.
In the description, the term “forming a ring via the combination with an adjacent group” may refer to forming a substituted or unsubstituted hydrocarbon ring or heterocycle by combining with an adjacent group. The term “hydrocarbon ring” includes an aliphatic hydrocarbon ring and an aromatic hydrocarbon ring. The term “heterocycle” includes an aliphatic heterocycle and an aromatic heterocycle. The ring formed by combining with an adjacent group may be a monocyclic ring or a polycyclic ring. In addition, the ring formed via combining with an adjacent group may be further combined with another ring to form a spiro structure.
In the description, the term “adjacent group” may refer to a substituent on an adjacently bonded atom, a substituent on the same atom, or a substituent sterically positioned at the nearest position to (e.g., within bonding distance of) a corresponding substituent. For example, in 1,2-dimethylbenzene, the two methyl groups may be interpreted as “adjacent groups” to each other, and in 1,1-diethylcyclopentene, the two ethyl groups may be interpreted as “adjacent groups” to each other.
In the description, non-limiting examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom or an iodine atom.
In the description, the term “alkyl group” may refer to a linear, branched or cyclic alkyl. The number of carbons in the alkyl group may be 1 to 50, 1 to 30, 1 to 20, 1 to 10, or 1 to 6. Non-limiting examples of the alkyl group may include methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, i-butyl, 2-ethylbutyl, 3,3-dimethylbutyl, n-pentyl, i-pentyl, neopentyl, t-pentyl, cyclopentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 2-butylhexyl, cyclohexyl, 4-methylcyclohexyl, 4-t-butylcyclohexyl, n-heptyl, 1-methylheptyl, 2,2-dimethylheptyl, 2-ethylheptyl, 2-butylheptyl, n-octyl, t-octyl, 2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, 3,7-dimethyloctyl, cyclooctyl, n-nonyl, n-decyl, adamantyl, 2-ethyldecyl, 2-butyldecyl, 2-hexyldecyl, 2-octyldecyl, n-undecyl, n-dodecyl, 2-ethyldodecyl, 2-butyldodecyl, 2-hexyldocecyl, 2-octyldodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, 2-ethylhexadecyl, 2-butylhexadecyl, 2-hexylhexadecyl, 2-octylhexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, n-eicosyl, 2-ethyleicosyl, 2-butyleicosyl, 2-hexyleicosyl, 2-octyleicosyl, n-henicosyl, n-docosyl, n-tricosyl, n-tetracosyl, n-pentacosyl, n-hexacosyl, n-heptacosyl, n-octacosyl, n-nonacosyl, n-triacontyl, etc.
In the description, the term “alkenyl group” refers to a hydrocarbon group including one or more carbon-carbon double bonds in the middle and/or at the terminus of an alkyl group including 2 or more carbon atoms. The alkenyl group may be a linear chain or a branched chain. The number of carbons in the alkenyl group is not specifically limited, but may be 2 to 30, 2 to 20, or 2 to 10. Non-limiting examples of the alkenyl group include a vinyl group, a 1-butenyl group, a 1-pentenyl group, a 1,3-butadienyl aryl group, a styrenyl group, a styryl vinyl group, etc.
In the description, the term “alkynyl group” refers to a hydrocarbon group including one or more carbon-carbon triple bonds in the middle or at the terminus of an alkyl group including more carbon atoms. The alkynyl group may be a linear chain or a branched chain. The number of carbons in the alkynyl group is not specifically limited, but may be 2 to 30, 2 to 20, or 2 to 10. Non-limiting examples of the alkynyl group include an ethynyl group, a propynyl group, etc.
In the description, the term “hydrocarbon ring group” may refer to an optional functional group or substituent derived from an aliphatic hydrocarbon ring, or an optional functional group or substituent derived from an aromatic hydrocarbon ring. The number of carbons in the hydrocarbon ring may be 5 to 60, 5 to 30, or 5 to 20.
In the description, the term “aryl group” refers to an optional functional group or substituent derived from an aromatic hydrocarbon ring. The aryl group may be a monocyclic aryl group or a polycyclic aryl group. The number of carbons in the ring of the aryl group may be 6 to 30, 6 to 20, or 6 to 15. Non-limiting examples of the aryl group may include phenyl, naphthyl, fluorenyl, anthracenyl, phenanthryl, biphenyl, terphenyl, quaterphenyl, quinqphenyl, sexiphenyl, triphenylenyl, pyrenyl, benzofluoranthenyl, chrysenyl, etc.
In the description, the term “heterocyclic group” refers to an optional functional group or substituent derived from a ring including one or more heteroatoms selected from boron (B), oxygen (O), nitrogen (N), phosphorus (P), silicon (Si) and sulfur (S). The heterocyclic group may be an aliphatic heterocyclic group or an aromatic heterocyclic group. The aromatic heterocyclic group may be a heteroaryl group. The aliphatic heterocycle and the aromatic heterocycle may each be a monocycle or polycycle.
In the description, the heterocyclic group may include one or more selected from B, O, N, P, Si and S as heteroatoms. If the heterocyclic group includes two or more heteroatoms, the two or more heteroatoms may be the same or different. The heterocyclic group may be a monocyclic heterocyclic group or a polycyclic heterocyclic group, and in some embodiments may include a heteroaryl group. The number of carbons in the ring of the heterocyclic group may be 2 to 30, 2 to 20, or 2 to 10.
In the description, the aliphatic heterocyclic group may include one or more selected from B, O, N, P, Si and S as heteroatoms. The number of carbons in the ring of the aliphatic heterocyclic group may be 2 to 30, 2 to 20, or 2 to 10. Non-limiting examples of the aliphatic heterocyclic group include an oxirane group, a thiirane group, a pyrrolidine group, a piperidine group, a tetrahydrofuran group, a tetrahydrothiophene group, a thiane group, a tetrahydropyrane group, a 1,4-dioxane group, etc.
In the description, the heteroaryl group may include one or more selected from B, O, N, P, Si and S as heteroatoms. If the heteroaryl group includes two or more heteroatoms, the two or more heteroatoms may be the same or different. The heteroaryl group may be a monocyclic heterocyclic group or a polycyclic heterocyclic group. The number of carbons in the ring of the heteroaryl group may be 2 to 30, 2 to 20, or 2 to 10. Non-limiting examples of the heteroaryl group include thiophene, furan, pyrrole, imidazole, triazole, pyridine, bipyridine, pyrimidine, triazine, triazole, acridyl, pyridazine, pyrazinyl, quinoline, quinazoline, quinoxaline, phenoxazine, phthalazine, pyrido pyrimidine, pyrido pyrazine, pyrazino pyrazine, isoquinoline, indole, carbazole, N-arylcarbazole, N-heteroarylcarbazole, N-alkylcarbazole, benzoxazole, benzimidazole, benzothiazole, benzocarbazole, benzothiophene, dibenzothiophene, thienothiophene, benzofuran, phenanthroline, thiazole, isooxazole, oxazole, oxadiazole, thiadiazole, phenothiazine, dibenzosilole, dibenzofuran, etc.
In the description, the arylene group may be similar to the aryl group except that the arylene group is a divalent group. The heteroarylene group may be similar to the heteroaryl group except that the heteroarylene group is a divalent group.
In the description, the term “silyl group” refers to an alkyl silyl group or an aryl silyl group. Non-limiting examples of the silyl group include a trimethylsilyl group, a triethylsilyl group, a t-butyldimethylsilyl group, a vinyldimethylsilyl group, a propyldimethylsilyl group, a triphenylsilyl group, a diphenylsilyl group, a phenylsilyl group, etc.
In the description, the term “boryl group” refers to an alkyl boryl group or an aryl boryl group. Non-limiting examples of the boryl group include a trimethylboryl group, a triethylboryl group, a t-butyldimethylboryl group, a triphenylboryl group, a diphenylboryl group, a phenylboryl group, etc.
In the description, the carbon number of the amine group is not specifically limited, but may be 1 to 30. The amine group may refer to an alkyl amine group, an aryl amine group, or a heteroaryl amine group. Non-limiting examples of the amine group include a methylamine group, a dimethylamine group, a phenylamine group, a diphenylamine group, a naphthylamine group, a 9-methyl-anthracenylamine group, a triphenylamine group, etc.
In the description, the term “oxy group” may refer to an alkoxy group or an aryl oxy group. The alkoxy group may include a linear, branched or cyclic alkyl chain. The number of carbons in the alkoxy group is not specifically limited, but may be, for example, 1 to 20 or 1 to 10. Non-limiting examples of the oxy group include methoxy, ethoxy, n-propoxy, isopropoxy, butoxy, pentyloxy, hexyloxy, octyloxy, nonyloxy, decyloxy, benzyloxy, etc.
In the description, the alkyl group in the alkyl thio group, the alkyl sulfoxy group, the alkyl aryl group, the alkyl amino group, the alkyl boryl group and the alkyl silyl group is the same as described above, including the examples.
In the description, the aryl group in the aryl oxy group, aryl thio group, aryl sulfoxy group, aryl amino group, aryl boron group, aryl silyl group, aryl selenium group, and aryl alkyl group is the same as described above, including the examples.
In the description, the term “direct linkage” may refer to a single bond.
In the description,
or “” refer to a connected position (e.g., to another formula).
The emission layer EML of the organic electroluminescence device 10 of an embodiment includes a host having a first luminescent onset wavelength, a first dopant having a second luminescent onset wavelength, and a second dopant having a third luminescent onset wavelength. In some embodiments, the host may include a first host and a second host that is different from the first host. The host may include a first host having a hole transport moiety and a second host having an electron transport moiety. For example, in the emission layer EML of the organic electroluminescence device 10 of an embodiment, the host may be an exciplex formed by the first host and the second host.
The emission layer EML of an embodiment may include the first host including a carbazole group derivative moiety. The first host may be represented by Formula H-1:
In Formula H-1, L1 may be a direct linkage, a substituted or unsubstituted arylene group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroarylene group of 2 to 30 carbon atoms for forming a ring. Ar1 may be a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring.
In Formula H-1, “a” and “b” may be each independently an integer of 0 to 4, and R1 and R2 may be each independently a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring. When “a” and “b” are each independently an integer of 2 or more, a plurality of R1 groups and a plurality of R2 groups may be the same or at least one thereof may be different. In some embodiments, in Formula H-1, “a” and “b” may be 0. In this case, the carbazole group is unsubstituted.
In Formula H-1, L1 may be a direct linkage, a phenylene group, a divalent biphenyl group, a divalent carbazole group, etc., but an embodiment of the present disclosure is not limited thereto. Ar1 may be a substituted or unsubstituted carbazole group, a substituted or unsubstituted dibenzofuran group, a substituted or unsubstituted dibenzothiophene group, a substituted or unsubstituted biphenyl group, etc., but an embodiment of the present disclosure is not limited thereto.
In the organic electroluminescence device 10 of an embodiment, the emission layer may include a compound represented by Formula H-2 as the second host:
In Formula H-2, Z1 to Z3 may each independently be CRy or N, and Ry and R11 to R13 may each independently be a hydrogen atom, a deuterium atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring.
For example, Formula H-2 may be represented by one of Formula H-2a or Formula H-2b:
In Formula H-2a and Formula H-2b, R11 to R13 may each independently be a hydrogen atom, a deuterium atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring.
In addition, in Formula H-2b, Ry1 to Ry3 may each independently be a hydrogen atom, a deuterium atom, a cyano group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring. In addition, in Formula H-2b, at least one selected from R11 to R13 and Ry1 to Ry3 may be a cyano group, an aryl group of 6 to 30 carbon atoms for forming a ring including at least one cyano group as a substituent, or a heteroaryl group of 2 to 30 carbon atoms for forming a ring including at least one cyano group as a substituent.
For example, the second host represented by Formula H-2a may include a triazine moiety, and the second host represented by Formula H-2b may include at least one cyano group.
In Formula H-2a, R11 to R13 may each independently be a substituted or unsubstituted phenyl group, a substituted or unsubstituted carbazole group, etc., but an embodiment of the present disclosure is not limited thereto.
In Formula H-2b, any one selected from R11 to R13 and Ry1 to Ry3 may be substituted with a cyano group, or at least one selected from R11 to R13 and Ry1 to Ry3 may be a heteroaryl group of 2 to 30 carbon atoms for forming a ring substituted with a cyano group. The heteroaryl group of 2 to 30 carbon atoms for forming a ring substituted with at least one cyano group may further include a substituent in addition to the cyano group, and the substituent may be a substituted or unsubstituted silyl group, a substituted or unsubstituted alkyl group of 1 to 10 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring.
The organic electroluminescence device 10 of an embodiment may include the first host represented by Formula H-1 and the second host represented by Formula H-2 simultaneously (e.g., at the same time) in the emission layer EML, and may also include a first dopant and a second dopant (described in more detail below), in the emission layer EML, and may show excellent emission efficiency and long-lifespan characteristics. In the emission layer EML of the organic electroluminescence device 10 of an embodiment, the host may be an exciplex formed by the first host represented by Formula H-1 and the second host represented by Formula H-2.
Among the two host materials included simultaneously in the emission layer EML, the first host may be a hole transport host, and the second host may be an electron transport host. The organic electroluminescence device 10 of an embodiment may include both (e.g., simultaneously) the first host having excellent hole transport properties and the second host having excellent electron transport properties in the emission layer EML, such that energy transfer to the dopant compounds may be efficient.
The emission layer EML may include an organometallic complex including iridium (Ir), ruthenium (Ru), rhodium (Rh), platinum (Pt), palladium (Pd), copper (Cu), or osmium (Os) as a central metal element, bonded to one or more ligands, as the first dopant. In the organic electroluminescence device 10 of an embodiment, the emission layer may include a compound represented by Formula D-1 as the first dopant:
In Formula D-1, M may be a metal element, such as a transition metal element. M may be Pt, Pd, Cu, Os, Ir, Ru, or Rh.
In Formula D-1, Q1 to Q4 may each independently be C or N.
In Formula D-1, C1 to C4 may each independently be a substituted or unsubstituted hydrocarbon ring of 5 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heterocycle of 2 to 30 carbon atoms for forming a ring.
In Formula D-1, L21 to L23 may each independently be a direct linkage, *—O—*, *—S—*,
a substituted or unsubstituted divalent alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted arylene group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroarylene group of 2 to 30 carbon atoms for forming a ring. In L21 to L23, -* means a connected part with C1 to C4.
In Formula D-1, e1 to e3 may each independently be 0 or 1. When e1 is 0, C1 and C2 may not be (are not) interconnected. When e2 is 0, C2 and C3 may not be (are not) interconnected. When e3 is 0, C3 and C4 may not be (are not) interconnected.
R21 to R26 may each independently be a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted amine group, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 1 to 30 carbon atoms for forming a ring, or may be combined with an adjacent group to form a ring. For example, when R21 to R26 are alkyl groups, R21 to R26 may be a methyl group, an isopropyl group, or a tert-butyl group. When R21 to R26 are amine groups, R21 to R26 may be a dimethylamine group. When R21 to R26 are halogen atoms, R21 to R26 may be a fluorine atom (F).
d1 to d4 may each independently be an integer of 0 to 4. When d1 to d4 are each integers of 2 or more, a plurality of R21 to R24 groups may all be the same, or at least one may be different.
“m” may be 1 or 2. When M is Pt, Pd, Cu, or Os, “m” may be 1. When M is Ir, Ru, or Rh, “m” may be 1 or 2, and e2 may be 0.
For example, Formula D-1 may be represented by Formula D-1a-1:
In Formula D-1a-1, C1 to C4, Q1 to Q4, R21 to R24, d1 to d4, L22, and e2 may be the same as described herein in connection with Formula D-1a.
In Formula D-1a-1, C1 to C4 may each independently be a substituted or unsubstituted hydrocarbon ring or a substituted or unsubstituted heterocycle, represented by any one of C-1 to C-3:
In C-1 to C-3, P1 may be C—* or CR54, P2 may be N—* or NR61, and P3 may be N—* or NR62. R51 to R64 may each independently be a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 6 to 30 carbon atoms for forming a ring, or may be combined with an adjacent group to form a ring.
In addition, in C-1 to C-3,
refers to a connection point with M1 (the central metal atom), and “-*” refers to a connection point with an adjacent ring group (C1 to C4) or a linker (L21 to L24).
For example, Formula D-1 may be represented by Formula D-1b-1:
In Formula D-1b-1, X1 to X4, Y1 to Y4, and Z1 to Z4 may each independently be CRn or N. In addition, Rp, Rq, and Rn may each independently be a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted hydrocarbon ring of 5 to 30 carbon atoms for forming a ring, a substituted or unsubstituted heterocycle of 2 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted amine group, or may be combined with an adjacent group to form a ring. In Formula D-1b-1, the hexagonal rings including X1 to X4, Y1 to Y4, or Z1 to Z4 as ring-forming atoms may each independently be a substituted or unsubstituted benzene ring, a substituted or unsubstituted pyridine ring, a substituted or unsubstituted pyrimidine ring, or a substituted or unsubstituted triazine ring. For example, in Formula D-1b-1, the hexagonal rings including X1 to X4, Y1 to Y4, or Z1 to Z4 as ring-forming atoms may each independently be a substituted or unsubstituted benzene ring, a substituted or unsubstituted pyridine ring, a substituted or unsubstituted pyrimidine ring, or a substituted or unsubstituted triazine ring.
The first dopant represented by Formula D-1a or Formula D-1b may be a phosphorescent dopant.
The organic electroluminescence device 10 of an embodiment may include a second dopant in addition to the first dopant represented by Formula D-1 in the emission layer EML. The second dopant may be a fluorescent dopant. The second dopant may be a material to emit blue light.
In the organic electroluminescence device 10 of an embodiment, the emission layer may include a compound represented by one of Formula D-2a or D-2b as the second dopant:
In Formulae D-2a, X1 and X2 may each independently be NRm or O, and Rm may be a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring. In Formula D-2, R31 to R41 may each independently be a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted amine group, a substituted or unsubstituted boryl group, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring, or may be combined with an adjacent group to form a ring.
For example, in Formula D-2a, R31 to R41 may each independently be a hydrogen atom, a substituted or unsubstituted phenyl group, a substituted or unsubstituted carbazole group, a substituted or unsubstituted aryl oxy group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkyl boryl group, or a substituted or unsubstituted aryl boryl group.
In Formula D-2a, R39 and R40 may be combined with each other to form a heterocycle. A condensed heterocycle formed by combining R39 and R40 with each other may include B, O, or N as a heteroatom. The condensed heterocycle may be unsubstituted, or substituted with a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group.
The second dopant represented by Formula D-2a may be represented by any one of Formula D-2a-1 to Formula D-2a-4:
In Formula D-2a-1 to Formula D-2a-4, Rm1 to Rm4 may each independently be a hydrogen atom, a deuterium atom, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring. R1 to R18 may each independently be a hydrogen atom, a deuterium atom, a halogen atom, a cyano group, a substituted or unsubstituted amine group, a substituted or unsubstituted boryl group, a substituted or unsubstituted oxy group, a substituted or unsubstituted alkyl group of 1 to 20 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring, or combined with an adjacent group to form a ring.
For example, Rm1 to Rm4 may each independently be a hydrogen atom or a substituted or unsubstituted phenyl group. In addition, R1 to R18 may each independently be a hydrogen atom, an alkyl group of 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted carbazole group, or a substituted or unsubstituted arylamine group of 6 to 20 carbon atoms for forming a ring. However, an embodiment of the present disclosure is not limited thereto.
D1-L2-A1 [Formula D-2b]
In Formula D-2b, L2 may be a direct linkage, a substituted or unsubstituted arylene group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroarylene group of 2 to 30 carbon atoms for forming a ring. For example, L2 may be a direct linkage, or a substituted or unsubstituted phenylene group.
In Formula D-2b, D1 may be represented by one of Formula D-2-1 or Formula D-2-2:
In Formulae D-2-1 and D-2-2, L3 and L4 may each independently be a direct linkage, or a substituted or unsubstituted arylene group of 6 to 30 carbon atoms for forming a ring. For example, L3 and L4 may each independently be a direct linkage, or a substituted or unsubstituted phenylene group.
R42 to R59 may each independently be a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted amine group, a substituted or unsubstituted silyl group, a substituted or unsubstituted alkyl group of 1 to 15 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring. In some embodiments, R42 to R59 may be combined with an adjacent group to form a ring.
Y1 may be a direct linkage, CRaRb, SiRcRd, GeReRf, NRg, O, or S. In an embodiment, Y1 may be a direct linkage, CRaRb, NRg, or O.
Ra to Rg may each independently be a substituted or unsubstituted alkyl group of 1 to 15 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring. Each pair of Ra and Rb, Rc and Rd, and Re and Rf may be combined with each other to form a ring.
In Formula D-2b, A1 may be represented by one of Formulae D-2-3 to D-2-10:
In Formula D-2-3, Y2 may be C═O, or S(C═O)2. In Formula D-2-4, Y3may be C═O, or O. In Formula D-2-5, Y4 and Y5 may be each independently O, or S. In Formula D-2-8, Y6 and Y7 may be each independently N, or CQ12. In Formula D-2-10, Y8 may be O or NQ13.
In Formulae D-2-3 to D-2-10, Q1 to Q13 may each independently be a substituted or unsubstituted alkyl group of 1 to 15 carbon atoms, a substituted or unsubstituted aryl group of 6 to 30 carbon atoms for forming a ring, or a substituted or unsubstituted heteroaryl group of 2 to 30 carbon atoms for forming a ring.
In Formulae D-2-3 to D-2-10, n1, n4, and n6 may each independently be 0 to 4; n3, n5, n7, n8, and n10 may each independently be an integer of 0 to 3; n2 may be an integer of 0 to 5; and n9 may be an integer of 0 to 2. When n1 to n10 are each independently an integer of 2 or more, a plurality of Q1 to Q10 may be the same, or at least one may be different.
The organic electroluminescence device 10 of an embodiment may include the first dopant represented by Formula D-1 and the second dopant represented by Formula D-2a or Formula D-2b in the emission layer EML. For example, the organic electroluminescence device 10 of an embodiment may include the first dopant and the second dopant simultaneously (e.g., together), and may show excellent emission efficiency and/or improved device lifespan characteristics.
The lowest triplet excitation energy level (T1 level) of the first dopant may be substantially equal to or greater than the lowest triplet excitation energy level (T1 level) of the second dopant. The lowest triplet excitation energy level of the host may be substantially equal to or greater than the lowest triplet excitation energy level of the second dopant. In an embodiment, the first dopant may play the role of an assistant dopant which transfers the energy of the host to the second dopant. The second dopant may be a light-emitting dopant that is excited by the transferred energy from the host via the first dopant, and subsequently emits light. In an embodiment, the lowest triplet excitation energy level of the host may be substantially equal to or greater than the lowest triplet excitation energy levels of the first dopant and the second dopant, respectively, and the lowest triplet excitation energy of the second dopant may be smaller than the lowest triplet excitation energy level of the host and the lowest triplet excitation energy level of the first dopant, respectively.
In an embodiment, the second dopant may be a thermally activated delayed fluorescence (TADF) dopant. For example, in an embodiment, the second dopant may have a reverse intersystem crossing constant (kRISC) of about 103 s−1 or more and/or f (oscillation strength) of about 0.1 or more, and thus, thermally activated delayed fluorescence may be easily produced.
In an embodiment, the second dopant is a light-emitting dopant to emit blue light, and the emission layer EML may be to emit fluorescence. For example, the emission layer EML may emit blue light as delayed fluorescence.
In an embodiment, the first dopant, which is the assistant dopant, may accelerate the delayed fluorescence of the second dopant. Accordingly, the emission efficiency of the emission layer of an embodiment may be improved. In addition, when the delayed fluorescence is accelerated, excitons formed in the emission layer EML may not be accumulated in the emission layer EML, but may rapidly emit light, thereby reducing device deterioration. Accordingly, the lifespan of the organic electroluminescence device 10 of an embodiment may increase.
In the organic electroluminescence device 10 of an embodiment, the emission layer EML may include all the first host, the second host, the first dopant, and the second dopant, and the amount of the first dopant may be about 10 wt % to about 15 wt %, and the amount of the second dopant may be about 1 wt % to about 5 wt % based on the total weight of the first host, the second host, the first dopant, and the second dopant.
If the amounts of the first dopant and the second dopant satisfy the above-described ratios, the first dopant may efficiently transfer energy to the second dopant, and thus, the emission efficiency and device lifespan may increase.
In the emission layer EML, the amount of the first host and the second host may be the remainder of the total weight, e.g., excluding the first dopant and the second dopant. For example, in the emission layer EML, the amount of the first host and the second host may be about 80 wt % to about 89 wt % based on the total weight of the first host, the second host, the first dopant, and the second dopant. Out of the total weight of the first host and the second host, the weight ratio of the first host and the second host may be about 3:7 to about 7:3.
When the amounts of the first host and the second host satisfy the above-described ratio, charge balance properties in the emission layer EML may be improved, and emission efficiency and/or device life may increase. When the amounts of the first host and the second host deviate from the above-described ratio range, charge balance in the emission layer EML may be broken, emission efficiency may be degraded, and a device may be easily deteriorated.
If the first host, the second host, the first dopant, and the second dopant included in the emission layer EML satisfy the above-described amounts and ratios, excellent emission efficiency and/or long life may be achieved.
The organic electroluminescence device 10 of an embodiment may include all of the first host, the second host, the first dopant, and the second dopant, and the emission layer EML may include the combination of two host materials and two dopant materials. In the organic electroluminescence device 10 of an embodiment, the emission layer EML may include two different hosts, a first dopant including an organometallic complex, and a second dopant emitting delayed fluorescence, and may thereby show excellent emission efficiency and/or lifespan characteristics.
In an embodiment, the first host represented by Formula H-1 may be represented by any one of the compounds represented in Compound Group 1. The emission layer EML may include at least one of the compounds represented in Compound Group 1 as the first host material.
In an embodiment, the second host represented by Formula H-2 may be represented by any one of the compounds represented in Compound Group 2-1 and Compound Group 2-2. The emission layer EML may include at least one of the compounds represented in Compound Group 2-1 and Compound Group 2-2 as the second host material. Compound Group 2-1 may correspond to the second host material represented by Formula H-2a, and Compound Group 2-2 may correspond to the second host material represented by Formula H-2b.
In an embodiment, the emission layer EML may include at least one of the compounds represented in Compound Group 3-1 and Compound Group 3-2 as the first dopant material. Compound Group 3-1 may correspond to the first dopant material represented by Formula D-1a, and Compound Group 3-2 may correspond to the first dopant material represented by Formula D-1b.
In Compound Group 3-2, in AD2-1 to AD2-4, AD2-13 to AD2-16, and AD2-25 to AD2-28, each R may independently be a hydrogen atom, a methyl group, an isopropyl group, a tert-butyl group, or a dimethylamine group.
In an embodiment, the second dopant represented by Formula D-2 may be represented by any one of the compounds represented in Compound Group 4-1 or
Compound Group 4-2. The emission layer EML may include at least one of the compounds represented in Compound Group 4-1 or Compound Group 4-2 as the second dopant material. Compound Group 4-1 may correspond to the second dopant material represented by Formula D-2a, and Compound Group 4-2 may correspond to the second dopant material represented by Formula D-2b.
In the organic electroluminescence device 10 of an embodiment, the host has a first luminescent onset wavelength, the first dopant has a second luminescent onset wavelength, and the second dopant has a third luminescent onset wavelength.
The third luminescent onset wavelength of the second dopant is greater than each of the first luminescent onset wavelength and the second luminescent onset wavelength. For example, the third luminescent onset wavelength of the second dopant may be greater than the second luminescent onset wavelength of the first dopant, and the second luminescent onset wavelength of the first dopant may be greater than the first luminescent onset wavelength of the host.
In the description, the term “luminescent onset wavelength” is defined as the wavelength at an x-intercept value of a tangent line that is drawn at a position (e.g., on the left side of the peak) where the light intensity y-value is about 0.5 in the normalized light emission spectrum.
In
Referring to
As shown in
In an embodiment of the present disclosure, the first luminescent onset wavelength may be about 380 nm to about 430 nm, the second luminescent onset wavelength may be about 400 nm to about 450 nm, and the third luminescent onset wavelength may be about 410 nm to about 460 nm.
In an embodiment of the present disclosure, the luminescent onset wavelength and luminescent onset energy are in inverse proportion to each other and may satisfy Equation 1:
Luminescent onset energy of host>luminescent onset energy of first dopant>luminescent onset energy of second dopant [Equation 1]
In the organic electroluminescence device 10 of an embodiment of the present disclosure, the emission layer EML includes a host having the first luminescent onset wavelength, a first dopant having the second luminescent onset wavelength, and a second dopant having the third luminescent onset wavelength, and the third luminescent onset wavelength has a greater value than each of the first luminescent onset wavelength and the second luminescent onset wavelength. For example, the third luminescent onset wavelength is greater than the second luminescent onset wavelength, and the second luminescent onset wavelength may have a greater value than the first luminescent onset wavelength.
In the organic electroluminescence device of an embodiment, the luminescent onset wavelength of the second dopant (which is a light-emitting body) is the greatest, the luminescent onset wavelength of the first dopant (which plays the role of an assistant dopant) is smaller than the luminescent onset wavelength of the second dopant, and the luminescent onset wavelength of the host has the smallest value. Accordingly, the energy transfer from the host to the first dopant, and from the first dopant to the second dopant may be easily achieved, and thus, the organic electroluminescence device may show excellent emission efficiency and/or lifespan characteristics.
Referring to
In some embodiments, the organic electroluminescence device 10 of an embodiment may include a plurality of emission layers. The plurality of emission layers may be provided by stacking in order. For example, an organic electroluminescence device 10 including a plurality of emission layers may be to emit white light. The organic electroluminescence device including a plurality of emission layers may be an organic electroluminescence device of a tandem structure. When an organic electroluminescence device 10 includes a plurality of emission layers, at least one emission layer EML may include all the first host, second host, first dopant, and second dopant, as described above.
In the organic electroluminescence devices 10 of an embodiment, shown in
The electron transport region ETR may have a single layer formed using a single material, a single layer formed using a plurality of different materials, or a multilayer structure having a plurality of layers formed using a plurality of different materials.
For example, the electron transport region ETR may have a single layer structure including an electron injection layer EIL or an electron transport layer ETL, or a single layer structure formed using an electron injection material and an electron transport material (e.g., together). Further, the electron transport region ETR may have a plurality of layers formed of a plurality of different materials, for example, a structure stacked from the emission layer EML of electron transport layer ETL/electron injection layer EIL, or hole blocking layer HBL/electron transport layer ETL/electron injection layer EIL, without limitation. The thickness of the electron transport region ETR may be, for example, about 1,000 Å to about 1,500 Å.
The electron transport region ETR may be formed using various suitable methods (such as a vacuum deposition method, a spin coating method, a cast method, a Langmuir-Blodgett (LB) method, an inkjet printing method, a laser printing method, and/or a laser induced thermal imaging (LITI) method).
If the electron transport region ETR includes an electron transport layer ETL, the electron transport region ETR may include an anthracene-based compound. The electron transport region may include, for example, tris(8-hydroxyquinolinato)aluminum (Alq3), 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, 2,4,6-tris(3′-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine, 2-(4-(N-phenylbenzoimidazolyl-1-ylphenyl)-9,10-dinaphthylanthracene, 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)benzene (TPBi), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen), 3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ), 4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole (NTAZ), 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (tBu-PBD), bis(2-methyl-8-quinolinolato-N1,O8)-(1,1′-biphenyl-4-olato)aluminum (BAlq), beryllium bis(benzoquinolin-10-olate (Bebq2), 9,10-di(naphthalene-2-yl)anthracene (ADN), 1,3-bis[3,5-di(pyridine-3-yl)phenyl]benzene (BmPyPhB), or a mixture thereof, without limitation. The thickness of the electron transport layer ETL may be about 100 Å to about 1,000 Å and may be, for example, about 150 Å to about 500 Å. If the thickness of the electron transport layer ETL satisfies the above-described range, satisfactory electron transport properties may be obtained without substantial increase of a driving voltage.
If the electron transport region ETR includes the electron injection layer EIL, the electron transport region ETR may include a metal halide (such as LiF, NaCl, CsF, RbCl, RbI, and/or CuI), a lanthanide metal (such as ytterbium (Yb)), a metal oxide (such as Li2O and/or BaO), or lithium quinolate (LiQ). However, an embodiment of the present disclosure is not limited thereto. For example, the electron injection layer EIL may be formed using a mixture of an electron transport material and an insulating organo metal salt. The organo metal salt may be a material having an energy band gap of about 4 eV or more. The organo metal salt may include, for example, metal acetates, metal benzoates, metal acetoacetates, metal acetylacetonates, and/or metal stearates. The thickness of the electron injection layer EIL may be about 1 Å to about 100 Å, or about 3 Å to about 90 Å. If the thickness of the electron injection layer EIL satisfies the above described range, satisfactory electron injection properties may be obtained without inducing substantial increase of a driving voltage.
The electron transport region ETR may include a hole blocking layer HBL as described above. The hole blocking layer HBL may include, for example, at least one of 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) or 4,7-diphenyl-1,10-phenanthroline (Bphen). However, an embodiment of the present disclosure is not limited thereto.
The second electrode EL2 is provided on the electron transport region ETR. The second electrode EL2 may be a common electrode or a cathode. The second electrode EL2 may be a transmissive electrode, a transflective electrode or a reflective electrode. If the second electrode EL2 is the transmissive electrode, the second electrode EL2 may include a transparent metal oxide, for example, ITO, IZO, ZnO, ITZO, etc.
If the second electrode EL2 is the transflective electrode or the reflective electrode, the second electrode EL2 may include Ag, Mg, Cu, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, LiF/Ca, LiF/Al, Mo, Ti, a compound thereof, or a mixture thereof (for example, a mixture of Ag and Mg). The second electrode EL2 may have a multilayered structure including a reflective layer or a transflective layer formed using the above-described materials and a transparent conductive layer formed using ITO, IZO, ZnO, ITZO, etc.
The second electrode EL2 may be connected with an auxiliary electrode. If the second electrode EL2 is connected with the auxiliary electrode, the resistance of the second electrode EL2 may decrease.
Referring to
On the second electrode EL2 of the organic electroluminescence device 10 of an embodiment, a capping layer CPL may be further disposed. The capping layer CPL may include, for example, α-NPD, NPB, TPD, m-MTDATA, Alq3, CuPc, N4,N4,N4′,N4′-tetra(biphenyl-4-yl) biphenyl-4,4′-diamine (TPD15), 4,4′,4″-tris(carbazol sol-9-yl) triphenylamine (TCTA), etc.
The compound of an embodiment may be included in a functional layer other than the emission layer EML as a material for an organic electroluminescence device 10. The organic electroluminescence device 10 according to an embodiment of the present disclosure may include the compound in at least one functional layer disposed between the first electrode EL1 and the second electrode EL2, or in a capping layer CPL disposed on the second electrode EL2.
The organic electroluminescence device 10 according to an embodiment of the present disclosure includes (e.g., optimizes) the combination of the host material and the dopant material of the emission layer EML as described above, and may show excellent emission efficiency and/or long-lifespan characteristics. In addition, the organic electroluminescence device 10 of an embodiment may show high efficiency and long-lifespan characteristics in a blue wavelength region.
Hereinafter, the compound according to an embodiment and the organic electroluminescence device of an embodiment of the present disclosure will be explained in more detail referring to embodiments and comparative embodiments. The following embodiments are only illustrations to assist the understanding of the present disclosure, and the scope of the present disclosure is not limited thereto.
The organic electroluminescence devices of the Examples and Comparative
Examples were manufactured as follows. An ITO glass substrate was cut into a size of 50 mm×50 mm×0.5 mm, washed by ultrasonic waves using isopropyl alcohol and distilled water for 10 minutes each, exposed to ultraviolet rays and ozone for about 10 minutes for washing, and installed in a vacuum deposition apparatus. Then, a hole injection layer HIL was formed at a thickness of about 40 Å using 2-MTDATA, and a hole transport layer HTL was formed at a thickness of about 10 Å using NPB. Then, the first host, the second host, the first dopant, and the second dopant according to embodiments were co-deposited to form an emission layer EML into a thickness of about 200 Å , and an electron transport layer ETL was formed using a compound ETL1 (shown below) at a thickness of about 300 Å. Then, a second electrode was formed using Al at a thickness of about 1,200 Å. All layers were formed by a vacuum deposition method.
The combinations of the materials for an emission layer used in the Examples and the Comparative Examples are shown in Table 1.
In each device of the Examples and the Comparative Examples, the lowest triplet excitation energy (T1) of a host, the lowest triplet excitation energy (T1) of a first dopant, the lowest triplet excitation energy (T1) of a second dopant, the luminescent onset wavelength of a host, the luminescent onset wavelengths of a first dopant, the luminescent onset wavelengths of a second dopant, normalized light intensity of the cross point (wavelength cross point) of the normalized light absorption spectrum and normalized light emission spectrum of a second dopant, and distance between light absorption/emission peaks, are shown in Table 2.
The evaluation of the properties of the organic electroluminescence devices was conducted using a brightness light distribution characteristics measurement system. In order to evaluate the properties of the organic electroluminescence devices according to the Examples and the Comparative examples, driving voltage, luminance, efficiency, emission wavelength, and lifespan (T95) were measured. Emission efficiencies (cd/A) for the organic electroluminescence devices thus manufactured were measured at a current density of about 10 mA/cm2 and a luminance of about 1,000 cd/m2. The device lifespan (T95) is the time period after which the luminance decreases to 95% from a standard (e.g., initial luminance) of about 1,000 cd/m2. The device life (T95) was measured by continuously (e.g., substantially continuously) driving at a current density of about 10 mA/cm2, and the results are shown in terms of hours.
Referring to the results of Table 3, it could be confirmed that the device emission efficiency and/or device life was improved for each of the Examples when compared with the Comparative Examples, because the emission layer according to an embodiment includes all the first host, the second host, the first dopant and the second dopant, and the luminescent onset wavelength of the second dopant has a greater value than the luminescent onset wavelength of the first dopant.
In Comparative Examples 1, 2, and 4 to 10, one of the first host, the second host, the first dopant and the second dopant was not included, and at least one among efficiency and life was therefore decreased when compared with the devices of the Examples. In addition, it could be confirmed that although Comparative Examples 3 and 11 to 17 each included all of the first host, the second host, the first dopant, and the second dopant, and the second dopant had a greater luminescent onset wavelength value than each of the first dopant and the host, Comparative Examples 3 and 11 to 17 showed decreased emission efficiency and device life when compared with the light-emitting devices of the Examples. It could be confirmed that although Comparative Examples 18 to 20 included all the first host, the second host, the first dopant, and the second dopant, and the first dopant and the host each had a smaller luminescent onset wavelength than the second dopant, the normalized light intensity at a wavelength cross point was less than about 1.5 and at the same time, the distance between light absorption/emission peaks was greater than about 50 nm. Accordingly, the emission efficiency and device life were decreased when compared with the light-emitting devices of the Examples.
In the organic electroluminescence device of an embodiment, the second dopant (which is a light-emitting body) has the greatest luminescent onset wavelength, the first dopant (which performs the function of an assistant dopant) has a smaller luminescent onset wavelength than the second dopant, and the host has the smallest luminescent onset wavelength. Accordingly, energy transfer between the materials in the emission layer may be improved, and high emission efficiency and/or long-lifespan characteristics may be achieved. Further, the organic electroluminescence device of an embodiment has a normalized light intensity of about 0.5 or more at the wavelength cross point of the normalized light absorption spectrum and normalized light emission spectrum of the second dopant (which is a light-emitting body), and energy transfer from the host and the first dopant to the second dopant may be improved, and high emission efficiency and/or long-lifespan characteristics may be shown.
The organic electroluminescence device of an embodiment may show improved device properties of long lifespan and/or high efficiency.
The organic electroluminescence device of an embodiment includes two host materials and two dopant materials, and may show high efficiency and long-lifespan characteristics.
Although the example embodiments of the present disclosure have been described, it is understood that the present disclosure should not be limited to these example embodiments, but various changes and modifications can be made by one ordinary skilled in the art within the spirit and scope of the present disclosure as described in the following claims and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2019-0121391 | Oct 2019 | KR | national |
