Material for organic electroluminescent device and organic electroluminescent device

Abstract

The present invention provides: an organic EL element compound from which an organic EL element having low driving voltage, high efficiency, and long lifespan properties is obtained; and an organic EL element using said compound. This organic EL element compound has an indolocarbazole backbone represented by general formula (1). Here, ring A represents a benzene ring, ring B represents formula (1b), Tp represents a triphenylene group, L represents an aromatic hydrocarbon group having 6-18 carbon atoms, each X represents N or C-H, at least one X represents N, and n represents an integer of 1-3.

Description

[Technical Field]

[0001] The present invention relates to a compound for an organic electroluminescent device (organic EL device) and an organic EL device containing a specific mixed host material. [Background technology]

[0002] When a voltage is applied to an organic EL element, holes are injected from the anode and electrons are injected from the cathode into the light-emitting layer. In the light-emitting layer, the injected holes and electrons recombine to generate excitons. At this time, due to the statistical laws of electron spin, singlet excitons and triplet excitons are generated in a ratio of 1:3. Fluorescent organic EL elements that use emission from singlet excitons are said to have an internal quantum efficiency limit of 25%. On the other hand, phosphorescent organic EL elements that use emission from triplet excitons are known to be able to increase their internal quantum efficiency to 100% if intersystem crossing from singlet excitons is efficiently achieved.

[0003] Recently, highly efficient organic EL devices utilizing delayed fluorescence have been developed. For example, Patent Document 1 discloses an organic EL device utilizing the TTF (Triplet-Triplet Fusion) mechanism, which is one of the mechanisms of delayed fluorescence. The TTF mechanism utilizes the phenomenon in which singlet excitons are generated by the collision of two triplet excitons, and it is believed that the internal quantum efficiency can theoretically be increased to 40%. However, since the efficiency is lower than that of phosphorescent organic EL devices, further improvements in efficiency and low-voltage characteristics are required.

[0004] Furthermore, Patent Document 2 discloses an organic EL device that utilizes the TADF (Thermally Activated Delayed Fluorescence) mechanism. The TADF mechanism utilizes the phenomenon of reverse intersystem crossing from triplet excitons to singlet excitons in a material with a small energy difference between the singlet and triplet levels, and is thought to theoretically be able to increase the internal quantum efficiency to 100%.

[0005] However, in both mechanisms, there is room for improvement in both efficiency and lifespan, and there is also a demand for improvements in reducing the driving voltage. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2010 / 134350 A [Patent Document 2] WO2011 / 070963 A [Patent Document 3] WO2008 / 056746 A [Patent Document 4] WO2008 / 146839 A [Patent Document 5] WO2013 / 056776 A [Patent Document 6] Japanese Patent Application Laid-Open No. 2012-140365 [Patent Document 7] KR2019-0069083 A [Patent Document 8] US2015 / 0171357 A [Patent Document 9] WO2012 / 039561 A

[0007] Patent Documents 3 and 4 disclose the use of an indolocarbazole compound as a host material. Patent Document 5 discloses the use of a compound in which indenocarbazole is substituted with triphenylene and a nitrogen-containing six-membered ring in an emitting layer. Patent Documents 6, 7, 8, and 9 disclose compounds in which triphenylene is substituted with indolocarbazole.

[0008] However, none of these methods can be said to be sufficient, and further improvements in the efficiency and life span of organic EL devices are desired. Summary of the Invention

[0009] In order to apply organic EL elements to display elements such as flat panel displays, it is necessary to improve the luminous efficiency of the elements and at the same time ensure a sufficiently long life of the elements. In view of the above-mentioned current situation, an object of the present invention is to provide an organic EL element that can be driven at a low voltage and has high efficiency and long life, and a compound suitable for the same.

[0010] As a result of extensive research, the present inventors have found that the use of a specific indolocarbazole compound in an organic EL device results in excellent properties, and have thus completed the present invention.

[0011] The present invention relates to a compound for an organic electroluminescent device represented by the following general formula (1). [ka]

[0012] In general formula (1), ring A is an aromatic ring represented by formula (1a) and is fused with an adjacent ring. Ring B is a five-membered heterocycle represented by formula (1b) and is fused to the adjacent ring. Tp is a triphenylene group represented by formula (1c), and * indicates the bonding position to L. R 1 each independently represents deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms. L represents a divalent substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. Each X independently represents N or C—H, and at least one X is N. Ar 1 each independently represents hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 5 of these aromatic rings are linked together. R 2each independently represents deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms, or a substituted or unsubstituted linking aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the above aromatic hydrocarbon groups and aromatic heterocyclic groups are linked together. a to f represent the number of substitutions, a to d represent integers of 0 to 4, e represents an integer of 0 to 3, f represents an integer of 0 to 2, and n represents the number of repetitions and is an integer of 1 to 3.

[0013] In the general formula (1), it is a preferred embodiment of the present invention that all X's are N, L is a phenylene group, n is 1, or a to f's are all 0.

[0014] The general formula (1) may be represented by any one of the following formulas (2) to (5). [ka] (where Tp, Ar 1 , L, R 1 , R 2 , a to f, and n have the same meanings as in general formula (1).

[0015] Furthermore, the above Tp may be expressed by the following formula (2c). [ka] (where R 2 , c, d, e and * have the same meanings as in general formula (1).

[0016] The present invention also relates to an organic electroluminescent device having an organic layer between an anode and a cathode laminated on a substrate, wherein the organic layer contains the compound for organic electroluminescent devices described above. The organic layer includes a light-emitting layer, which preferably contains the compound for organic electroluminescent devices as a host material.

[0017] In order to apply organic EL elements to display devices such as flat panel displays and light sources, it is necessary to improve the luminous efficiency of the elements and extend their lifespan. To achieve this, the materials used in the organic layers must be highly resistant to heat and electrical charges.

[0018] The compound for organic EL devices of the present invention has a nitrogen-containing six-membered ring with high electron transport properties on one N of indolocarbazole, which is expected to have high hole transport properties and high stability against electric charges, and triphenylene, which is expected to have high stability against heat and electric charges, on the other N, thereby substituting it, and it is believed that when used as a host material in an organic EL device, it can achieve a long life of the device. Furthermore, in the case of delayed fluorescent EL elements and phosphorescent EL elements, it is assumed that the minimum excited triplet energy is high enough to confine the excitation energy generated in the emitting layer, and that the introduction of a rigid triphenylene group reduces the loss of excitation energy due to molecular rotation and vibration. This prevents energy from leaking from the emitting layer to surrounding layers, and it is assumed that it has unexpectedly become possible to produce organic EL elements that are highly efficient and have a long life despite operating at a low voltage. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an example of an organic EL element. DETAILED DESCRIPTION OF THE INVENTION

[0020] The compound for an organic EL device of the present invention is represented by the above general formula (1). The compound for an organic EL device of the present invention is also called the material of the present invention or the compound of general formula (1).

[0021] In general formula (1), ring A is a benzene ring represented by formula (1a) and is fused with two adjacent rings. Ring B is a five-membered heterocycle represented by formula (1b), and is fused to two adjacent rings at any position, but not at the edge containing N. Therefore, the indolocarbazole ring has several isomeric structures, but the number is limited. Specifically, it can have a structure represented by the above formulas (2) to (5), and is preferably a compound represented by the above formulas (3) to (5).

[0022] In the general formula (1), formulas (2) to (5) and formula (2c), common symbols have the same meaning. Each X is independently CH or N, and at least one is N. Preferably, at least two Xs are N, and more preferably, all of Xs are N.

[0023] a to f represent the number of substitutions, a to d are integers of 0 to 4, e is an integer of 0 to 3, and f is an integer of 0 to 2. Preferably, a to f are 0 to 1, and more preferably 0. n represents the number of repetitions and is an integer of 1 to 3, preferably 1 or 2, and more preferably 1.

[0024] Ar 1 are each independently hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 5 of these aromatic rings are linked together. Preferred are hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 5 of the aromatic hydrocarbon groups are linked together. More preferred are a substituted or unsubstituted phenyl group or a substituted or unsubstituted linked aromatic group in which 2 to 3 phenyl groups are linked together.

[0025] Specific examples of the unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, the unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or the unsubstituted linked aromatic group in which 2 to 5 of these aromatic rings are linked together include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, fluorene, triphenylene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, pyrazine, furan, isoxazole, quinoline, Examples of the group include groups derived by removing one hydrogen atom from phosphorus, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazole, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, or a compound formed by linking 2 to 5 of these. Preferred examples include groups derived from benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, fluorene, triphenylene, or a compound formed by linking 2 to 5 of these. More preferred are phenyl, biphenyl, and terphenyl groups. The terphenyl group may be linear or branched.

[0026] L is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. It is preferably a substituted or unsubstituted phenylene group. When n is 2 or 3, L forms a structure in which L is linked, and the linking mode may be ortho-, meta-, or para-linking. This linked structure is a structure in which aromatic hydrocarbon rings are linked to each other by a single bond.

[0027] When L is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, it is the same as the above Ar except that it is a divalent group formed by removing two hydrogen atoms from an aromatic hydrocarbon compound. 1The same applies as when is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. A phenylene group is preferred.

[0028] R 1 are each independently deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms.

[0029] Specific examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, etc. Preferred are alkyl groups having 1 to 4 carbon atoms.

[0030] In general formula (1), Tp is a triphenylene group represented by formula (1c), preferably a triphenylene group represented by formula (2c).

[0031] R 2 each independently represent deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group having 2 to 5 of these aromatic rings linked together, preferably deuterium, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted linked aromatic group having 2 to 5 of these aromatic rings linked together, more preferably a substituted or unsubstituted phenyl group, or a linked aromatic group having 2 to 3 of these aromatic rings linked together.

[0032] Specific examples of the aliphatic hydrocarbon group having 1 to 10 carbon atoms include R 1 is an aliphatic hydrocarbon group having 1 to 10 carbon atoms.

[0033] Specific examples of the unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, the unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or the unsubstituted linked aromatic group in which 2 to 5 of these aromatic rings are linked together include Ar 1 is the same as in these cases. Preferred examples of the aromatic group include aromatic groups derived from benzene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, pyrazine, furan, isoxazole, oxazole, quinoline, isoquinoline, quinoxaline, quinazoline, oxadiazole, thiadiazole, benzotriazine, phthalazine, tetrazole, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzisothiazole, or benzothiadiazole. More preferred examples of the aromatic group include aromatic groups derived from benzene.

[0034] In this specification, the aromatic hydrocarbon group, aromatic heterocyclic group, or linking aromatic group may each have a substituent. When the substituent has a substituent, the substituent is preferably deuterium, halogen, cyano group, triarylsilyl group, aliphatic hydrocarbon group having 1 to 10 carbon atoms, alkenyl group having 2 to 5 carbon atoms, alkoxy group having 1 to 5 carbon atoms, or diarylamino group having 12 to 44 carbon atoms. When the substituent is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, it may be linear, branched, or cyclic. When the triarylsilyl group or diarylamino group is substituted with the aromatic hydrocarbon group, aromatic heterocyclic group, or linking aromatic group, silicon and carbon, or nitrogen and carbon, respectively, are bonded by a single bond. The number of the substituents is 0 to 5, preferably 0 to 2. When the aromatic hydrocarbon group or aromatic heterocyclic group has a substituent, the number of carbon atoms in the substituent is not included in the calculation of the number of carbon atoms. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituent, falls within the above range.

[0035] Specific examples of the substituent include cyano, methyl, ethyl, propyl, i-propyl, butyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, vinyl, propenyl, butenyl, pentenyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthranylamino, diphenanthrenylamino, dipyrenylamino, etc. Preferred are cyano, methyl, ethyl, t-butyl, propyl, butyl, pentyl, hexyl, heptyl, or octyldiphenylamino, naphthylphenylamino, or dinaphthylamino.

[0036] In this specification, a linking aromatic group refers to an aromatic group selected from an aromatic hydrocarbon group and an aromatic heterocyclic group, in which carbon atoms in the aromatic rings are linked together by a single bond. It is an aromatic group in which two or more aromatic groups are linked together, and these may be linear or branched. The aromatic group may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and the multiple aromatic groups may be the same or different. An aromatic group that corresponds to a linking aromatic group is different from a substituted aromatic group.

[0037] In addition, some or all of the hydrogen atoms in the unsubstituted aromatic hydrocarbon group, unsubstituted aromatic heterocyclic group, unsubstituted linking aromatic group, substituents of these aromatic groups, or the aliphatic hydrocarbon group may be deuterated.In addition, some or all of the hydrogen atoms in the general formula (1), formulas (1a) to (1c), formulas (2) to (5), and formula (2c) may be deuterated.

[0038] Specific examples of the compound represented by general formula (1) are shown below, but the compound is not limited to these exemplary compounds.

[0039] [ka] [ka] [ka]

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[0045] The compound for an organic EL device of the present invention is contained in an organic layer of the organic EL device, and this organic layer is preferably selected from the group consisting of a light-emitting layer, a hole-injection layer, a hole-transport layer, an electron-transport layer, an electron-injection layer, a hole-blocking layer, and an electron-blocking layer. Preferably, it is a light-emitting layer, and the light-emitting layer preferably contains at least one light-emitting dopant.

[0046] When the compound for an organic EL device of the present invention is contained in the light-emitting layer, it is preferably contained as a host.

[0047] Next, the structure of the organic EL element of the present invention will be described with reference to the drawings, but the structure of the organic EL element of the present invention is not limited to this.

[0048] FIG. 1 is a cross-sectional view showing an example of the structure of a typical organic EL device used in the present invention, where 1 represents a substrate, 2 represents an anode, 3 represents a hole injection layer, 4 represents a hole transport layer, 5 represents an emitting layer, 6 represents an electron transport layer, and 7 represents a cathode. The organic EL device of the present invention may have an exciton blocking layer adjacent to the emitting layer, or an electron blocking layer between the emitting layer and the hole injection layer. The exciton blocking layer can be inserted on either the anode side or the cathode side of the emitting layer, or both simultaneously. The organic EL device of the present invention has an anode, an emitting layer, and a cathode as essential layers, but may also have a hole injection transport layer and an electron injection transport layer in addition to the essential layers, and may further have a hole blocking layer between the emitting layer and the electron injection transport layer. Note that the hole injection transport layer refers to either the hole injection layer or the hole transport layer, or both, and the electron injection transport layer refers to either the electron injection layer or the electron transport layer, or both.

[0049] It is also possible to have the reverse structure to that shown in Figure 1, i.e., to stack the cathode 7, electron transport layer 6, light-emitting layer 5, hole transport layer 4, and anode 2 on the substrate 1 in this order, and in this case too, layers can be added or omitted as necessary.

[0050] -substrate- The organic EL device of the present invention is preferably supported by a substrate. There are no particular limitations on the substrate, and any substrate conventionally used in organic EL devices, such as glass, transparent plastic, or quartz, can be used.

[0051] -anode- Anode materials for organic EL devices are preferably metals, alloys, electrically conductive compounds, or mixtures thereof with a high work function (4 eV or higher). Specific examples of such electrode materials include metals such as Au, and conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2, and ZnO. Amorphous materials capable of forming transparent conductive films, such as IDIXO (In2O3-ZnO), may also be used. These electrode materials may be formed into thin films by vapor deposition or sputtering, and then patterned into the desired shape by photolithography. Alternatively, if pattern precision is not required (approximately 100 μm or higher), a pattern may be formed using a mask of the desired shape during vapor deposition or sputtering of the electrode material. Alternatively, when a coatable material such as an organic conductive compound is used, wet film formation methods such as printing or coating can be used. When light is emitted from this anode, a transmittance of more than 10% is desirable, and the sheet resistance of the anode is preferably less than several hundred Ω / □. The film thickness varies depending on the material, but is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

[0052] -cathode- On the other hand, cathode materials are typically made of metals (electron injecting metals), alloys, electrically conductive compounds, or mixtures thereof with a low work function (4 eV or less). Specific examples of such electrode materials include sodium, sodium-potassium alloys, magnesium, lithium, magnesium / copper mixtures, magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al2O3) mixtures, indium, lithium / aluminum mixtures, and rare earth metals. Among these, mixtures of electron injecting metals and stable second metals with higher work functions, such as magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide mixtures, lithium / aluminum mixtures, and aluminum, are preferred in terms of electron injecting properties and durability against oxidation. Cathode materials can be fabricated by forming thin films of these cathode materials by methods such as vapor deposition or sputtering. Furthermore, the cathode preferably has a sheet resistance of several hundred Ω / □ or less, and the film thickness is typically selected from the range of 10 nm to 5 μm, preferably 50 to 200 nm. It is advantageous if either the anode or cathode of the organic EL element is transparent or semi-transparent to allow the emitted light to pass through, as this improves the luminance of the emitted light.

[0053] Furthermore, after forming the above metal to a film thickness of 1 to 20 nm, a transparent or semitransparent cathode can be fabricated by forming the conductive transparent material mentioned in the description of the anode on top of it. By applying this, it is possible to fabricate an element in which both the anode and cathode are transparent.

[0054] -Emitting layer- The light-emitting layer is a layer that emits light after excitons are generated by recombination of holes and electrons injected from the anode and cathode, respectively, and preferably contains an organic light-emitting dopant material and a host.

[0055] The compound for organic EL devices of the present invention is preferably used as the host. The compound of the present invention as a host may be used alone or in combination with two or more different compounds. If necessary, one or more other host materials, such as known host materials, may be used in combination. The other host material is preferably a compound that has hole transporting ability and electron transporting ability, prevents the emission wavelength from shifting to a longer wavelength, and has a high glass transition temperature.

[0056] Known host materials are known from many patent documents and can be selected from them. Specific examples of the host material include, but are not limited to, indolocarbazole derivatives described in WO2008 / 056746A, WO2008 / 146839A, etc., carbazole derivatives described in WO2009 / 086028A, WO2012 / 077520A, etc., CBP (N,N-biscarbazolylbiphenyl) derivatives, triazine derivatives described in WO2014 / 185595A, WO2018 / 021663A, etc., indenocarbazole derivatives described in WO2010 / 136109A, WO2011 / 000455A, etc., and the like. Dibenzofuran derivatives, triazole derivatives, indole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidene compounds, porphyrin compounds, anthraquinodimethane, etc. derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, heterocyclic tetracarboxylic acid anhydrides such as naphthalene perylene, phthalocyanine derivatives, metal complexes of 8-quinolinol derivatives, metal phthalocyanines, various metal complexes typified by metal complexes of benzoxazole and benzothiazole derivatives, polysilane compounds, poly(N-vinylcarbazole) derivatives, aniline copolymers, thiophene oligomers, polythiophene derivatives, polyphenylene derivatives, polyphenylenevinylene derivatives, polyfluorene derivatives, and other polymer compounds.

[0057] Specific examples of known host materials are shown below, but the present invention is not limited to these. [ka]

[0058] When a phosphorescent dopant is used as the luminescent dopant material, the phosphorescent dopant preferably contains an organometallic complex containing at least one metal selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. Specifically, iridium complexes described in J.Am.Chem.Soc.2001,123,4304, JP2013-530515A, US2016 / 0049599A, US2017 / 0069848A, US2018 / 0282356A, or US2019 / 0036043A, or platinum complexes described in US2018 / 0013078A or KR2018-094482A are preferably used, but are not limited to these.

[0059] The light-emitting layer may contain only one type of phosphorescent dopant material, or two or more types of phosphorescent dopant materials. The content of the phosphorescent dopant material is preferably 0.1 to 30 wt %, more preferably 1 to 20 wt %, relative to the host material.

[0060] The phosphorescent dopant material is not particularly limited, but specific examples include the following.

[0061] [ka] [ka]

[0062] When a fluorescent dopant is used as the light-emitting dopant material, the fluorescent dopant is not particularly limited, and examples thereof include benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives, condensed aromatic compounds, perinone derivatives, oxadiazole derivatives, oxazine derivatives, aldazine derivatives, pyrrolidine derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolopyridine derivatives, styrylamine derivatives, diketopyrrolopyrrole derivatives, aromatic dimethylidine compounds, various metal complexes typified by metal complexes of 8-quinolinol derivatives, metal complexes of pyrromethene derivatives, rare earth complexes, and transition metal complexes, polymer compounds such as polythiophene, polyphenylene, and polyphenylenevinylene, and organic silane derivatives. Preferred examples include fused aromatic derivatives, styryl derivatives, diketopyrrolopyrrole derivatives, oxazine derivatives, pyrromethene metal complexes, transition metal complexes, and lanthanoid complexes, and more preferred examples include naphthalene, pyrene, chrysene, triphenylene, benzo[c]phenanthrene, benzo[a]anthracene, pentacene, perylene, fluoranthene, acenaphthofluoranthene, dibenzo[a,j]anthracene, dibenzo[a,h]anthracene, benzo[a]naphthalene, hexacene, naphtho[2,1-f]isoquinoline, α-naphthaphenanthridine, phenanthroxazole, quinolino[6,5-f]quinoline, and benzothiophanthrene. These may have an alkyl group, an aryl group, an aromatic heterocyclic group, or a diarylamino group as a substituent.

[0063] The light-emitting layer may contain one or more fluorescent dopant materials, and the content of the fluorescent dopant material is preferably 0.1 to 20%, more preferably 1 to 10%, relative to the host material.

[0064] When a thermally activated delayed fluorescent dopant is used as the luminescent dopant material, examples of the thermally activated delayed fluorescent dopant include, but are not limited to, metal complexes such as tin complexes and copper complexes, indolocarbazole derivatives described in WO2011 / 070963A, cyanobenzene derivatives and carbazole derivatives described in Nature 2012,492,234, phenazine derivatives, oxadiazole derivatives, triazole derivatives, sulfone derivatives, phenoxazine derivatives and acridine derivatives described in Nature Photonics 2014,8,326, and the like.

[0065] The thermally activated delayed fluorescent dopant material is not particularly limited, but specific examples include the following.

[0066] [ka]

[0067] The light-emitting layer may contain only one type of thermally activated delayed fluorescent dopant material, or two or more types. The thermally activated delayed fluorescent dopant may be mixed with a phosphorescent dopant or a fluorescent dopant. The content of the thermally activated delayed fluorescent dopant material is preferably 0.1 to 50%, more preferably 1 to 30%, of the host material.

[0068] -Injection layer- The injection layer is a layer provided between an electrode and an organic layer to reduce the driving voltage and improve the luminance of light emitted, and includes a hole injection layer and an electron injection layer, and may be provided between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer. The injection layer can be provided as needed.

[0069] -Hole blocking layer- In a broad sense, a hole-blocking layer functions as an electron-transporting layer and is made of a hole-blocking material that has the ability to transport electrons but has an extremely low ability to transport holes. By transporting electrons while blocking holes, the hole-blocking layer can improve the probability of recombination of electrons and holes in the light-emitting layer.

[0070] -Electron blocking layer- In a broad sense, the electron blocking layer functions as a hole transport layer, and can improve the probability of recombination of electrons and holes in the light-emitting layer by blocking electrons while transporting holes.

[0071] As the material for the electron blocking layer, known electron blocking layer materials can be used, and the materials for the hole transport layer described below can also be used as needed. The thickness of the electron blocking layer is preferably 3 to 100 nm, more preferably 5 to 30 nm.

[0072] -Exciton blocking layer- The exciton-blocking layer is a layer that prevents excitons generated by the recombination of holes and electrons in the light-emitting layer from diffusing into the charge-transporting layer. Inserting this layer makes it possible to efficiently confine excitons within the light-emitting layer, thereby improving the luminous efficiency of the device. In devices with two or more adjacent light-emitting layers, the exciton-blocking layer can be inserted between two adjacent light-emitting layers.

[0073] The exciton blocking layer may be made of any known exciton blocking layer material, such as 1,3-dicarbazolylbenzene (mCP) or bis(2-methyl-8-quinolinolato)-4-phenylphenolatoaluminum(III) (BAlq).

[0074] -Hole transport layer- The hole transport layer is made of a hole transport material having a function of transporting holes, and the hole transport layer may be provided as a single layer or as a plurality of layers.

[0075] The hole transport material has either hole injection or transport properties or electron barrier properties, and may be either organic or inorganic. Any conventionally known compound can be selected and used for the hole transport layer. Examples of such hole transport materials include porphyrin derivatives, arylamine derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, and conductive polymer oligomers, particularly thiophene oligomers. Porphyrin derivatives, arylamine derivatives, and styrylamine derivatives are preferred, and arylamine compounds are more preferred.

[0076] -Electron transport layer- The electron transport layer is made of a material having the function of transporting electrons, and the electron transport layer may be a single layer or a plurality of layers.

[0077] The electron transport material (which may also serve as a hole blocking material) may have the function of transporting electrons injected from the cathode to the light-emitting layer. The electron transport layer may be formed from any of conventionally known compounds, including polycyclic aromatic derivatives such as naphthalene, anthracene, and phenanthroline, tris(8-quinolinolato)aluminum(III) derivatives, phosphine oxide derivatives, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, bipyridine derivatives, quinoline derivatives, oxadiazole derivatives, benzimidazole derivatives, benzothiazole derivatives, and indolocarbazole derivatives. Furthermore, polymeric materials in which these materials are incorporated into a polymer chain or in which these materials form the polymer backbone may also be used. [Example]

[0078] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples and can be implemented in various forms as long as they do not depart from the gist of the invention.

[0079] Example 1 Compound (2) was synthesized according to the following reaction scheme. [ka] To 20 g of compound (a), 36 g of compound (b), 1.5 g of copper iodide, 43 g of potassium carbonate, 0.06 g of 18-crown-6-ether, and 900 ml of 1,3-dimethyl-2-imidazolidinone were added, and the mixture was stirred at 190°C for 19 hours under a nitrogen atmosphere. After cooling to room temperature, the mixture was purified by silica gel column chromatography and crystallization to obtain 31 g of intermediate (1-1) as a white solid (yield 71%). Under a nitrogen atmosphere, 1.4 g of 60 wt% sodium hydride was added to 30 ml of N,N'-dimethylacetamide (DMAc) to prepare a suspension. 17 g of intermediate (1-1) dissolved in 170 ml of DMAc was added thereto and stirred for 30 minutes. 7.9 g of compound (c) was added thereto and stirred for 4 hours. The reaction solution was added to a mixed solution of methanol (300 ml) and distilled water (100 ml) with stirring, and the resulting precipitated solid was collected by filtration. The resulting solid was purified by silica gel column chromatography and crystallization purification to obtain 20 g (70% yield) of compound (2) as a yellow solid (APCI-TOFMS, m / z 790 [M+H] + ).

[0080] Example 2 Compound (81) was synthesized according to the following reaction scheme. [ka] To 20 g of compound (d), 36 g of compound (b), 1.5 g of copper iodide, 43 g of potassium carbonate, 0.06 g of 18-crown-6-ether, and 900 ml of 1,3-dimethyl-2-imidazolidinone were added and stirred for 72 hours. The reaction product was separated and purified to obtain 32 g (73% yield) of intermediate (2-1) as a white solid. 1.4 g of 60 wt% sodium hydride was added to 30 ml of DMAc, and 17 g of intermediate (2-1) dissolved in DMAc was added thereto and stirred for 30 minutes. 7.9 g of compound (c) was then added thereto and stirred for 24 hours. The reaction product was separated and purified to obtain 18 g (76% yield) of compound (81) as a yellow solid.

[0081] Example 3 Compound (82) was synthesized according to the following reaction scheme. [ka] To 20 g of compound (d), 36 g of compound (e), 1.5 g of copper iodide, 43 g of potassium carbonate, 0.06 g of 18-crown-6-ether, and 900 ml of 1,3-dimethyl-2-imidazolidinone were added and stirred for 72 hours. The reaction product was separated and purified to obtain 28 g (64% yield) of intermediate (3-1) as a white solid. 1.4 g of 60 wt% sodium hydride was added to 30 ml of DMAc, and 17 g of intermediate (3-1) dissolved in DMAc was added thereto and stirred for 30 minutes. 7.9 g of compound (c) was added thereto and stirred for 4 hours. The reaction product was separated and purified to obtain 21 g (89% yield) of compound (82) as a yellow solid.

[0082] Example 4 Compound (83) was synthesized according to the following reaction scheme. [ka] To 10.8 g of compound (d), 15 g of compound (f), 36 g of tripotassium phosphate, 2.8 g of 18-crown-6-ether, and 180 ml of 1,3-dimethyl-2-imidazolidinone were added and stirred for 90 hours. The reaction product was separated and purified to obtain 25 g of intermediate (4-1) as a white solid (yield 57%). 0.6 g of 60 wt% sodium hydride was added to 20 ml of DMAc, and 9 g of intermediate (4-1) dissolved in DMAc was added thereto and stirred for 30 minutes. 4.6 g of compound (c) was then added thereto and stirred for 27 hours. The reaction product was separated and purified to obtain 9 g of compound (83) as a yellow solid (70% yield).

[0083] Example 5 Compound (85) was synthesized according to the following reaction scheme. [ka] 1.4 g of 60 wt% sodium hydride was added to 30 ml of DMAc, and 11 g of intermediate (3-1) dissolved in DMAc was added thereto and stirred for 30 minutes. 7.9 g of compound (g) was then added thereto and stirred for 24 hours. The reaction product was separated and purified to obtain 19 g (73% yield) of compound (85) as a yellow solid.

[0084] Example 6 Compound (93) was synthesized according to the following reaction scheme. [ka] To 20 g of compound (d), 43 g of compound (h), 1.5 g of copper iodide, 43 g of potassium carbonate, 0.06 g of 18-crown-6-ether, and 900 ml of 1,3-dimethyl-2-imidazolidinone were added and stirred for 72 hours. The reaction product was separated and purified to obtain 37 g (75% yield) of intermediate (6-1) as a white solid. 1.4 g of 60 wt% sodium hydride was added to 30 ml of DMAc, and 11 g of intermediate (6-1) dissolved in DMAc was added thereto and stirred for 30 minutes. 7.9 g of compound (c) was then added thereto and stirred for 72 hours. The reaction product was separated and purified to obtain 22 g (86% yield) of compound (93) as a yellow solid.

[0085] Example 7 Compound (103) was synthesized according to the following reaction scheme. [ka] 1.4 g of 60 wt% sodium hydride was added to 30 ml of DMAc, and 11 g of intermediate (3-1) dissolved in DMAc was added thereto and stirred for 30 minutes. 11 g of compound (i) was then added thereto and stirred for 72 hours. The reaction product was separated and purified to obtain 19 g (72% yield) of compound (103) as a yellow solid.

[0086] Example 8 Each thin film was deposited by vacuum deposition on a glass substrate with an anode made of ITO with a film thickness of 110 nm at a vacuum of 4.0 × 10 -5 The layers were laminated using a Pa process. First, HAT-CN was formed to a thickness of 25 nm as a hole-injection layer on ITO, and then Spiro-TPD was formed to a thickness of 30 nm as a hole-transport layer. Next, HT-1 was formed to a thickness of 10 nm as an electron-blocking layer. Next, compound (2) as a host material and Ir(ppy)3 as an emitting dopant were co-evaporated from different evaporation sources to form a 40 nm-thick emitting layer. The Ir(ppy)3 concentration was 10 wt%. Next, ET-1 was formed to a thickness of 20 nm as an electron-transport layer. Furthermore, LiF was formed to a thickness of 1 nm as an electron-injection layer on the electron-transport layer. Finally, Al was formed to a thickness of 70 nm as a cathode on the electron-injection layer to fabricate an organic EL device.

[0087] Examples 9 to 14 Organic EL devices were prepared in the same manner as in Example 8, except that compounds (81), (82), (83), (85), (93), and (103) obtained in Examples 2 to 7 were used as host materials for the emitting layer. Table 3 shows the emitting characteristics.

[0088] Comparative Examples 1 to 6 An organic EL device was prepared in the same manner as in Example 8, except that Compound A, B, C, D, E, or F was used as the host material of the light-emitting layer in Example 8.

[0089] When an external power supply was connected to the organic EL elements obtained in the examples and comparative examples and a DC voltage was applied, an emission spectrum with a maximum wavelength of 517 nm was observed in all the organic EL elements, indicating that light emission was obtained from Ir(ppy). The evaluation results of the fabricated organic EL devices are shown in Table 1. In the table, the luminance, driving voltage, power efficiency, and LT70 are measured at a driving current of 20 mA / cm 2 LT70 is the time it takes for the initial luminance of 9000 cd / A to decrease to 70%, and indicates the lifespan characteristics.

[0090] [Table 1]

[0091] It can be seen from Table 1 that Examples 8 to 14 have improved power efficiency and life span compared to the comparative example, and exhibit favorable characteristics.

[0092] The compounds used in the examples and comparative examples are listed below. [ka] [Explanation of symbols]

[0093] 1; substrate; 2; anode; 3; hole injection layer; 4; hole transport layer; 5; light-emitting layer; 6; electron transport layer; 7; cathode

Claims

1. A compound for organic electroluminescent devices represented by any one of the following formulas (2) to (5): 【Chemistry 1】 【change】 【Chemistry 2】 Here, Tp is a triphenylene group represented by formula (1c), and * represents the bonding position with L. R １ each independently represents deuterium or an aliphatic hydrocarbon group having 1 to 10 carbon atoms. L represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. Ar １ each independently represents hydrogen, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 5 of these aromatic rings are linked together. R ２ each independently represents deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms, or a substituted or unsubstituted linked aromatic group in which 2 to 5 aromatic rings of an aromatic group selected from the above aromatic hydrocarbon groups and aromatic heterocyclic groups are linked together. a to f represent the number of substitutions, a to d represent integers of 0 to 4, e represents an integer of 0 to 3, f represents an integer of 0 to 2, and n represents the number of repetitions and is an integer of 1 to 3.

2. (delete)

3. 2. The compound for organic electroluminescent devices according to claim 1, wherein L is a phenylene group.

4. 4. The compound for organic electroluminescent devices according to claim 1, wherein n is 1.

5. 5. The compound for organic electroluminescent devices according to claim 1, 3 or 4, wherein all of a to f are 0.

6. (delete)

7. The compound for organic electroluminescent devices according to any one of claims 1 and 3 to 5, wherein in the formulas (2) to (5), Tp is represented by the following formula (2c): 【Transformation 3】 Here, R ２ , c, d, e and * have the same meanings as in formulas (2) to (5).

8. An organic electroluminescent device having an organic layer between an anode and a cathode laminated on a substrate, wherein the organic layer contains the compound for organic electroluminescent devices according to any one of claims 1, 3 to 5, and 7.

9. The organic electroluminescent element according to claim 8, wherein the organic layer is an emitting layer, and the emitting layer contains a luminescent dopant and the compound for organic electroluminescent elements according to any one of claims 1, 3 to 5, and 7 as a host material.

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