Mixed material for organic electroluminescent element, and organic electroluminescent element

Abstract

With the present invention, it is possible to obtain an organic EL element that emits light with high efficiency, has long lifespan characteristics, and is useful in practical applications.　Specifically, this material for an organic electroluminescent element is represented by general formula (1). In general formula (1), Ar0 is a substituted or unsubstituted C6-20 aromatic hydrocarbon group or similar, Y1 and Y2 are each hydrogen, deuterium, or a carbazolyl group represented by formula (2), and at least one of Y1 and Y2 is a carbazolyl group represented by formula (2). Y3 is a carbazolyl group represented by formula (2). Additionally, some or all of the hydrogen in the compound represented by general formula (1) may be substituted with deuterium. In general formula (2), R1 and R2 are each independently hydrogen or similar, and * indicates the site of bonding with the carbazolyl group in formula (1).

Description

Mixed material for organic electroluminescent device and organic electroluminescent device

[0001] The present invention relates to an organic electroluminescent device (referred to as an organic EL device) capable of converting electrical energy into light, and a material for the organic electroluminescent device used therein.

[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. The injected holes and electrons then recombine in the light-emitting layer, generating 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. It is said that the internal quantum efficiency of fluorescent organic EL elements that use emission from singlet excitons is limited to 25%. On the other hand, it is known that the internal quantum efficiency of phosphorescent organic EL elements that use emission from triplet excitons can be increased to 100% if intersystem crossing from singlet excitons is efficiently performed.

[0003] In recent years, technology for extending the lifetime of phosphorescent organic EL elements has progressed, and they are beginning to be applied to displays of mobile phones, etc. However, with regard to blue organic EL elements, no practical phosphorescent organic EL elements have been developed, and there is a demand for the development of blue organic EL elements that are highly efficient and have a long lifetime.

[0004] More recently, highly efficient delayed fluorescence organic EL elements utilizing delayed fluorescence have been developed. For example, Patent Document 1 discloses an organic EL element 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 is thought to theoretically increase the internal quantum efficiency to 40%. However, since the efficiency is lower than that of phosphorescent organic EL elements, further improvement in efficiency is required.

[0005] On the other hand, Patent Document 2 discloses an organic EL device that utilizes the thermally activated delayed fluorescence (TADF) 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 increase the internal quantum efficiency to 100%.

[0006] Here, Non-Patent Document 1 discloses a device using a predetermined mixed host (SiTrzCz2 and SiCzCz) in addition to a predetermined phosphorescent dopant, TADF dopant.

[0007] Furthermore, Patent Document 3 discloses a device using a mixed host of a compound having a plurality of linked carbazoles and a compound having an indolocarbazole skeleton.

[0008] Furthermore, Patent Document 3 discloses a device using a compound having a substituent at the 4-position of carbazole, and Patent Document 4 discloses a device using a compound having substituents at the 3- and 6-positions of carbazole.

[0009] Furthermore, Patent Documents 5 to 8 disclose elements using a mixed material containing a compound having a carbazole skeleton and a compound having a triazine skeleton.

[0010] WO2010 / 134350 Publication WO2011 / 070963 Publication WO2016 / 158191 Publication JP 2011-225801 AWO2021 / 200252 publication WO2020 / 218188 publication WO2012 / 077520 publication WO2022 / 045272 publication

[0011] Kim et al., Sci. Adv. 8, eabq1641 (2022)

[0012] In order to apply organic EL elements as display elements or light sources for flat panel displays and the like, it is necessary to improve the luminous efficiency of the elements and at the same time ensure sufficient stability during operation. However, these cannot be achieved with materials consisting of combinations of conventionally known compounds.

[0013] The present invention has been made in view of the above-mentioned circumstances, and aims to provide a material for organic electroluminescence devices that can provide practically useful organic EL devices that emit light with high efficiency and have long life characteristics, and also aims to provide an organic EL device using such a material.

[0014] That is, the present invention provides a material for an organic electroluminescent device represented by the following general formula (1): Here, Ar ０ represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups. 1 , and Y 2 is hydrogen, deuterium, or a carbazolyl group represented by the following formula (2), and Y 1 and Y 2 At least one of Y is a carbazolyl group represented by the following formula (2): ３ is a carbazolyl group represented by the following formula (2). In the general formula (2), R １ and R ２ R each independently represents hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted triarylsilyl group having 18 to 36 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. １ and R ２Preferably, at least one of the above is a substituted or unsubstituted carbazolyl group. * in the general formula (2) represents the point of attachment to the carbazolyl group in the general formula (1). The carbazolyl group in the general formula (2) is bonded to the 1st, 2nd, 3rd, or 4th position of the carbazolyl group in the general formula (1), preferably to the 2nd, 3rd, or 4th position. In addition, some or all of the hydrogen atoms in the compound represented by the general formula (1) may be substituted with deuterium. Preferably, some or all of the hydrogen atoms in the compound represented by the general formula (1) are substituted with deuterium.

[0015] The compound represented by the general formula (1) preferably contains at least one deuterated carbazolyl group represented by any one of the following formulae (1c) to (1k): D in the formulae (1c) to (1k) represents deuterium, and Ar ０ , Y 1 ~Y ３ and * have the same meanings as in the general formula (1).

[0016] Furthermore, it is preferable that the compound represented by the general formula (2) contains at least one bond structure represented by the following formulas (3a) to (3c). More preferably, the compound represented by the general formula (2) contains at least two bond structures represented by the formulas (3a) to (3c). Some or all of the hydrogen atoms in the bond structures represented by the formulas (3a) to (3c) may be substituted with deuterium atoms. Furthermore, * in the formulas (3a) to (3c) represents the point of attachment to the adjacent carbazolyl group in the general formula (1). R ３ represents hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted triarylsilyl group having 18 to 36 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking two aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups.

[0017] In a preferred embodiment, the compound represented by the general formula (1) contains at least one bonding structure represented by the formula (3a), the compound represented by the general formula (1) contains at least one bonding structure represented by the formula (3b), or the compound represented by the general formula (1) contains at least one bonding structure represented by the formula (3c).

[0018] The material for organic electroluminescent device represented by the general formula (1) preferably has an average deuteration rate of 50% or more of all hydrogen atoms contained in the general formula (1).

[0019] The material for organic electroluminescent device represented by the general formula (1) preferably has an energy level of the highest occupied molecular orbital (HOMO) of −5.3 eV or higher and an energy level of the lowest unoccupied molecular orbital (LUMO) of −1.4 eV or higher, which are obtained by a structural optimization calculation using density functional theory calculation B3LYP / 6-31G(d).

[0020] The present invention also relates to a mixed material for an organic electroluminescent device, comprising a compound represented by the general formula (1) and a cyclic azine compound, and the cyclic azine compound is preferably a compound represented by any one of the following general formulas (4) to (10): Here, Ar １ ~Ar １８ each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 20 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. １９ and Ar ２０ L each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups. 1 ~L 7each independently represents a single bond or a substituted or unsubstituted phenyl group, preferably a single bond. Note that hydrogen in the compounds represented by the general formulas (4) to (10) may be substituted with deuterium.

[0021] The present invention also relates to an organic electroluminescent device comprising one or more organic layers between opposing anodes and cathodes, characterized in that at least one organic layer contains a material for organic electroluminescent devices represented by general formula (1) or a mixed material for organic electroluminescent devices comprising a mixed material for organic electroluminescent devices represented by general formula (1) and a cyclic azine compound. Preferably, the organic layer contains the compound represented by general formula (1) and a compound represented by general formulas (4) to (10) as a cyclic azine compound. In the organic electroluminescent device of the present invention, the material for organic electroluminescent devices or the mixed material for organic electroluminescent devices is preferably contained in the light-emitting layer, and more preferably, these compounds are contained as host materials in the light-emitting layer. The compound represented by general formula (1) and the compounds represented by general formulas (4) to (10) may be supplied separately to the organic layer, or may be supplied as a premixed material for organic electroluminescent devices.

[0022] In the organic electroluminescent device of the present invention, the light-emitting layer preferably contains a thermally activated delayed fluorescent material or a phosphorescent material, and more preferably contains both a thermally activated delayed fluorescent material and a phosphorescent material. The thermally activated delayed fluorescent material preferably contains a boron atom, and the phosphorescent material preferably contains a platinum atom.

[0023] The present invention also relates to an organic electroluminescent element having an emissive layer, a hole transport layer, and an electron transport layer between opposing anode and cathode, the emissive layer containing a material for organic electroluminescent elements represented by general formula (1), wherein the difference (absolute value) in energy levels of the highest occupied molecular orbital (HOMO) between the material for organic electroluminescent elements and the hole transport material contained in the hole transport layer is 0.70 eV or less, and the difference (absolute value) in energy levels of the lowest unoccupied molecular orbital (LUMO) between the material for organic electroluminescent elements and the electron transport material contained in the electron transport layer is 0.80 eV or less. Preferably, the HOMO is −4.8 eV to −5.3 eV, and the LUMO is −0.80 eV to −1.3 eV.

[0024] The present invention also relates to a method for producing an organic electroluminescent element comprising one or more organic layers between opposing anode and cathode electrodes, at least one of which is an emissive layer, the method comprising premixing a compound represented by formula (1) with a cyclic azine to form a premixed material for the organic electroluminescent element, and depositing the premixed material from a single deposition source. The cyclic azine compound is preferably a compound represented by any one of formulas (4) to (10).

[0025] According to the present invention, it is possible to obtain a practically useful organic EL element which emits light with high efficiency and has a long life.

[0026] FIG. 1 is a cross-sectional view showing an example of the structure of an organic EL element used in the present invention.

[0027] The compound represented by general formula (1) and the compounds represented by general formulas (4) to (10) of the present invention will be described in detail below.

[0028] First, the general formula (1) is as described above, and Ar ０represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. Preferably, it is a substituted or unsubstituted phenyl group, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 phenyl groups, more preferably a substituted or unsubstituted phenyl group. Y 1 and Y 2 is hydrogen, deuterium, or a carbazolyl group represented by the formula (2), and Y 1 and Y 2 At least one of the groups is a carbazolyl group represented by the formula (2), and Y ３ is a carbazolyl group represented by the formula (2). In the formula (2), * represents the point of attachment to the carbazolyl group in the formula (1). 1 and R ２ R each independently represents hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted triarylsilyl group having 18 to 36 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups. Preferred are hydrogen, deuterium, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 phenyl groups, and more preferred are hydrogen, deuterium, and a substituted or unsubstituted phenyl group. ３each independently represents hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted triarylsilyl group having 18 to 36 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking two aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. Preferred are hydrogen, deuterium, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted linked aromatic group formed by linking two phenyl groups, and more preferred are hydrogen, deuterium, and a substituted or unsubstituted phenyl group.

[0029] In addition, some or all of the hydrogen atoms in the compound represented by general formula (1) may be substituted with deuterium atoms. Preferably, the average deuteration ratio of all hydrogen atoms in the compound represented by general formula (1) is 20% or more, more preferably 50% or more, and even more preferably 80% or more. Furthermore, it is preferable that the compound represented by general formula (1) contains at least one deuterated carbazolyl group represented by any of formulas (1c) to (1k). Here, the average deuteration ratio in the present invention includes, for example, in the case of a compound represented by general formula (1), both a single compound and a mixture of two or more compounds represented by general formula (1). Specifically, an average deuteration ratio of 50% means that, on average, half of all hydrogen atoms are substituted with deuterium atoms, and the compound may be composed of a single compound or a mixture of compounds with different deuteration ratios.

[0030] The average deuteration ratio can be determined by mass spectrometry or proton nuclear magnetic resonance spectroscopy. For example, when determining the average deuteration ratio by proton nuclear magnetic resonance spectroscopy, a measurement sample is first prepared by adding and dissolving a compound and an internal standard in a deuterated solvent, and the proton concentration [mol / g] of the compound contained in the measurement sample is calculated from the integrated intensity ratio derived from the internal standard and the compound. Next, the ratio of the proton concentration of the deuterated compound to the proton concentration of the corresponding non-deuterated compound is calculated, and the average deuteration ratio of the deuterated compound can be calculated by subtracting this ratio from 1. Furthermore, the average deuteration ratio of a substructure can be calculated from the integrated intensity of the chemical shift derived from the target substructure using the same procedure as described above.

[0031] The compound represented by general formula (2) preferably contains at least one bonding structure represented by any one of formulas (3a) to (3c), more preferably at least two. Of these, the compound represented by general formula (1) preferably contains at least one bonding structure represented by formula (3a), at least one bonding structure represented by formula (3b), or at least one bonding structure represented by formula (3c). Here, "bonding structure" means that the bonding points between adjacent carbazoles are specific. Note that some or all of the hydrogen atoms in the bonding structures represented by formulas (3a) to (3c) may be substituted with deuterium. Furthermore, * in the formula indicates the bonding points to adjacent carbazoles in general formula (1).

[0032] The R 1 , R ２ and R ３ When is an unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms, specific examples include methyl, ethyl, propyl, i-propyl, butyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, and decyl. Preferred are methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl.

[0033] In addition, the R 1 , R ２ and R ３Specific examples of when is an unsubstituted triarylsilyl group having 18 to 36 carbon atoms include triphenylsilyl, biphenyldiphenylsilyl, bisbiphenylphenylsilyl, and trisbiphenylsilyl. Preferred are triphenylsilyl, biphenyldiphenylsilyl, and bisbiphenylphenylsilyl.

[0034] The R 1 and R ２Specific examples of the linked aromatic group formed by linking two or three aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, pyrazine, Examples thereof include benzofuran, furan, isoxazole, quinoline, 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, and groups derived from linked aromatic groups formed by linking 2 to 3 of these aromatic groups. Preferably, R is benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, phenanthrene, fluorene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, pyrazine, furan, isoxazole, quinoline, 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 group derived from a linked aromatic group formed by linking 2 to 3 of these aromatic groups. ３Specific examples of the linked aromatic group formed by linking two aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups include the above-mentioned R 1 , R ２ This is the same as in the case of

[0035] The Ar ０ Specific examples of the linked aromatic group formed by linking two or three aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups include the above-mentioned R １ and R ２ Preferred are benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, phenanthrene, fluorene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, pyrazine, furan, isoxazole, quinoline, 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 group derived from a linked aromatic group formed by linking 2 to 3 of these aromatic groups.

[0036] The cyclic azine compounds represented by the general formulas (4) to (10) are also as described above, but Ar 1 ~Ar 18each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 20 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. Preferably, each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 15 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 18 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. More preferably, each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 15 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups. 1９ , Ar ２０ each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. Preferably, it represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 15 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 15 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. More preferably, it represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 15 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups. Furthermore, L １ ~L ７ represents a single bond or a substituted or unsubstituted phenyl group, preferably a single bond. Note that some or all of the hydrogen atoms in the compounds represented by general formulas (4) to (10) may be substituted with deuterium atoms. Preferably, the average deuteration rate of all hydrogen atoms in the compounds represented by general formulas (4) to (10) is 20% or more, more preferably 50% or more, and even more preferably 80% or more.

[0037] Furthermore, the Ar １ ~Ar １８is an unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, an unsubstituted aromatic heterocyclic group having 2 to 20 carbon atoms, or a linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups, specific examples thereof include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, pyrazine, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, pyrazine, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, benzo[a]anthracene, pyridine, pyridine, pyridine, pyrrole, pyrazole, benzo[a]anthracene, pyridine, pyridine, pyridine, benzo[a]anthracene ... Examples thereof include oran, isoxazole, quinoline, 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, indolocarbazole, and a group derived from a linked aromatic group formed by linking 2 to 3 of these aromatic groups. Preferred are benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, phenanthrene, fluorene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, pyrazine, furan, isoxazole, quinoline, 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, indolocarbazole, or a group derived from a linked aromatic group formed by linking 2 to 3 of these aromatic groups.

[0038] The Ar １９ and Ar ２０is an unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, an unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups, specific examples thereof include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, Examples thereof include pyrazine, furan, isoxazole, quinoline, 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, and groups derived from linked aromatic groups formed by linking 2 to 3 of these aromatic groups. Preferred are benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, phenanthrene, fluorene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, pyrazine, furan, isoxazole, quinoline, 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 group derived from a linked aromatic group formed by linking 2 to 3 of these aromatic groups.

[0039] In this specification, the unsubstituted triarylsilyl group, aromatic hydrocarbon group, aromatic heterocyclic group, or linking aromatic group may each have a substituent. When the group has a substituent, the substituent is preferably deuterium, halogen, cyano group, alkyl group having 1 to 10 carbon atoms, triarylsilyl group having 9 to 30 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. The number of the substituents is 0 to 5, preferably 0 to 2. When the aromatic hydrocarbon group, aromatic heterocyclic group, or linking aromatic group has a substituent, the number of carbon atoms in the substituent is not included in the calculation of the carbon number. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituent, satisfies the above range.

[0040] Specific examples of the substituent include deuterium, cyano, bromo, fluorine, methyl, ethyl, propyl, i-propyl, butyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, triphenylsilyl, biphenyldiphenylsilyl, bisbiphenylphenylsilyl, trisbiphenylsilyl, vinyl, propenyl, butenyl, pentenyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthranylamino, diphenanthrenylamino, dipyrenylamino, etc. Preferred are deuterium, cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, vinyl, propenyl, butenyl, pentenyl, and triphenylsilyl.

[0041] In this specification, a linking aromatic group refers to an aromatic group in which the aromatic rings of two or more aromatic groups are linked by a single bond. These linking aromatic groups may be linear or branched. The linking position when benzene rings are linked may be ortho, meta, or para. 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.

[0042] The material for organic electroluminescent devices of the present invention preferably has a highest occupied molecular orbital (HOMO) energy level of −5.3 eV or higher and a lowest unoccupied molecular orbital (LUMO) energy level of −1.4 eV or higher, as obtained by structure optimization calculation using density functional theory calculation B3LYP / 6-31G(d), and more preferably has a highest occupied molecular orbital (HOMO) energy level of −4.5 eV to −5.3 eV and a lowest unoccupied molecular orbital (LUMO) energy level in the range of −1.2 eV to −1.4 eV.

[0043] The mixed material for organic electroluminescent elements in the present invention may be in the form of a powder, solid, or thin film, as long as it contains the compound represented by the general formula (1) and the cyclic azine compound. For example, when this material is used to form an emissive layer of an organic EL element, the compound represented by the general formula (1) and the cyclic azine compound may be supplied separately to the emissive layer, or the compound represented by the general formula (1) and the cyclic azine compound may be supplied as a premixed material for organic electroluminescent elements in which they are premixed. It is particularly preferred that the compound represented by the general formula (1) and the cyclic azine compound be supplied as a premixed material for organic electroluminescent elements in which they are premixed. It is preferable to use a compound represented by any of the general formulae (4) to (10) as the cyclic azine compound.

[0044] The mixed material for organic electroluminescent devices may be prepared by mixing the compound represented by general formula (1) and the compounds represented by general formulas (4) to (10) in powder form, by melt-mixing by heating under reduced pressure or in an inert gas atmosphere such as nitrogen, or by sublimating the mixed compounds together. It may also be prepared as a thin film by vapor deposition or the like. On the other hand, if the compound represented by general formula (1) and the compounds represented by general formulas (4) to (10) constituting the mixed material are not premixed in advance, they may be contained in different organic layers of the device. For example, the compound represented by general formula (1) may be contained in an electron-blocking layer, and the compounds represented by general formulas (4) to (10) may be contained in an emitting layer. The premixed material for organic electroluminescent devices refers to a mixed material for organic electroluminescent devices in which the compound represented by general formula (1) and the cyclic azine compound are premixed in powder form, or a premixed material in which these powders are premixed by heating and melting. The cyclic azine compound is preferably a compound represented by general formulas (4) to (10).

[0045] In the present invention, in the mixed material for organic electroluminescent elements comprising the compound represented by the general formula (1) and the cyclic azine compound, the mixing ratio (mass ratio) in the mixed material is preferably 40 to 90 mass%, more preferably 50 to 90 mass%, and even more preferably 60 to 90 mass%, of the compound represented by the general formula (1) relative to the total of the compound represented by the general formula (1) and the cyclic azine compound. When the cyclic azine compound is a compound represented by any of the general formulas (4) to (10), the ratio of the compound represented by the general formula (1) relative to the total of the compounds represented by the general formulas (4) to (10) is preferably as described above. The mixing ratio in the premixed material for organic electroluminescent elements is also the same as described above.

[0046] Specific examples of the compound represented by the general formula (1) are shown below, but the present invention is not limited to these exemplary compounds. In addition, in Dn described in 1-76 to 1-141 and 1-150 to 1-157, D represents deuterium, and n represents the average number of substitutions with deuterium in each of the compounds, which varies depending on the average deuteration rate.

[0047]

[0048] Specific examples of the compounds represented by the general formulas (4) to (10) are shown below, but the present invention is not limited to these exemplary compounds. In addition, in Dn described in 2-77 to 2-81, D represents deuterium, and n represents the average number of substitutions with deuterium in each of the compounds, which varies depending on the average deuteration rate.

[0049] The present invention also relates to an organic electroluminescent device comprising one or more organic layers between opposing anode and cathode, wherein at least one of the organic layers contains a compound represented by general formula (1) or a mixed material for organic electroluminescent devices comprising a compound represented by general formula (1) and the cyclic azine compound. Preferably, the cyclic azine compound is a compound represented by any one of general formulas (4) to (10).

[0050] The organic electroluminescent device preferably has at least one organic layer that is an emitting layer and contains the mixed material for organic electroluminescent devices in the emitting layer. More preferably, the emitting layer further contains a thermally activated delayed fluorescent material or a phosphorescent material, and even more preferably, the emitting layer contains both a thermally activated delayed fluorescent material and a phosphorescent material. Furthermore, the thermally activated delayed fluorescent material preferably contains a boron atom, and the phosphorescent material preferably contains a platinum atom.

[0051] That is, an excellent organic EL device can be obtained by incorporating at least one host material in the light-emitting layer together with the thermally activated delayed fluorescent material or the phosphorescent material as necessary, and it is preferable that at least one host material is a material for an organic electroluminescent device that is a compound represented by the general formula (1). Furthermore, when the light-emitting layer contains at least two host materials, it is preferable to use a compound represented by the general formula (1) as the first host and a compound represented by any of the general formulas (4) to (10) as the second host.

[0052] In an organic electroluminescent device having an emitting layer, a hole transport layer, and an electron transport layer between opposing anode and cathode, and the emitting layer containing a material for organic electroluminescent devices represented by the general formula (1), the difference (absolute value) in energy levels of the highest occupied molecular orbital (HOMO) between the material for organic electroluminescent devices represented by the general formula (1) and a hole transport material contained in the hole transport layer, obtained by a structural optimization calculation using density functional theory calculation B3LYP / 6-31G(d), is 0.70 eV or less, and the material for organic electroluminescent devices represented by the general formula (1) obtained by the structural optimization calculation It is preferable that the difference (absolute value) in energy levels of the lowest unoccupied molecular orbital (LUMO) between the material for organic electroluminescent elements represented by the general formula (1) and the electron transport material contained in the electron transport layer is 0.80 eV or less, and more preferably the difference (absolute value) in energy levels of the highest occupied molecular orbital (HOMO) between the material for organic electroluminescent elements represented by the general formula (1) and the hole transport material is in the range of 0.30 to 0.70 eV, and the difference (absolute value) in energy levels of the lowest unoccupied molecular orbital (LUMO) between the material for organic electroluminescent elements represented by the general formula (1) and the electron transport material is in the range of 0.30 to 0.80 eV.

[0053] Furthermore, the present invention relates to an organic electroluminescent element including one or more organic layers between opposing anode and cathode, the organic electroluminescent element having a light-emitting layer formed by vapor deposition from a single vapor deposition source using a premixed material for organic electroluminescent elements, the premixed material being a mixture of a compound represented by the general formula (1) and a cyclic azine compound. The cyclic azine compound is preferably a compound represented by any one of the general formulae (4) to (10). In forming the organic layer of the organic electroluminescent element, the premixed material for organic electroluminescent elements can be a premixed material in which the compound represented by the general formula (1) and the cyclic azine compound are each formed into powders, or a premixed material in which these powders are premixed by heating and melting the powders, and the premixed material can be vapor-deposited from a single vapor deposition source to form the light-emitting layer of the organic EL element.

[0054] 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.

[0055] 1 is a cross-sectional view showing an example of the structure of a general organic EL element used in the present invention, in which 1 represents a substrate, 2 represents an anode, 3 represents a hole injection layer, 4 represents a hole transport layer, 5 represents a light-emitting layer, 6 represents an electron transport layer, and 7 represents a cathode. The organic EL element of the present invention has an anode, a light-emitting layer, and a cathode as essential layers, but may also have a hole injection layer, a hole transport layer, an electron transport layer, and an electron injection layer in addition to the essential layers, and may further have an electron blocking layer between the hole transport layer and the light-emitting layer, and a hole blocking layer between the light-emitting layer and the electron transport layer.

[0056] 1 , it is also possible to laminate the cathode 7, electron transport layer 6, light-emitting layer 5, hole transport layer 4, hole injection layer 3, and anode 2 in this order on the substrate 1, and in this case too, layers can be added or omitted as necessary. In the organic EL element described above, layers constituting the laminated structure on the substrate other than electrodes such as the anode and cathode may be collectively referred to as organic layers.

[0057] The organic EL device of the present invention is preferably supported on 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.

[0058] Anode: Anode materials for organic EL devices are preferably metals, alloys, electrically conductive compounds, or mixtures thereof, each having a large work function (4 eV or more). Specific examples of such electrode materials include metals such as Au, CuI, indium tin oxide (ITO), and SnO. ２ Examples of suitable conductive transparent materials include ZnO and ZnO. Amorphous materials, such as IDIXO (In2O3-ZnO), that can be used to fabricate transparent conductive films, may also be used. The anode may be formed by depositing a thin film of these electrode materials using methods such as vapor deposition or sputtering, followed by forming a desired pattern using photolithography. Alternatively, if pattern precision is not required (approximately 100 μm or greater), a pattern may be formed using a mask of the desired shape during vapor deposition or sputtering of the electrode material. Alternatively, when using a coatable material such as an organic conductive compound, wet film formation methods such as printing or coating can be used. When extracting light from this anode, a transmittance of greater than 10% is desirable, and the sheet resistance of the anode is preferably several hundred Ω / □ or less. The film thickness, depending on the material, is typically selected in the range of 10 to 1,000 nm, preferably 10 to 200 nm.

[0059] - Cathode - On the other hand, the cathode material is made of a metal (called an electron injecting metal), alloy, electrically conductive compound, or a mixture thereof, each of which has a small work function (4 eV or less). Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, and aluminum / aluminum oxide (Al ２ O ３Among these, in view of electron injection property and durability against oxidation, etc., mixtures of an electron injection metal and a second metal which is a metal having a larger and more stable work function than the electron injection metal, such as magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ２ O ３ ) mixture, lithium / aluminum mixture, aluminum, etc. are suitable. The cathode can be produced by forming a thin film of these cathode materials by methods such as vapor deposition or sputtering. The cathode preferably has a sheet resistance of several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. In order to transmit emitted light, it is advantageous if either the anode or cathode of the organic EL element is transparent or semitransparent, as this improves the luminance of the emitted light.

[0060] Furthermore, a transparent or semi-transparent cathode can be fabricated by forming the above metal in a thickness of 1 to 20 nm as the cathode and then forming the conductive transparent material described in the description of the anode thereon. This can be applied to fabricate an element in which both the anode and cathode are transparent.

[0061] -Light-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. The light-emitting layer may be a single layer or multiple layers, and each layer contains an organic light-emitting dopant material and a host material.

[0062] The light-emitting layer may contain only one type of organic light-emitting dopant, or may contain two or more types of organic light-emitting dopant. The content of the organic light-emitting dopant is preferably 0.1 to 50% by mass, more preferably 0.1 to 40% by mass, based on the host material.

[0063] When a phosphorescent dopant is used as the organic light-emitting 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. More preferably, the phosphorescent dopant is an organometallic complex containing platinum. Specific examples of suitable dopants include, but are not limited to, the iridium complexes described in J. Am. Chem. Soc. 2001, 123, 4304 and JP-A-2013-530515 and the platinum complexes described in Adv. Mater. 2014, 26, 7116 and JP-A-2018-2722.

[0064] The phosphorescent dopant material is not particularly limited, but specific examples include the following.

[0065] When a fluorescent dopant is used as the light-emitting dopant material, the fluorescent dopant is not particularly limited, but examples thereof include fused polycyclic aromatic derivatives, styrylamine derivatives, fused-ring amine derivatives, boron-containing compounds, pyrrole derivatives, indole derivatives, and carbazole derivatives. Among these, fused-ring amine derivatives, boron-containing compounds, and carbazole derivatives are preferred. Examples of fused-ring amine derivatives include diaminepyrene derivatives, diaminochrysene derivatives, diaminoanthracene derivatives, diaminofluorenone derivatives, and diaminofluorene derivatives having one or more fused benzofuro skeletons. Examples of boron-containing compounds include pyrromethene derivatives and polycyclic aromatic compounds described in WO2015 / 102118 and the like.

[0066] The fluorescent dopant material is not particularly limited, but specific examples include the following.

[0067] When a thermally activated delayed fluorescent dopant is used as the luminescent dopant material, the thermally activated delayed fluorescent dopant is not particularly limited, and examples thereof include those containing boron atoms, metal complexes such as tin complexes and copper complexes, cyanobenzene derivatives and carbazole derivatives described in Nature 2012,492,234, phenazine derivatives, oxadiazole derivatives, triazole derivatives, sulfone derivatives, phenoxazine derivatives, acridine derivatives described in Nature Photonics 2014,8,326, and polycyclic aromatic compounds described in WO2015 / 102118, etc. Preferably, the thermally activated delayed fluorescent dopant contains a boron atom.

[0068] The thermally activated delayed fluorescent dopant material is not particularly limited, but specific examples include the following: A cyclic azine compound may be used as the thermally activated delayed fluorescent dopant material, but it is preferable that the compound is not one of the compounds represented by the general formulas (4) to (10).

[0069] The host material in the light-emitting layer is preferably a compound represented by the general formula (1) and / or the general formulas (4) to (10). When the compound represented by the general formula (1) or the general formulas (4) to (10) is used in any organic layer other than the light-emitting layer, the compound represented by the general formula (1) or the general formulas (4) to (10) may or may not be contained in the light-emitting layer. In this case, the light-emitting layer may also contain a known host material used in phosphorescent or fluorescent light-emitting devices. Note that multiple known host materials may be used in combination, or each may be used alone. The known host material that can be used is preferably a compound that has hole-transporting ability and electron-transporting ability and a high glass transition temperature, and has a triplet excitation energy (T1) greater than the triplet excitation energy (T1) of the light-emitting dopant material. A TADF-active compound may also be used as the host material, and in this case, a compound in which the difference between the singlet excitation energy (S1) and the triplet excitation energy (T1) (ΔEST=S1-T1) is 0.20 eV or less is preferred. The compound represented by the general formula (1) may be contained alone as the host material in the light-emitting layer, and another known host material may be used in combination. However, in order to improve the properties of the organic EL device, it is preferable to use the cyclic azine compound in combination as the host material, and the cyclic azine compound is preferably a compound represented by any of the general formulae (4) to (10). Note that a plurality of types of the other known host materials may also be used in combination.

[0070] Here, S1 and T1 are measured as follows: －４ A sample compound (thermally activated delayed fluorescent material) is vapor-deposited under conditions of 0.1 Pa or less to form a vapor-deposited film with a thickness of 100 nm. S1 is calculated by measuring the emission spectrum of this vapor-deposited film, drawing a tangent to the rising edge on the short wavelength side of the emission spectrum, and substituting the wavelength value λedge [nm] at the intersection of the tangent and the horizontal axis into the following formula (i): S1 [eV] = 1239.85 / λedge (i)

[0071] On the other hand, T1 is calculated by measuring the phosphorescence spectrum of the vapor-deposited film, drawing a tangent to the rising edge on the short wavelength side of this phosphorescence spectrum, and substituting the wavelength value λedge [nm] at the intersection of this tangent line and the horizontal axis into the following formula (ii): T1 [eV] = 1239.85 / λedge (ii)

[0072] The other known host materials can be selected from those known in numerous patent documents, etc. Specific examples of the host material include, but are not particularly limited to, indole compounds, carbazole compounds, pyridine compounds, pyrimidine compounds, triazine compounds, triazole compounds, oxazole compounds, oxadiazole compounds, imidazole compounds, phenylenediamine compounds, arylamine compounds, anthracene compounds, fluorenone compounds, stilbene compounds, triphenylene compounds, carborane compounds, porphyrin compounds, phthalocyanine compounds, metal complexes of 8-quinolinol compounds, metal phthalocyanines, various metal complexes typified by metal complexes of benzoxazole and benzothiazole compounds, polymer compounds such as poly(N-vinylcarbazole) compounds, aniline copolymer compounds, thiophene oligomers, polythiophene compounds, polyphenylene compounds, polyphenylenevinylene compounds, and polyfluorene compounds. Preferred examples include carbazole compounds, indolocarbazole compounds, pyridine compounds, pyrimidine compounds, triazine compounds, anthracene compounds, triphenylene compounds, carborane compounds, and porphyrin compounds.

[0073] The other known hosts are not particularly limited, but specific examples include the following compounds.

[0074] When multiple types of hosts are used, each host can be vapor-deposited from a different vapor deposition source, or multiple types of hosts can be simultaneously vapor-deposited from a single vapor deposition source by premixing them in advance before vapor deposition to form a premixed material.

[0075] When a plurality of hosts are used, the host is preferably a mixed material for organic electroluminescent devices obtained by mixing a compound represented by the general formula (1) with a compound represented by any one of the general formulas (4) to (10).

[0076] When two types of hosts are premixed in advance, the 50% weight loss temperature (T ５０ The 50% weight loss temperature is the temperature at which the weight is reduced by 50% when the temperature is raised from room temperature to 550°C at a rate of 10°C per minute in TG-DTA measurement under reduced pressure (1 Pa) of nitrogen gas flow. It is believed that vaporization by evaporation or sublimation occurs most actively around this temperature.

[0077] In a premixed material in which two types of hosts are premixed in advance, the difference in the 50% weight loss temperatures of the two types of hosts is preferably within 20°C. By vaporizing and depositing this premix from a single evaporation source, it is possible to obtain a uniform deposited film. In this case, a luminescent dopant material required for forming the emitting layer or other hosts to be used as needed may be mixed into the premix. However, if there is a large difference in the temperatures at which the desired vapor pressure is achieved, it is preferable to deposit them from different evaporation sources.

[0078] When two types of hosts are used, the mixing ratio (mass ratio) of the first host to the second host is preferably 40 to 90%, more preferably 50 to 90%, and even more preferably 60 to 90% of the total of the first host and the second host. When the compound represented by general formula (1) and the compounds represented by general formulas (4) to (10) are used as hosts, the first host is the compound represented by general formula (1), and the compounds represented by general formulas (4) to (10) are the second hosts.

[0079] As described above, the method for premixing the host is preferably a method that allows mixing as uniformly as possible, and examples thereof include pulverization and mixing, a method of heating and melting under reduced pressure or in an inert gas atmosphere such as nitrogen, and sublimation, but are not limited to these methods.

[0080] The host and its premixed material may be in the form of powder, stick, or granules.

[0081] Injection layer: An injection layer is a layer provided between an electrode and an organic layer to reduce driving voltage and improve luminance, and includes a hole injection layer and an electron injection layer. An injection layer 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. An injection layer can be provided as needed.

[0082] -Hole Blocking Layer- In a broad sense, a hole blocking layer functions as an electron transport layer and is made of a hole blocking material that has the ability to transport electrons but has a significantly low ability to transport holes. By transporting electrons while blocking holes, the probability of electron and hole recombination in the light-emitting layer can be improved. For the hole blocking layer, it is preferable to use a compound represented by any of the general formulas (4) to (10), but known hole blocking materials can also be used. Furthermore, multiple hole blocking materials may be used in combination.

[0083] -Electron Blocking Layer- In a broad sense, the electron blocking layer functions as a hole transport layer, and by transporting holes while blocking electrons, it is possible to improve the probability of electrons and holes recombining in the light-emitting layer. As the material for the electron blocking layer, it is preferable to use the compound represented by the general formula (1) or the mixed material, but known electron blocking layer materials can also be used. When the compound represented by the general formula (1) or the mixed material is used in the electron blocking layer, the host material may be the compound represented by the general formula (1), the known host materials described above, or a host material obtained by combining two or more of these.

[0084] Layers adjacent to the light-emitting layer include a hole-blocking layer and an electron-blocking layer, but if these layers are not provided, a hole-transporting layer, an electron-transporting layer, etc. will be the adjacent layers.

[0085] -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.

[0086] The hole transport material has either hole injection or transport properties or electron barrier properties, and may be either organic or inorganic. Any hole transport material can be selected from conventionally known compounds. Examples of such hole transport materials include porphyrin derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane 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.

[0087] - Electron Transport Layer - The electron transport layer is made of a material having a function of transporting electrons, and the electron transport layer may be a single layer or multiple layers.

[0088] 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, for example, 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, carbodiimide derivatives, 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.

[0089] When the organic EL element of the present invention is produced, the method for forming each layer is not particularly limited, and the layers may be produced by either a dry process or a wet process.

[0090] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples.

[0091] Calculation Example: Calculation of HOMO and LUMO Values ​​The compounds 1-1, 1-2, 1-4, 1-6, 1-17, 1-20, 1-27, 1-67, 1-76, 1-77, 1-78, 1-80 represented by the general formula (1), as well as the HT-1 compound of the hole transport material, and the compound 2-82 of the electron transport material, were calculated for their respective HOMO and LUMO. The calculations were performed using density functional theory (DFT) calculations, using Gaussian as the calculation program, and were calculated by structural optimization calculations using density functional calculation B3LYP / 6-31G (d). The results are shown in Table 1. It can be seen that the energy level differences (absolute values) of the highest occupied molecular orbital (HOMO) of compounds 1-1, 1-2, 1-4, 1-6, 1-17, 1-20, 1-27, 1-67, 1-76, 1-77, 1-78, and 1-80 and that of HT-1 are all 0.70 eV or less, and the energy level differences (absolute values) of the lowest unoccupied molecular orbital (LUMO) of compounds 1-1, 1-2, 1-4, 1-6, 1-17, 1-20, 1-27, 1-67, 1-76, 1-77, 1-78, and 1-80 and that of compound 2-82 are all 0.80 eV or less.

[0092]

[0093] The compounds used in the examples and comparative examples are as follows: "α" in HT-9 represents the average deuteration rate, and the compound used had an average deuteration rate of 88%.

[0094] As representative examples, the synthesis of compounds 1-1, 1-27, 1-68, and 1-76 is shown below. Other compounds were synthesized in a similar manner. The deuteration ratio was determined by proton nuclear magnetic resonance spectroscopy. Synthesis Example 1 To 25.0 g of compound (a), 39.2 g of compound (b), 36.1 g of potassium carbonate, 6.5 g of tetrakistriphenylphosphine palladium, 300 mL of toluene, 50 mL of ethanol, and 50 mL of water were added and stirred at 100°C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 300 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography to obtain 34.4 g of compound (c) as a white solid (79% yield).

[0095] Synthesis Example 2 To 34.40 g of compound (c), 70.8 g of triphenylphosphine and 300 mL of m-xylene were added, and the mixture was stirred at 150°C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, the mixture was concentrated and dried. Purification was carried out by silica gel column chromatography to obtain 31.5 g of compound (d) as a brown solid (yield 99%).

[0096] Synthesis Example 3 To 31.5 g of compound (d), 27.5 g of compound (e), 1.7 g of copper(I) iodide, 2.1 g of trans-1,2-cyclohexanediamine, 40.2 g of tripotassium phosphate, and 300 mL of 1,4-dioxane were added and stirred at 110°C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 200 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography to obtain 24.8 g of compound (f) as a white solid (yield 65%).

[0097] Synthesis Example 4 To 12.0 g of compound (f), 5.7 g of compound (g), 27.5 g of cesium carbonate, and 140 mL of N,N-dimethylacetamide were added and stirred at 180 °C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 200 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography to obtain 12.9 g of compound 1-1 as a white solid (yield 80%).

[0098] Synthesis Example 5 To 31.5 g of compound (d), 33.3 g of compound (h), 1.7 g of copper(I) iodide, 2.1 g of trans-1,2-cyclohexanediamine, 40.2 g of tripotassium phosphate, and 300 mL of 1,4-dioxane were added and stirred at 110°C for 28 hours under a nitrogen atmosphere. After cooling to room temperature, 200 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography to obtain 34.8 g of compound (i) as a white solid (75% yield).

[0099] Synthesis Example 6 To 14.5 g of compound (i), 5.7 g of compound (g), 27.5 g of cesium carbonate, and 140 mL of N,N-dimethylacetamide were added and stirred at 180 °C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 200 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography to obtain 14.1 g of compound 1-27 as a white solid (yield 76%).

[0100] Synthesis Example 7 To 12.0 g of compound (f), 5.9 g of compound (j), 27.5 g of cesium carbonate, and 140 mL of N,N-dimethylacetamide were added and stirred at 180 °C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 200 mL of water was added. The aqueous and organic phases were separated, the aqueous phase was extracted with toluene, and the organic phase was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography to obtain 13.4 g of compound 1-68 as a white solid (yield 82%, average deuteration rate 28%).

[0101] Synthesis Example 8 To 5.0 g of compound 1-1, 100 ml of deuterated benzene (C6D6) and 8.0 g of trifluoromethanesulfonic acid (TfOH) were added, and the mixture was heated and stirred at 50°C for 3 hours under a nitrogen atmosphere. The reaction mixture was added to a heavy water solution (100 ml) of potassium carbonate (5.0 g) and quenched. The aqueous and organic phases were separated, and the aqueous phase was extracted with toluene. The organic phase was dried over magnesium sulfate and concentrated to dryness. Purification was carried out by silica gel column chromatography, yielding 3.8 g of compound 1-76 as a white solid (average deuteration rate: 88%).

[0102] Example 1 On a glass substrate on which an anode made of ITO with a film thickness of 70 nm was formed, each of the thin films shown below was deposited by vacuum deposition at a vacuum degree of 4.0 × 10 －５The layers were laminated at a pressure of 10 Pa. First, HAT-CN, as previously described, was formed on ITO as a hole injection layer to a thickness of 10 nm. Next, HT-1 was formed as a hole transport layer to a thickness of 60 nm. Next, HT-2 was formed as an electron blocking layer to a thickness of 5 nm. Next, compound 1-1 was co-deposited as a host, BD-2 as a phosphorescent dopant, and BD-1 as a thermally activated delayed fluorescent dopant from different deposition sources to form an emitting layer having a thickness of 40 nm. At this time, the co-deposition was performed under deposition conditions such that the concentrations of BD-2, BD-1, and 1-1 were 13% by mass, 0.4% by mass, and 86.6% by mass, respectively. Next, compound 2-82 was formed as a hole blocking layer to a thickness of 5 nm. Next, compound 2-82 was formed as an electron transport layer to a thickness of 31 nm. Furthermore, lithium fluoride (LiF) was formed as an electron injection layer to a thickness of 1 nm on the electron transport layer. Finally, aluminum (Al) was formed as a cathode on the electron injection layer to a thickness of 70 nm, thereby completing the organic EL element according to Example 1.

[0103] Comparative Example 1 As shown in Table 2-2, an organic EL device was prepared in the same manner as in Example 1, except that the host was changed to HT-2.

[0104] Examples 2 to 9 Organic EL devices were fabricated in the same manner as in Example 1, except that the electron-blocking layer material and the first host were the compounds shown in Table 2-1.

[0105] Example 10: On a glass substrate on which an anode made of ITO with a film thickness of 70 nm was formed, each of the thin films shown below was deposited by vacuum deposition at a vacuum degree of 4.0×10 －５The layers were laminated at a pressure of 10 Pa. First, HAT-CN, as previously described, was formed on ITO as a hole injection layer to a thickness of 10 nm, and then HT-1 was formed as a hole transport layer to a thickness of 60 nm. Next, HT-2 was formed as an electron blocking layer to a thickness of 5 nm. Next, Compound 1-1 was used as a first host, Compound 2-60 was used as a second host, BD-2 was used as a phosphorescent dopant, and BD-1 was used as a thermally activated delayed fluorescent dopant, all of which were co-deposited from different deposition sources to form an emitting layer having a thickness of 40 nm. At this time, the co-deposition was carried out under deposition conditions such that the concentration of BD-2 was 13% by mass, the concentration of BD-1 was 0.4% by mass, and the mass ratio of the first host to the second host was 50:50. Next, Compound 2-82 was formed as a hole blocking layer to a thickness of 5 nm. Next, Compound 2-82 was formed as an electron transport layer to a thickness of 31 nm. Furthermore, lithium fluoride (LiF) was formed as an electron injection layer to a thickness of 1 nm on the electron transport layer, and finally, aluminum (Al) was formed as a cathode to a thickness of 70 nm on the electron injection layer, thereby producing an organic EL device according to Example 10.

[0106] Examples 11 to 29 and Comparative Examples 2 to 12-4 Organic EL devices were fabricated in the same manner as in Example 10, except that the electron-blocking layer material, first host, and second host were the compounds shown in Tables 2-1 and 2-2. Compounds 1-68, 1-76, 1-77, 1-78, 1-80, and 2-80 had average deuteration ratios of 28%, 88%, 85%, 87%, 84%, and 82%, respectively. The average deuteration ratio indicates the proportion of hydrogen contained in the compound that is deuterated, and was determined by mass spectrometry or proton nuclear magnetic resonance spectroscopy.

[0107] The method for determining the average deuteration ratio of Compound 1-76 by proton nuclear magnetic resonance spectroscopy is as follows. First, a measurement sample was prepared by dissolving Compound 1-118 (5.0 mg) and dimethyl sulfone (2.0 mg) as an internal standard in deuterated tetrahydrofuran (1.0 ml). The average proton concentration [mol / g] of Compound 1-76 contained in the measurement sample was calculated from the integrated intensity ratio derived from the internal standard and Compound 1-76. The average proton concentration [mol / g] of the non-deuterated form of Compound 1-76 (corresponding to Exemplary Compound 1-1) was also calculated in the same manner. Next, the ratio of the proton concentration of Compound 1-76 to the proton concentration of the non-deuterated form of Compound 1-76 was calculated and subtracted from 1 to calculate the average deuteration ratio of Compound 1-76 as 88%. The average deuteration ratios of Compounds 1-77, 1-78, 1-80, and 2-80 were also calculated in the same manner.

[0108]

[0109] The evaluation results of the fabricated organic EL elements are shown in Tables 3-1 and 3-2. When an external power source 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 emission wavelength of 450 nm to 480 nm was observed in all organic EL elements, demonstrating that light was emitted from BD-1. The voltage and power efficiency in the tables are values ​​at a drive current of 2.5 mA / cm2 and represent initial characteristics. Furthermore, the lifetime is the time it takes for the brightness to decay to 97% of the initial brightness at a drive current of 4.0 mA / cm2, assuming that the initial brightness is 100%, and represents the lifetime characteristics. Furthermore, the emission color was confirmed by the emission spectrum of the organic EL element. The results of the Examples shown in Table 3-1 and the Comparative Examples shown in Table 3-2 demonstrate that organic EL elements using the mixed material for organic electroluminescent elements of the present invention as a host in the light-emitting layer emit blue light and have high efficiency and long lifetime characteristics.

[0110]

[0111] Example 30: On a glass substrate on which an anode made of ITO with a film thickness of 70 nm was formed, each of the following thin films was deposited by vacuum deposition at a vacuum degree of 4.0×10－５ The layers were laminated at a pressure of 10 Pa. First, HAT-CN, as previously described, was formed on ITO as a hole injection layer to a thickness of 10 nm. Next, HT-1 was formed as a hole transport layer to a thickness of 60 nm. Next, HT-2 was formed as an electron blocking layer to a thickness of 5 nm. Next, compound 1-1 as a first host and BD-2 as a phosphorescent dopant were co-deposited from different deposition sources to form an emitting layer having a thickness of 40 nm. This co-deposition was performed under deposition conditions such that the concentration of BD-2 was 13% by mass. Next, compound 2-82 was formed as a hole blocking layer to a thickness of 5 nm. Next, compound 2-82 was formed as an electron transport layer to a thickness of 31 nm. Furthermore, lithium fluoride (LiF) was formed as an electron injection layer to a thickness of 1 nm on the electron transport layer. Finally, aluminum (Al) was formed as a cathode to a thickness of 70 nm on the electron injection layer, thereby producing an organic EL device according to Example 30.

[0112] Examples 31 to 38 and Comparative Example 13 Organic EL devices were prepared in the same manner as in Example 30, except that the first host was changed to the compounds shown in Tables 4-1 and 4-2.

[0113] Example 39 On a glass substrate on which an anode made of ITO with a film thickness of 70 nm was formed, each of the thin films shown below was deposited by vacuum deposition at a vacuum degree of 4.0 × 10 －５ The layers were laminated at a pressure of 10 Pa. First, HAT-CN, as previously described, was formed on ITO as a hole injection layer to a thickness of 10 nm. Next, HT-1 was formed as a hole transport layer to a thickness of 60 nm. Next, HT-2 was formed as an electron blocking layer to a thickness of 5 nm. Next, compound 1-1 was co-deposited as a first host, compound 2-60 as a second host, and BD-2 as a phosphorescent dopant from different evaporation sources to form an emitting layer having a thickness of 40 nm. This co-deposition was carried out under evaporation conditions such that the concentration of BD-2 was 13% by mass. Next, compound 2-82 was formed as a hole blocking layer to a thickness of 5 nm. Next, compound 2-82 was formed as an electron transport layer to a thickness of 31 nm. Furthermore, lithium fluoride (LiF) was formed as an electron injection layer to a thickness of 1 nm on the electron transport layer. Finally, aluminum (Al) was formed as a cathode on the electron injection layer to a thickness of 70 nm, thereby completing the organic EL device according to Example 39.

[0114] Examples 40 to 58 and Comparative Examples 14 to 28 Organic EL devices were prepared in the same manner as in Example 39, except that the electron-blocking layer material, first host, and second host were the compounds shown in Tables 4-1 and 4-2.

[0115]

[0116] The evaluation results of the fabricated organic EL devices are shown in Table 5. The voltage and power efficiency in the table are values ​​at a driving current of 2.5 mA / cm2, which are initial characteristics. The lifetime is the time it takes for the brightness to decay to 97%, assuming the initial brightness at a driving current of 4.0 mA / cm2 is 100%, and represents the lifetime characteristics. The emitted color was confirmed by the emission spectrum of the organic EL device.

[0117]

[0118] 1 Substrate, 2 Anode, 3 Hole injection layer, 4 Hole transport layer, 5 Light-emitting layer, 6 Electron transport layer, 7 Cathode

[0119] According to the present invention, it is possible to obtain a practically useful organic EL element which emits light with high efficiency and has a long life.

Claims

1. A material for organic electroluminescent devices represented by the following general formula (1): (In the general formula (1), Ar ０ represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups. 1 , and Y 2 is hydrogen, deuterium, or a carbazolyl group represented by the following formula (2), and Y 1 , and Y 2 At least one of Y is a carbazolyl group represented by the following formula (2): ３ is a carbazolyl group represented by the following formula (2): In addition, some or all of the hydrogen atoms in the compound represented by the general formula (1) may be substituted with deuterium atoms. In the general formula (2), R １ , and R ２ each independently represents hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted triarylsilyl group having 18 to 36 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups. In the general formula (2), * indicates the point of attachment to the carbazolyl group in formula (1).

2. The material for organic electroluminescent devices according to claim 1, wherein part or all of the hydrogen atoms in the compound represented by the general formula (1) are substituted with deuterium atoms.

3. R ​​in the compound represented by the general formula (1) １ , R ２ 2. The material for an organic electroluminescent device according to claim 1, wherein either one of the above is a substituted or unsubstituted carbazolyl group.

4. The material for organic electroluminescent devices according to claim 1, characterized in that the compound represented by formula (1) contains at least one deuterated carbazolyl group represented by any one of the following formulas (1c) to (1k): D represents deuterium, Ar ０ , Y 1 ~Y ３ , and * are the same as those described in claim 1.

5. The material for organic electroluminescent devices according to claim 1, wherein the compound represented by the general formula (2) contains at least one bond structure represented by the following formulas (3a) to (3c): (Part or all of the hydrogen atoms in the bond structures represented by formulas (3a) to (3c) may be substituted with deuterium atoms. * indicates the point of attachment to the adjacent carbazolyl group in the compound represented by general formula (1). R ２ is the same as that described in claim 1. ３ represents hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted triarylsilyl group having 18 to 36 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking two aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups.

6. The material for organic electroluminescent devices according to claim 5, wherein the compound represented by the general formula (1) contains at least one bond structure represented by the formula (3a).

7. The material for organic electroluminescent devices according to claim 5, wherein the compound represented by the general formula (1) contains at least one bond structure represented by the formula (3b).

8. The material for organic electroluminescent devices according to claim 5, wherein the compound represented by the general formula (1) contains at least one bond structure represented by the formula (3c).

9. The material for organic electroluminescent devices according to claim 5, characterized in that the compound represented by the general formula (1) contains at least two bonding structures represented by the formulas (3a) to (3c).

10. The material for organic electroluminescent devices according to claim 1, wherein the average deuteration rate of all hydrogen atoms in the compound represented by the general formula (1) is 50% or more.

11. The material for organic electroluminescent devices according to claim 1, characterized in that the energy level of the highest occupied molecular orbital (HOMO) obtained by a structure optimization calculation using density functional calculation B3LYP / 6-31G(d) is -5.3 eV or higher and the energy level of the lowest unoccupied molecular orbital (LUMO) is -1.4 eV or higher.

12. A mixed material for organic electroluminescent devices, comprising the material for organic electroluminescent devices represented by the general formula (1) described in claim 1 and a cyclic azine compound.

13. The mixed material for organic electroluminescent devices according to claim 12, wherein the cyclic azine compound is represented by any one of the following general formulas (4) to (10): (where Ar １ ~Ar １８ each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 20 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and the aromatic heterocyclic groups. １９ , and Ar ２０ L each independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 3 aromatic groups selected from the aromatic hydrocarbon groups and aromatic heterocyclic groups. 1 ~L 7 each independently represents a single bond or a substituted or unsubstituted phenyl group. Hydrogen in the compounds represented by the general formulas (4) to (10) may be substituted with deuterium.

14. L in the general formulas (4) to (10) １ ~L 7 The mixed material for an organic electroluminescent device according to claim 13, characterized in that is a single bond.

15. An organic electroluminescent device comprising one or more organic layers between opposing anode and cathode, wherein at least one of the organic layers contains the material for organic electroluminescent devices according to claim 1 or the mixed material for organic electroluminescent devices according to claim 12.

16. The organic electroluminescent device according to claim 15, wherein at least one of the organic layers is an emitting layer, and the emitting layer contains a thermally activated delayed fluorescent material.

17. The organic electroluminescent device according to claim 15, wherein at least one of the organic layers is an emitting layer, and the emitting layer contains a thermally activated delayed fluorescent material containing a boron atom.

18. The organic electroluminescent device according to claim 15, wherein at least one of the organic layers is a light-emitting layer, and the light-emitting layer contains a phosphorescent material.

19. The organic electroluminescent device according to claim 15, wherein at least one of the organic layers is a light-emitting layer, and the light-emitting layer contains a phosphorescent material containing platinum atoms.

20. The organic electroluminescent device according to claim 15, wherein at least one of the organic layers is an emitting layer, and the emitting layer contains a thermally activated delayed fluorescent material containing boron atoms and a phosphorescent material containing platinum atoms.

21. The organic electroluminescent device according to claim 15, wherein at least one of the organic layers is an emitting layer, and the emitting layer contains, as a host material, the material for organic electroluminescent devices according to claim 1 or the mixed material for organic electroluminescent devices according to claim 12.

22. An organic electroluminescent device having a light-emitting layer, a hole-transporting layer, and an electron-transporting layer between opposing anode and cathode, wherein the light-emitting layer contains the material for organic electroluminescent devices described in claim 1, wherein the difference (absolute value) in energy levels of the highest occupied molecular orbital (HOMO) between the material for organic electroluminescent devices described in claim 1 and the hole-transporting material contained in the hole-transporting layer is 0.70 eV or less, and the difference (absolute value) in energy levels of the lowest unoccupied molecular orbital (LUMO) between the material for organic electroluminescent devices described in claim 1 and the electron-transporting material contained in the electron-transporting layer is 0.80 eV or less.

23. A method for producing an organic electroluminescent device comprising one or more organic layers between opposing anode and cathode, at least one of which is an emissive layer, the method comprising: mixing a material for organic electroluminescent devices represented by general formula (1) set forth in claim 1 with a cyclic azine compound in advance to form a premixed material for organic electroluminescent devices; and depositing this premixed material from a single deposition source.

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