Organic electroluminescent element material, organic electroluminescent element mixed material, and organic electroluminescent element

Abstract

Provided are: a practically useful organic electroluminescent element material which emits light with high efficiency while being driven at a low voltage, and has long service life characteristics; and an organic electroluminescent element using the same.　This organic electroluminescent element material is characterized by being a compound represented by general formulae (1a)-(1d), and is characterized in that the average deuteration rate of hydrogen in the compound is at least 10%. Ar1 represents a structure in which a carbazolyl group and a substituted or unsubstituted aromatic hydrocarbon group are linked, and R2-R9 each independently represent hydrogen, deuterium, or an aliphatic hydrocarbon group having 1-10 carbon atoms.

Description

Materials for organic electroluminescent devices, mixed materials for organic electroluminescent devices, and organic electroluminescent devices.

[0001] This invention relates to an organic electroluminescent element (referred to as an organic EL element) that can convert electrical energy into light, and to a material for such an organic electroluminescent element.

[0002] When a voltage is applied to an organic EL element, holes are injected from the anode and electrons 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, according 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 limited to 25%. On the other hand, phosphorescent organic EL elements that use emission from triplet excitons are known to have an internal quantum efficiency of up to 100% if intersystem crossing from singlet excitons is performed efficiently.

[0003] In recent years, advancements have been made in technologies for extending the lifespan of phosphorescent organic EL elements, and these are being applied to displays in mobile phones and other devices. However, no practical phosphorescent organic EL elements have been developed for blue light, and there is a need for the development of highly efficient and long-lasting blue organic EL elements.

[0004] More recently, highly efficient delayed fluorescence type organic EL elements have been developed using delayed fluorescence. For example, Patent Document 1 discloses an organic EL element that utilizes the TTF (Triplet-Triplet Fusion) mechanism, one of the mechanisms of delayed fluorescence. The TTF mechanism utilizes the phenomenon in which a singlet exciton is generated by the collision of two triplet excitons, and it is theoretically thought that the internal quantum efficiency can be increased to 40%. However, since its efficiency is lower compared to phosphorescent type organic EL elements, further improvements in efficiency are needed.

[0005] On the other hand, Patent Document 2 discloses an organic EL device utilizing the thermally activated delayed fluorescence (TADF) mechanism. The TADF mechanism utilizes the phenomenon in which reverse intersystem crossing occurs from triplet excitons to singlet excitons in materials where the energy difference between the singlet and triplet levels is small, and it is theoretically thought that the internal quantum efficiency can be increased to 100%.

[0006] Here, Non-Patent Document 1 discloses a device that uses a predetermined phosphorescent dopant and TADF dopant, in addition to a predetermined mixed host (SiTrz2Cz and SiCzCz).

[0007] Furthermore, while Patent Documents 3 and 4 disclose devices using compounds in which multiple carbazoles are linked together, they do not disclose devices using compounds in which multiple deuterated carbazoles are linked together.

[0008] Furthermore, Patent Document 5 discloses an element that uses a compound in which multiple deuterated carbazoles are linked together.

[0009] Furthermore, while Patent Documents 6, 7, and 8 disclose devices using compounds in which a skeleton of multiple deuterated carbazoles is further bonded to carbazoles via aromatic hydrocarbons, they only disclose the properties of devices using compounds containing aromatic hydrocarbons linked at specific substitution positions.

[0010] Publication No. WO2010 / 134350, Publication No. WO2011 / 070963, Publication No. WO2012 / 077520, Publication No. US2015 / 243894, Publication No. WO2023 / 162701, Publication No. JP2022 / 132157, Publication No. US2022 / 029106, Publication No. US2024 / 0276875

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

[0012] In order to apply organic EL elements as display elements or light sources in flat panel displays and the like, it is necessary to improve the luminous efficiency of the elements while simultaneously ensuring sufficient stability during operation. However, conventional materials consisting of known combinations of compounds cannot achieve these goals.

[0013] This invention has been made in view of the current situation, and aims to provide an organic electroluminescent element material that can produce a practically useful organic EL element that emits light with high efficiency and has long lifespan characteristics, even when driven at low voltage. Furthermore, this invention aims to provide an organic EL element using such a material.

[0014] In other words, the present invention relates to an organic electroluminescent material comprising any compound represented by the following general formulas (1a) to (1d), characterized in that the average deuteration rate of hydrogen in the compound is 10% or more. Preferably, the organic electroluminescent material comprises any compound represented by the following general formulas (1a), (1c), or (1d). Furthermore, the average deuteration rate is preferably 20% or more, more preferably 50% or more, even more preferably 70% or more, and most preferably 80% or more. Ar １ Each of these is independently represented by the following general formulas (2a) to (2o), and Ar １ It is preferable that is (2b), (2c), (2e), (2f), (2g), (2i), (2j), (2k), (2l), or (2n). More preferably, Ar of the general formula (1c) １ It is often (2n) or (2o), and Ar of the general formula (1b) １ It is also good that (2n) is true. * indicates the bonding position with the general formulas (1a) to (1d) above. R ２ ~R ９ Each of these independently represents hydrogen, deuterium, or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and is preferably hydrogen or deuterium.

[0015] Here, the general formulas (1a) to (1d) all consist of a carbazole dimer and another carbazole (Ar in formula (1)) via an aromatic hydrocarbon. １ ) has a structure in which carbazole dimers are linked. Generally, carbazole dimers are highly electron-donating and have a relatively small ionization potential, so the excitation level of molecules having carbazole dimers is lowered. In thin films, interactions occur between carbazole dimers, further lowering the excitation level, but (1a) to (1d) have a structure in which carbazole is linked to carbazole dimers via aromatic hydrocarbons, as in (2a) to (2o), which suppresses the interaction between carbazole dimers and suppresses the decrease in the excitation level. When the excitation level of a molecule decreases, excitation energy is more easily transferred to that molecule, making it more susceptible to degradation reactions from the excited state, but the framework of carbazole linked via aromatic hydrocarbons, as in (2a) to (2o) of the general formulas (1a) to (1d), can suppress this. Furthermore, the carbazole skeletons linked via aromatic hydrocarbons, such as (2a) to (2o), are expected to have the effect of keeping molecules apart and making excitation energy transfer less likely. Therefore, compounds having the general formulas (1a) to (1d) are less likely to enter an excited state. On the other hand, suppressing the decrease in the excitation level leads to a higher energy excited state, and the stability of the excited state decreases. The stability of the compound can be increased by deuteration. In other words, the present invention compensates for the instability of compounds of the general formulas (1a) to (1d) having skeletons like (2a) to (2o) that are less likely to enter an excited state by deuteration, and by satisfying these two conditions, the lifespan of organic EL elements is extended compared to conventional devices.

[0016] The compound represented by the general formula (1a) to (1d) is preferably any one of the following formulas (1-1), (1-3), (1-9), (1-12), (1-14), (1-17), (1-20), (1-24), (1-25), (1-38), (1-42), (1-49), (1-50), (1-51), (1-52), (1-53), (1-57), (1-58), and (1-73). Here, D represents deuterium, n represents the average number of substitution numbers substituted with deuterium in each of the above compounds, and varies according to the average deuteration rate.

[0017] Further, the material for an organic electroluminescent device of the present invention may be a mixed material for an organic electroluminescent device so as to include any compound represented by the general formula (1a) to (1d) and a second compound different from the compound represented by the general formula (1a) to (1d). Preferably, it is a mixed material for an organic electroluminescent device including any one compound represented by the general formula (1a) to (1d) and a cyclic azine compound represented by the following general formula (10). More preferably, it is a preliminary mixed material for an organic electroluminescent device obtained by preliminarily mixing any one compound represented by the general formula (1a) to (1d) and a cyclic azine compound represented by the following general formula (10) to form a preliminary mixture. Here, Ar ２ and Ar ３Each of these independently represents hydrogen, 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 composed of 2 to 5 aromatic groups selected from the aromatic hydrocarbon group and the aromatic heterocyclic group, preferably hydrogen, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and a substituted or unsubstituted aromatic group having 6 to 20 carbon atoms. A group hydrocarbon group, a substituted or unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group composed of 2 to 5 aromatic groups selected from the aromatic heterocyclic group linked together, more preferably 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 composed of 2 to 5 aromatic groups selected from the aromatic hydrocarbon group linked together. １ represents a single bond, a substituted or unsubstituted phenyl group, preferably a single bond. Some or all of the hydrogen atoms in the compound represented by the general formula (10) may be substituted with deuterium.

[0018] Further, the present invention provides an organic electroluminescent device including one or more organic layers between opposing anodes and cathodes, wherein at least one of the organic layers contains a material for an organic electroluminescent device comprising any of the compounds represented by the general formulas (1a) to (1d). Preferably, the organic layer contains any of the compounds represented by the general formulas (1a) to (1d) and a second compound different from the compounds represented by these general formulas (1a) to (1d). More preferably, the organic layer contains a mixed material for an organic electroluminescent device comprising any of the compounds represented by the general formulas (1a) to (1d) and a cyclic azine compound represented by the general formula (10). Even more preferably, the organic electroluminescent device includes a preliminary mixed material for an organic electroluminescent device in which any of the compounds represented by the general formulas (1a) to (1d) and the cyclic azine compound represented by the general formula (10) are pre-mixed. Note that any of the compounds represented by the general formulas (1a) to (1d) and the cyclic azine compound represented by the general formula (10) may be individually supplied to the organic layer, or may be supplied as the pre-mixed material for an organic electroluminescent device pre-mixed as described above.

[0019] In the organic electroluminescent device of the present invention, it is preferable that the organic layer containing the mixed material for an organic electroluminescent device is a light-emitting layer, and the light-emitting layer preferably contains a thermally activated delayed fluorescence material, and it is more preferable that the thermally activated delayed fluorescence material contains a boron atom.

[0020] Further, in the organic electroluminescent device of the present invention, it is preferable that the organic layer containing the mixed material for an organic electroluminescent device is a light-emitting layer, and the light-emitting layer preferably contains a phosphorescent material, and it is more preferable that the phosphorescent material contains a platinum atom or an iridium atom.

[0021] Furthermore, in the organic electroluminescent device of the present invention, it is preferable that the organic layer containing the mixed material for an organic electroluminescent device is a light-emitting layer, and the light-emitting layer further contains a thermally activated delayed fluorescence material containing a boron atom and a phosphorescent material containing a platinum atom or an iridium atom.

[0022] Further, in the organic electroluminescent device of the present invention, an organic layer containing the mixed material for the organic electroluminescent device is a light-emitting layer, and the light-emitting layer contains the mixed material for the organic electroluminescent device as a host material, and further preferably contains a thermally activated delayed fluorescence emitting material containing a boron atom and a phosphorescent emitting material containing a platinum atom or an iridium atom.

[0023] Further, the present invention provides an organic electroluminescent device having one or more organic layers between a counter anode and a cathode, wherein at least one organic layer is a light-emitting layer, and in forming the light-emitting layer, a preliminary mixed material for an organic electroluminescent device in which the compound represented by the general formula (1a) to (1d) of the present invention and the compound represented by the general formula (10) are pre-mixed is used, and vapor deposition is performed from one vapor deposition source. It is a method for manufacturing an organic electroluminescent device characterized by the above.

[0024] According to the present invention, an organic EL device that is useful in practical applications can be obtained, which emits light with high efficiency and has long-life characteristics while being driven at a low voltage.

[0025] FIG. 1 is a cross-sectional schematic view showing an example of the structure of the organic EL device used in the present invention.

[0026] The compounds represented by the general formula (1a) to (1d) and the compound represented by the general formula (10) in the present invention will be described in detail respectively.

[0027] First, the compounds represented by the general formula (1a) to (1d) in the present invention are as follows. Ar １ are each independently represented by the following general formula (2a) to (2o), and Ar １ is preferably (2b), (2c), (2e), (2f), (2g), (2i), (2j), (2k), (2l), or (2n). More preferably, Ar of the general formula (1c) １ is (2n) or (2o), and Ar of the general formula (1b) １ may also be (2n). R ２ ~R ９Each of these independently represents hydrogen, deuterium, or an aliphatic hydrocarbon group having 1 to 10 carbon atoms. Preferably, it represents hydrogen or deuterium. In an organic electroluminescent material comprising any of the compounds represented by the general formulas (1a) to (1d), the average deuteration rate of all hydrogen in the compound is 10% or more, preferably 20% or more, more preferably 50% or more, even more preferably 70% or more, and most preferably 80% or more. Theoretically, the upper limit of the average deuteration rate is 100%. Furthermore, to explain the average deuteration rate in the present invention, for example, in the case of a compound represented by general formula (1a), it includes both cases where it consists of a single compound and cases where it consists of a mixture of two or more compounds represented by general formula (1a). That is, to explain the average deuteration rate specifically, if the average deuteration rate is 50%, it means that on average half of the total hydrogen is replaced with deuterium, and it may consist of a single compound or a mixture of different deuteration rates.

[0028] The average deuterated rate can be determined by mass spectrometry or proton nuclear magnetic resonance spectroscopy. For example, when determining the rate by proton nuclear magnetic resonance spectroscopy, the sample is first prepared by adding the compound and an internal standard substance to a deuterated solvent and dissolving them. The proton concentration [mol / g] of the compound contained in the sample is then calculated from the integral intensity ratio derived from the internal standard substance and the compound. Next, the ratio of the proton concentration of the deuterated compound to the corresponding proton concentration of the non-deuterated compound is calculated, and the average deuterated rate of the deuterated compound can be calculated by subtracting this ratio from 1. The average deuterated rate of a substructure can also be calculated from the integral intensity of the chemical shift derived from the target substructure using the same procedure as described above.

[0029] The compounds represented by the general formulas (1a) to (1d) are preferably any of (1-1), (1-3), (1-9), (1-12), (1-14), (1-17), (1-20), (1-24), (1-25), (1-38), (1-42), (1-49), (1-50), (1-51), (1-52), (1-53), (1-57), (1-58), and (1-73). D represents deuterium, and n means the average number of substitutions with deuterium in each of the above compounds, and changes according to the average deuterated rate.

[0030] The aforementioned R ２ ~R ９ Specific examples of cases where is an unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms include methyl, ethyl, propyl, i-propyl, butyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, and decyl. Preferably, it is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or octyl. Preferably, it is methyl, butyl, t-butyl, or octyl.

[0031] Furthermore, in the present invention, the cyclic azine compound represented by general formula (10) is as follows. Ar ２ and Ar ３Each of these independently represents hydrogen, 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 composed of 2 to 5 aromatic groups selected from the aromatic hydrocarbon group and the aromatic heterocyclic group. Preferably, it is a substituted or unsubstituted linked aromatic group composed of hydrogen, an aliphatic hydrocarbon group having 1 to 10 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 composed of 2 to 5 aromatic groups selected from the aromatic hydrocarbon group and the aromatic heterocyclic group linked together. More preferably, it is 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 composed of 2 to 5 aromatic groups selected from the aromatic hydrocarbon group and the aromatic heterocyclic group linked together. １ represents a single bond, a substituted or unsubstituted phenyl group, preferably a single bond. Some or all of the hydrogens in the compound represented by the general formula (10) above may be substituted with deuterium. The average deuterated rate of the compound represented by the general formula (10) above is preferably 20% or more, more preferably 50% or more, even more preferably 70% or more, and most preferably 80% or more.

[0032] The Ar ２ and Ar ３ A specific example of the case where is an unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms is the aforementioned R ２ ~R ９ This is similar to the specific example where is an unsubstituted aliphatic hydrocarbon group having 1 to 10 carbon atoms.

[0033] Furthermore, the Ar ２ and Ar ３Specific examples of the case where is an unsubstituted triarylsilyl group having 18 to 36 carbon atoms include triphenylsilyl, biphenyldiphenylsilyl, bisbiphenylphenylsilyl, and trisbiphenylsilyl. Preferably, it is triphenylsilyl, biphenyldiphenylsilyl, or bisbiphenylphenylsilyl. More preferably, it is triphenylsilyl or biphenyldiphenylsilyl.

[0034] Furthermore, the aforementioned Ar ２ and Ar ３Specific examples of cases where is an unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, an unsubstituted aromatic heterocyclic group having 2 to 17 carbon atoms, or an unsubstituted linked aromatic group composed of 2 to 5 aromatic groups selected from the aromatic hydrocarbon group and the aromatic heterocyclic group linked together 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, thiadi Examples include azoles, pyrazines, furans, isoxazoles, quinolines, isoquinolines, quinoxalines, quinazolins, thiadiazoles, phthalazines, tetrazoles, indoles, benzofurans, benzothiophenes, benzoxazoles, benzothiazoles, indazoles, benzimidazoles, benzotriazoles, benzoisothiazoles, benzothiadiazoles, purines, pyranones, coumarins, isocoumarins, chromones, dibenzofurans, dibenzothiophenes, dibenzoselenophenes, carbazoles, or groups formed by removing one hydrogen atom from a group consisting of 2 to 5 of these groups linked together. Preferably, the group is benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, phenanthrene, fluorene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazole, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, or a group formed by removing one hydrogen atom from a group consisting of 2 to 5 of these groups linked together.

[0035] In this specification, unsubstituted triarylsilyl groups, aromatic hydrocarbon groups, aromatic heterocyclic groups, or linked aromatic groups may each have substituents. When substituents are present, preferred substituents are deuterium, halogens, cyano groups, C1-C10 alkyl groups, C2-C5 alkenyl groups, C1-C5 alkoxy groups, C18-C36 triarylsilyl groups, or C12-C44 diarylamino groups. The number of substituents is preferably 0-5, more preferably 0-2. Note that when calculating the carbon number of an aromatic hydrocarbon group, aromatic heterocyclic group, or linked aromatic group with substituents, the carbon number of the substituents is not included. However, it is preferable that the total carbon number including the carbon number of substituents satisfies the above range.

[0036] Specific examples of the substituents include deuterium, cyano, bromo, fluorine, 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, triphenylsilyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthranylamino, diphenanthrenylamino, dipyrenylamino, etc. Preferably, deuterium, cyano, methyl, ethyl, propyl, butyl, t-butyl, pentyl, hexyl, heptyl, octyl, vinyl, propenyl, butenyl, pentenyl, methoxy, ethoxy, propoxy, butoxy, pentoxy, triphenylsilyl.

[0037] In this specification, a linked aromatic group refers to an aromatic group in which two or more aromatic rings are linked by a single bond. These linked aromatic groups may be linear or branched. The linking positions of the benzene rings may be ortho, meta, or para. The aromatic groups may be aromatic hydrocarbon groups or aromatic heterocyclic groups, and the multiple aromatic groups may be the same or different.

[0038] The mixed material for organic electroluminescent devices in the present invention may be in powder, solid, or thin film form, as long as it contains the organic electroluminescent device material represented by general formulas (1a) to (1d) and the cyclic azine compound represented by general formula (10). For example, when forming the light-emitting layer of an organic EL element using this material, the organic electroluminescent device material represented by general formulas (1a) to (1d) and the compound represented by general formula (10) may be supplied separately to the light-emitting layer, or the material may be supplied as a pre-mixed organic electroluminescent device material in which the organic electroluminescent device material represented by general formulas (1a) to (1d) and the compound represented by general formula (10) are pre-mixed. In particular, it is preferable that the material be supplied as a pre-mixed organic electroluminescent device material in which the organic electroluminescent device material represented by general formulas (1a) to (1d) and the compound represented by general formula (10) are pre-mixed.

[0039] The mixed material for the organic electroluminescent element may be prepared by mixing the compounds represented by general formulas (1a) to (1d) and the compound represented by general formula (10) in powder form, by melting and mixing them by heating under reduced pressure or inert gas atmosphere such as nitrogen, or by sublimating the compounds together. It may also be prepared as a thin film by vapor deposition or the like. On the other hand, if the compounds represented by general formulas (1a) to (1d) and the compound represented by general formula (10) that constitute the mixed material are not pre-mixed, they may be included in different organic layers of the element. For example, the electron blocking layer may contain the compounds represented by general formulas (1a) to (1d), and the light-emitting layer may contain the compound represented by general formula (10). The pre-mixed material for the organic electroluminescent element refers to a mixed material for the organic electroluminescent element in which the organic electroluminescent element materials represented by general formulas (1a) to (1d) and the compound represented by general formula (10) are pre-mixed in powder form, or pre-mixed by heating and melting these powders.

[0040] In the mixed material for organic electroluminescent elements and the premixed material for organic electroluminescent elements, the mixing ratio (mass ratio) of the first compound represented by general formulas (1a) to (1d) and the second compound represented by general formula (10) is such that the proportion of the first compound represented by general formulas (1a) to (1d) to the total of the first compound represented by general formulas (1a) to (1d) and the second compound represented by general formula (10) is preferably 40 to 90% by mass, more preferably 50 to 90% by mass, and more preferably 60 to 90% by mass. The difference between the 50% weight loss temperature of the first compound and the 50% weight loss temperature of the second compound in the premixture is preferably 20°C or less, and more preferably 15°C or less.

[0041] Specific examples of organic electroluminescent material represented by general formulas (1a) to (1d) are shown below, but the present invention is not limited to these exemplary compounds. Note that D represents deuterium, and the substitution number n is the average number, which changes depending on the average deuteration rate.

[0042]

[0043] Furthermore, specific examples of compounds represented by general formula (10) are shown below, but the present invention is not limited to these exemplary compounds. Note that D represents deuterium, and the number of substitutions n represents the average number, which changes depending on the average deuterated rate.

[0044] Furthermore, the present invention relates to an organic electroluminescent element comprising one or more organic layers between opposing anodes and cathodes, wherein at least one organic layer comprises an organic electroluminescent element material consisting of any compound represented by the general formulas (1a) to (1d), or an organic electroluminescent element mixed material comprising an organic electroluminescent element material consisting of any compound represented by the general formulas (1a) to (1d) and a compound represented by the general formula (10). Preferably, the organic layer comprises an organic electroluminescent element premixed material obtained by premixing an organic electroluminescent element material consisting of any compound represented by the general formulas (1a) to (1d) and a compound represented by the general formula (10).

[0045] The organic electroluminescent device of the present invention preferably has at least one organic layer as an emissive layer, and preferably contains the mixed material for the organic electroluminescent device in the emissive layer. More preferably, the organic electroluminescent device further contains a thermally activated delayed fluorescence material or a phosphorescent material in the emissive layer, and even more preferably, the organic electroluminescent device further contains a thermally activated delayed fluorescence material and a phosphorescent material in the emissive layer. Furthermore, the thermally activated delayed fluorescence material preferably contains boron atoms, and the phosphorescent material preferably contains platinum atoms or iridium atoms.

[0046] In other words, an excellent organic EL element is obtained by including at least one host material together with a thermally activated delayed fluorescence material or a phosphorescent material in the light-emitting layer as needed, but it is preferable that at least one host material is an organic electroluminescent element material made of any compound represented by the general formulas (1a) to (1d). Furthermore, when the light-emitting layer contains at least two host materials, it is preferable to use an organic electroluminescent element material made of any compound represented by the general formulas (1a) to (1d) as the first host and a compound represented by the general formula (10) as the second host.

[0047] Furthermore, the present invention relates to a method for manufacturing an organic electroluminescent element, in which an organic electroluminescent element includes one or more organic layers between opposing anodes and cathodes, wherein at least one organic layer is a light-emitting layer, and the light-emitting layer is formed by pre-mixing an organic electroluminescent element pre-mixing an organic electroluminescent element material consisting of any of the compounds represented by general formulas (1a) to (1d) and a cyclic azine compound represented by general formula (10) from a single deposition source. Specifically, in preparing the organic layer of the organic electroluminescent element, the organic electroluminescent element material consisting of any of the compounds represented by general formulas (1a) to (1d) and the compound represented by general formula (10) are each made into powders and pre-mixed in advance, or these powders are pre-mixed in advance by heating and melting to obtain an organic electroluminescent element pre-mixing material, and the light-emitting layer of the organic EL element can be manufactured by pre-mixing this from a single deposition source.

[0048] 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 thereto.

[0049] Figure 1 is a cross-sectional view showing an example of the structure of a typical organic EL element used in the present invention, where 1 is the substrate, 2 is the anode, 3 is the hole injection layer, 4 is the hole transport layer, 5 is the light-emitting layer, 6 is the electron transport layer, and 7 is the cathode. The organic EL element of the present invention has an anode, a light-emitting layer, and a cathode as essential layers, but it is common to 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 furthermore, an electron blocking layer may be included between the hole transport layer and the light-emitting layer, and a hole blocking layer may be included between the light-emitting layer and the electron transport layer.

[0050] It is also possible to stack the cathode 7, electron transport layer 6, light-emitting layer 5, hole transport layer 4, hole injection layer 3, and anode 2 on the substrate 1 in the reverse order of Figure 1. In this case as well, layers can be added or omitted as needed. In organic EL elements as described above, layers other than electrodes such as anodes and cathodes that constitute the stacked structure on the substrate are sometimes collectively referred to as organic layers.

[0051] -Substrate- The organic EL element of the present invention is preferably supported on a substrate. There are no particular restrictions on the substrate; any substrate that has been conventionally used in organic EL elements is acceptable, such as those made of glass, transparent plastic, quartz, etc.

[0052] - Anode - As the anode material for an organic EL device, materials consisting of metals, alloys, electrically conductive compounds, or mixtures thereof with a large work function (4 eV or more) are preferably used. Specific examples of such electrode materials include metals such as Au, CuI, indium tin oxide (ITO), and SnO ２Examples include conductive transparent materials such as ZnO. Alternatively, amorphous materials capable of producing transparent conductive films, such as IDIXO (In2O3-ZnO), may be used. The anode may be formed by creating a thin film from these electrode materials using methods such as vapor deposition or sputtering, and then forming a pattern of the desired shape using photolithography. Alternatively, if high pattern accuracy is not required (approximately 100 μm or more), the pattern may be formed via a mask of the desired shape during vapor deposition or sputtering of the electrode material. In the case of coating-applicable materials such as organic conductive compounds, wet film formation methods such as printing or coating can also be used. When extracting light from this anode, it is desirable to have a transmittance greater than 10%, and the sheet resistance of the anode is preferably several hundred Ω / □ or less. The film thickness depends on the material, but is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.

[0053] - Cathode - On the other hand, materials consisting of metals (called electron-injection metals), alloys, electrically conductive compounds, or mixtures thereof with a small work function (4 eV or less) are used as cathode materials. 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, aluminum / aluminum oxide (Al ２ O ３ Examples include mixtures, indium, lithium / aluminum mixtures, and rare earth metals. Among these, from the standpoint of electron injection properties and durability against oxidation, mixtures of electron-injectable metals and metallic compounds that have a larger work function and are more stable, such as magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, and aluminum / aluminum oxide (Al ２ O ３Suitable materials include mixtures, lithium / aluminum mixtures, and aluminum. The cathode can be fabricated by forming a thin film of these cathode materials by methods such as vapor deposition or sputtering. The sheet resistance of the cathode is preferably 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. It is advantageous that the luminescence brightness is improved if either the anode or cathode of the organic EL element is transparent or semi-transparent in order to transmit the emitted light.

[0054] Furthermore, by forming the above-mentioned metal on the cathode with a film thickness of 1 to 20 nm, and then forming the conductive transparent material mentioned in the description of the anode on top of it, a transparent or translucent cathode can be fabricated. By applying this, it is possible to fabricate an element in which both the anode and cathode are transparent.

[0055] -Emitting Layer- The emissive layer is a layer that emits light after excitons are generated by the recombination of holes and electrons injected from the anode and cathode, respectively. The emissive layer may be a single layer or multiple layers, each containing an organic luminescent dopant material and a host material.

[0056] The organic luminescent dopant may be contained in the luminescent layer by one type or by two or more types. The content of the organic luminescent dopant is preferably 0.1 to 50% by mass, and more preferably 0.1 to 40% by mass, relative to the host material.

[0057] When using a phosphorescent dopant as an organic luminescent dopant material, the phosphorescent dopant should contain an organometallic complex comprising at least one metal selected from ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. More preferably, an organometallic complex containing platinum is used. Specifically, iridium complexes described in J.Am.Chem.Soc.2001,123,4304 and JP 2013-530515, and platinum complexes described in Adv. Mater.2014,26,7116 and JP 2018-2722 are suitably used, but are not limited to these.

[0058] Phosphorescent dopant materials are not particularly limited, but specific examples include the following:

[0059]

[0060] When using a fluorescent dopant as a luminescent dopant material, the fluorescent dopant is not particularly limited, but examples include condensed polycyclic aromatic derivatives, styrylamine derivatives, condensed ring amine derivatives, boron-containing compounds, pyrrole derivatives, indole derivatives, and carbazole derivatives. Among these, condensed ring amine derivatives, boron-containing compound derivatives, and carbazole derivatives are preferred. Examples of condensed ring amine derivatives include diaminepyrene derivatives, diaminochrysene derivatives, diaminoanthracene derivatives, diaminofluorenone derivatives, and diaminofluorene derivatives having one or more benzoflo skeletons fused together. Examples of boron-containing compounds include pyromethene derivatives and polycyclic aromatic compounds described in publication WO2015 / 102118, etc.

[0061] Fluorescent dopant materials are not particularly limited, but specific examples include the following:

[0062]

[0063] When using a thermally activated delayed fluorescence dopant as a luminescent dopant material, the thermally activated delayed fluorescence dopant is not particularly limited, but examples 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 publication WO2015 / 102118, etc. Preferably, it is a thermally activated delayed fluorescence dopant containing a boron atom.

[0064] The thermally activated delayed fluorescence dopant material is not particularly limited, but specific examples include the following. A cyclic azine compound may be used as the thermally activated delayed fluorescence dopant material, but it is preferable that it is not a compound represented by the general formula (10) above.

[0065]

[0066] As the host material in the light-emitting layer, it is preferable to use organic electroluminescent material represented by general formulas (1a) to (1d) and / or a compound represented by general formula (10). When a compound represented by general formulas (1a) to (1d) or general formula (10) is used in any organic layer other than the light-emitting layer, the compound represented by general formulas (1a) to (1d) or general formula (10) may or may not be included in the light-emitting layer. In this case, a known host material used in phosphorescent light-emitting devices and fluorescent light-emitting devices may also be used in combination in the light-emitting layer. Multiple known host materials may be used in combination, or each may be used individually. As a known host material that can be used, it is preferable that it is a compound that has hole transport ability, electron transport ability, and a high glass transition temperature, and has a triplet excitation energy (T1(h)) that is greater than the triplet excitation energy (T1(exp)) of the luminescent dopant material. Furthermore, a compound exhibiting delayed fluorescence (TADF) activity may be used as the host material. In this case, a compound with a difference between the singlet excitation energy (S1(h)) and the triplet excitation energy (T1(h)) (ΔEST = S1(h) - T1(h)) of 0.20 eV or less is preferred. Alternatively, one of the compounds represented by the general formulas (1a) to (1d) may be included alone as the host material in the light-emitting layer, and other known host materials may be used in combination. However, to improve the characteristics of the organic EL device, it is preferable to use the compound represented by the general formula (10) as the host material in combination. Note that multiple types of known host materials may be used in combination. Here, S1(h), T1(h), and ΔEST = S1(h) - T1(h) are measured as follows: Vacuum deposition is performed on a quartz substrate at a vacuum level of 10. －４A sample compound (a compound exhibiting delayed fluorescence (TADF) activity) is deposited under conditions of Pa or less to form a deposited film with a thickness of 100 nm. S1(h) is calculated by measuring the emission spectrum of this deposited film, drawing a tangent to the rising edge of 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 equation (i): S1(h) [eV] = 1239.85 / λedge (i) On the other hand, T1(h) is calculated by measuring the phosphorescence spectrum of the deposited film, drawing a tangent to the rising edge of the short-wavelength side of this phosphorescence spectrum, and substituting the wavelength value λedge [nm] at the intersection of the tangent and the horizontal axis into the following equation (ii): T1(h) [eV] = 1239.85 / λedge (ii) From the above, ΔEST can be determined from S1(h) and T1(h).

[0067] The known host materials can be selected from those known through numerous patent documents, etc. Specific examples of host materials are not 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 and metal phthalocyanines, various metal complexes represented by metal complexes of benzoxazole and benzothiazole compounds, poly(N-vinylcarbazole) compounds, aniline copolymers, thiophene oligomers, polythiophene compounds, polyphenylene compounds, polyphenylene vinylene compounds, polyfluorene compounds, and other polymer compounds. Preferably, examples include carbazole compounds, indrocarbazole compounds, pyridine compounds, pyrimidine compounds, triazine compounds, anthracene compounds, triphenylene compounds, carborane compounds, and porphyrin compounds.

[0068] The known hosts mentioned above are not limited to the following compounds.

[0069] When using multiple types of hosts, each host can be deposited from a different deposition source, or multiple types of hosts can be pre-mixed and deposited simultaneously from a single deposition source.

[0070] When multiple types of hosts are used, the host is preferably the mixed material for the organic electroluminescent element containing the compounds represented by the general formulas (1a) to (1d) and the compound represented by the general formula (10). When two types of hosts are used, the premixed material for the organic electroluminescent element is preferably composed of the compounds represented by the general formulas (1a) to (1d) and the compound represented by the general formula (10). Furthermore, when the compounds represented by the general formulas (1a) to (1d) and the compound represented by the general formula (10) are used as hosts, the compounds represented by the general formulas (1a) to (1d) become the first host, and the compound represented by the general formula (10) becomes the second host.

[0071] In order to reproducibly fabricate organic EL elements with good characteristics, the mixed material for organic electroluminescent elements and the premixed material for organic electroluminescent elements are configured such that the 50% weight loss temperature (T) of the first host and the second host is controlled. 50 It is desirable that the difference between the 50% weight loss temperatures is small, and preferably the difference in 50% weight loss temperatures is within 20°C. The 50% weight loss temperature is the temperature at which the weight decreases by 50% when the temperature is raised from room temperature to 550°C at a rate of 10°C per minute in TG-DTA measurements under reduced pressure of nitrogen gas flow (1 Pa). Around this temperature, vaporization by evaporation or sublimation is considered to occur most actively. If the difference in 50% weight loss temperatures between the first host and the second host is within 20°C, it is possible to obtain a uniform deposited film by vaporizing and depositing from a single evaporation source. In this case, the mixed material for the organic electroluminescent element may contain, in addition to the first host and the second host, a luminescent dopant material necessary for forming the light-emitting layer or the known host used as needed. However, if there is a large difference in the temperature at which the desired vapor pressure is reached, it is preferable to deposit from a different deposition source.

[0072] Furthermore, when using two types of hosts, the mixing ratio (mass ratio) of the first host to the second host is preferably 40-90%, more preferably 50-90%, and more preferably 60-90%, of the total amount of the first host relative to the sum of the first and second hosts.

[0073] When using multiple types of hosts, a method that allows for as uniform a mixture as possible is desirable for pre-mixing the hosts. Examples of such methods include grinding and mixing, heating and melting under reduced pressure or inert gas atmosphere such as nitrogen, and sublimation, but the method is not limited to these.

[0074] Furthermore, the host and its premixed material may be in the form of a powder, stick, or granules.

[0075] -Injection Layer- An injection layer is a layer provided between the electrode and the organic layer to reduce the driving voltage and improve the luminescence brightness. There are hole injection layers and electron injection layers, and they may be present between the anode and the light-emitting layer or hole transport layer, and between the cathode and the light-emitting layer or electron transport layer. The injection layer can be provided as needed.

[0076] -Hole Blocking Layer- In a broad sense, the hole blocking layer functions as an electron transport layer. It consists of a hole blocking material that has the function of transporting electrons but has a remarkably low ability to transport holes. By blocking holes while transporting electrons, it is possible to improve the probability of electron-hole recombination in the light-emitting layer. Known hole blocking materials can be used for the hole blocking layer. Multiple types of hole blocking materials may also be used in combination.

[0077] -Electron Blocking Layer- In a broad sense, the electron blocking layer functions as a hole transport layer, and by blocking electrons while transporting holes, it can 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 compounds represented by the general formulas (1a) to (1d) or the mixed materials, but known electron blocking layer materials can also be used. When using the compounds represented by the general formulas (1a) to (1d) or the mixed materials as the electron blocking layer, the host material may be the compounds represented by the general formulas (1a) to (1d), the known host materials mentioned above, or host materials that combine multiple types thereof.

[0078] Layers adjacent to the light-emitting layer include hole blocking layers and electron blocking layers. However, if these layers cannot be provided, hole transport layers and electron transport layers become the adjacent layers.

[0079] - Hole Transport Layer - The hole transport layer consists of a hole transport material that has the function of transporting holes, and the hole transport layer can be a single layer or multiple layers.

[0080] The hole transport material has either hole injection or transport properties, or electron barrier properties, and may be either organic or inorganic. Any compound from conventionally known compounds can be selected and used as the hole transport material. Examples of such hole transport materials include porphyrin derivatives, arylamine 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 copolymers, and conductive polymer oligomers, particularly thiophene oligomers.

[0081] - Electron Transport Layer - The electron transport layer consists of a material that has the function of transporting electrons, and the electron transport layer can be a single layer or multiple layers.

[0082] The electron transport material (which may also serve as a hole-blocking material) only needs to have the function of transferring electrons injected from the cathode to the light-emitting layer. Any compound from conventionally known compounds can be selected and used for the electron transport layer. Examples include polycyclic aromatic derivatives such as naphthalene, anthracene, and phenanthroline; tris(8-quinolinolate)aluminum(III) derivatives; phosphine oxide derivatives; nitro-substituted fluorene derivatives; diphenylquinone derivatives; thiopyrandioxide derivatives; carbodiimide derivatives; phreolenylidenemethane derivatives; anthraquinodimethane and anthrone derivatives; bipyridine derivatives; quinoline derivatives; oxadiazole derivatives; benzimidazole derivatives; benzothiazole derivatives; and indolocarbazole derivatives. Furthermore, polymer materials can be used in which these materials are incorporated into polymer chains, or in which these materials are used as the main chain of the polymer.

[0083] The method for fabricating each layer of the organic EL element of the present invention is not particularly limited, and may be fabricated using either a dry process or a wet process.

[0084] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0085] As representative examples, the synthesis of compounds 1-58, 1-24, and 1-51 is shown. Other compounds were synthesized using similar methods. The deuteration rate was determined by proton nuclear magnetic resonance spectroscopy. In the formulas, Dn independently indicates that some or all of the hydrogen atoms in each compound are deuterated.

[0086] Synthesis Example 1 To 15.0 g of compound (a), 18.6 g of compound (b), 19.3 g of potassium carbonate, 4.4 g of copper iodide, 1.2 g of 18-crown-6, and 230 mL of 1,3-dimethyl-2-imidazolidinone were added, and the mixture was stirred at 180°C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 500 ml of water was added to precipitate the solid, and the solid was filtered off. Purification by silica gel column chromatography yielded 18.7 g of compound (c) as a white solid (yield 70%).

[0087] Synthesis Example 2 To 15.0 g of compound (c), 150 ml of deuterated benzene (C6D6) and 7.9 g of deuterated trifluoromethanesulfonic acid (TfOD) 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 32 ml of a heavy aqueous solution of potassium carbonate (8.0 g), rapidly cooled, separated, and purified to obtain 13.2 g of compound (1-58), which is a deuterated compound.

[0088] Synthesis Example 3 To 15.0 g of compound (d), 23.8 g of compound (e), 58.4 g of cesium carbonate, and 150 mL of N,N-dimethylacetamide were added, and the mixture was stirred at 180°C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 500 mL of water was added to precipitate the solid, and the solid was filtered off. Purification by silica gel column chromatography yielded 27.3 g of compound (f) as a white solid (yield 81%).

[0089] Synthesis Example 4 To 15.0 g of compound (f), 5.3 g of compound (g), 11.0 g of potassium carbonate, 2.5 g of copper iodide, 0.7 g of 18-crown-6, and 100 mL of 1,3-dimethyl-2-imidazolidinone were added, and the mixture was stirred at 180°C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 500 ml of water was added to precipitate the solid, and the solid was filtered off. Purification by silica gel column chromatography yielded 11.7 g of compound (h) as a white solid (yield 68%).

[0090] Synthesis Example 5 10.0 g of compound (h) was mixed with 120 ml of deuterated benzene (C6D6) and 5.2 g of deuterated trifluoromethanesulfonic acid (TfOD), and the mixture was heated and stirred at 50°C for 3 hours under a nitrogen atmosphere. The reaction mixture was added to 24 ml of a heavy aqueous solution of potassium carbonate (5.3 g), rapidly cooled, separated, and purified to obtain 7.8 g of compound (1-24), which is a deuterated compound.

[0091] Synthesis Example 6 To 15.0 g of compound (i), 18.6 g of compound (j), 19.3 g of potassium carbonate, 4.4 g of copper iodide, 1.2 g of 18-crown-6, and 230 mL of 1,3-dimethyl-2-imidazolidinone were added, and the mixture was stirred at 180°C for 24 hours under a nitrogen atmosphere. After cooling to room temperature, 500 ml of water was added to precipitate the solid, and the solid was filtered off. Purification by silica gel column chromatography yielded 17.4 g of compound (k) as a white solid (yield 65%).

[0092] Synthesis Example 7 15.0 g of compound (k) was mixed with 150 ml of deuterated benzene (C6D6) and 7.9 g of deuterated trifluoromethanesulfonic acid (TfOD), and the mixture was heated and stirred at 50°C for 3 hours under a nitrogen atmosphere. The reaction mixture was added to 32 ml of a heavy aqueous solution of potassium carbonate (8.0 g), rapidly cooled, separated, and purified to obtain 11.6 g of compound (1-51), which is a deuterated compound.

[0093] Table 1 below shows the average deuterated rates of the compounds used in the examples and comparative examples. The average deuterated rate indicates the proportion of hydrogen contained in the compound that has been deuterated, and was determined by mass spectrometry or proton nuclear magnetic resonance spectroscopy. As a representative example, the method for determining the average deuterated rate of compound (1-58) by proton nuclear magnetic resonance spectroscopy is shown below. First, a sample was prepared by dissolving compound (1-58) (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 (1-58) contained in the sample was calculated from the integrated intensity ratio derived from the internal standard and compound (1-58). Similarly, the average proton concentration [mol / g] of the non-deuterated compound (c) of compound (1-58) was also calculated. Next, the ratio of the proton concentration of compound (1-58) to the proton concentration of the non-deuterated compound (c) of compound (1-58) was calculated and subtracted from 1 to determine the average deuteration rate of compound (1-58). The average deuteration rates of the other compounds used in the examples and comparative examples were determined in the same manner. The results are shown in Table 1.

[0094]

[0095] The compounds used in the examples and comparative examples are shown below.

[0096] Example 1 A glass substrate on which an anode made of ITO with a thickness of 70 nm was formed was deposited with the following thin films by vacuum deposition at a vacuum of 4.0 × 10⁻⁶ －５ The layers were laminated with Pa. First, the previously shown HAT-CN was formed on ITO to a thickness of 10 nm as a hole injection layer, and then HT-1 was formed to a thickness of 50 nm as a hole transport layer. Next, HT-2 was formed to a thickness of 5 nm as an electron blocking layer. Then, compound 1-58 was co-deposited as a host, BD-2 as a phosphorescent dopant, and BD-1 as a thermally activated delayed fluorescence dopant from different deposition sources to form an emissive layer with a thickness of 40 nm. At this time, the co-deposit conditions were such that the concentration of BD-2 was 13 mass%, the concentration of BD-1 was 0.4 mass%, and the concentration of compound 1-58 was 86.6 mass%. Next, ET-2 was formed to a thickness of 5 nm as a hole blocking layer. Next, ET-2 was formed to a thickness of 31 nm as an electron transport layer. Furthermore, lithium fluoride (LiF) was formed to a thickness of 1 nm as an electron injection layer on the electron transport layer. Finally, an aluminum (Al) cathode was formed on the electron injection layer to a thickness of 70 nm to create the organic electroluminescent device according to Example 1.

[0097] Examples 2-3 and Comparative Example 1: Organic electroluminescent devices were fabricated in the same manner as in Example 1, except that the electron blocking layer material and the first host were compounds shown in Table 2.

[0098] Example 4 A glass substrate on which an anode made of ITO with a thickness of 70 nm was formed was deposited with the following thin films by vacuum deposition at a vacuum of 4.0 × 10⁻⁶ －５The layers were laminated with Pa. First, the previously shown HAT-CN was formed on ITO to a thickness of 10 nm as a hole injection layer, and then HT-1 was formed to a thickness of 50 nm as a hole transport layer. Next, HT-2 was formed to a thickness of 5 nm as an electron blocking layer. Next, compound (1-58) was co-deposited as the first host, compound (2-49) as the second host, BD-2 as the phosphorescent dopant, and BD-1 as the thermally activated delayed fluorescence dopant, from different deposition sources to form an emissive layer with a thickness of 40 nm. At this time, the co-deposit conditions were such that the concentration of BD-2 was 13 mass%, the concentration of BD-1 was 0.4 mass%, and the mass ratio of the first host to the second host was 50:50. Next, ET-2 was formed to a thickness of 5 nm as a hole blocking layer. Next, ET-2 was formed to a thickness of 31 nm as an electron transport layer. Furthermore, lithium fluoride (LiF) was formed on the electron transport layer to a thickness of 1 nm as an electron injection layer. Finally, aluminum (Al) was formed on the electron injection layer to a thickness of 70 nm as a cathode, and the organic electroluminescent device according to Example 4 was fabricated.

[0099] Examples 5-28 and Comparative Examples 2-7: Organic electroluminescent devices were fabricated in the same manner as in Example 4, except that the electron blocking layer material, the first host, and the second host were the compounds shown in Table 2, and the mixing ratio of the first host and the second host was the mixing ratio shown in Table 2.

[0100]

[0101] Table 3 shows the evaluation results of the fabricated organic electroluminescent devices. When an external power supply was connected to the organic electroluminescent devices 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 electroluminescent devices, indicating that emission was obtained from BD-1. The voltage and power efficiency in the table are values ​​at a drive current of 2.5 mA / cm² and represent the initial characteristics. The lifetime is the time it takes for the brightness to decay to 97% when the initial brightness at a drive current of 4.0 mA / cm² is set to 100%, and represents the device lifetime characteristics. The emission color was confirmed by the emission spectrum of the organic electroluminescent device. From the results of the examples and comparative examples shown in Table 3, it can be seen that the organic electroluminescent device using the mixed material for organic electroluminescent devices of the present invention as a host in the light-emitting layer emits blue light and has high efficiency and long lifetime characteristics.

[0102]

[0103] Example 29 A glass substrate on which an anode made of ITO with a thickness of 70 nm was formed was deposited with the following thin films by vacuum deposition at a vacuum of 4.0 × 10⁻⁶ －５ The layers were stacked using Pa. First, the previously shown HAT-CN was formed on ITO to a thickness of 10 nm as a hole injection layer, and then HT-1 was formed to a thickness of 50 nm as a hole transport layer. Next, HT-2 was formed to a thickness of 5 nm as an electron blocking layer. Then, compound (1-58) was co-deposited as the first host and BD-2 as a phosphorescent dopant from different deposition sources to form an emissive layer with a thickness of 40 nm. At this time, co-depositing was performed under deposition conditions that resulted in a BD-2 concentration of 13 mass%. Next, ET-2 was formed to a thickness of 5 nm as a hole blocking layer. Next, ET-2 was formed to a thickness of 31 nm as an electron transport layer. Furthermore, lithium fluoride (LiF) was formed to a thickness of 1 nm as an electron injection layer on the electron transport layer. Finally, aluminum (Al) was formed to a thickness of 70 nm as a cathode on the electron injection layer to fabricate the organic EL device according to Example 29.

[0104] Examples 30-31 and Comparative Example 8: Organic EL elements were fabricated in the same manner as in Example 29, except that the first host was one of the compounds shown in Table 4.

[0105] Example 32 A glass substrate on which an anode made of ITO with a thickness of 70 nm was formed was deposited with the following thin films by vacuum deposition at a vacuum of 4.0 × 10⁻⁶ －５ The layers were stacked using Pa. First, the previously shown HAT-CN was formed on ITO to a thickness of 10 nm as a hole injection layer, and then HT-1 was formed to a thickness of 50 nm as a hole transport layer. Next, HT-2 was formed to a thickness of 5 nm as an electron blocking layer. Then, compound (1-58) was co-deposited as the first host, compound (2-49) as the second host, and BD-2 as a phosphorescent dopant from different deposition sources to form an emissive layer with a thickness of 40 nm. At this time, co-depositing was performed under deposition conditions that resulted in a BD-2 concentration of 13 mass%. Next, ET-2 was formed to a thickness of 5 nm as a hole blocking layer. Next, ET-2 was formed to a thickness of 31 nm as an electron transport layer. Furthermore, lithium fluoride (LiF) was formed to a thickness of 1 nm as an electron injection layer on the electron transport layer. Finally, an aluminum (Al) cathode was formed on the electron injection layer to a thickness of 70 nm to create the organic EL element according to Example 32.

[0106] Examples 33-56 and Comparative Examples 9-14: Organic EL elements were fabricated in the same manner as in Example 32, except that the electron blocking layer material, the first host, and the second host were the compounds shown in Table 4, and the mixing ratio of the first host and the second host was the mixing ratio shown in Table 4.

[0107]

[0108] Table 5 shows the evaluation results of the fabricated organic EL elements. The voltage and power efficiency values ​​in the table are for a drive current of 2.5 mA / cm² and represent the initial characteristics. The lifetime is the time it takes for the brightness to decay to 97% when the initial brightness at a drive current of 4.0 mA / cm² is set to 100%, and represents the element's lifetime characteristics. The emitted color was confirmed by the emission spectrum of the organic EL element.

[0109]

[0110] 1: Substrate, 2: Anode, 3: Hole injection layer, 4: Hole transport layer, 5: Light-emitting layer, 6: Electron transport layer, 7: Cathode.

Claims

1. An organic electroluminescent material comprising any compound represented by the following general formulas (1a) to (1d), characterized in that the average deuteration rate of hydrogen in the compound is 10% or more. Ar １ Each of these can be independently represented by the following general formulas (2a) to (2o). * indicates the bonding position with the general formulas (1a) to (1d) above. R ２ ~R ９ Each of these independently represents hydrogen, deuterium, and an aliphatic hydrocarbon group having 1 to 10 carbon atoms.

2. The material for an organic electroluminescent element according to claim 1, characterized in that the average deuterated rate of the compound represented by the general formulas (1a) to (1d) is 50% or more.

3. The organic electroluminescent material according to claim 1, characterized in that the organic electroluminescent material comprises any compound represented by the general formula (1a), (1c), or (1d).

4. Ar of the general formulas (1a) to (1d) １ The material for an organic electroluminescent element according to claim 1, characterized in that (2b), (2c), (2e), (2f), (2g), (2i), (2j), (2k), (2l), or (2n).

5. Ar of the general formula (1c) １ The organic electroluminescent material according to claim 1, characterized in that (2n) or (2o) is the above.

6. Ar of the general formula (1b) １ The material for an organic electroluminescent element according to claim 1, characterized in that (2n).

7. The compound represented by the general formulas (1a) to (1d) described in claim 1 is characterized in that it is any of the following formulas (1-1), (1-3), (1-9), (1-12), (1-14), (1-17), (1-20), (1-24), (1-25), (1-38), (1-42), (1-49), (1-50), (1-51), (1-52), (1-53), (1-57), (1-58), and (1-73) for an organic electroluminescent element material. Note that D represents deuterium, and n represents the average number of substitutions by deuterium in each of the above compounds, and changes according to the average deuteration rate.

8. An organic electroluminescent device material comprising any one of the compounds represented by the general formulas (1a) to (1d) according to claim 1, and a cyclic azine compound represented by the following general formula (10): An organic electroluminescent device hybrid material characterized by including. (Here, Ar ２ and Ar ３ each independently represents hydrogen, 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 5 aromatic groups selected from the aromatic hydrocarbon group and the aromatic heterocyclic group. L １ represents a single bond or a substituted or unsubstituted phenyl group. Part or all of the hydrogen in the compound represented by the general formula (10) may be substituted with deuterium.) 9. Ar of the general formula (10) ２ and Ar ３ The mixed material for an organic electroluminescent element according to claim 8, characterized in that each of these is independently a hydrogen atom, a C1-C10 aliphatic hydrocarbon group substituted or unsubstituted C6-C20 aromatic hydrocarbon group, a C2-C17 substituted or unsubstituted aromatic heterocyclic group, or a substituted or unsubstituted linked aromatic group composed of 2 to 5 aromatic groups selected from the aromatic hydrocarbon group and the aromatic heterocyclic group linked together.

10. An organic electroluminescent element comprising one or more organic layers between opposing anodes and cathodes, characterized in that at least one organic layer contains an organic electroluminescent element material comprising any compound represented by one of the general formulas (1a) to (1d) described in claim 1.

11. An organic electroluminescent element comprising one or more organic layers between opposing anodes and cathodes, characterized in that at least one organic layer contains the mixed material for organic electroluminescent elements described in claim 8.

12. The organic electroluminescent element according to claim 11, characterized in that the organic layer containing the mixed material for the organic electroluminescent element is an emissive layer, and the emissive layer further contains a thermally activated delayed fluorescence emissive material.

13. The organic electroluminescent element according to claim 12, characterized in that the thermally activated delayed fluorescence material is a thermally activated delayed fluorescence material containing boron atoms.

14. The organic electroluminescent element according to claim 11, characterized in that the organic layer containing the mixed material for the organic electroluminescent element is an emissive layer, and the emissive layer further contains a phosphorescent material.

15. The organic electroluminescent device according to claim 14, characterized in that the phosphorescent material is a phosphorescent material containing platinum atoms or iridium atoms.

16. An organic electroluminescent element comprising one or more organic layers between opposing anodes and cathodes, wherein at least one organic layer is a light-emitting layer, and the light-emitting layer contains the mixed material for organic electroluminescent elements described in claim 8 as a mixed host material, and further contains a thermally activated delayed fluorescence light-emitting material containing boron atoms and a phosphorescent light-emitting material containing platinum atoms or iridium atoms.

17. A pre-mixed material for an organic electroluminescent element, obtained by pre-mixing an organic electroluminescent element material consisting of any compound represented by one of the general formulas (1a) to (1d) described in claim 1 with a cyclic azine compound represented by the following general formula (10). (Here, Ar ２ and Ar ３ Each of these independently represents hydrogen, 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 composed of 2 to 5 aromatic groups selected from the aromatic hydrocarbon group and the aromatic heterocyclic group. １ represents a single bond, substituted, or unsubstituted phenyl group. Some or all of the hydrogen atoms in the compound represented by the general formula (10) may be substituted with deuterium.

18. A method for manufacturing an organic electroluminescent element having one or more organic layers between opposing anodes and cathodes, wherein at least one organic layer is a light-emitting layer, and the light-emitting layer is manufactured by depositing it from a single deposition source using the premixed material for organic electroluminescent elements described in claim 17.

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