Organic electroluminescent element

Abstract

Provided is a blue light-emitting organic EL element having high luminous efficiency and long life. An organic electroluminescent element, which is an organic electroluminescent element including one or more light-emitting layers between a pair of electrodes, at least one of the light-emitting layers containing an organic light-emitting material having a difference (ΔEST) between an excited singlet state energy (S1) and an excited triplet state energy (T1) of 0.20 eV or less as a light-emitting dopant, and containing a first host selected from a compound represented by the following general formula (1) and a second host selected from a compound represented by the following general formula (2).

Description

Technical Field

[0001] This invention relates to an organic electric field light-emitting element (referred to as an organic EL element). Background Technology

[0002] By applying a voltage to an organic EL (electroluminescence) device, holes are injected into the emissive layer from the anode, and electrons are injected into the emissive layer from the cathode. Furthermore, in the emissive layer, the injected holes and electrons recombine to generate excitons. At this point, according to the statistical law of electron spin, singlet and triplet excitons are generated in a 1:3 ratio. Regarding fluorescent organic EL devices using light emission generated by singlet excitons, the internal quantum efficiency is considered to be limited to 25%. On the other hand, it is known that phosphorescent organic EL devices using light emission generated by triplet excitons achieve an internal quantum efficiency of 100% when intersystem crossings are efficiently performed from singlet excitons.

[0003] However, extending the lifetime of blue phosphorescent organic EL devices has become a technical challenge.

[0004] Furthermore, high-efficiency organic EL devices utilizing delayed fluorescence are currently being developed. For example, Patent Document 1 discloses an organic EL device that utilizes the triplet-triplet fusion (TTF) mechanism, one of the mechanisms of delayed fluorescence. The TTF mechanism utilizes the phenomenon of generating singlet excitons through the collision of two triplet excitons, theoretically increasing the internal quantum efficiency to 40%. However, compared to phosphorescent organic EL devices, its efficiency is low, thus requiring further improvements in efficiency.

[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 that, in materials with a small energy difference between singlet and triplet levels, an inverse intersystem crossing from a triplet exciton to a singlet exciton occurs; theoretically, this can increase the internal quantum efficiency to 100%. However, similar to phosphorescent luminescent devices, further improvements in lifetime characteristics are required.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: WO2010 / 134350

[0009] Patent Document 2: WO2011 / 070963

[0010] Patent Document 3: WO2015 / 102118

[0011] Patent Document 4: WO2018 / 212169

[0012] Patent Documents 3 and 4 disclose an organic EL element that uses a TADF material containing a polycyclic aromatic compound represented by the following compounds as a luminescent dopant.

[0013] [Chemistry 1]

[0014] Summary of the Invention

[0015] To apply organic EL elements to display elements or light sources such as flat panel displays, it is necessary to ensure sufficient stability during driving while improving the luminous efficiency of the element. The object of this invention is to provide a practically useful organic EL element with low driving voltage, high efficiency, and high driving stability.

[0016] The present invention is an organic EL element, which is an organic electric field light-emitting element comprising one or more light-emitting layers between opposing anodes and cathodes. At least one light-emitting layer comprises an organic light-emitting material as a light-emitting dopant whose difference (ΔEST) between the excitation singlet energy (S1) and the excitation triplet energy (T1) is less than 0.20 eV, and contains a first host selected from compounds represented by the following general formula (1) and a second host selected from compounds represented by the following general formula (2).

[0017] [Chemistry 2]

[0018]

[0019] Here, X 1 Indicates O, S or N-Ar 1 Ar 1 Independently refers to an aromatic hydrocarbon group having 6 to 18 carbon atoms, substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group consisting of 2 to 8 of these aromatic rings. R 1 Independently representing deuterium, aliphatic hydrocarbon group with 1 to 10 carbon atoms, aromatic hydrocarbon group with 6 to 18 carbon atoms (substituted or unsubstituted), or aromatic heterocyclic group with 3 to 17 carbon atoms (substituted or unsubstituted). a and d represent integers from 0 to 4, and b and c represent integers from 0 to 3.

[0020] [Chemistry 3]

[0021]

[0022] Here, X 2 Independently represent N or CH, with at least two X's. 2 Represents N. Ar 2 R represents an aromatic hydrocarbon group having 6 to 18 carbon atoms, substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group consisting of 2 to 8 of these aromatic rings. 2 Independently representing deuterium, aliphatic hydrocarbon group with 1 to 10 carbon atoms, substituted or unsubstituted aromatic hydrocarbon group with 6 to 18 carbon atoms, or substituted or unsubstituted aromatic heterocyclic group with 3 to 17 carbon atoms. e, f, g, h represent integers from 0 to 4.

[0023] As a preferred form of organic light-emitting material, there are boron-containing polycyclic aromatic compounds represented by the following general formula (3) or general formula (4), and more preferably the following general formula (4).

[0024] [Chemistry 4]

[0025]

[0026] Here, X 3 Indicates N-Ar 3 O, or S, at least one X 3 Indicates N-Ar 3 Ar 3 Independently refers to an aromatic hydrocarbon group having 6 to 18 carbon atoms, substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group consisting of 2 to 8 of these aromatic rings. R 3 Independently representing cyano, deuterium, diarylamino with 12 to 44 carbons, aliphatic hydrocarbon group with 1 to 10 carbons, substituted or unsubstituted aromatic hydrocarbon group with 6 to 18 carbons, or substituted or unsubstituted aromatic heterocyclic group with 3 to 17 carbons. i and j represent integers from 0 to 4, and k represents integers from 0 to 3.

[0027] [Chemistry 5]

[0028]

[0029] Here, X 4 Indicates N-Ar 4 O, or S, at least one X 4 Indicates N-Ar 4 Ar 4Independently refers to an aromatic hydrocarbon group having 6 to 18 carbon atoms, substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group consisting of 2 to 8 of these aromatic rings. R 4 Independently representing cyano, deuterium, diarylamino with 12–44 carbons, aliphatic hydrocarbon group with 1–10 carbons, substituted or unsubstituted aromatic hydrocarbon group with 6–18 carbons, or substituted or unsubstituted aromatic heterocyclic group with 3–17 carbons. m and n represent integers from 0 to 4, o and p represent integers from 0 to 3, and q represents integers from 0 to 2.

[0030] Preferably, X is in general formula (4) 4 For N-Ar 4 .

[0031] Preferably, X is in general formula (1) 1 For N-Ar 1 .

[0032] As a preferred form of the compound represented by general formula (1), there is the compound represented by general formula (5).

[0033] [Chemistry 6]

[0034]

[0035] Here, Ar 1 Ar in general formula (1) 1 They have the same meaning.

[0036] More preferably, the ΔEST of the organic light-emitting material is below 0.10 eV.

[0037] Preferably, the substrate contains 99.1 wt% to 90 wt% of the luminescent dopant at a concentration of 0.1 wt% to 10 wt%, and the substrate contains 10 wt% to 90 wt% of a first substrate and 90 wt% to 10 wt% of a second substrate.

[0038] The organic EL element of the present invention contains specific luminescent dopants and various specific host materials in the luminescent layer, which can become an organic EL element with low driving voltage, high luminous efficiency and long lifetime. Attached Figure Description

[0039] Figure 1 This is a schematic cross-sectional view showing an example of an organic EL element.

[0040] [Explanation of Symbols]

[0041] 1: Substrate

[0042] 2: Anode

[0043] 3: Hole injection layer

[0044] 4: Hole transport layer

[0045] 5: Emissive layer

[0046] 6: Electron transport layer

[0047] 7: Cathode Detailed Implementation

[0048] The organic EL element of the present invention has one or more light-emitting layers between opposing anodes and cathodes, and at least one light-emitting layer contains an organic light-emitting material as a light-emitting dopant whose difference (ΔEST) between the excitation singlet energy (S1) and the excitation triplet energy (T1) is less than 0.20 eV, and contains a first host selected from compounds represented by the following general formula (1) and a second host selected from compounds represented by the following general formula (2).

[0049] In the organic EL element of the present invention, the ΔEST of the organic light-emitting material used as a light-emitting dopant is 0.20 eV or less. Preferably, it is 0.15 eV or less, and more preferably 0.10 eV or less.

[0050] ΔEST represents the difference between the excited singlet energy (S1) and the excited triplet energy (T1). Here, S1 and T1 are measured as follows.

[0051] On a quartz substrate, vacuum evaporation is used at a vacuum degree of 10. -4 The sample compound was vapor-deposited under conditions below Pa to form a vapor-deposited film with a thickness of 100 nm. Regarding S1, the emission spectrum of the vapor-deposited film was measured, and a tangent was drawn from the starting point of the short wavelength side of the emission spectrum. The wavelength value λedge [nm] of the intersection of the tangent and the horizontal axis was substituted into the following equation (i) to calculate S1.

[0052] S1[eV]=1239.85 / λedge (i)

[0053] Regarding T1, the phosphorescence spectrum of the vapor-deposited film is measured, and a tangent is drawn from the starting point of the short wavelength side of the phosphorescence spectrum. The wavelength value λedge[nm] at the intersection of the tangent and the horizontal axis is substituted into equation (ii) to calculate T1.

[0054] T1[eV]=1239.85 / λedge (ii)

[0055] The compound represented by the general formula (1) used as the first subject in this invention will be described.

[0056] X 1 Indicates O, S or N-Ar1 Preferably, it represents O or N-Ar. 1 More preferably, it represents N-Ar 1 .

[0057] As a more preferred form of general formula (1), general formula (5) can be listed. In general formula (1) and formula (5), the common symbols have the same meaning.

[0058] Ar 1 Independently refers to an aromatic hydrocarbon group having 6 to 18 carbon atoms, either substituted or unsubstituted, an aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group consisting of 2 to 8 of these aromatic rings. Preferably, it refers to an aromatic hydrocarbon group having 6 to 12 carbon atoms, either substituted or unsubstituted, or a substituted or unsubstituted linked aromatic group consisting of 2 to 4 of these linked. More preferably, it is phenyl, biphenyl, or terphenyl.

[0059] As an irreplaceable Ar 1 Specific examples include: benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline The group is formed by removing one hydrogen atom from compounds consisting of quinoxaline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, or compounds formed by linking 2 to 8 of these. Preferably, the group is formed by removing one hydrogen atom from compounds consisting of benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, or compounds formed by linking 2 to 4 of these. More preferably, the group is formed by removing one hydrogen atom from compounds consisting of benzene, or compounds formed by linking 2 to 3 of these.

[0060] These aromatic hydrocarbon groups, aromatic heterocyclic groups, or linked aromatic groups may each have substituents. When substituents are present, the substituents are cyano, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, or diarylamino groups with 12 to 44 carbon atoms. Furthermore, the number of substituents may be 0 to 5, preferably 0 to 2. The number of carbon atoms in aromatic hydrocarbon groups and aromatic heterocyclic groups when substituents are present does not include the number of carbon atoms in the substituents. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituents, satisfies the aforementioned range.

[0061] Specific examples of the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, etc. Preferably, the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, diphenylamino, naphthylphenylamino, or dinaphthylamino.

[0062] R 1 Independently represented are deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms (substituted or unsubstituted), or an aromatic heterocyclic group having 3 to 17 carbon atoms (substituted or unsubstituted). Preferably, it is an aliphatic hydrocarbon group having 1 to 8 carbon atoms, an aromatic hydrocarbon group having 6 to 12 carbon atoms (substituted or unsubstituted), or an aromatic heterocyclic group having 3 to 15 carbon atoms (substituted or unsubstituted). More preferably, it is an aromatic hydrocarbon group having 6 to 10 carbon atoms (substituted or unsubstituted), or an aromatic heterocyclic group having 3 to 12 carbon atoms (substituted or unsubstituted).

[0063] a and d represent integers from 0 to 4, and b and c represent integers from 0 to 3.

[0064] As R 1 Specific examples of aliphatic hydrocarbon groups having 1 to 10 carbon atoms include: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, and nonyl. Preferably, the following groups are also included: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, and octyl.

[0065] As R 1 Specific examples of unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, or unsubstituted aromatic heterocyclic groups having 3 to 17 carbon atoms, include: benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyridine ... A radical formed by removing a hydrogen atom from azines, furans, isoxazoles, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiphene, dibenzoselenophene, and carbazole.

[0066] Preferred examples include: radicals formed by removing one hydrogen atom from benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, pyridine, pyrimidine, triazine, thiophene, isothiazol, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, and carbazole.

[0067] More preferably, the following groups are listed: radicals formed by removing one hydrogen atom from benzene, naphthalene, azurite, pyridine, pyrimidine, triazine, thiophene, isothiazol, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenene, and carbazole.

[0068] These aromatic hydrocarbon groups or aromatic heterocyclic groups may each have substituents. When substituents are present, the substituents are cyano, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, or diarylamino groups with 12 to 44 carbon atoms. Furthermore, the number of substituents may be 0 to 5, preferably 0 to 2. The number of carbon atoms in aromatic hydrocarbon groups and aromatic heterocyclic groups when substituents are present does not include the number of carbon atoms in the substituents. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituents, satisfies the aforementioned range.

[0069] Specific examples of the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, etc.

[0070] Preferred compounds include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, diphenylamino, naphthylphenylamino, or dinaphthylamino.

[0071] The following are specific examples of compounds represented by general formula (1), but are not limited to these exemplified compounds.

[0072] [Chemistry 7]

[0073]

[0074] [Chemistry 8]

[0075]

[0076] [Chemistry 9]

[0077]

[0078] [Chemistry 10]

[0079]

[0080] [Chemistry 11]

[0081]

[0082] [Chemistry 12]

[0083]

[0084] [Chemistry 13]

[0085]

[0086] [Chemistry 14]

[0087]

[0088] [Chemistry 15]

[0089]

[0090] [Chemistry 16]

[0091]

[0092] [Chemistry 17]

[0093]

[0094] [Chemistry 18]

[0095]

[0096] [Chemistry 19]

[0097]

[0098] [Chemistry 20]

[0099]

[0100] [Chemistry 21]

[0101]

[0102] [Chemistry 22]

[0103]

[0104] [Chemistry 23]

[0105]

[0106] [Chemistry 24]

[0107]

[0108] [Chemistry 25]

[0109]

[0110] The compound represented by the general formula (2) used as the second body in this invention will be described.

[0111] X 2 Independently represent N or CH, with at least two X's. 2 N represents the number of X's. Preferably, there are three X's. 2 N represents N.

[0112] Ar 2 It refers to an aromatic hydrocarbon group with 6 to 18 carbon atoms that is substituted or unsubstituted, an aromatic heterocyclic group with 3 to 17 carbon atoms that is substituted or unsubstituted, or a linked aromatic group consisting of 2 to 8 of these aromatic rings.

[0113] Preferably, it represents an aromatic hydrocarbon group having 6 to 12 carbon atoms that has been substituted or unsubstituted, an aromatic heterocyclic group having 3 to 12 carbon atoms that has been substituted or unsubstituted, or a linked aromatic group consisting of 2 to 6 of these aromatic rings.

[0114] More preferably, it refers to an aromatic hydrocarbon group having 6 to 10 carbon atoms that has been substituted or unsubstituted, an aromatic heterocyclic group having 3 to 10 carbon atoms that has been substituted or unsubstituted, or a substituted or unsubstituted linked aromatic group consisting of 2 to 4 of these aromatic rings linked together.

[0115] As an irreplaceable Ar 2 Specific examples can be listed as follows: radicals formed by removing a hydrogen atom from compounds composed of benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenene, carbazole, or 2 to 8 of these linked together.

[0116] Preferred examples include: radicals formed by removing a hydrogen atom from compounds composed of benzene, naphthalene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, crromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, or 2 to 6 of these linked together.

[0117] More preferably, a group is formed by removing a hydrogen atom from a compound consisting of benzene, naphthalene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, or two to four of these linked together.

[0118] These aromatic hydrocarbon groups, aromatic heterocyclic groups, or linked aromatic groups may each have substituents. When substituents are present, the substituents are cyano, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, diarylamino groups with 12 to 44 carbon atoms, or triphenylsilyl groups. Furthermore, the number of substituents may be 0 to 5, preferably 0 to 2. The number of carbon atoms in aromatic hydrocarbon groups and aromatic heterocyclic groups when substituents are present does not include the number of carbon atoms in the substituents. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituents, satisfies the aforementioned range.

[0119] Specific examples of the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, etc. Preferably, the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, diphenylamino, naphthylphenylamino, or dinaphthylamino.

[0120] R 2 Independently, it represents deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms (substituted or unsubstituted), an aromatic heterocyclic group having 3 to 17 carbon atoms (substituted or unsubstituted), or a triphenylsilyl group. Preferably, it is an aromatic hydrocarbon group having 6 to 12 carbon atoms (substituted or unsubstituted), or an aromatic heterocyclic group having 3 to 15 carbon atoms (substituted or unsubstituted). More preferably, it is an aromatic hydrocarbon group having 6 to 10 carbon atoms. e, f, g, h represent integers from 0 to 4.

[0121] As R 2Specific examples of aliphatic hydrocarbon groups with 1 to 10 carbon atoms include: methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, and nonyl.

[0122] As R 2 Specific examples of unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, or unsubstituted aromatic heterocyclic groups having 3 to 17 carbon atoms, include: benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine. Furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, crromone, dibenzofuran, dibenzothiphene, dibenzoselenophene, or carbazole by removing a hydrogen atom to form a group.

[0123] Preferred examples include: radicals formed by removing one hydrogen atom from benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, pyridine, pyrimidine, triazine, thiophene, isothiazol, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, and carbazole.

[0124] More preferably, it is a group formed by removing a hydrogen atom from benzene or naphthalene.

[0125] These aromatic hydrocarbon groups or aromatic heterocyclic groups may each have substituents. When substituents are present, the substituents are cyano, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, or diarylamino groups with 12 to 44 carbon atoms. Furthermore, the number of substituents may be 0 to 5, preferably 0 to 2. The number of carbon atoms in aromatic hydrocarbon groups and aromatic heterocyclic groups when substituents are present does not include the number of carbon atoms in the substituents. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituents, satisfies the aforementioned range.

[0126] Specific examples of the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, etc. Preferably, the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, diphenylamino, naphthylphenylamino, or dinaphthylamino.

[0127] The following are specific examples of compounds represented by general formula (2), but are not limited to these exemplified compounds.

[0128] [Chemistry 26]

[0129]

[0130] [Chemistry 27]

[0131]

[0132] [Chemistry 28]

[0133]

[0134] [Chemistry 29]

[0135]

[0136] [Chemistry 30]

[0137]

[0138] [Chemistry 31]

[0139]

[0140] [Chemistry 32]

[0141]

[0142] [Chemistry 33]

[0143]

[0144] [Chemistry 34]

[0145]

[0146] As a preferred form of organic light-emitting material used in the organic EL element of the present invention, there are boron-containing polycyclic aromatic compounds represented by the following general formula (3) or general formula (4), and more preferably boron-containing polycyclic aromatic compounds represented by general formula (4).

[0147] The boron-containing polycyclic aromatic compounds represented by general formula (3) will be described.

[0148] X 3 Indicates O, S, or N-Ar 3 At least one X 3 Indicates N-Ar 3 Preferably, it represents O or N-Ar. 3 More preferably, it represents N-Ar 3 .

[0149] Ar 3 It refers to an aromatic hydrocarbon group with 6 to 18 carbon atoms that is substituted or unsubstituted, an aromatic heterocyclic group with 3 to 17 carbon atoms that is substituted or unsubstituted, or a linked aromatic group consisting of 2 to 8 of these aromatic rings.

[0150] Preferably, it represents an aromatic hydrocarbon group having 6 to 12 carbon atoms that has been substituted or unsubstituted, an aromatic heterocyclic group having 3 to 12 carbon atoms that has been substituted or unsubstituted, or a linked aromatic group consisting of 2 to 6 of these aromatic rings.

[0151] More preferably, it refers to an aromatic hydrocarbon group having 6 to 10 carbon atoms that has been substituted or unsubstituted, an aromatic heterocyclic group having 3 to 10 carbon atoms that has been substituted or unsubstituted, or a substituted or unsubstituted linked aromatic group consisting of 2 to 4 of these aromatic rings linked together.

[0152] As an irreplaceable Ar 3 Specific examples can be listed as follows: radicals formed by removing a hydrogen atom from compounds composed of benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenene, carbazole, or 2 to 8 of these linked together.

[0153] Preferred examples include: radicals formed by removing a hydrogen atom from compounds composed of benzene, naphthalene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, crromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, or 2 to 6 of these linked together.

[0154] More preferably, a group is formed by removing a hydrogen atom from a compound consisting of benzene, naphthalene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, or two to four of these linked together.

[0155] These aromatic hydrocarbon groups, or aromatic heterocyclic groups, or linked aromatic groups may each have substituents. When substituents are present, the substituents are cyano, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, or diarylamino groups with 12 to 44 carbon atoms. Furthermore, the number of substituents may be 0 to 5, preferably 0 to 2. The number of carbon atoms in aromatic hydrocarbon groups and aromatic heterocyclic groups when substituents are present does not include the number of carbon atoms in the substituents. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituents, satisfies the aforementioned range.

[0156] Specific examples of the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, etc. Preferably, the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, diphenylamino, naphthylphenylamino, or dinaphthylamino.

[0157] R 3 Independently represented are cyano, deuterium, diarylamino with 12 to 44 carbons, aliphatic hydrocarbon group with 1 to 10 carbons, substituted or unsubstituted aromatic hydrocarbon group with 6 to 18 carbons, or substituted or unsubstituted aromatic heterocyclic group with 3 to 17 carbons. Preferably, it is a diarylamino with 12 to 36 carbons, an substituted or unsubstituted aromatic hydrocarbon group with 6 to 12 carbons, or a substituted or unsubstituted aromatic heterocyclic group with 3 to 15 carbons. More preferably, it is a diarylamino with 12 to 24 carbons, an substituted or unsubstituted aromatic hydrocarbon group with 6 to 10 carbons, or a substituted or unsubstituted aromatic heterocyclic group with 3 to 12 carbons. i and j represent integers from 0 to 4, and k represents an integer from 0 to 3.

[0158] As R 3Specific examples of diarylamino groups having 12 to 44 carbon atoms and aliphatic hydrocarbon groups having 1 to 10 carbon atoms include: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, (9-phenylcarbazolyl)phenylamino, dibenzofuranylphenyl, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, and nonyl. Preferably, examples include: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, and dipyreneamino. More preferably, examples include: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, and dinaphthylamino.

[0159] As R 3 Specific examples of unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, or unsubstituted aromatic heterocyclic groups having 3 to 17 carbon atoms, include: benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyridine ... A radical formed by removing a hydrogen atom from azines, furans, isoxazoles, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiphene, dibenzoselenophene, and carbazole.

[0160] Preferred examples include: radicals formed by removing one hydrogen atom from benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, pyridine, pyrimidine, triazine, thiophene, isothiazol, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, and carbazole.

[0161] More preferably, it is a group formed by removing a hydrogen atom from benzene or naphthalene.

[0162] These aromatic hydrocarbon groups or aromatic heterocyclic groups may each have substituents. When substituents are present, the substituents are cyano, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, or diarylamino groups with 12 to 44 carbon atoms. Furthermore, the number of substituents may be 0 to 5, preferably 0 to 2. The number of carbon atoms in aromatic hydrocarbon groups and aromatic heterocyclic groups when substituents are present does not include the number of carbon atoms in the substituents. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituents, satisfies the aforementioned range.

[0163] Specific examples of the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, etc. Preferably, the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, diphenylamino, naphthylphenylamino, or dinaphthylamino.

[0164] The following are specific examples of compounds represented by general formula (3), but are not limited to these exemplified compounds.

[0165] [Chemistry 35]

[0166]

[0167] [Chemistry 36]

[0168]

[0169] [Chemistry 37]

[0170]

[0171] [Chemistry 38]

[0172]

[0173] [Chemistry 39]

[0174]

[0175] [Chemistry 40]

[0176]

[0177] [Chemistry 41]

[0178]

[0179] [Chemistry 42]

[0180]

[0181] The boron-containing polycyclic aromatic compounds represented by general formula (4) will be described.

[0182] X 4 Indicates O, S, or N-Ar 4 At least one X 4 Indicates N-Ar 4 Preferably, it represents O or N-Ar. 3 More preferably, it represents N-Ar 3 .

[0183] Ar 4 It refers to an aromatic hydrocarbon group with 6 to 18 carbon atoms that is substituted or unsubstituted, an aromatic heterocyclic group with 3 to 17 carbon atoms that is substituted or unsubstituted, or a linked aromatic group consisting of 2 to 8 of these aromatic rings.

[0184] Preferably, it represents an aromatic hydrocarbon group having 6 to 12 carbon atoms that has been substituted or unsubstituted, an aromatic heterocyclic group having 3 to 12 carbon atoms that has been substituted or unsubstituted, or a linked aromatic group consisting of 2 to 6 of these aromatic rings.

[0185] More preferably, it refers to an aromatic hydrocarbon group having 6 to 10 carbon atoms that has been substituted or unsubstituted, an aromatic heterocyclic group having 3 to 10 carbon atoms that has been substituted or unsubstituted, or a substituted or unsubstituted linked aromatic group consisting of 2 to 4 of these aromatic rings linked together.

[0186] As an irreplaceable Ar 4 Specific examples can be listed as follows: radicals formed by removing a hydrogen atom from compounds composed of benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenene, carbazole, or 2 to 8 of these linked together.

[0187] Preferred examples include: radicals formed by removing a hydrogen atom from compounds composed of benzene, naphthalene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, crromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, or 2 to 6 of these linked together.

[0188] More preferably, a group is formed by removing a hydrogen atom from a compound consisting of benzene, naphthalene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, or two to four of these linked together.

[0189] These aromatic hydrocarbon groups, aromatic heterocyclic groups, or linked aromatic groups may each have substituents. When substituents are present, the substituents are cyano, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, or diarylamino groups with 12 to 44 carbon atoms. Furthermore, the number of substituents may be 0 to 5, preferably 0 to 2. The number of carbon atoms in aromatic hydrocarbon groups and aromatic heterocyclic groups when substituents are present does not include the number of carbon atoms in the substituents. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituents, satisfies the aforementioned range.

[0190] Specific examples of the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, etc.

[0191] Preferred compounds include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, diphenylamino, naphthylphenylamino, or dinaphthylamino.

[0192] R 4 Independently representing cyano, deuterium, diarylamino with 12 to 44 carbons, aliphatic hydrocarbon with 1 to 10 carbons, substituted or unsubstituted aromatic hydrocarbon with 6 to 18 carbons, or substituted or unsubstituted aromatic heterocyclic group with 3 to 17 carbons.

[0193] Preferably, it is a diarylamino group with 12 to 36 carbon atoms, an aromatic hydrocarbon group with 6 to 12 carbon atoms (substituted or unsubstituted), or an aromatic heterocyclic group with 3 to 15 carbon atoms (substituted or unsubstituted).

[0194] More preferably, it is a diarylamino group with 12 to 24 carbon atoms, an aromatic hydrocarbon group with 6 to 10 carbon atoms (substituted or unsubstituted), or an aromatic heterocyclic group with 3 to 12 carbon atoms (substituted or unsubstituted). m and n represent integers from 0 to 4, o and p represent integers from 0 to 3, and q represents integers from 0 to 2.

[0195] As R 4Specific examples of diarylamino groups with 12 to 44 carbon atoms and aliphatic hydrocarbon groups with 1 to 10 carbon atoms include: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, and nonyl.

[0196] Preferred examples include: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, and dipyreneamino.

[0197] More preferably, examples include: diphenylamino, diphenylamino, phenyldiphenylamino, naphthylphenylamino, and dinaphthylamino.

[0198] As R 4 Specific examples of unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, or unsubstituted aromatic heterocyclic groups having 3 to 17 carbon atoms, include: benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyridine ... A radical formed by removing a hydrogen atom from azines, furans, isoxazoles, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiphene, dibenzoselenophene, and carbazole.

[0199] Preferred examples include: radicals formed by removing one hydrogen atom from benzene, naphthalene, dihydroacenaphthene, acenaphthene, azulene, pyridine, pyrimidine, triazine, thiophene, isothiazol, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxoline, quinazoline, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, and carbazole.

[0200] More preferably, it is a group formed by removing a hydrogen atom from benzene or naphthalene.

[0201] These aromatic hydrocarbon groups or aromatic heterocyclic groups may each have substituents. When substituents are present, the substituents are cyano, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, or diarylamino groups with 12 to 44 carbon atoms. Furthermore, the number of substituents may be 0 to 5, preferably 0 to 2. The number of carbon atoms in aromatic hydrocarbon groups and aromatic heterocyclic groups when substituents are present does not include the number of carbon atoms in the substituents. However, it is preferable that the total number of carbon atoms, including the number of carbon atoms in the substituents, satisfies the aforementioned range.

[0202] Specific examples of the substituents include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino, etc.

[0203] Preferred compounds include: cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, diphenylamino, naphthylphenylamino, or dinaphthylamino.

[0204] The following are specific examples of compounds represented by general formula (4), but are not limited to these exemplified compounds.

[0205] [Chemistry 43]

[0206]

[0207] [Chemistry 44]

[0208]

[0209] [Chemistry 45]

[0210]

[0211] [Chemistry 46]

[0212]

[0213] [Chemistry 47]

[0214]

[0215] By using materials selected from compounds represented by general formula (3) or general formula (4) as luminescent dopants, materials selected from compounds represented by general formula (1) as first host materials, and materials selected from compounds represented by general formula (2) as second host materials, excellent organic EL devices can be provided.

[0216] Next, the structure of the organic EL element of the present invention will be described with reference to the accompanying drawings, but the structure of the organic EL element of the present invention is not limited thereto.

[0217] Figure 1 This is a cross-sectional view showing a typical organic EL element structure used in this invention. 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 this invention may have an exciton blocking layer adjacent to the light-emitting layer, and may also have an electron blocking layer between the light-emitting layer and the hole injection layer. The exciton blocking layer may be inserted to either the anode side or the cathode side of the light-emitting layer, or simultaneously to both sides. In the organic EL element of this invention, an anode, a light-emitting layer, and a cathode are required layers, but in addition to these required layers, a hole injection transport layer and an electron injection transport layer may also be included, and a hole blocking layer may be present between the light-emitting layer and the electron injection transport layer. Furthermore, a hole injection transport layer refers to either or both of the hole injection layer and the hole transport layer, and an electron injection transport layer refers to either or both of the electron injection layer and the electron transport layer.

[0218] It can also be with Figure 1 In the opposite structure, the cathode 7, electron transport layer 6, light-emitting layer 5, hole transport layer 4, and anode 2 are sequentially stacked on the substrate 1. In this case, layers may be added or omitted as needed.

[0219] -Substrate-

[0220] The organic EL element of the present invention is preferably supported on a substrate. The substrate is not particularly limited, as long as it is a substrate that has been used for organic EL elements before, such as a substrate containing glass, transparent plastic, quartz, etc.

[0221] -anode-

[0222] As the anode material in an organic electroluminescent (EL) element, materials containing metals, alloys, electrically conductive compounds, or mixtures thereof with a high work function (4 eV or higher) are preferably used. Specific examples of such electrode materials include metals such as Au; conductive transparent materials such as CuI, indium tin oxide (ITO), SnO2, and ZnO. Alternatively, amorphous materials such as IDIXO (In2O3-ZnO) that can be formed into transparent conductive films can also be used. The anode can be formed into a thin film using methods such as vapor deposition or sputtering, and a pattern of the desired shape can be formed using photolithography. Alternatively, when pattern precision is not critical (around 100 μm or higher), a pattern can be formed by separating the desired shape from the electrode material during vapor deposition or sputtering. Alternatively, when using a coatable substance such as an organic conductive compound, wet film formation methods such as printing or coating can be used. When light is emitted from the anode, it is ideal to have a transmittance greater than 10%, and the sheet resistance of the anode is preferably less than several hundred Ω / Y. The film thickness also depends on the material, and is usually selected in the range of 10 nm to 1000 nm, preferably 10 nm to 200 nm.

[0223] -cathode-

[0224] On the other hand, as cathode materials, materials containing metals (called electron-injecting metals), alloys, electrically conductive compounds, or mixtures thereof with low work functions (below 4 eV) can be used. Specific examples of such electrode materials include: sodium, sodium-potassium alloys, magnesium, lithium, magnesium / copper mixtures, magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / alumina (Al₂O₃) mixtures, indium, lithium / aluminum mixtures, rare earth metals, etc. Among these, in terms of electron injection performance and durability against oxidation, mixtures of electron-injecting metals and second metals that are more stable and have a larger work function than the first metal are suitable, such as magnesium / silver mixtures, magnesium / aluminum mixtures, magnesium / indium mixtures, aluminum / alumina (Al₂O₃) mixtures, lithium / aluminum mixtures, aluminum, etc. Cathodes can be fabricated by forming thin films from these cathode materials using methods such as vapor deposition or sputtering. Furthermore, as a cathode, the sheet resistance is preferably several hundred Ω / Y or less, and the film thickness is typically selected in the range of 10 nm to 5 μm, preferably 50 nm to 200 nm. Furthermore, in order for the emitted light to pass through, if either the anode or cathode of the organic EL element is transparent or translucent, the luminous brightness will be increased, which is appropriate.

[0225] Furthermore, after forming the metal on the cathode with a film thickness of 1 nm to 20 nm, a conductive transparent material listed in the description of the anode is formed on it, thereby making a transparent or semi-transparent cathode. By applying the method described above, an element in which both the anode and cathode are permeable can be made.

[0226] -Emitting Layer-

[0227] The light-emitting 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, and contains a light-emitting dopant and a host.

[0228] Regarding the luminescent dopant and the host, for example, the host can be used at 99.9 wt% to 90 wt% relative to 0.1 wt% to 10 wt% of the luminescent dopant. Preferably, the luminescent dopant is 1 wt% to 5 wt% and the host is 99 wt% to 95 wt%, more preferably, the luminescent dopant is 1 wt% to 3 wt% and the host is 99 wt% to 97 wt%.

[0229] As the main body in the light-emitting layer, a first main body represented by general formula (1) and a second main body represented by general formula (2) are used. Regarding the first and second main bodies, for example, the first main body can be used at 10wt% to 90wt%, and the second main body at 90wt% to 10wt%. Preferably, the first main body is 30wt% to 70wt% and the second main body is 70wt% to 30wt%, more preferably, the first main body is 40wt% to 60wt% and the second main body is 60wt% to 40wt%.

[0230] Furthermore, one or more known main components may be used together, but the amount used relative to the total amount of the main components may be set to 50 wt% or less, preferably 25 wt% or less.

[0231] As a known usable host, a compound with hole transport capability, electron transport capability and a high glass transition temperature is preferred, and a T1 greater than that of a luminescent dopant is preferred.

[0232] Other subjects are known from numerous patent documents and other sources, and can therefore be selected from these. Specific examples of subjects are not particularly limited, but can include: metal complexes representing metal complexes or metal phthalocyanines, benzoxazoles, benzoxazolium, benzoxazolium, triazoles, oxazoles, oxadiazoles, imidazoles, phenylenediamines, arylamines, styrene-anthracene, fluorene, stilbene, triphenylene, carboranes, porphyrins, phthalocyanines, 8-hydroxyquinoline derivatives, benzoxazoles, or benzothiazoles; poly(N-vinylcarbazole) derivatives, aniline copolymers, thiophene oligomers, polythiophene derivatives, polyphenylene derivatives, polyphenylene oxide derivatives, polyfluorene derivatives, and other polymers.

[0233] When using multiple substrates, each substrate can be vapor-deposited from different vapor deposition sources, or a premix can be prepared by pre-mixing before vapor deposition, thereby allowing multiple substrates to be vapor-deposited simultaneously from a single vapor deposition source.

[0234] Ideally, premixing methods should aim to achieve the most uniform mixing possible. Examples include pulverization and mixing, heating and melting under reduced pressure or inert gas conditions such as nitrogen, or sublimation, but these methods are not the only options.

[0235] As the luminescent dopant in the luminescent layer, an organic luminescent material with a difference (ΔEST) between the excitation singlet energy (S1) and the excitation triplet energy (T1) of 0.20 eV or less is used. Preferably, the organic luminescent material is a compound represented by general formula (3) or general formula (4).

[0236] The organic light-emitting dopant may be present in the light-emitting layer as a single type or as two or more types. The content of the organic light-emitting dopant relative to the host material is preferably 0.1 wt% to 50 wt%, more preferably 1 wt% to 40 wt%.

[0237] The organic light-emitting dopant and the first or second host can be deposited from separate evaporation sources, or a premixed mixture can be prepared by premixing before evaporation, thereby depositing the light-emitting dopant and the first or second host simultaneously from a single evaporation source.

[0238] -Injection Layer-

[0239] An injection layer is a layer placed between the electrode and the organic layer to reduce the driving voltage or increase the luminous brightness. There are hole injection layers and electron injection layers, which can exist between the anode and the luminescent layer or hole transport layer, and between the cathode and the luminescent layer or electron transport layer. The injection layer can be set as needed.

[0240] -hole blocking layer-

[0241] A hole blocking layer, broadly speaking, functions as an electron transport layer. It comprises hole-blocking materials that can transport electrons but have a significantly lower hole-transporting capacity. By transporting electrons and blocking holes, it increases the recombination probability of electrons and holes in the luminescent layer. Known hole-blocking materials can be used in the hole blocking layer. To leverage the properties of the luminescent dopant, a material used as a second host can also be used as the hole blocking layer material. Furthermore, multiple hole-blocking materials can be used in combination.

[0242] -Electron blocking layer-

[0243] In a broad sense, an electron blocking layer functions as a hole transport layer, increasing the probability of electron-hole recombination in the luminescent layer by transporting holes and blocking electrons. Known electron blocking layer materials can be used as the electron blocking layer material. To leverage the properties of the luminescent dopant, the material used as the primary host can also be used as the electron blocking layer material.

[0244] The thickness of the electron blocking layer is preferably 3nm to 100nm, and more preferably 5nm to 30nm.

[0245] -Exciton blocking layer-

[0246] An exciton blocking layer is a layer used to prevent excitons generated by the recombination of holes and electrons in the light-emitting layer from diffusing into the charge transport layer. By inserting this layer, excitons can be efficiently sealed into the light-emitting layer, thereby improving the luminous efficiency of the device. In devices with two or more adjacent light-emitting layers, the exciton blocking layer can be inserted between two adjacent light-emitting layers.

[0247] Known exciton blocking layer materials can be used as the material for the exciton blocking layer.

[0248] As layers adjacent to the light-emitting layer, there are hole blocking layers, electron blocking layers, exciton blocking layers, etc. In the absence of these layers, hole transport layers, electron transport layers, etc. become adjacent layers.

[0249] -Hole transport layer-

[0250] A hole transport layer is a hole transport material that has the function of transporting holes. A hole transport layer can be a single layer or multiple layers.

[0251] The hole transport material is any material that possesses either hole injection or transport or electron barrier properties, and can be either organic or inorganic. In the hole transport layer, any compound selected from previously known compounds can be used. Examples of such hole transport materials include: porphyrin derivatives, arylamine derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, phenylenediamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrene-anthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, and conductive polymeric oligomers, particularly thiophene oligomers. Porphyrin derivatives, arylamine derivatives, and styrene-anthracene derivatives are preferred, and arylamine derivatives are more preferred.

[0252] -Electron transport layer-

[0253] An electron transport layer consists of materials that can transport electrons, and can be a single layer or multiple layers.

[0254] As an electron transport material (and sometimes also a hole blocking material), it only needs to have the function of transporting electrons injected from the cathode to the emitting layer. The electron transport layer can be any of the previously known compounds, such as: polycyclic aromatic derivatives of naphthalene, anthracene, phenanthroline, etc.; tris(8-hydroxyquinoline)aluminum(III) derivatives; phosphine oxide derivatives; nitro-substituted fluorene derivatives; diphenylquinone derivatives; thiamethane dioxide derivatives; carbodiimide; fluorenemethane derivatives; anthraquinone dimethane and anthrone derivatives; bipyridine derivatives; quinoline derivatives; oxadiazole derivatives; benzimidazole derivatives; benzothiazole derivatives; indolecarbazole derivatives, etc. Furthermore, polymers incorporating these materials into polymer chains or using these materials as the backbone of polymers can also be used.

[0255] There are no particular limitations on the film-forming methods for each layer when manufacturing the organic EL element of the present invention; either dry or wet processes can be used.

[0256] Example

[0257] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0258] The following examples and comparative examples show the compounds used in them.

[0259] [Chemistry 48]

[0260]

[0261] The S1 and T1 of compounds (3-2) and (4-2) were determined.

[0262] S1 and T1 are determined in the following manner.

[0263] On a quartz substrate, vacuum evaporation is used at a vacuum degree of 10. -4 Under conditions below Pa, BH1 as the host and compound (3-2) or compound (4-2) as the luminescent dopant are co-deposited from different evaporation sources to form an evaporation film with a thickness of 100 nm. Co-deposition is performed under evaporation conditions where the concentration of compound (3-2) or compound (4-2) is 3 wt%. Regarding S1, the emission spectrum of the evaporation film is measured, and a tangent is drawn from the starting point of the short-wavelength side of the emission spectrum. The wavelength value λedge [nm] at the intersection of the tangent and the horizontal axis is substituted into equation (i) shown below to calculate S1.

[0264] S1[eV]=1239.85 / λedge (i)

[0265] Regarding T1, the phosphorescence spectrum of the vapor-deposited film is measured, and a tangent is drawn from the starting point of the short wavelength side of the phosphorescence spectrum. The wavelength value λedge[nm] at the intersection of the tangent and the horizontal axis is substituted into equation (ii) to calculate T1.

[0266] T1[eV]=1239.85 / λedge (ii)

[0267] [Table 1]

[0268] compound S1(eV) T1(eV) S1-T1(eV) 3-2 2.79 2.61 0.18 4-2 2.71 2.67 0.04

[0269] Example 1

[0270] On a glass substrate with an ITO-containing anode having a film thickness of 70 nm, vacuum evaporation was performed at a vacuum degree of 4.0 × 10⁻⁶. -5Pa is used to stack the thin films. First, HAT-CN is formed to a thickness of 10 nm as a hole injection layer on ITO. Next, HT-1 is formed to a thickness of 25 nm as a hole transport layer. Next, compound (1-77) is formed to a thickness of 5 nm as an electron blocking layer. Next, compound (1-77) as the first host, compound (2-1) as the second host, and compound (4-2) as the luminescent dopant are co-deposited from different evaporation sources to form a luminescent layer to a thickness of 30 nm. At this time, co-deposition is performed under evaporation conditions where the concentration of compound (4-2) is 2 wt% and the weight ratio of the first host to the second host is 50:50. Next, compound (2-1) is formed to a thickness of 5 nm as a hole blocking layer. Next, ET-1 is formed to a thickness of 40 nm as an electron transport layer. Furthermore, lithium fluoride (LiF) is formed to a thickness of 1 nm on the electron transport layer as an electron injection layer. Finally, aluminum (Al) is formed on the electron injection layer to a thickness of 70 nm as a cathode to fabricate an organic EL device.

[0271] Examples 2 to 10

[0272] Organic EL elements were fabricated in the same manner as in Example 1, except that the luminescent dopant, the first host, the second host, and the weight ratio of the first host to the second host were set to the compounds shown in Table 2.

[0273] Comparative Example 1

[0274] On a glass substrate with an ITO-containing anode having a film thickness of 70 nm, vacuum evaporation was performed at a vacuum degree of 4.0 × 10⁻⁶. -5 Pa is used to stack various thin films. First, HAT-CN is formed to a thickness of 10 nm as a hole injection layer on ITO. Next, HT-1 is formed to a thickness of 25 nm as a hole transport layer. Next, compound (1-77) is formed to a thickness of 5 nm as an electron blocking layer. Next, compound (1-77) as the first host and compound (4-2) as a luminescent dopant are co-deposited from different evaporation sources to form a luminescent layer to a thickness of 30 nm. At this time, co-deposition is performed under evaporation conditions where the concentration of compound (4-2) is 2 wt%. Next, compound (2-1) is formed to a thickness of 5 nm as a hole blocking layer. Next, ET-1 is formed to a thickness of 40 nm as an electron transport layer. Furthermore, lithium fluoride (LiF) is formed to a thickness of 1 nm on the electron transport layer as an electron injection layer. Finally, aluminum (Al) is formed to a thickness of 70 nm on the electron injection layer as a cathode, thereby fabricating an organic EL device.

[0275] Comparative Example 2, Comparative Example 3, Comparative Example 5, Comparative Example 6, Comparative Example 7

[0276] Organic EL elements were fabricated in the same manner as in Comparative Example 1, except that the luminescent dopant and the first host (without a second host) were set to the compounds shown in Table 2.

[0277] Comparative Example 4, Comparative Example 8

[0278] Organic EL elements were fabricated in the same manner as in Example 1, except that the luminescent dopant, the first host, and the second host were set to the compounds shown in Table 2.

[0279] [Table 2]

[0280] Luminescent dopants First subject Second subject Example 1 4-2 1-77(50％) 2-1(50％) Example 2 4-2 1-77(30％) 2-1(70％) Example 3 4-2 1-77(70％) 2-1(30％) Example 4 4-2 1-120(50％) 2-1(50％) Example 5 4-2 1-132(50％) 2-1(50％) Example 6 4-2 1-89(50％) 2-1(50％) Example 7 4-2 1-77(50％) 2-3(50％) Example 8 4-2 1-77(50％) 2-15(50％) Example 9 4-2 1-77(50％) 2-37(50％) Example 10 3-2 1-134(50％) 2-1(50％) Comparative Example 1 4-2 1-77 - Comparative Example 2 4-2 2-1 - Comparative Example 3 4-2 mCBP - Comparative Example 4 4-2 mCBP (50%) 2-1(50％) Comparative Example 5 3-2 1-134 Comparative Example 6 3-2 2-1 Comparative Example 7 3-2 mCBP Comparative Example 8 3-2 mCBP (50%) 2-1(50％)

[0281] Table 3 shows the voltage, maximum emission wavelength, external quantum efficiency, and lifetime of the organic EL devices fabricated in the examples and comparative examples. The voltage, maximum emission wavelength, and external quantum efficiency are based on a luminance of 500 cd / m². 2 The value at that time represents the initial characteristics. Regarding lifetime, the initial luminance was measured to be 500 cd / m². 2 The time it takes for the brightness to decrease to 50% of its initial brightness.

[0282] [Table 3]

[0283]

[0284] As shown in Table 3, in organic EL elements that use the compound represented by general formula (1) as the first host, the compound represented by general formula (2) as the second host, and the compound represented by general formula (3) or general formula (4) as the luminescent dopant, the EL element emits blue light according to the maximum emission wavelength and has the characteristics of low voltage, high efficiency and long lifetime.

[0285] Industrial availability

[0286] The organic EL element of the present invention has the characteristics of low driving voltage, high luminous efficiency and long lifespan, and is therefore suitable for use as a display element or light source in flat panel displays and other applications.

Claims

1. An organic electric field light-emitting element, comprising one or more light-emitting layers between opposing anodes and cathodes, characterized in that: At least one luminescent layer comprises an organic light-emitting material as a luminescent dopant whose difference between the excitation singlet energy and the excitation triplet energy is less than 0.20 eV, and contains a first host selected from compounds represented by the following general formula (5) and a second host selected from compounds represented by the following general formula (2), wherein the organic light-emitting material is a boron-containing polycyclic aromatic compound represented by the following general formula (3) or general formula (4). Here, Ar 1 Independently representing an aromatic hydrocarbon group having 6 to 18 carbon atoms, a heterocyclic aromatic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of two linked aromatic rings of these. Here, X 2 Independently represent N or CH, with at least two X's. 2 N; Ar 2 It refers to an aromatic hydrocarbon group with 6 to 18 carbon atoms that has been substituted or unsubstituted, an aromatic heterocyclic group with 3 to 17 carbon atoms that has been substituted or unsubstituted, or a linked aromatic group consisting of two linked aromatic rings of these. R 2 Independently representing deuterium, aliphatic hydrocarbon group with 1 to 10 carbons, substituted or unsubstituted aromatic hydrocarbon group with 6 to 18 carbons, or substituted or unsubstituted aromatic heterocyclic group with 3 to 17 carbons; e, f, g, and h represent integers from 0 to 4; Here, X 3 Indicates N-Ar 3 Ar 3 Independently representing an aromatic hydrocarbon group with 6 to 10 carbon atoms, whether substituted or unsubstituted, or an aromatic heterocyclic group with 3 to 10 carbon atoms, whether substituted or unsubstituted; R 3 Independently representing cyano, deuterium, diarylamino with 12 to 44 carbons, aliphatic hydrocarbon group with 1 to 10 carbons, substituted or unsubstituted aromatic hydrocarbon group with 6 to 18 carbons, or substituted or unsubstituted aromatic heterocyclic group with 3 to 17 carbons; i and j represent integers from 0 to 4, and k represents integers from 0 to 3. Here, X 4 Indicates N-Ar 4 O, or S, at least one X 4 Indicates N-Ar 4 Ar 4 Independently representing an aromatic hydrocarbon group with 6 to 18 carbon atoms, substituted or unsubstituted, or an aromatic heterocyclic group with 3 to 17 carbon atoms, substituted or unsubstituted; R 4 Independently representing cyano, deuterium, diarylamino with 12–44 carbons, aliphatic hydrocarbon group with 1–10 carbons, substituted or unsubstituted aromatic hydrocarbon group with 6–18 carbons, or substituted or unsubstituted aromatic heterocyclic group with 3–17 carbons; m and n represent integers 0–4, o and p represent integers 0–3, and q represent integers 0–2. The substituent is selected from cyano, aliphatic hydrocarbon group having 1 to 10 carbon atoms, or diarylamino group having 12 to 44 carbon atoms.

2. The organic electric field light-emitting element according to claim 1, characterized in that: The organic light-emitting material is represented by the general formula (4).

3. The organic electric field light-emitting element according to claim 1, characterized in that: X in the general formula (4) 4 For N-Ar 4 .

4. The organic electric field light-emitting element according to claim 1, characterized in that: The ΔEST of organic light-emitting materials is below 0.10 eV.

5. The organic electric field light-emitting element according to claim 1, characterized in that: The host is contained in 99.9 wt% to 90 wt% relative to 0.1 wt% to 10 wt% of the luminescent dopant, and in the host, a first host is contained in 10 wt% to 90 wt% and a second host is contained in 90 wt% to 10 wt%.

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