Organic electroluminescent element

Abstract

The present application provides a blue light-emitting organic electroluminescent element with high luminous efficiency and long lifetime. The organic EL element comprises one or more light-emitting layers between facing anode and cathode, and at least one light-emitting layer contains a first host selected from indolocarbazole compounds and a second host selected from compounds represented by the following general formula (2), and contains a polycyclic aromatic compound represented by the following general formula (3) or a polycyclic aromatic compound having a structure represented by general formula (3) as a partial structure as a light-emitting dopant. Here, Y 4 is B, P, P=O, P=S, Al, Ga, As, Si-R 4 or Ge-R 5 , X 4 is O, N-Ar 4 , S or Se.

Description

Technical Field

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

[0002] By applying a voltage to an organic EL element, holes are injected into the emissive layer from the anode, and electrons are injected into the emissive layer from the cathode. 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. For fluorescent organic EL elements utilizing light emission from singlet excitons, the internal quantum efficiency is considered to be limited to 25%. On the other hand, phosphorescent organic EL elements utilizing light emission from triplet excitons have achieved an internal quantum efficiency of up to 100% when intersystem crossings are efficiently performed from singlet excitons.

[0003] Furthermore, high-efficiency organic EL devices utilizing delayed fluorescence are currently being developed. For example, Patent Document 1 discloses an organic EL device utilizing a 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, and it is believed that the internal quantum efficiency can be theoretically increased to 40%. However, compared with phosphorescent organic EL devices, the efficiency is low, thus requiring further improvement in efficiency.

[0004] On the other hand, Patent Document 2 discloses an organic EL device utilizing a 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 occurs from a triplet exciton to a singlet exciton, theoretically increasing the internal quantum efficiency to 100%. However, similar to phosphorescent luminescent devices, further improvements in lifetime characteristics are required.

[0005] 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, but do not disclose specific lifetime characteristics.

[0006] [Chemistry 1]

[0007]

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: WO2010 / 134350

[0011] Patent Document 2: WO2011 / 070963

[0012] Patent Document 3: WO2015 / 102118

[0013] Patent Document 4: WO2018 / 212169 Summary of the Invention

[0014] To apply organic EL elements to display elements or light sources such as flat panel displays, it is necessary to improve the luminous efficiency of the elements while ensuring sufficient stability during driving. The object of this invention is to provide a practically useful organic EL element that features low driving voltage, high efficiency, and long lifespan.

[0015] The present invention is an organic electric field light-emitting element, which includes one or more light-emitting layers between opposing anodes and cathodes. The organic electric field light-emitting element is characterized in that: at least one light-emitting layer 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), and contains a polycyclic aromatic compound represented by the following general formula (3) or a polycyclic aromatic compound having the structure represented by the following general formula (3) as a partial structure as a light-emitting dopant.

[0016] [Chemistry 2]

[0017]

[0018] Here, Z represents the group containing an indolocarbazole ring as shown in general formula (1a), and * represents the group with L. 1 The bond position.

[0019] Ring A is a heterocyclic ring represented by equation (1b), which is condensed at any position with the adjacent ring.

[0020] L 1 With L 2 Each is independently an aromatic hydrocarbon group with 6 to 30 carbon atoms, either substituted or unsubstituted, or an aromatic heterocyclic group with 3 to 17 carbon atoms, either substituted or unsubstituted.

[0021] Ar 1 with Ar 2Each of these can be independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these.

[0022] R 1 They are, independently, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, substituted or unsubstituted aromatic hydrocarbon groups with 6 to 18 carbon atoms, or substituted or unsubstituted aromatic heterocyclic groups with 3 to 17 carbon atoms.

[0023] a represents an integer from 1 to 3, b represents an integer from 0 to 3, c and d independently represent integers from 0 to 4, e represents an integer from 0 to 2, and f represents an integer from 0 to 3.

[0024] [Chemistry 3]

[0025]

[0026] Here, X 1 Each can be represented independently as N or CH, and at least one X. 1 N represents the number of X's. Preferably, there are three X's. 1 Let N be the number of elements in the array.

[0027] Ar 3 Each of these can be independently represented as an aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these aromatic rings.

[0028] [Chemistry 4]

[0029]

[0030] Here, ring C, ring D, and ring E are independently substituted or unsubstituted aromatic hydrocarbon rings with 6 to 24 carbon atoms, or substituted or unsubstituted aromatic heterocycles with 3 to 17 carbon atoms.

[0031] Y 4 For B, P, P=O, P=S, Al, Ga, As, Si-R 4 or Ge-R 5 R 4 and R 5 They are, independently, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, substituted or unsubstituted aromatic hydrocarbon groups with 6 to 18 carbon atoms, or substituted or unsubstituted aromatic heterocyclic groups with 3 to 17 carbon atoms.

[0032] X 4 Independently, O and N-Ar respectively 4 ,S or Se, Ar 4Each is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these, N-Ar 4 It can bond with any of the C-ring, D-ring, or E-ring to form a heterocycle containing N.

[0033] R 3 Each of the following can be independently represented: cyano, deuterium, diarylamino with 12 to 44 carbons, arylheteroarylamino with 12 to 44 carbons, diheteroarylamino 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.

[0034] C ring, D ring, E ring, R 3 R 4 R 5 and Ar 4 At least one hydrogen atom in the atom may be replaced by a halogen or deuterium.

[0035] v represents an integer from 0 to 4, and x represents an integer from 0 to 3.

[0036] As a polycyclic aromatic compound having the structure represented by the general formula (3) as a part of its structure, examples include polycyclic aromatic compounds represented by the following general formula (4), or polycyclic aromatic compounds containing boron represented by the following formula (5).

[0037] [Chemistry 5]

[0038]

[0039] Here, rings F, G, H, I, and J are independently substituted or unsubstituted aromatic hydrocarbon rings with 6 to 24 carbon atoms, or substituted or unsubstituted aromatic heterocycles with 3 to 17 carbon atoms. 4 Y 4 R 3 x and v have the same meaning as in general formula (3), w represents an integer from 0 to 4, y represents an integer from 0 to 3, and z represents an integer from 0 to 2.

[0040] At least one hydrogen atom in the F, G, H, I, and J rings may be substituted with a halogen or deuterium.

[0041] [Chemistry 6]

[0042]

[0043] Here, X 9 N-Ar are represented independently. 6 O or S, at least one X9 Indicates N-Ar 6 Ar 6 Each of these groups independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these aromatic rings. N-Ar 6 It can also bond with the aromatic ring to form a heterocycle containing N.

[0044] R 9 Each of the following can be independently represented: 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.

[0045] m and n independently represent integers from 0 to 4, o and p independently represent integers from 0 to 3, and q represents integers from 0 to 2.

[0046] As a preferred embodiment of the general formula (2), formulas (6) or (7) can be listed below.

[0047] [Chemistry 7]

[0048]

[0049] Here, Ar 3 and X 1 It has the same meaning as general formula (2).

[0050] R 2 Each of these can be independently represented as deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a triarylsilyl group, 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).

[0051] g, h, i, and j each independently represent integers from 0 to 4.

[0052] As a preferred embodiment of the general formula (1), the following formulas (8a) or (8b) can be listed.

[0053] [Chemistry 8]

[0054]

[0055] [Chemistry 9]

[0056]

[0057] Here, L 3 L 4 Ar 4 Ar5 k and l are respectively related to L in general formula (1) 1 L 2 Ar 1 Ar 2 a and b have the same meaning.

[0058] The difference (ΔEST) between the excited singlet energy (S1) and the excited triplet energy (T1) of the luminescent dopant can be less than 0.20 eV, and ideally less than 0.10 eV.

[0059] The light-emitting layer may contain 0.10% to 10% by mass of a luminescent dopant and 99.9% to 90% by mass of a host, and the host may contain 10% to 90% by mass of the first host and 90% to 10% by mass of the second host.

[0060] In addition, the present invention is an organic EL element, which includes one or more light-emitting layers between opposing anodes and cathodes. The organic EL element is characterized in that: at least one light-emitting layer contains an organic light-emitting material as a light-emitting dopant with a difference (ΔEST) between the excitation singlet energy (S1) and the excitation triplet energy (T1) of less than 0.20 eV, and contains a first host and a second host.

[0061] The organic EL element of the present invention contains specific luminescent dopants and various specific host materials in the light-emitting layer, thus it can be an organic EL element with low driving voltage, high luminous efficiency and long lifetime.

[0062] The main reason for the low driving voltage of the organic EL element of the present invention is assumed to be that the indole-carbazole compound, as the first host material, has the characteristic of easily injecting holes, and the nitrogen-containing six-membered ring compound, as the second host material, has the characteristic of easily injecting electrons. Therefore, holes and electrons can be injected at a lower voltage to generate excitons. Furthermore, the main reason for the high luminous efficiency of the organic EL element of the present invention is assumed to be that the indole-carbazole compound has the characteristic of easily injecting holes, and the nitrogen-containing six-membered ring compound has the characteristic of easily injecting electrons. Therefore, the balance of holes and electrons in the luminescent layer can be maintained. It is speculated that the main reason for the long lifetime of the organic EL element of the present invention is that, when a voltage is applied to the organic EL element, by preferentially injecting holes into the first host containing the indole-carbazole compound and preferentially injecting electrons into the second host containing the nitrogen-containing six-membered ring compound, the electrochemical load on the luminescent dopant can be reduced. Attached Figure Description

[0063] Figure 1 This is a schematic cross-sectional view showing an example of an organic EL element.

[0064] Explanation of symbols

[0065] 1: Substrate

[0066] 2: Anode

[0067] 3: Hole injection layer

[0068] 4: Hole transport layer

[0069] 5: Emissive layer

[0070] 6: Electron transport layer

[0071] 7: Cathode Detailed Implementation

[0072] The organic EL element of the present invention has one or more light-emitting layers between opposing anodes and cathodes. At least one light-emitting layer contains a first host selected from compounds represented by the general formula (1) and a second host selected from compounds represented by the general formula (2), and contains a polycyclic aromatic compound represented by the general formula (3) or a polycyclic aromatic compound having the structure represented by the general formula (3) as a part of the structure as a light-emitting dopant.

[0073] The compound represented by the general formula (1) used as the first subject in this invention will be described.

[0074] In general formula (1), Z is a group containing an indole-carbazole ring as represented by general formula (1a), and ring A is a heterocycle represented by formula (1b), which is condensed with the adjacent ring at any position.

[0075] a represents an integer from 1 to 3, b represents an integer from 0 to 3, c and d independently represent integers from 0 to 4, e represents an integer from 0 to 2, and f represents an integer from 0 to 3. Preferably, a is 1 to 2, b is 0 to 2, c and d are 0 to 1, e is 0 to 2, and f is 0 to 2.

[0076] As a preferred embodiment of general formula (1), there is formula (8a) or formula (8b), more preferably formula (8b).

[0077] In general formula (1), formula (8a) and formula (8b), the common symbols have the same meaning.

[0078] k and l represent integers from 0 to 3. More preferably, k and l are from 0 to 2.

[0079] L 1 L 2 L 3 and L 4Each group independently represents an aromatic hydrocarbon group with 6 to 30 carbon atoms, either substituted or unsubstituted, or an aromatic heterocyclic group with 3 to 17 carbon atoms, either substituted or unsubstituted. Preferably, it is an aromatic hydrocarbon group with 6 to 20 carbon atoms, or an aromatic heterocyclic group with 3 to 15 carbon atoms. More preferably, it is phenyl, naphthyl, pyridyl, triazine, dibenzofuranyl, or carbazoleyl. Furthermore, L 1 L 2 L 3 and L 4 These are the bases for valences a+b, f+1, k+1, and l+1, respectively.

[0080] Specific examples of the unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or the substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, include benzene, naphthalene, acenaphthene, acenaphthene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, tetraphenylene, pentaphenylene, hexaphenylene, hexabenzophenyl, heptaphenylene, heptaphenylene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyridine, pyridine Azole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole.

[0081] Ar 1 Ar 2 Ar 4 and Ar 5 Each of these groups is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these groups. Preferably, the linked aromatic group consists of a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic ring consisting of 2 to 4 of these groups. More preferably, it is a phenyl, biphenyl, or terphenyl group.

[0082] As Ar 1 Ar 2 Ar 4 and Ar 5 Specific examples of unsubstituted aromatic hydrocarbon groups and unsubstituted aromatic heterocyclic groups, with L 1 The situation is the same (sometimes the price may differ; the same applies below).

[0083] Preferably, the group is formed by removing one hydrogen atom from a compound consisting of benzene, naphthalene, acenaphthene, acenaphthene, azulene, pyridine, triazine, dibenzofuran, dibenzothiophene, carbazole, or two to four of these linked together. More preferably, the group is formed from a compound consisting of benzene, or two to three of these linked together.

[0084] In this specification, linked aromatic groups refer to aromatic hydrocarbon groups or aromatic heterocyclic groups whose aromatic rings are linked by single bonds. These can be linked in a straight chain or in a branched manner, and the aromatic rings can be the same or different. In cases equivalent to linked aromatic groups, they differ from substituted aromatic hydrocarbon groups or aromatic heterocyclic groups.

[0085] R 1 Each group independently represents 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).

[0086] 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.

[0087] As R 1Specific 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, 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. A radical formed by removing a hydrogen atom from isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole. Preferably, the group can be derived from benzene, naphthalene, acenaphthene, acenaphthene, azulene, pyridine, pyrimidine, triazine, thiophene, isothiazol, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromogenone, dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole. More preferably, groups can be listed as those formed from benzene, naphthalene, azulene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromogenone, dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole.

[0088] In this specification, these aromatic hydrocarbon groups, aromatic heterocyclic groups, or linked aromatic groups may each have substituents. The substituents are preferably deuterium, cyano, triarylsilyl, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, or diarylamino with 12 to 44 carbon atoms. Here, when the substituent is an aliphatic hydrocarbon group with 1 to 10 carbon atoms, it can be linear, branched, or cyclic. Furthermore, the number of substituents can be 0 to 5, preferably 0 to 2. When calculating the carbon number of aromatic hydrocarbon groups and aromatic heterocyclic groups 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 the substituents, meets the aforementioned range.

[0089] Specific examples of the substituents include: cyano, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, 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.

[0090] In this specification, hydrogen can be understood to be deuterium. That is, in general formulas (1) to (4), etc., the skeleton of carbazole, R 1 Or Ar 1 The H in such substituents can be some or all of deuterium.

[0091] The following are specific examples of compounds represented by general formula (1), but are not limited to these exemplified compounds.

[0092] [Chemistry 10]

[0093]

[0094] [Chemistry 11]

[0095]

[0096] [Chemistry 12]

[0097]

[0098] [Chemistry 13]

[0099]

[0100] [Chemistry 14]

[0101]

[0102] [Chemistry 15]

[0103]

[0104] [Chemistry 16]

[0105]

[0106] [Chemistry 17]

[0107]

[0108] [Chemistry 18]

[0109]

[0110] [Chemistry 19]

[0111]

[0112] [Chemistry 20]

[0113]

[0114] [Chemistry 21]

[0115]

[0116] [Chemistry 22]

[0117]

[0118] [Chemistry 23]

[0119]

[0120] [Chemistry 24]

[0121]

[0122] The compound represented by the general formula (2) used as the second body in this invention will be described.

[0123] In general formula (2), X 1 Independently represent N or CH, with at least one X 1 N represents the number of X's. Preferably, there are two X's. 1 N represents the number of X's. Preferably, there are three X's. 1 Triazine compounds with N atoms.

[0124] As a preferred embodiment of general formula (2), there are formulas (6) or (7), with formula (7) being more preferred. In general formula (2), formula (6) and formula (7), the common symbols have the same meaning.

[0125] g, h, i, and j represent integers from 0 to 4. More preferably, g, h, i, and j are from 0 to 2.

[0126] Ar 3This refers to a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group consisting of 2 to 8 of these aromatic rings. Preferably, it refers to a substituted or unsubstituted linked aromatic group having 6 to 12 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms, or a substituted or unsubstituted linked aromatic group consisting of 2 to 6 of these aromatic rings. More preferably, it refers to a substituted or unsubstituted linked aromatic group having 6 to 10 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 10 carbon atoms, or a substituted or unsubstituted linked aromatic group consisting of 2 to 4 of these aromatic rings.

[0127] As Ar 3 Specific examples of unsubstituted aromatic hydrocarbon groups or unsubstituted aromatic heterocyclic groups, and the Ar 1 Or R 1 The same applies to these cases. As an unsubstituted linked aromatic group, it is related to the Ar... 1 The same applies to these cases.

[0128] Preferably, the group is formed by removing a hydrogen atom from a compound consisting of two to four links of benzene, naphthalene, acenaphthene, acenaphthene, azulene, pyridine, triazine, dibenzofuran, dibenzothiophene, carbazole, or the like. More preferably, the group is formed from a compound consisting of two to three links of benzene, carbazole, or a benzene ring.

[0129] In equations (6) and (7), R 2 Independently representing deuterium, aliphatic hydrocarbon group having 1 to 10 carbon atoms, triarylsilyl, substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms. Preferably, it is an aromatic hydrocarbon group having 6 to 12 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 15 carbon atoms. More preferably, it is an aromatic hydrocarbon group having 6 to 10 carbon atoms. g, h, i, and j represent integers from 0 to 4.

[0130] As R 2 Specific examples when referring to aliphatic hydrocarbon groups with 1 to 10 carbon atoms, substituted or unsubstituted aromatic hydrocarbon groups with 6 to 18 carbon atoms, or substituted or unsubstituted aromatic heterocyclic groups with 3 to 17 carbon atoms, are related to R. 1The description is the same as described above. Preferably, the radical is formed by removing a hydrogen atom from benzene, naphthalene, acenaphthene, acenaphthene, azulene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, triphenylsilane, or carbazole.

[0131] The following are specific examples of compounds represented by general formula (2), formula (6) or formula (7), but are not limited to these exemplified compounds.

[0132] [Chemistry 25]

[0133]

[0134] [Chemistry 26]

[0135]

[0136] [Chemistry 27]

[0137]

[0138] [Chemistry 28]

[0139]

[0140] [Chemistry 29]

[0141]

[0142] [Chemistry 30]

[0143]

[0144] [Chemistry 31]

[0145]

[0146] [Chemistry 32]

[0147]

[0148] [Chemistry 33]

[0149]

[0150] [Chemistry 34]

[0151]

[0152] [Chemistry 35]

[0153]

[0154] [Chemistry 36]

[0155]

[0156] The luminescent dopant used in the organic EL element of the present invention is a polycyclic aromatic compound represented by the general formula (3) or a polycyclic aromatic compound having the structure represented by the general formula (3) as a partial structure (also called a partially structured polycyclic aromatic compound).

[0157] The partially structured polycyclic aromatic compound is preferably a partially structured polycyclic aromatic compound represented by the general formula (4), and more preferably a partially structured polycyclic aromatic compound containing boron represented by the formula (5).

[0158] In addition, some of the structural polycyclic aromatic compounds represented by general formula (4) or formula (5) can be regarded as condensates of compounds represented by general formula (3) or their analogues.

[0159] In general formulas (3) and (4), rings C, D, E, F, G, H, I, and J are each independently an aromatic hydrocarbon ring with 6 to 24 carbon atoms or an aromatic heterocycle with 3 to 17 carbon atoms, preferably an aromatic hydrocarbon ring with 6 to 20 carbon atoms or an aromatic heterocycle with 3 to 15 carbon atoms. Since rings C to J are aromatic hydrocarbon rings or aromatic heterocycles as described above, they are also called aromatic rings.

[0160] Specific examples of the aromatic rings mentioned above include rings containing benzene, naphthalene, acenaphthene, 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, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazolium, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole. More preferably, it is a benzene ring, a naphthalene ring, an anthracene ring, a triphenylene ring, a phenanthrene ring, a pyrene ring, a pyridine ring, a dibenzofuran ring, a dibenzothiophene ring, or a carbazole ring.

[0161] In general formula (3), Y 4 For B, P, P=O, P=S, Al, Ga, As, Si-R 4 or Ge-R 5Preferably, it is B, P, P=O or P=S, and more preferably B.

[0162] R 4 and R 5 Independently representing 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).

[0163] As R 4 and R 5 When R is an aliphatic hydrocarbon group with 1 to 10 carbon atoms 4 and R 5 Specific examples of the use of substituted or unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, or substituted or unsubstituted aromatic heterocyclic groups having 3 to 17 carbon atoms, are related to R in general formula (1). 1 The same applies to these bases.

[0164] X 4 Independently, O and N-Ar respectively 4 S or Se, preferably O or N-Ar 4 Or S, more preferably O or N-Ar 4 .

[0165] Ar 4 Each of the following is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these. Phenyl, biphenyl, or terphenyl are preferred.

[0166] As Ar 4 Specific examples of aromatic hydrocarbon groups having 6 to 18 carbon atoms that are substituted or unsubstituted, aromatic heterocyclic groups having 3 to 17 carbon atoms that are substituted or unsubstituted, or linked aromatic groups consisting of 2 to 8 of these, are related to Ar in general formula (1). 1 The same applies to these groups. However, the number of carbon atoms in aromatic hydrocarbon groups differs.

[0167] N-Ar 4 It can also bond with aromatic rings selected from C, D, or E rings to form heterocycles containing N. Additionally, C, D, E, and R rings... 4 R 41 R 42 and Ar 4At least one hydrogen atom in the atom may be replaced by a halogen or deuterium.

[0168] R 3 Substituents representing the C, D, and E rings can independently represent cyano, deuterium, a diarylamino group with 12-44 carbon atoms, an arylheteroarylamino group with 12-44 carbon atoms, a diheteroarylamino group with 12-44 carbon atoms, an aliphatic hydrocarbon group with 1-10 carbon atoms, an aromatic hydrocarbon group with 6-18 carbon atoms (substituted or unsubstituted), or an aromatic heterocyclic group with 3-17 carbon atoms (substituted or unsubstituted). Preferably, they are diarylamino groups with 12-36 carbon atoms, arylheteroarylamino groups with 12-36 carbon atoms, diheteroarylamino groups with 6-12 carbon atoms (substituted or unsubstituted), or aromatic heterocyclic groups with 3-15 carbon atoms (substituted or unsubstituted). More preferably, it is a diarylamino group with 12 to 24 carbons, an arylheteroarylamino group with 12 to 24 carbons, a diheteroarylamino group with 12 to 24 carbons, an aromatic hydrocarbon group with 6 to 10 carbons that has been substituted or not substituted, or an aromatic heterocyclic group with 3 to 12 carbons that has been substituted or not substituted.

[0169] As R 3 Specific examples of diarylamino, arylheteroarylamino, diheteroarylamino, or aliphatic hydrocarbon groups having 12 to 44 carbon atoms can be listed as follows: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenanthylamino, dipyreneamino, dibenzofuranylphenylamino, dibenzofuranylbiphenylamino, dibenzofuranylnaphthylamino, dibenzofuranylanthrylamino, dibenzofuranylphenanthylamino, dibenzofuranylpyreneamino, bisdibenzofuranylamino, carbazoylphenylamino, carbazoylnaphthylamino, carbazoylanthrylamino, carbazoylphenanthylamino, carbazoylpyreneamino, dicarbazoylamino, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, or nonyl. Preferably, the following are examples: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, or dipyreneamino. More preferably, the following are examples: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dibenzofuranylphenylamino, or carbazoleylphenylamino.

[0170] v represents an integer from 0 to 4, preferably an integer from 0 to 2, and more preferably 0 to 1. x represents an integer from 0 to 3, preferably an integer from 0 to 2, and more preferably 0 to 1.

[0171] As a partial structural polycyclic aromatic compound, there are compounds represented by the general formula (4) or formula (5).

[0172] In general formulas (3), (4) and (5), the common symbols have the same meaning.

[0173] In general formula (4), w represents an integer from 0 to 4, y represents an integer from 0 to 3, and z represents an integer from 0 to 2. In formula (5), m and n represent integers from 0 to 4, o and p represent integers from 0 to 3, and q represents an integer from 0 to 2. Preferably, w, y, z, m, and n are independently 0 or 1.

[0174] In general formula (4), F ring ~ J ring are as described above.

[0175] The F ring, G ring and C ring and D ring in general formula (3) have the same meaning, the H ring, J ring and E ring have the same meaning, and the I ring is a common structure, so it becomes a tetravalent base (when z = 0).

[0176] In equation (5), X 9 Independently represent N-Ar 6 O or S, at least one X 9 Indicates N-Ar 6 Ar 6 Ar of general formula (3) 4 They have the same meaning. N-Ar 6 It can also bond with the aromatic ring to form a heterocycle containing N.

[0177] R 9 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.

[0178] As a specific example, with R 3 The same applies to these cases.

[0179] The following descriptions of some structural polycyclic aromatic compounds refer to general formulas (4) and (5).

[0180] General formula (4) includes the structure represented by general formula (3) and a portion thereof. From another perspective, although there are two structures represented by general formula (3), they become a structure sharing a common I-ring. That is, the structure represented by general formula (3) is set as a partial structure.

[0181] Similarly, formula (5) becomes a structure with a common central benzene ring, which can be understood as including the structure represented by general formula (3) and a part of its structure.

[0182] The partial structure of the polycyclic aromatic compounds described in this invention has the structure represented by general formula (3) as a partial structure. It is preferable to have a structure lacking any one of the C-rings to E-rings in general formula (3) as another partial structure. Furthermore, it is preferable to have one structure represented by general formula (3) as a partial structure and one to three of the other partial structures. The bond between the structure represented by general formula (3) and the other partial structures can be a bond based on the condensation or formation of one or more rings, or a bond based on one or more interlocking bonds.

[0183] As a preferred embodiment of the general formula (3), general formula (4) or formula (5), or partially structural polycyclic aromatic compounds, there are the following formulas (4-a) to (4-h).

[0184] [Chemistry 37]

[0185]

[0186] The partial structure of polycyclic aromatic compounds represented by formula (4-a) corresponds, for example, to compounds represented by formulas (3-64) described later. That is, formula (4-a) is a structure in which the central benzene ring has two general formulas (3), and can be understood as a compound containing a structural unit of general formula (3) and containing one of the partial structures.

[0187] The partial structure of polycyclic aromatic compounds represented by formula (4-b) corresponds, for example, to compounds represented by formulas (3-65) described later. That is, formula (4-b) is a structure with two general formulas (3) in the central benzene ring, and can be understood as a compound containing a structural unit of general formula (3) and containing one of the aforementioned partial structures. If explained using general formula (3), then X 4 One is N-Ar 4 It becomes a ring structure that bonds with another aromatic ring to form a ring (condensed ring structure).

[0188] The partial structure of polycyclic aromatic compounds represented by formula (4-c) corresponds, for example, to compounds represented by formulas (3-66) described later. That is, if explained using general formula (3), the structure has three unit structures represented by general formula (3) because it contains a benzene ring as the E ring. In other words, it can be understood as a compound having a unit structure represented by general formula (3) as a partial structure, and including two structures obtained by removing one benzene ring from general formula (3), i.e., the partial structure. Furthermore, X 4 For N-Ar 4 It becomes a ring structure that forms a ring with another adjacent ring.

[0189] [Chemistry 38]

[0190]

[0191] In addition, some of the structural polycyclic aromatic compounds represented by formulas (4-d), (4-e), (4-f), and (4-g) correspond to compounds represented by formulas (3-67), (3-68), (3-69), and (3-70) as described later.

[0192] That is, a compound having two or three unit structures represented by general formula (3) in one compound, which are shared as benzene rings (or D rings). That is, it can be understood as a compound having a unit structure represented by general formula (3) as a partial structure, and containing a structure obtained by removing a benzene ring from general formula (3), namely the partial structure.

[0193] The partial structure of polycyclic aromatic compounds represented by formula (4-h) corresponds, for example, to compounds represented by formulas (3-71), (3-72), (3-73), (3-74), and (3-75) described later. That is, if explained using general formula (3), it is a partial structure of polycyclic aromatic compounds in which the C ring is a naphthalene ring and the ring is shared, and the compound has two unit structures represented by general formula (3) in one compound. That is, it can be understood as a compound having the unit structure represented by general formula (3) as a partial structure, and containing one or two structures obtained by removing one C ring (naphthalene ring) from general formula (3), i.e., the partial structure.

[0194] In equations (4-a) to (4-h), X 4 and Y 4 R has the same meaning as general formula (3). 6 , k, l and m and R in equation (5) 9 , m, o, and q have the same meaning. s ranges from 0 to 1, with 0 being the preferred value.

[0195] Some of the structural polycyclic aromatic compounds of the present invention may refer to the following compounds: compounds of multiple general formula (4) having one or two rings (C ring to E ring) in the structural unit of general formula (4) and linked together, and containing at least one structural unit of general formula (4).

[0196] The number of compounds forming the general formula (4) is 2 to 5, preferably 2 to 3. The number of rings (C-rings to E-rings) can be one, two, or three.

[0197] The following are specific examples of polycyclic aromatic compounds represented by general formula (3), general formula (4) or formula (5) and some structural polycyclic aromatic compounds, but are not limited to these exemplified compounds.

[0198] [Chemistry 39]

[0199]

[0200] [Chemistry 40]

[0201]

[0202] [Chemistry 41]

[0203]

[0204] [Chemistry 42]

[0205]

[0206] [Chemistry 43]

[0207]

[0208] [Chemistry 44]

[0209]

[0210] [Chemistry 45]

[0211]

[0212] [Chemistry 46]

[0213]

[0214] [Chemistry 47]

[0215]

[0216] [Chemistry 48]

[0217]

[0218] [Chemistry 49]

[0219]

[0220] [Transformation 50]

[0221]

[0222] [Chemistry 51]

[0223]

[0224] [Chemistry 52]

[0225]

[0226] [Chemistry 53]

[0227]

[0228] [Chemistry 54]

[0229]

[0230] The ΔEST of the organic light-emitting material used as a light-emitting dopant in the organic EL element of the present invention can be 0.20 eV or less, preferably 0.15 eV or less, and more preferably 0.10 eV or less.

[0231] ΔEST represents the difference between the excited singlet energy (S1) and the excited triplet energy (T1). Here, S1 and T1 are determined using the method described in the examples.

[0232] An excellent organic EL element can be provided by using a material selected from the polycyclic aromatic compounds or partially structured polycyclic aromatic compounds represented by the general formula (3) as a luminescent dopant, and using a material selected from the compound represented by the general formula (1) as a first host and a material selected from the compound represented by the general formula (2) as a second host.

[0233] In other embodiments of the invention, a compound with a ΔEST of 0.20 eV or less is used as the luminescent dopant. In this case, the compound used as the luminescent dopant does not need to be the polycyclic aromatic compound material, as long as it is a compound with a ΔEST of 0.20 eV or less, preferably 0.15 eV or less, and more preferably 0.10 eV or less. Such compounds are known from numerous documents such as Patent Document 2 and are known as thermally activated delayed fluorescence (TADF) materials, and therefore can be selected from these.

[0234] 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.

[0235] Figure 1This is a cross-sectional view showing a typical organic EL element structure used in this invention. 1 represents the substrate, 2 represents the anode, 3 represents the hole injection layer, 4 represents the hole transport layer, 5 represents the light-emitting layer, 6 represents the electron transport layer, and 7 represents the cathode. The organic EL element of this invention may also have an exciton blocking layer adjacent to the light-emitting layer. Furthermore, an electron blocking layer may also be present between the light-emitting layer and the hole injection layer. The exciton blocking layer may be inserted into either the anode side or the cathode side of the light-emitting layer, or simultaneously into both sides. In the organic EL element of this invention, an anode, a light-emitting layer, and a cathode are essential layers. However, in addition to these essential layers, a hole injection transport layer and an electron injection transport layer may also be present, and a hole blocking layer may also be present between the light-emitting layer and the electron injection transport layer. Furthermore, the hole injection transport layer refers to either or both of the hole injection layer and the hole transport layer, and the electron injection transport layer refers to either or both of the electron injection layer and the electron transport layer.

[0236] It can also be with Figure 1 In the opposite structure, where 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, layers can be added or omitted as needed.

[0237] -Substrate-

[0238] 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 in organic EL elements before, such as a substrate containing glass, transparent plastic, quartz, etc.

[0239] -anode-

[0240] As the anode material in an organic electroluminescent (EL) element, materials containing metals, alloys, 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 by methods such as evaporation or sputtering, and then patterned into the desired shape using photolithography. Alternatively, when pattern precision is not critical (around 100 μm or higher), a mask of the desired shape can be used during the evaporation or sputtering of the electrode material to form the pattern. Alternatively, when using a coatable substance such as an organic conductive compound, wet film formation methods such as printing or coating can be used. In the case of extracting light 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.

[0241] -cathode-

[0242] On the other hand, as cathode materials, materials containing metals (called electron-injecting metals), alloys, 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 a second metal that is stable and has a work function greater than that 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 through 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 to allow 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 advantageous.

[0243] 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.

[0244] -Emitting Layer-

[0245] 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 the light-emitting layer contains a light-emitting dopant and a host.

[0246] Regarding the luminescent dopant and the substrate, for example, the luminescent dopant can be used at 0.10% to 10% and the substrate at 99.9% to 90%. Preferably, the luminescent dopant is 1.0% to 5.0% and the substrate is 99% to 95%, more preferably, the luminescent dopant is 1.0% to 3.0% and the substrate is 99% to 97%.

[0247] Unless otherwise specified, % in this specification refers to mass.

[0248] The first and second subjects are used as the main components in the light-emitting layer. For example, 10% to 90% of the first subject and 90% to 10% of the second subject can be used. Preferably, the first subject is 30% to 70% and the second subject is 70% to 30%, more preferably the first subject is 40% to 60% and the second subject is 60% to 40%.

[0249] Furthermore, as other than the aforementioned main body, one or more existing main bodies may be used in combination, and their usage may be set to 50% or less, preferably 25% or less, in the total amount of main body material.

[0250] As other existing entities that can be used, compounds with hole transport capability, electron transport capability and high glass transition temperature are preferred, and those with a T1 greater than that of luminescent dopants are preferred.

[0251] The preferred substrate is a compound possessing hole transport capability, electron transport capability, and a high glass transition temperature, and having a T1 greater than that of the luminescent dopant. Specifically, the T1 of the substrate is preferably 0.010 eV or more higher than that of the luminescent dopant, more preferably 0.030 eV or more, and even more preferably 0.10 eV or more. Furthermore, a TADF-active compound can be used as the substrate material, preferably a compound with a ΔEST of 0.20 eV or less.

[0252] Other entities are known from numerous patent documents and other sources, and can therefore be selected from these. Specific examples of entities are not particularly limited, but can include various metal complexes represented by metal complexes of indole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, phenylenediamine derivatives, arylamine derivatives, styrene-anthracene derivatives, fluorene derivatives, stilbene derivatives, triphenylene derivatives, carborane derivatives, porphyrin derivatives, phthalocyanine derivatives, 8-hydroxyquinoline derivatives, or metal phthalocyanines, benzoxazole, or benzothiazole derivatives; poly(N-vinylcarbazole) derivatives, aniline copolymers, thiophene oligomers, polythiophene derivatives, polyphenylene derivatives, polyphenylene vinylidene derivatives, polyfluorene derivatives, and other polymeric compounds.

[0253] 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.

[0254] Ideally, premixing methods should be those that can mix as uniformly as possible. Examples of such methods include pulverizing and mixing, heating and melting under reduced pressure or inert gas environments such as nitrogen, or sublimation, but these methods are not the only ones that can be used.

[0255] As the luminescent dopant in the luminescent layer, the polycyclic aromatic compound material or an organic luminescent material with a ΔEST of 0.20 eV or less can be used. Preferably, the polycyclic aromatic compound material with a ΔEST of 0.20 eV or less is used.

[0256] The luminescent layer may contain two or more luminescent dopants. For example, it may be the polycyclic aromatic compound material and luminescent dopants containing other compounds. In this case, the luminescent dopant containing other compounds is preferably ΔEST of 0.20 eV or less, but is not limited thereto.

[0257] When the luminescent layer contains two or more luminescent dopants, the first dopant may be a compound represented by general formula (2), general formula (3) or general formula (4), or a partially structured polycyclic aromatic compound having the structure represented by general formula (2) as a partial structure. Existing compounds may also be used as luminescent dopants in the second dopant. Preferably, the content of the first dopant is 0.050% to 50% relative to the host material, and the content of the second dopant is 0.050% to 50% relative to the host material, and the total content of the first dopant and the second dopant relative to the host material does not exceed 50%.

[0258] Other luminescent dopants are known from numerous patent documents and other sources, and can be selected from these. Specific examples of dopants are not particularly limited, but can include: phenanthrene, anthracene, pyrene, tetraphenylene, pentaphenylene, perylene, naphthylpyrene, dibenzo[a]pyrene, rubrene, and condensation ring derivatives such as 1,2-benzophenanthrene; benzoxazole derivatives, benzothiazole derivatives, benzimidazole derivatives, benzotriazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, imidazole derivatives, thiadiazole derivatives, triazole derivatives, pyrazoline derivatives, stilbene derivatives, thiophene derivatives, tetraphenylbutadiene derivatives, cyclopentadiene derivatives, bis(styrene)-anthracene derivatives or bis(styrene)-phenylene derivatives, bis(styrene)-aryl derivatives, diazabenzodiinden derivatives, furan derivatives, benzofuran derivatives, isobenzofuran derivatives, dibenzofuran derivatives, coumarin derivatives, dicyandiamide derivatives, etc. Methylpyran derivatives, dicyanomethylenethiaran derivatives, polymethimide derivatives, anthocyanin derivatives, oxobenzanthracene derivatives, xanthracene derivatives, rhodamine derivatives, fluorescein derivatives, piperanium derivatives, 2-hydroxyquinoline (carbostyril) derivatives, acridine derivatives, oxazine derivatives, phenylene oxide derivatives, quinacridone derivatives, quinazoline derivatives, pyrrolopyridine derivatives, furopyridine derivatives, 1,2,5-thiadiazopyrene derivatives, pyrrolemethylene derivatives, violetone derivatives, pyrrolopyrrole derivatives, squaric acid lactone derivatives, violetanone derivatives, phenazine derivatives, acridineone derivatives, deazaflavin derivatives, fluorene derivatives, and benzo[a]fluorene derivatives, etc.

[0259] The luminescent dopant and the first or second host can be deposited from different evaporation sources, or they can be premixed before evaporation to form a premix, thereby depositing the luminescent dopant and the first or second host simultaneously from a single evaporation source.

[0260] -Injection Layer-

[0261] 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 added as needed.

[0262] -hole blocking layer-

[0263] In a broad sense, a hole blocking layer 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. Existing 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.

[0264] -Electron blocking layer-

[0265] In a broad sense, the 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. Existing electron blocking layer materials can be used as the electron blocking layer material. To leverage the properties of the luminescent dopant, a material used as the primary substrate can also be used as the electron blocking layer material. The preferred thickness of the electron blocking layer is 3 nm to 100 nm, more preferably 5 nm to 30 nm.

[0266] -Exciton blocking layer-

[0267] An exciton blocking layer is 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.

[0268] Existing exciton blocking layer materials can be used as the material for the exciton blocking layer.

[0269] 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.

[0270] -Hole transport layer-

[0271] The hole transport layer contains hole transport material with the function of transporting holes, and the hole transport layer can be a single layer or multiple layers.

[0272] 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 can be selected from existing compounds. 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-amine derivatives are preferred, and arylamine derivatives are more preferred.

[0273] -Electron transport layer-

[0274] The electron transport layer contains materials that can transport electrons, and the electron transport layer can be a single layer or multiple layers.

[0275] As an electron transport material (and sometimes a hole blocking material), it only needs to have the function of transmitting electrons injected from the cathode to the light-emitting layer. The electron transport layer can be any compound selected from existing compounds, such as polycyclic aromatic derivatives of naphthalene, anthracene, phenanthroline, 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 them as the backbone of polymers can also be used.

[0276] 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.

[0277] Example

[0278] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0279] The following examples and comparative examples show the compounds used.

[0280] [Chemistry 55]

[0281]

[0282] For compounds (3-2) and (5-2), S1 and T1 were determined. The results are shown in Table 1.

[0283] S1 and T1 are determined in the following manner.

[0284] On a quartz substrate, vacuum evaporation is used at a vacuum degree of 10. -4 Under conditions below Pa, using BH1 as the host, compounds (3-2) or (5-2) as luminescent dopants are co-deposited from different evaporation sources to form a evaporation film with a thickness of 100 nm. Co-deposition is then performed under evaporation conditions where the concentration of compound (3-2) or compound (5-2) is 3%.

[0285] Regarding S1, the emission spectrum of the vapor-deposited film is measured, and a tangent line is drawn at the starting point of the short wavelength side of the emission spectrum. The wavelength value λedge[nm] at the intersection of the tangent line and the horizontal axis is substituted into the following equation (i) to calculate S1.

[0286] S1[eV]=1239.85 / λedge (i)

[0287] Regarding T1, the phosphorescence spectrum of the vapor-deposited film is measured, and a tangent line is drawn at the starting point of the short wavelength side of the phosphorescence spectrum. The wavelength value λedge[nm] at the intersection of the tangent line and the horizontal axis is substituted into equation (ii) to calculate T1.

[0288] T1[eV]=1239.85 / λedge (ii)

[0289] The measurement results are shown in Table 1.

[0290] [Table 1]

[0291] compound S1(eV) T1(eV) S1-T1(eV) 3-2 2.79 2.61 0.18 5-2 2.71 2.67 0.04

[0292] Example 1

[0293] On a glass substrate with an ITO-containing anode having a film thickness of 70 nm, a vacuum evaporation method was used to deposit the film at a vacuum degree of 4.0 × 10⁻⁶. -5Pa is used to stack the thin films. First, on ITO, HAT-CN is formed to a thickness of 10 nm as a hole injection layer, and then HT-1 is formed to a thickness of 25 nm as a hole transport layer. Next, compound (1-56) is formed to a thickness of 5 nm as an electron blocking layer. Next, using compound (1-56) as a first host, compound (2-6) as a second host, and compound (5-2) as a luminescent dopant, co-deposition is performed 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 (5-2) is 2% and the mass ratio of the first host to the second host is 70:30. Next, compound (2-6) 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, on the electron transport layer, lithium fluoride (LiF) is formed to a thickness of 1 nm 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.

[0294] Examples 2 to 11

[0295] The types of luminescent dopants, the first host and the second host, and the mass ratio of the first host to the second host are set as shown in Table 2. Otherwise, the organic EL element is fabricated in the same manner as in Example 1.

[0296] Comparative Example 1

[0297] On a glass substrate with an ITO-containing anode having a film thickness of 70 nm, a vacuum evaporation method was used to deposit the film at a vacuum degree of 4.0 × 10⁻⁶. -5 Pa is used to stack various thin films. First, on ITO, HAT-CN is formed to a thickness of 10 nm as a hole injection layer, and then HT-1 is formed to a thickness of 25 nm as a hole transport layer. Next, compound (1-56) is formed to a thickness of 5 nm as an electron blocking layer. Next, compound (1-56) as the first host and compound (5-2) 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 (5-2) is 2%. Next, compound (2-6) 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, on the electron transport layer, lithium fluoride (LiF) is formed to a thickness of 1 nm as an electron injection layer. Finally, on the electron injection layer, aluminum (Al) is formed to a thickness of 70 nm as a cathode, thereby fabricating an organic EL device.

[0298] Comparative Example 2, Comparative Example 3, Comparative Example 5, Comparative Example 6, Comparative Example 7

[0299] An organic EL element was 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.

[0300] Comparative Example 4, Comparative Example 8

[0301] The luminescent dopant, the first host, and the second host are the compounds shown in Table 2. Otherwise, the organic EL element is fabricated in the same manner as in Example 1.

[0302] [Table 2]

[0303] dopant First subject Second subject Example 1 5-2 1-56(70％) 2-6(30％) Example 2 5-2 1-56(30％) 2-6(70％) Example 3 5-2 1-55(50％) 2-6(50％) Example 4 5-2 1-38(50％) 2-6(50％) Example 5 5-2 1-48(50％) 2-6(50％) Example 6 5-2 1-56(50％) 2-3(50％) Example 7 5-2 1-56(50％) 2-15(50％) Example 8 5-2 1-56(50％) 2-38(50％) Example 9 3-2 1-56(50％) 2-6(50％) Example 10 5-2 1-138(50％) 2-6(50％) Example 11 5-2 1-56(70％) 2-87(30％) Comparative Example 1 5-2 1-56 - Comparative Example 2 5-2 2-6 - Comparative Example 3 5-2 mCBP - Comparative Example 4 5-2 mCBP (50%) 2-6(50％) Comparative Example 5 3-2 1-48 Comparative Example 6 3-2 2-6 Comparative Example 7 3-2 mCBP Comparative Example 8 3-2 mCBP (50%) 2-6(50％)

[0304] 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 lifespan, the initial luminance was measured at 500 cd / m². 2 The time it takes for the brightness to decrease to 50% of its initial brightness.

[0305] [Table 3]

[0306]

[0307] According to Table 3, the organic EL element of the embodiment has the characteristics of low voltage, high efficiency, and long life, and emits blue light according to the maximum emission wavelength.

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 light-emitting layer 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), and contains a polycyclic aromatic compound represented by the following general formula (3) or a polycyclic aromatic compound having the structure represented by the following general formula (3) as a partial structure as a luminescent dopant. Here, Z represents the group containing an indolocarbazole ring as shown in general formula (1a). To be with L 1 The bond position, Ring A is a heterocyclic ring as represented by equation (1b), and ring A and its adjacent rings are condensed at any position; L 1 With L 2 Each is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 6 to 17 carbon atoms. Ar 1 with Ar 2 Each is independently an aromatic hydrocarbon group with 6 to 30 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 2 to 8 of these. R 1 They are, independently, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, substituted or unsubstituted aromatic hydrocarbon groups with 6 to 18 carbon atoms, or substituted or unsubstituted aromatic heterocyclic groups with 3 to 17 carbon atoms; a represents integers from 1 to 3, b represents integers from 0 to 3, c and d independently represent integers from 0 to 4, e represents integers from 0 to 2, and f represents integers from 0 to 3. Here, X 1 Each can be represented independently as N or CH, and at least one X. 1 N represents N; Ar 3 Each of these can be independently represented as an aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these aromatic rings. Here, rings C, D, and E are independently substituted or unsubstituted aromatic hydrocarbon rings with 6 to 24 carbon atoms, or substituted or unsubstituted aromatic heterocycles with 3 to 17 carbon atoms. Y 4 For B, P, P=O, P=S, Al, Ga, As, Si-R 4 or Ge-R 5 , R 4 and R 5 They are, independently, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms. X 4 Independently, O and N-Ar respectively 4 S or Se, Ar 4 Each is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these, N-Ar 4 It can bond with any of the C-ring, D-ring, or E-ring to form a heterocycle containing N. R 3 Each of these groups independently represents a cyano group, a deuterium group, a diarylamino group with 12–44 carbon atoms, an arylheteroarylamino group with 12–44 carbon atoms, a diheteroarylamino group with 12–10 carbon atoms, an aromatic hydrocarbon group with 6–18 carbon atoms (substituted or unsubstituted), or an aromatic heterocyclic group with 3–17 carbon atoms (substituted or unsubstituted). C ring, D ring, E ring, R 3 R 4 R 5 and Ar 4 At least one hydrogen in it may be replaced by a halogen or deuterium; v represents an integer from 0 to 4, and x represents an integer from 0 to 3.

2. The organic electric field light-emitting element according to claim 1, characterized in that... Polycyclic aromatic compounds having the structure represented by the general formula (3) as a partial structure are polycyclic aromatic compounds represented by the following general formula (4). Here, rings F, G, H, I, and J are independently substituted or unsubstituted aromatic hydrocarbon rings with 6 to 24 carbon atoms, or substituted or unsubstituted aromatic heterocycles with 3 to 17 carbon atoms. 4 Y 4 R 3 x and v have the same meaning as in general formula (3), w represents an integer from 0 to 4, y represents an integer from 0 to 3, and z represents an integer from 0 to 2; At least one hydrogen atom in the F, G, H, I, and J rings may be substituted with a halogen or deuterium.

3. The organic electric field light-emitting element according to claim 1, characterized in that... Polycyclic aromatic compounds having the structure represented by the general formula (3) as a partial structure are boron-containing polycyclic aromatic compounds represented by the following formula (5). Here, X 9 N-Ar are represented independently. 6 O or S, at least one X 9 Indicates N-Ar 6 ; Ar 6 Each of the following independently represents a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these aromatic rings; N-Ar 6 It can also bond with the aromatic ring to form a heterocycle containing N; R 9 Each of the following can be independently represented: 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. m and n independently represent integers from 0 to 4, o and p independently represent integers from 0 to 3, and q represents integers from 0 to 2.

4. The organic electric field light-emitting element according to claim 1, characterized in that... The general formula (2) is the following formula (6). Here, Ar 3 and X 1 It has the same meaning as general formula (2); R 2 Each of the following can be independently represented: deuterium, aliphatic hydrocarbon group with 1 to 10 carbon atoms, triarylsilyl group, 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. g and h represent integers from 0 to 4 independently.

5. The organic electric field light-emitting element according to claim 1, characterized in that... The general formula (2) is the following formula (7). Here, Ar 3 and X 1 R has the same meaning as general formula (2). 2 It has the same meaning as equation (6); g, h, i, and j each independently represent integers from 0 to 4.

6. The organic electric field light-emitting element according to claim 1, characterized in that... In the general formula (2), X 1 All are N.

7. The organic electric field light-emitting element according to claim 1, characterized in that... The general formula (1) is either formula (8a) or formula (8b) below. Here, L 3 and L 4 Each can be independently represented as a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 6 to 17 carbon atoms; Ar 4 and Ar 5 Each is independently an aromatic hydrocarbon group with 6 to 30 carbon atoms that has been substituted or unsubstituted, an aromatic heterocyclic group with 6 to 17 carbon atoms that has been substituted or unsubstituted, or a linked aromatic group consisting of 2 to 8 of these. k and l independently represent integers from 0 to 3.

8. The organic electric field light-emitting element according to claim 1, characterized in that... The difference ΔEST between the excited singlet energy S1 and the excited triplet energy T1 of the luminescent dopant is less than 0.20 eV.

9. The organic electric field light-emitting element according to claim 8, characterized in that... The ΔEST is below 0.10 eV.

10. The organic electric field light-emitting element according to any one of claims 1 to 9, characterized in that... It contains 0.10% to 10% by mass of a luminescent dopant and 99.9% to 90% by mass of a host, wherein the host contains 10% to 90% by mass of the first host and 90% to 10% by mass of the second host.

11. 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 light-emitting layer contains a first host selected from compounds represented by the following general formula (1), a second host selected from compounds represented by the following general formula (2), and a luminescent dopant whose difference ΔEST between the excited singlet energy S1 and the excited triplet energy T1 is less than 0.20 eV. Here, Z represents the group containing an indolocarbazole ring as shown in general formula (1a). To be with L 1 The bond position, Ring A is a heterocyclic ring as represented by equation (1b), and ring A and its adjacent rings are condensed at any position; L 1 With L 2 Each is independently a substituted or unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 6 to 17 carbon atoms. Ar 1 with Ar 2 Each is independently an aromatic hydrocarbon group with 6 to 30 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 2 to 8 of these. R 1 They are, independently, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, substituted or unsubstituted aromatic hydrocarbon groups with 6 to 18 carbon atoms, or substituted or unsubstituted aromatic heterocyclic groups with 3 to 17 carbon atoms; a represents integers from 1 to 3, b represents integers from 0 to 3, c and d independently represent integers from 0 to 4, e represents integers from 0 to 2, and f represents integers from 0 to 3. Here, X 1 Each can be represented independently as N or CH, and at least one X. 1 N represents N; Ar 3 Each of these can be independently represented as an aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a linked aromatic group consisting of 2 to 8 of these aromatic rings.

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