Organic electroluminescent element

Abstract

The present application provides a blue light-emitting organic electroluminescent element with high luminous efficiency and long lifetime. The organic electroluminescent element has one or more light-emitting layers between facing anode and cathode, at least one light-emitting layer contains one or more hosts selected from indolocarbazole compounds represented by the following general formula (1), and contains a polycyclic aromatic compound having a structure represented by the following general formula (2) or a polycyclic aromatic compound having the structure as a partial structure as a light-emitting dopant. In the formula, Z is a group containing an indolocarbazole ring, X 1 is O, N-Ar 3 , S or Se, Y 1 is B, P, P=O, P=S, Al, Ga, As, Si-R 2 or Ge-R 3 .

Description

Technical Field

[0001] This invention relates to an organic electric field light-emitting element (hereinafter 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] However, extending the lifetime of blue phosphorescent organic EL devices remains 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 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.

[0005] 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 the singlet and triplet energy levels, an inverse intersystem crossing occurs from the triplet exciton to the singlet exciton, theoretically increasing 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 Document 5: WO2014 / 166585

[0013] Patent Document 6: WO2016 / 042997

[0014] Patent documents 3 and 4 disclose a high-efficiency organic EL element that emits blue light by using a TADF material containing a polycyclic aromatic compound represented by the following compounds as a luminescent dopant and using a material containing a carbazole ring as the host, but do not disclose specific lifetime characteristics.

[0015] [Chemistry 1]

[0016]

[0017] Patent document 5 discloses an organic EL element that uses TADF material as a luminescent dopant and a material containing a compound with an indole-carbazole ring as the main body, but does not show the usefulness of the present invention.

[0018] Patent document 6 discloses an organic EL element that uses a material made by premixing two or more compounds containing indole-carbazole rings as the main body, but does not disclose an element that uses a TADF material containing the polycyclic aromatic compound as a luminescent dopant. Summary of the Invention

[0019] 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 a durable and practically applicable lifespan. The object of this invention is to provide a practically useful organic EL element that features low driving voltage, high efficiency, and long lifespan.

[0020] The present invention is an organic electric field light-emitting element, which includes one or more light-emitting layers between opposing anodes and cathodes. At least one light-emitting layer of the organic electric field light-emitting element contains a main body selected from compounds represented by the following general formula (1), and contains a polycyclic aromatic compound represented by the following general formula (2) or a polycyclic aromatic compound having the structure represented by the following general formula (2) as a partial structure as a light-emitting dopant.

[0021] [Chemistry 2]

[0022]

[0023]

[0024]

[0025] Here, Z represents the group containing an indolocarbazole ring as shown in formula (1a).

[0026] *For L 1 The bond position,

[0027] Ring A is a heterocyclic ring as represented by equation (1b), and ring A and its adjacent rings are condensed at any position.

[0028] L 1 and 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 3 to 17 carbon atoms.

[0029] Ar 1 and Ar 2 Each 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.

[0030] 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.

[0031] 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.

[0032] [Chemistry 3]

[0033]

[0034] Here, rings C, D, and E are independently aromatic hydrocarbon rings with 6 to 24 carbon atoms, or aromatic heterocycles with 3 to 17 carbon atoms.

[0035] Y 1 For B, P, P=O, P=S, Al, Ga, As, Si-R 2 or Ge-R 3 R 2 and R 3They 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.

[0036] X 1 Independently, O and N-Ar respectively 3 S or Se,

[0037] Ar 3 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 3 It can bond with any of the C-ring, D-ring, or E-ring to form a heterocycle containing N.

[0038] C ring, D ring, E ring, R 2 R 3 R 6 and Ar 3 At least one hydrogen atom in the atom may be replaced by a halogen or deuterium.

[0039] R 6 The substituents representing the C, D, and E rings independently represent cyano, deuterium, diarylamino with 12–44 carbons, arylheteroarylamino with 12–44 carbons, diheteroarylamino 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.

[0040] v represents an integer from 0 to 4, and x represents an integer from 0 to 3.

[0041] As a polycyclic aromatic compound having the structure represented by the general formula (2) as a part of the structure, there are polycyclic aromatic compounds represented by the following formula (3) or polycyclic aromatic compounds containing boron represented by the following formula (4).

[0042] [Chemistry 4]

[0043]

[0044] Here, rings F, G, H, I, and J are each independently an aromatic hydrocarbon ring with 6 to 24 carbon atoms, either substituted or unsubstituted, or an aromatic heterocycle with 3 to 17 carbon atoms, either substituted or unsubstituted.

[0045] Y 2 Y of the general formula (2) 1 They have the same meaning.

[0046] X2 X of the general formula (2) 1 They have the same meaning.

[0047] At least one hydrogen atom in the F, G, H, I, and J rings may be substituted with a halogen or deuterium.

[0048] R 6 x and v have the same meaning as the general formula (2).

[0049] 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.

[0050] [Chemistry 5]

[0051]

[0052] Here, X 3 N-Ar are represented independently. 5 O or S, at least one X 3 Indicates N-Ar 5 .

[0053] Ar 5 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 5 It can also be used with X 3 Any of the bonded aromatic rings can be bonded together to form a heterocycle containing N.

[0054] R 61 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.

[0055] g and h independently represent integers from 0 to 4, i and j independently represent integers from 0 to 3, and k represents integers from 0 to 2.

[0056] The light-emitting layer may contain two or more main components selected from the compounds represented by the general formula (1).

[0057] Selected from at least one of the main components of the compound represented by the general formula (1), it is possible to L 1 and L 2 Only one of them is a nitrogen-containing aromatic heterocyclic group with 3 to 17 carbon atoms.

[0058] The light-emitting layer may include a first subject represented by formula (5a) or formula (5b) below, and a second subject represented by formula (6) below, as subjects selected from the compound represented by the general formula (1).

[0059] [Chemistry 6]

[0060]

[0061]

[0062]

[0063] Here, Z and Ar 1 a and b have the same meaning as in general formula (1).

[0064] X 4 It represents O or S.

[0065] b1 represents an integer from 0 to 2, and is a number that is 1 less than b.

[0066] X 5 Each can independently represent N, CH, C-, or CR. 7 At least one X 5 N. X 5 When it is C-, it is related to Ar. 1 Bond.

[0067] R 7 Independently represents a cyano group, an aliphatic hydrocarbon group with 1 to 10 carbon atoms, or a diarylamino group with 12 to 44 carbon atoms.

[0068] At least one of the main bodies selected from the compounds represented by the general formula (1) may be compounds represented by formula (7) or formula (8), preferably compounds represented by formula (7).

[0069] [Chemistry 7]

[0070]

[0071]

[0072] Here, L 1 L 2 Ar 1 Ar 2 b and f have the same meaning as the general formula (1).

[0073] The difference (ΔEST) between the excited singlet energy (S1) and the excited triplet energy (T1) of the luminescent dopant is preferably 0.20 eV or less, more preferably 0.10 eV or less.

[0074] The light-emitting layer may contain 99.9% to 90% of a host material relative to 0.10% to 10% of the luminescent dopant, and more preferably contains 10% to 90% of the first host material and 90% to 10% of the second host material.

[0075] The organic EL element of the present invention contains specific luminescent dopants and a host material in its light-emitting layer, thus achieving a low driving voltage, high luminous efficiency, and long lifetime. It is assumed that the main reason for the low driving voltage of the organic EL element is that the indole-carbazole compound, as the host material, has the characteristic of easily injecting holes. It is believed that by using two or more host materials containing indole-carbazole compounds with different electron or hole injection transport properties in the light-emitting layer, the balance between holes and electrons can be maintained more precisely, thus resulting in an organic EL element with higher luminous efficiency. It is believed 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 or electrons into the host material containing the indole-carbazole compound, the electrochemical load on the luminescent dopants can be reduced. Attached Figure Description

[0076] Figure 1 This is a schematic cross-sectional view showing an example of an organic EL element.

[0077] Explanation of symbols

[0078] 1: Substrate

[0079] 2: Anode

[0080] 3: Hole injection layer

[0081] 4: Hole transport layer

[0082] 5: Emissive layer

[0083] 6: Electron transport layer

[0084] 7: Cathode Detailed Implementation

[0085] The organic EL element of the present invention includes one or more light-emitting layers between opposing anodes and cathodes, and at least one light-emitting layer contains a host and a light-emitting dopant.

[0086] As a host, it contains one or more host compounds selected from those represented by the general formula (1). As a luminescent dopant, it contains a polycyclic aromatic compound represented by the general formula (2) or a polycyclic aromatic compound having the structure represented by the general formula (2) as a partial structure.

[0087] The compound represented by the general formula (1) used as the main body will be described.

[0088] In general formula (1), Z is the group containing an indolocarbazole ring as represented by formula (1a), and ring A is the heterocycle represented by formula (1b). The heterocycle of ring A is condensed with the adjacent ring at any position.

[0089] L 1 and L 2 Each 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 represents an aromatic hydrocarbon group with 6 to 20 carbon atoms or an aromatic heterocyclic group with 3 to 15 carbon atoms.

[0090] Preferably L 1 With L 2 One of them is a nitrogen-containing aromatic heterocyclic group with 3 to 17 carbon atoms.

[0091] When using two or more compounds represented by general formula (1), it is preferable to use at least one compound L. 1 and L 2 One of them is a nitrogen-containing aromatic heterocyclic group with substituted or unsubstituted carbons of 3 to 17.

[0092] As L 1 and L 2 Specific examples of unsubstituted aromatic hydrocarbon groups or aromatic heterocyclic groups 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, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan. The groups formed 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, dibenzothiphene, dibenzoselenophene, or carbazole. Here, "formed group" refers to a group formed by removing a specified number of hydrogen atoms from these compounds. 1 and L 2 These are the bases with valences of a+b and c+d, respectively.

[0093] More preferably, it is a group formed from benzene, naphthalene, pyridine, triazine, dibenzofuran, or carbazole.

[0094] Ar 1 and Ar 2Each 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 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 15 carbon atoms, or a linked aromatic group consisting of 2 to 4 of these groups. More preferably, the linked aromatic group consists of a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms, or a linked aromatic group consisting of 2 to 3 of these groups.

[0095] As Ar 1 and Ar 2 Specific examples of unsubstituted aromatic hydrocarbon groups, aromatic heterocyclic groups, or those linked to aromatic groups include benzene, naphthalene, acenaphthene, acenaphthene, azulene, anthracene, 1,2-benzophenanthrene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, tetraphenylene, pentaphenylene, hexaphenylene, hexabenzophenyl, heptaphenylene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, A group formed by removing a hydrogen atom from compounds consisting of 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, carbazole, or compounds consisting of 2 to 8 of these linked together. Preferably, a group formed by removing a hydrogen atom from compounds consisting of benzene, naphthalene, acenaphthene, acenaphthene, azulene, pyridine, pyrimidine, triazine, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, or compounds consisting of 2 to 4 of these linked together. More preferably, a group is formed by removing a hydrogen atom from a compound consisting of two to three of the following: benzene, pyridine, pyrimidine, triazine, dibenzofuran, dibenzothiophene, carbazole, or the like.

[0096] Ar 1 and Ar 2 The preferred compounds are phenyl, biphenyl, or terphenyl. Terphenyl compounds can be linear or branched.

[0097] R 1Each 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).

[0098] 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, or octyl.

[0099] 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, 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, and furan. The radical formed by removing one 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, dibenzothiphene, dibenzoselenophene, and carbazole. Preferably, the radical is formed by removing one hydrogen atom from the following compounds: 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, and carbazole.

[0100] Preferably, the group can be derived from benzene, naphthalene, azurite, 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, and carbazole.

[0101] In this specification, the unsubstituted aromatic hydrocarbon group or aromatic heterocyclic group described may each have substituents. When substituents are present, the substituents are preferably deuterium, cyano, triarylsilyl, aliphatic hydrocarbon group having 1 to 10 carbon atoms, or diarylamino with 12 to 44 carbon atoms. Here, when the substituent is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, it may be linear, branched, or cyclic.

[0102] 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 having 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, satisfies the aforementioned range.

[0103] 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.

[0104] In this specification, a linked aromatic group refers to an aromatic group in which the carbon atoms of the aromatic ring are linked together by single bonds. An aromatic group is formed by the linkage of two or more aromatic groups; these can be linear or branched. The aromatic group can be an aromatic hydrocarbon group or an aromatic heterocyclic group; multiple aromatic groups can be the same or different. A linked aromatic group is different from a substituted aromatic group.

[0105] 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.

[0106] In general formula (1), a represents an integer from 1 to 3, b represents an integer from 0 to 3, and f represents an integer from 0 to 3. Preferably, a is 1 to 2, b is 0 to 2, and f is 0 to 2.

[0107] c and d independently represent integers from 0 to 4, and e represents integers from 0 to 2. Preferably, c and d are either 0 or 1.

[0108] In the light-emitting layer, one or more compounds represented by general formula (1) are used, preferably two or more.

[0109] More preferably, the first subject is a compound represented by formula (5a) or formula (5b), and the second subject is a compound represented by formula (6).

[0110] In general formula (1), and formula (5a), (5b), or (6), the common symbols have the same meaning.

[0111] In equation (5a), X 4 Let O or S be the number. In equation (5b), b1 is an integer from 0 to 2, and represents a number that is 1 less than b.

[0112] In equation (6), X 5 Each can independently represent N, CH, C-, or CR. 7 At least one X 5 N. X 5 When it is C-, it is related to Ar. 1 Bonding. R 7 Independently represents a cyano group, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a diarylamino group having 12 to 44 carbon atoms. R 7 Specific examples can be understood from the description of the substituents.

[0113] As a preferred embodiment of general formula (1), there is formula (7) or formula (8), and more preferably formula (7).

[0114] In general formulas (1), (7), and (8), the common symbols have the same meaning.

[0115] The following are specific examples of compounds represented by general formula (1), but are not limited to these exemplified compounds.

[0116] [Chemistry 8]

[0117]

[0118] [Chemistry 9]

[0119]

[0120] [Chemistry 10]

[0121]

[0122] [Chemistry 11]

[0123]

[0124] [Chemistry 12]

[0125]

[0126] [Chemistry 13]

[0127]

[0128] [Chemistry 14]

[0129]

[0130] [Chemistry 15]

[0131]

[0132] [Chemistry 16]

[0133]

[0134] [Chemistry 17]

[0135]

[0136] [Chemistry 18]

[0137]

[0138] [Chemistry 19]

[0139]

[0140] [Chemistry 20]

[0141]

[0142] [Chemistry 21]

[0143]

[0144] [Chemistry 22]

[0145]

[0146] [Chemistry 23]

[0147]

[0148] [Chemistry 24]

[0149]

[0150] [Chemistry 25]

[0151]

[0152] [Chemistry 26]

[0153]

[0154] [Chemistry 27]

[0155]

[0156] [Chemistry 28]

[0157]

[0158] [Chemistry 29]

[0159]

[0160] [Chemistry 30]

[0161]

[0162] [Chemistry 31]

[0163]

[0164] [Chemistry 32]

[0165]

[0166] [Chemistry 33]

[0167]

[0168] [Chemistry 34]

[0169]

[0170] [Chemistry 35]

[0171]

[0172] [Chemistry 36]

[0173]

[0174] [Chemistry 37]

[0175]

[0176] [Chemistry 38]

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[0178] [Chemistry 39]

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[0180] [Chemistry 40]

[0181]

[0182] [Chemistry 41]

[0183]

[0184] [Chemistry 42]

[0185]

[0186] [Chemistry 43]

[0187]

[0188] [Chemistry 44]

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[0190] [Chemistry 45]

[0191]

[0192] [Chemistry 46]

[0193]

[0194] [Chemistry 47]

[0195]

[0196] [Chemistry 48]

[0197]

[0198] The luminescent dopant used in the organic EL element of the present invention is a polycyclic aromatic compound represented by the general formula (2) or a polycyclic aromatic compound having the structure represented by the general formula (2) as part of its structure.

[0199] As a polycyclic aromatic compound having the structure represented by general formula (2) as a part of the structure, it is preferably a polycyclic aromatic compound represented by general formula (3), and more preferably a boron-containing polycyclic aromatic compound represented by formula (4).

[0200] In general formulas (2) and (3), 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.

[0201] 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.

[0202] R 6 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.

[0203] As R 6 Specific examples when referring to aliphatic hydrocarbon groups with 1 to 10 carbon atoms, and R 1 The situation is the same.

[0204] As R 6Specific examples of unsubstituted aromatic hydrocarbon groups having 6 to 18 carbon atoms, or unsubstituted aromatic heterocyclic groups having 3 to 17 carbon atoms, can be listed from benzene, naphthalene, acenaphthene, 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 The radical formed by removing one 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, dibenzothiphene, dibenzoselenophene, and carbazole. Preferably, the group can be derived 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, chromogenone, dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole. More preferably, the group can be derived from benzene or naphthalene.

[0205] As R 6 Specific examples of diarylamino, arylheteroarylamino, diheteroarylamino, and aliphatic hydrocarbon groups having 12-44 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, and nonyl. Preferably, the following are examples: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthrylamino, diphenoxyamino, dipyreneamino. More preferably, the following are examples: diphenylamino, diphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dibenzofuranylphenylamino, or carbazoleylphenylamino.

[0206] v represents an integer from 0 to 4, preferably an integer from 0 to 2, and more preferably an integer from 0 to 1.

[0207] x represents an integer from 0 to 3, preferably an integer from 0 to 2, and more preferably 0 to 1.

[0208] Y 1 For B, P, P=O, P=S, Al, Ga, As, Si-R 2 or Ge-R 3 Preferably, it is B, P, P=O or P=S, and more preferably B.

[0209] R 2 and R 3 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).

[0210] As R 2 and R 3 Specific examples when it is an aliphatic hydrocarbon group with 1 to 10 carbon atoms, an unsubstituted aromatic hydrocarbon group with 6 to 18 carbon atoms, or an unsubstituted aromatic heterocyclic group with 3 to 17 carbon atoms, are related to R. 1 The same applies to these cases.

[0211] X 1 Independently, O and N-Ar respectively 3 S or Se, preferably O or N-Ar 3 Or S, more preferably O or N-Ar 3 .

[0212] Ar 3 Each of these groups 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 groups. Preferably, it represents 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 linked aromatic group consisting of 2 to 6 of these groups. More preferably, it represents 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 linked aromatic group consisting of 2 to 4 of these groups.

[0213] More preferably, it is phenyl, biphenyl, or terphenyl.

[0214] Specific examples of unsubstituted aromatic hydrocarbon groups, aromatic heterocyclic groups, or groups linked to aromatic groups include benzene, naphthalene, acenaphthene, 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, quinoxaline. The group is formed by removing one hydrogen atom from compounds consisting of quinazoline, thiadiazole, 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 from compounds consisting of 2 to 4 links of benzene, naphthalene, acenaphthene, acenaphthene, azulene, or these. More preferably, the group is formed from compounds consisting of 2 to 3 links of benzene.

[0215] These unsubstituted aromatic hydrocarbon groups, aromatic heterocyclic groups, or linked aromatic groups may each have substituents. When substituents are present, the substituents may be cyano, aliphatic hydrocarbon group having 1 to 10 carbon atoms, or diarylamino group having 12 to 44 carbon atoms, as described above.

[0216] N-Ar 3 It can also bond with any of the C-ring, D-ring, or E-ring to form a heterocycle containing N. Additionally, C-rings, D-rings, E-rings, and R-rings... 2 R 3 R 6 and Ar 3 At least one hydrogen atom in the atom may be replaced by a halogen or deuterium.

[0217] Polycyclic aromatic compounds having the structure represented by general formula (2) as a partial structure (hereinafter also referred to as partially structured polycyclic aromatic compounds) will be described.

[0218] As a partial structural polycyclic aromatic compound, there are compounds represented by the general formula (3) or formula (4).

[0219] In general formulas (2), (3) and (4), the common symbols have the same meaning.

[0220] In general formula (3), X 2 Having X with general formula (2) 1 The same meaning, Y 2 Having Y with general formula (2) 1 They have the same meaning. 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. Preferably, w is 0 or 2, y is 0 or 1, and z is 0 or 1.

[0221] The F, G, H, I, and J rings are aromatic rings as described above, and 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, preferably aromatic hydrocarbon rings with 6 to 20 carbon atoms, or aromatic heterocycles with 3 to 15 carbon atoms. Specifically, the description is the same as that of the C to E rings in general formula (2).

[0222] The F ring, G ring and C ring and D ring in general formula (2) 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).

[0223] In equation (4), X 3 N-Ar are represented independently. 5 O or S, at least one X 3 Indicates N-Ar 5 Preferably, it represents O or N-Ar. 5 More preferably, it represents N-Ar 5 .

[0224] N-Ar 5 Or Ar 5 N-Ar of general formula (2) 3 Or Ar 3 They have the same meaning.

[0225] R 61 Each of these groups independently represents a cyano group, a deuterium group, a diarylamino group with 12 to 44 carbon atoms, an aliphatic hydrocarbon group with 1 to 10 carbon atoms, 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). 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). 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).

[0226] g and h independently represent integers from 0 to 4, i and j independently represent integers from 0 to 3, and k represents integers from 0 to 2. Preferably, g and h independently represent integers from 0 to 2, i and j are 0 or 1 independently, and k is 0.

[0227] Ar 5 and R 61 Specific examples can be found in Ar of general formula (2). 3 and R 6 The explanation is for understanding.

[0228] Furthermore, N-Ar5 It can also bond with the aromatic ring to form a heterocycle containing N. In this case, Ar 3 It can be directly bonded to the aromatic ring, or it can be bonded via a linker group.

[0229] The following descriptions of some structural polycyclic aromatic compounds refer to equations (3) and (4).

[0230] Equation (3) includes the structure represented by general equation (2) and a portion thereof. From another perspective, although there are two structures represented by general equation (2), they become a structure sharing a common I-ring. That is, the structure represented by general equation (2) is set as a partial structure.

[0231] Similarly, formula (4) becomes a structure with a common central benzene ring, which can be understood as including the structure represented by general formula (2) and a part of its structure.

[0232] The partial structure of the polycyclic aromatic compounds described in this invention has the structure represented by general formula (2) as a partial structure. It is preferable to have a structure that omits any one of the C-rings to E-rings in general formula (2) as another partial structure. Moreover, it is preferable to have one structure represented by general formula (2) as a partial structure and one to three of the other partial structures.

[0233] Examples of such partially structured polycyclic aromatic compounds include those represented by formulas (2-a) to (2-h).

[0234] The compounds represented by the following formula (2-a) correspond, for example, to compounds represented by formula (2-64) described later.

[0235] Formula (2-a) is a structure in which two compounds of general formula (2) share a central benzene ring, and can be understood as a compound containing the structural unit of general formula (2) and containing one of the said partial structures.

[0236] Formula (2-b) is a structure in which two compounds of general formula (2) share a central benzene ring, and can be understood as a compound containing the structural unit of general formula (2) and containing one of the aforementioned partial structures. Additionally, X 1 One is N-Ar 3 It becomes a ring structure that bonds with another aromatic ring to form a ring (condensed ring structure).

[0237] [Chemistry 49]

[0238]

[0239] Furthermore, the partial structure of polycyclic aromatic compounds represented by formula (2-c) corresponds, for example, to compounds represented by formula (2-66) described later. That is, if explained using general formula (2), the structure has three unit structures represented by general formula (2) because it has a benzene ring as the E ring. That is, it can be understood as a compound having a unit structure represented by general formula (2) as a partial structure, and including two structures obtained by removing one benzene ring from general formula (2), i.e., the partial structure. In addition, X 1 For N-Ar 3 It becomes a ring structure that bonds with another aromatic ring.

[0240] In addition, some of the structural polycyclic aromatic compounds represented by formula (2-d), formula (2-e), formula (2-f), and formula (2-g) below correspond to compounds represented by formulas (2-67), (2-68), (2-69), and (2-70) described later.

[0241] If explained using general formula (2), it refers to a compound having two or three unit structures represented by general formula (2) in one compound, which are benzene rings that are C-rings (or D-rings). That is, it can be understood as a compound having a unit structure represented by general formula (2) as a partial structure, and containing a structure obtained by removing a benzene ring from general formula (2), namely the partial structure.

[0242] [Transformation 50]

[0243]

[0244] In addition, some of the structural polycyclic aromatic compounds represented by formula (2-h) correspond to compounds represented by formulas (2-71), (2-72), (2-73), (2-74), and (2-75) described later.

[0245] If explained using general formula (2), it refers to a compound having, for example, a naphthalene ring as the C ring and sharing the ring, and having two unit structures represented by general formula (2) in one compound. That is, it can be understood as a compound having a unit structure represented by general formula (2) as a partial structure, and containing one or two structures obtained by removing one C ring (naphthalene ring) from general formula (2), i.e., the partial structure.

[0246] Some of the structural polycyclic aromatic compounds of the present invention may refer to the following compounds: a plurality of compounds of general formula (2) having one or two aromatic rings (C ring to E ring) in the structural unit of general formula (2) and linked together, and containing at least one structural unit of general formula (2).

[0247] The number of compounds forming the general formula (2) is 2 to 5, preferably 2 to 3. The number of rings (C-rings to E-rings) can be one, two, or three.

[0248] In the formula, X 1 and Y 1 It has the same meaning as general formula (2). 7 R in equation (4) 61 For the same meaning, the preferred groups are cyano, aliphatic hydrocarbon groups with 1 to 10 carbon atoms, or diarylamino with 12 to 44 carbon atoms.

[0249] l is an independent integer from 0 to 4, m is an independent integer from 0 to 1, n is an independent integer from 0 to 3, and o is an independent integer from 0 to 2. Preferably, l and n can be 0 to 2. O is preferably 0 to 1.

[0250] The following examples show specific examples of polycyclic aromatic compounds represented by general formula (2), general formula (3) or formula (4) and other partially structured polycyclic aromatic compounds, but are not limited to these exemplified compounds.

[0251] [Chemistry 51]

[0252]

[0253] [Chemistry 52]

[0254]

[0255] [Chemistry 53]

[0256]

[0257] [Chemistry 54]

[0258]

[0259] [Chemistry 55]

[0260]

[0261] [Chemistry 56]

[0262]

[0263] [Chemistry 57]

[0264]

[0265] [Chem.58]

[0266]

[0267] [Chemistry 59]

[0268]

[0269] [Transformation 60]

[0270]

[0271] [Chemistry 61]

[0272]

[0273] [Chemistry 62]

[0274]

[0275] [Chemistry 63]

[0276]

[0277] [Chemistry 64]

[0278]

[0279] [Chemistry 65]

[0280]

[0281] [Chemistry 66]

[0282]

[0283] [Chemistry 67]

[0284]

[0285] [Chemistry 68]

[0286]

[0287] In the organic EL element of the present invention, the ΔEST of the organic light-emitting material used as a light-emitting dopant is preferably 0.20 eV or less. More preferably, it is 0.15 eV or less, and particularly preferably 0.10 eV or less.

[0288] 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.

[0289] Excellent organic EL devices can be provided by using materials selected from compounds represented by general formula (2), general formula (3) or general formula (4), or polycyclic aromatic compounds having the structure represented by general formula (2) as luminescent dopants, and using materials selected from compounds represented by general formula (1), general formula (5a), general formula (5b), general formula (6), general formula (7) or general formula (8) as the host.

[0290] 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.

[0291] Figure 1 This 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.

[0292] 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.

[0293] -Substrate-

[0294] 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.

[0295] -anode-

[0296] 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.

[0297] -cathode-

[0298] 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.

[0299] 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.

[0300] -Emitting Layer-

[0301] 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.

[0302] Regarding the luminescent dopant and the host, for example, a host of 99.9% to 90% can be used relative to 0.10% to 10% (mass%) of the luminescent dopant. Preferably, the luminescent dopant is 1.0% to 5.0% and the host is 99% to 95%, more preferably, the luminescent dopant is 1.0% to 3.0% and the host is 99% to 97%.

[0303] Unless otherwise specified, % in this specification refers to mass.

[0304] As the main body in the light-emitting layer, two or more main bodies represented by general formula (1) can be used. Regarding the first main body and the second main body, for example, 10% to 90% of the first main body and 90% to 10% of the second main body can be used. Preferably, the first main body is 30% to 70% and the second main body is 70% to 30%, more preferably the first main body is 40% to 60% and the second main body is 60% to 40%.

[0305] Furthermore, as other entities besides those mentioned above, one or more existing entities may be used in combination, and the amount used relative to the total amount of the entity material may be set to 50% or less, preferably 25% or less.

[0306] The host material is a compound possessing hole transport capability, electron transport capability, and a high glass transition temperature, and preferably has a T1 greater than that of the luminescent dopant. Specifically, the T1 of the host material 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 host material, preferably a compound with a ΔEST of 0.20 eV or less.

[0307] 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.

[0308] 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.

[0309] 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.

[0310] As the luminescent dopant in the luminescent layer, a polycyclic aromatic compound represented by the general formula (2) or a polycyclic aromatic compound having the structure represented by the general formula (2) as a partial structure (partially structured polycyclic aromatic compound) is used. As a polycyclic aromatic compound having the structure represented by the general formula (2) as a partial structure, a partially structured polycyclic aromatic compound represented by the general formula (3) is preferred, and a boron-containing partially structured polycyclic aromatic compound represented by the formula (4) is more preferred. As the luminescent dopant, a compound with a difference (ΔEST) between the excited singlet energy (S1) and the excited triplet energy (T1) of 0.20 eV or less is preferred.

[0311] The luminescent dopant may be present in the luminescent layer as a single type or as two or more types. The content of the luminescent dopant relative to the host material is preferably 0.050% to 50%, more preferably 0.10% to 40%.

[0312] In cases where the luminescent layer contains two or more luminescent dopants, the first dopant is a compound represented by general formula (2), general formula (3), or general formula (4), or a partially structured polycyclic aromatic compound, and 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 and second dopants relative to the host material does not exceed 50%.

[0313] Other luminescent dopants are known from numerous patent documents and can be selected from these. Specific examples of dopants are not particularly limited, but can include: phenanthrene, anthracene, pyrene, tetraphenylene, pentaphenylene, perylene, naphthylpyrene, dibenzopyrene, 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.

[0314] 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.

[0315] -Injection Layer-

[0316] 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.

[0317] -hole blocking layer-

[0318] 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, the material used as the host can also be used as the hole blocking layer material. Furthermore, multiple hole-blocking materials can be used in combination.

[0319] -Electron blocking layer-

[0320] 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. Existing electron blocking layer materials can be used as the electron blocking layer material. To leverage the properties of luminescent dopants, materials used as the host material can also be used as the electron blocking layer material.

[0321] The thickness of the electron blocking layer is preferably 3nm to 100nm, and more preferably 5nm to 30nm.

[0322] -Exciton blocking layer-

[0323] 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.

[0324] Existing exciton blocking layer materials can be used as the material for the exciton blocking layer.

[0325] 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.

[0326] -Hole transport layer-

[0327] 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.

[0328] 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 existing compound can be selected for use. 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.

[0329] -Electron transport layer-

[0330] The electron transport layer contains materials that can transport electrons, and the electron transport layer can be a single layer or multiple layers.

[0331] 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.

[0332] 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.

[0333] Example

[0334] The present invention will be described in more detail below through embodiments, but the present invention is not limited to these embodiments.

[0335] The following examples and comparative examples show the compounds used.

[0336] [Chemistry 69]

[0337]

[0338] The S1 and T1 of compounds (2-2) and (4-2) were determined.

[0339] S1 and T1 are determined in the following manner.

[0340] On a quartz substrate, vacuum evaporation is used at a vacuum degree of 10. -4 Under conditions below Pa, BH1 was used as the host material, and compound (2-2) or compound (4-2) was used as the luminescent dopant. Co-evaporation was performed from different evaporation sources to form a evaporation film with a thickness of 100 nm. At this time, co-evaporation was performed under evaporation conditions where the concentration of compound (2-2) or compound (4-2) was 3%.

[0341] 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.

[0342] S1[eV]=1239.85 / λedge (i)

[0343] 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.

[0344] T1[eV]=1239.85 / λedge (ii)

[0345] The measurement results are shown in Table 1.

[0346] [Table 1]

[0347]

[0348] Example 1

[0349] 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 (1-148) is formed to a thickness of 5 nm as an electron blocking layer. Next, compound (1-148) as the first host, compound (1-331) 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% and the weight ratio of the first host to the second host is 50:50. Next, compound (1-331) 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.

[0350] Examples 2 to 19

[0351] The organic EL element was 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 as shown in Table 2.

[0352] Examples 20 to 25

[0353] Organic EL elements were fabricated in the same manner as in Example 1, except that the luminescent dopant and the first or second host were set to the compounds shown in Table 2.

[0354] Comparative Example 1

[0355] 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 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 mCBP is formed to a thickness of 5 nm as an electron blocking layer. Next, compound mCBP 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%. Next, compound (1-331) 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.

[0356] Comparative Example 2

[0357] 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.

[0358] [Table 2]

[0359] dopant First subject Second subject Example 1 4-2 1-148(50％) 1-331(50％) Example 2 4-2 1-148(30％) 1-331(70％) Example 3 4-2 1-148(70％) 1-331(30％) Example 4 4-2 1-115(50％) 1-331(50％) Example 5 4-2 1-184(50％) 1-331(50％) Example 6 4-2 1-151(50％) 1-331(50％) Example 7 4-2 1-148(50％) 1-289(50％) Example 8 4-2 1-148(50％) 1-356(50％) Example 9 4-2 1-184(50％) 1-373(50％) Example 10 2-2 1-10(50％) 1-331(50％) Example 11 4-2 1-148(50％) 1-383(50％) Example 12 4-2 1-148(70％) 1-364(30％) Example 13 4-2 1-148(70％) 1-310(30％) Example 14 4-2 1-148(70％) 1-613(30％) Example 15 4-2 1-148(70％) 1-299(30％) Example 16 4-2 1-148(70％) 1-478(30％) Example 17 4-2 1-148(70％) 1-469(30％) Example 18 4-2 1-148(70％) 1-614(30％) Example 19 4-2 1-615(70％) 1-364(30％) Example 20 4-2 1-148 - Example 21 4-2 1-115 - Example 22 4-2 1-331 - Example 23 4-2 1-356 - Example 24 2-2 1-115 - Example 25 4-2 - 1-364 Comparative Example 1 4-2 mCBP - Comparative Example 2 2-2 mCBP -

[0360] 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. Lifespan is defined as the initial brightness of 500 cd / m². 2 The time until the brightness decays to 50% of the initial brightness is measured.

[0361] [Table 3]

[0362]

[0363] According to Table 3, the organic EL element in the embodiment of the present invention has the characteristics of low voltage, high efficiency, and long lifespan, 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 host compound selected from compounds represented by the following general formula (1), and contains a polycyclic aromatic compound represented by the following general formula (4) as a light-emitting dopant. Here, Z represents the group containing an indolocarbazole ring as shown in 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 and 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 3 to 17 carbon atoms. Ar 1 and 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 3 N-Ar are represented independently. 5 Or S, at least one X 3 Indicates N-Ar 5 ; Ar 5 It is phenyl; N-Ar 5 It can also be used with X 3 Any of the bonded aromatic rings can be bonded together to form a heterocycle containing N; R 61 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. g and h independently represent integers from 0 to 4, i and j independently represent integers from 0 to 3, and k represents integers from 0 to 2.

2. The organic electric field light-emitting element according to claim 1, characterized in that, The luminescent layer contains two or more main components selected from compounds represented by the general formula (1).

3. The organic electric field light-emitting element according to claim 1, characterized in that, L is selected from at least one of the main components of the compound represented by the general formula (1). 1 and L 2 Only one of them is a nitrogen-containing aromatic heterocyclic group with 3 to 17 carbon atoms, either substituted or unsubstituted.

4. The organic electric field light-emitting element according to claim 1, characterized in that, The compound comprises a first subject represented by formula (5a) or formula (5b) below, and a second subject represented by formula (6) below, selected from compounds represented by the general formula (1). Here, Z and Ar 1 a and b have the same meaning as in general formula (1); X 4 Indicates O or S; b1 represents an integer from 0 to 2; X 5 Each can independently represent N, CH, C-, or CR. 7 At least one X 5 N represents N; R 7 Independently represents a cyano group, an aliphatic hydrocarbon group with 1 to 10 carbon atoms, or a diarylamino group with 12 to 44 carbon atoms.

5. The organic electric field light-emitting element according to claim 1, characterized in that, At least one of the main bodies selected from the compounds represented by the general formula (1) is a compound represented by formula (7) or formula (8) below. Here, L 1 L 2 Ar 1 Ar 2 b and f have the same meaning as the general formula (1).

6. The organic electric field light-emitting element according to claim 5, characterized in that, At least two of the main bodies selected from the compounds represented by the general formula (1) are represented by the formula (7).

7. 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.

8. The organic electric field light-emitting element according to claim 7, characterized in that, The ΔEST is below 0.10 eV.

9. The organic electric field light-emitting element according to claim 4, 7 or 8, characterized in that, The host contains 99.9% to 90% of a host at 0.10% to 10% of the luminescent dopant, and the host contains 10% to 90% of the first host represented by formula (5a) or formula (5b) and 90% to 10% of the second host represented by formula (6).

10. The organic electric field light-emitting element according to claim 1, characterized in that, In the compound represented by the general formula (1), the aromatic hydrocarbon group, aromatic heterocyclic group or linked aromatic group contains deuterium as a substituent.

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