Organic electroluminescent element

Abstract

Provided is a blue light-emitting-type organic EL device having high luminous efficiency and a long lifespan. This organic EL device includes one or more light-emitting layers between opposing positive and negative electrodes, wherein at least one of the light-emitting layers contains a first host, a second host, and a light-emitting dopant, the first host is a carbazole compound or bicarbazole compound, the second host is an indolocarbazole compound, and the light-emitting dopant is a polycyclic aromatic compound represented by general formula (4) or a polycyclic aromatic compound having this structure as a partial structure. In the formula, Y4 is B, P, P=O, P=S, AL, Ga, As, Si-R4, or Ge-R41, and X4 is O, N-Ar4, S, or Se.

Description

Technical Field

[0001] The present invention relates to an organic electroluminescent element (referred to as an organic EL element).

[0002] By applying a voltage to the organic EL element, holes are injected from the anode and electrons are injected from the cathode into the light-emitting layer, respectively. In the light-emitting layer, the injected holes and electrons recombine to generate excitons. At this time, singlet excitons and triplet excitons are generated at a ratio of 1:3 according to the statistical rule of electron spin. It is said that the internal quantum efficiency of a fluorescent organic EL element using light emission by singlet excitons has a limit of 25%. On the other hand, it is known that the internal quantum efficiency of a phosphorescent organic EL element using light emission by triplet excitons can be increased to 100% when intersystem crossing occurs efficiently from singlet excitons. However, regarding blue phosphorescent organic EL elements, extending the lifetime has been a technical issue.

[0003] Recently, high-efficiency organic EL elements using delayed fluorescence have been developed. For example, Patent Document 1 discloses an organic EL element using a TTF (Triplet-Triplet Fusion) mechanism, which is one of the mechanisms of delayed fluorescence. The TTF mechanism utilizes the phenomenon in which singlet excitons are generated by the collision of two triplet excitons, and it is considered that the internal quantum efficiency can be increased to 40% theoretically. However, since the efficiency is lower compared to phosphorescent organic EL elements, further improvement in efficiency is required.

[0004] Patent Document 2 discloses an organic EL element using a TADF (Thermally Activated Delayed Fluorescence) mechanism. The TADF mechanism utilizes the phenomenon in which reverse intersystem crossing occurs from triplet excitons to singlet excitons in a material with a small energy difference between the singlet level and the triplet level, and it is considered that the internal quantum efficiency can be increased to 100% theoretically. However, similar to phosphorescent elements, further improvement in lifetime characteristics is required.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0006] Patent Document 3 discloses an organic EL element using a TADF material represented by the following polycyclic aromatic compound as a light-emitting dopant, but does not disclose practical life characteristics.

Chemical Formula

[0007] Patent Document 4 discloses a phosphorescent organic EL element in which an indolocarbazole compound and a carbazole compound represented by the following compound are mixed and used in a light-emitting layer, but does not disclose an organic EL element having a light-emitting layer mixed with a polycyclic aromatic compound represented by the general formula (4) and showing practical life characteristics.

Chemical Formula

[0008] Patent Document 5 discloses an organic EL element in which a boron-based compound (a5), a TADF compound (a6), and a carbazole compound (a7) are mixed and used in a light-emitting layer, but does not disclose an organic EL element showing practical life characteristics in which a first host represented by the general formula (1) or the general formula (2) and a second host represented by the general formula (3) are mixed and used in the light-emitting layer.

Chemical Formula

Summary of the Invention

[0009] In order to apply an organic EL element to a display element such as a flat panel display or a light source, it is necessary to improve the light emission efficiency of the element and at the same time ensure sufficient stability during driving. An object of the present invention is to provide a practically useful organic EL element having high efficiency and long life.

[0010] The present invention relates to an organic electroluminescent element including one or more light emitting layers between a counter anode and cathode, wherein at least one light emitting layer includes a host and a light emitting dopant, the host includes a first host represented by general formula (1) or general formula (2), and a second host represented by general formula (3), and the light emitting dopant includes a polycyclic aromatic compound represented by general formula (4) or a polycyclic aromatic compound having a structure represented by general formula (4) as a partial structure. The organic electroluminescent element is characterized by this.

[0011]

Chemical formula

[0012]

Chemical formula

[0013]

Chemical formula

[0014] [Chemical formula] Here, ring C, ring D, and ring E are each independently an aromatic hydrocarbon ring having 6 to 24 carbon atoms or an aromatic heterocyclic ring having 3 to 17 carbon atoms. Y 4 is B, P, P=O, P=S, AL, Ga, As, Si-R 4 , or Ge-R 41 and X 4 is independently O, N-Ar 4 , S, or Se, and R 4 , and R 41 are each 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, Ar 4 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 formed by linking 2 to 8 of them, and N-Ar 4 may combine with any of ring C, ring D, or ring E to form a heterocyclic ring containing N, R 42 each independently represents a cyano group, deuterium, a diarylamino group having 12 to 44 carbon atoms, an arylheteroarylamino group having 12 to 44 carbon atoms, a diheteroarylamino group having 12 to 44 carbon atoms, 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, v each independently represents an integer from 0 to 4, and x represents an integer from 0 to 3. Ring C, ring D, ring E, R 4 , R 41 , R 42 , and Ar 4At least one hydrogen in it may be substituted with a halogen or deuterium.

[0015] Examples of the polycyclic aromatic compound having a structure represented by the general formula (4) as a partial structure include a polycyclic aromatic compound represented by the following formula (5) or a boron-containing polycyclic aromatic compound represented by the following formula (6).

Chemical formula

[0016]

Chemical formula

[0017] As the first host, the first host represented by the general formula (1) is preferable. Also, Y in the general formula (1) 1 is preferably N-Ar 1 A preferable general formula (1) is represented by the following formula (7).

Chemical formula

[0018] Another aspect of the present invention is the above organic electroluminescent device, characterized in that the light-emitting layer contains a first host represented by the general formula (2) and a second host represented by the general formula (3).

[0019] A preferable general formula (2) is represented by the following formula (8).

Chemical formula

[0020] It is preferable that the difference (ΔEST) between the singlet excitation energy (S1) and the triplet excitation energy (T1) of the light-emitting dopant is 0.20 eV or less, and more preferably 0.10 eV or less.

[0021] In the light-emitting layer, it is preferably contained at 99.9 to 90 wt% of the host with respect to 0.10 to 10 wt% of the light-emitting dopant, and in the host, the first host is contained at 10 to 90 wt% and the second host is contained at 90 to 10 wt%.

[0022] Also, the present invention relates to an organic EL element including one or more light-emitting layers between opposing anodes and cathodes, wherein at least one light-emitting layer contains an organic light-emitting material having a difference (ΔEST) between singlet excitation energy (S1) and triplet excitation energy (T1) of 0.20 eV or less as a light-emitting dopant, and the first host and the second host. The organic EL element is characterized by this.

[0023] Since the organic EL element of the present invention contains a specific light-emitting dopant and a plurality of specific host materials in the light-emitting layer, it is considered that an organic EL element with a low driving voltage, high luminous efficiency, and long lifespan can be obtained. The reason why the organic EL element of the present invention has a low driving voltage is considered to be that the carbazole compound, which is the first host material, has a property that holes are easily injected, and the indolocarbazole compound, which is the second host material, has a property that electrons are easily injected. It is assumed that holes and electrons are injected at a lower voltage and excitons are generated. Also, the reason why the organic EL element of the present invention has high luminous efficiency is considered to be that the carbazole compound has a property that holes are easily injected, and the indolocarbazole compound has a property that electrons are easily injected, and thus the balance between holes and electrons in the light-emitting layer can be maintained. The reason why the organic EL element of the present invention has a long lifespan is considered to be that when a voltage is applied to the organic EL element, holes are preferentially injected into the first host made of a carbazole compound and electrons are preferentially injected into the second host made of an indolocarbazole compound, thereby reducing the electrochemical load on the light-emitting dopant.

Brief Description of the Drawings

[0024]

Figure 1

Embodiments for Carrying Out the Invention

[0025] The organic EL element of the present invention has one or more light-emitting layers between a pair of opposed anode and cathode, and at least one of the light-emitting layers contains a first host, a second host, and a light-emitting dopant. The above first host is selected from compounds represented by general formula (1) or general formula (2), and the second host is selected from compounds represented by general formula (3). The light-emitting dopant is selected from polycyclic aromatic compounds represented by general formula (4) or polycyclic aromatic compounds having a structure represented by general formula (4) as a partial structure. A polycyclic aromatic compound having a structure represented by general formula (4) as a partial structure is also referred to as a partial structure type polycyclic aromatic compound.

[0026] The compound represented by the above general formula (1) or (2) used as the first host in the present invention will be described.

[0027] In general formula (1), Y 1 represents O, S, or N-Ar 1 Preferably, it represents O or N-Ar 1 More preferably, it represents N-Ar 1 represents.

[0028] As a preferred embodiment of general formula (1), general formula (7) is exemplified. In general formula (1) and formula (7), common symbols have the same meaning.

[0029] Ar 1 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 substituted or unsubstituted linked aromatic group formed by linking 2 to 8 of these aromatic rings. Preferably, it is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 4 of these aromatic rings. More preferably, it is a phenyl group, a biphenyl group, or a terphenyl group.

[0030] Ar 1 ​When it is an unsubstituted aromatic hydrocarbon group, aromatic heterocyclic group, or linked aromatic group, specific examples include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazole, indole, pyridine, pyrimidine, triazine, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, carbazole, or a group formed by removing one hydrogen from a compound composed of 2 to 8 of these linked together. Preferably, examples include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, or a group formed by removing one hydrogen from a compound composed of 2 to 4 of these linked together. More preferably, examples include a group derived from benzene, biphenyl, or terphenyl.

[0031] In this specification, a linked aromatic group refers to a group in which aromatic rings of an aromatic hydrocarbon group or aromatic heterocyclic group are linked by single bonds, and these may be linked linearly or branched, and the aromatic rings may be the same or different. When it corresponds to a linked aromatic group, it is different from a substituted aromatic hydrocarbon group or substituted aromatic heterocyclic group.

[0032] R 1independently represents deuterium, 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. Preferably, it is an aliphatic hydrocarbon group having 1 to 8 carbon atoms, a substituted or unsubstituted 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 a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms. Note that Ar 1 and R 1 are preferably not groups derived from pyridine, pyrimidine, or triazine.

[0033] a represents an integer of 0 to 4, and b represents an integer of 0 to 3. Preferably, a is an integer of 0 to 1, and b is an integer of 0 to 1.

[0034] R 1 When R is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, specific examples include methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, or nonyl. Preferably, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, or octyl is included.

[0035] R 1 When R is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, or an unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, specific examples are the same as those described for the above Ar 1 as described above.

[0036] In this specification, the substituted aromatic hydrocarbon group, aromatic heterocyclic group, or linked aromatic group may have a substituent. Preferred substituents include deuterium, a cyano group, a triarylsilyl group, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, and a diarylamino group having 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. The number of substituents is preferably 0 to 5, more preferably 0 to 2. In calculating the number of carbon atoms when the aromatic hydrocarbon group and the aromatic heterocyclic group have substituents, the number of carbon atoms of the substituents is not included. However, it is preferable that the total number of carbon atoms including the carbon atoms of the substituents satisfies the above range.

[0037] Specific examples of the above substituents include cyano, methyl, ethyl, propyl, i-propyl, butyl, t-butyl, pentyl, cyclopentyl, hexyl, cyclohexyl, heptyl, octyl, nonyl, decyl, diphenylamino, naphthylphenylamino, dinaphthylamino, dianthranylamino, diphenanthrenylamino, dipyrenylamino, etc. Preferably, cyano, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, diphenylamino, naphthylphenylamino, or dinaphthylamino is mentioned.

[0038] In this specification, it is understood that hydrogen may be deuterium. That is, in general formulas (1) to (4), etc., some or all of the H in the skeletons such as carbazole, R 1 and Ar 1 and other substituents may be deuterium.

[0039] Specific examples of the compound represented by general formula (1) are shown below, but the present invention is not limited to these exemplified compounds.

[0040]

Chemical formula

Chemical formula

Chemical formula

[0041]

Chem.

Chem.

Chem.

Chem.

[0042]

Chem.

Chem.

Chem.

[0043]

Chem.

Chem.

Chem.

[0044]

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Chem.

Chem.

[0045]

Chem.

[0046] The compound represented by the general formula (2) will be described. In the general formula (2), c is independently an integer of 0 to 5, d is independently an integer of 0 to 2, and at least one d is 1 or more. e is independently an integer of 0 to 2. Preferably, c is an integer of 1 to 2, the sum of two d's is an integer of 1 to 4, and e is an integer of 0 to 1.

[0047] R 2 is independently a cyano group, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. Preferably, it is an aliphatic hydrocarbon group having 1 to 8 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, and more preferably, it is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms.

[0048] R 2 When R is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, specific examples are the same as those when R in the general formula (1) is these. 1 is the same as in these cases.

[0049] R 2 When R is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, specific examples are the same as the description of Ar above. 1 is the same as the above description.

[0050] L 2 is 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. Preferably, it is a substituted or unsubstituted 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 a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms.

[0051] L 2When it is an unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms or an unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, specific examples are as follows. In general formula (1), Ar 1 is the same as the case where it is these. Note that the valence may be different. L 2 is understood as a (2d + 1)-valent group.

[0052] Ar 2 independently represents hydrogen, deuterium, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, 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 formed by linking 2 to 3 of these. Preferably, it is an aliphatic hydrocarbon group having 1 to 8 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 12 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 15 carbon atoms, or a linked aromatic group formed by linking 2 to 3 of these. More preferably, it is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms, or a linked aromatic group formed by linking 2 to 3 of these. Note that Ar 2 , L 2 , R 2 are preferably not groups derived from pyridine, pyrimidine, or triazine.

[0053] Ar 2 When it is an aliphatic hydrocarbon group having 1 to 10 carbon atoms, specific examples are the same as the case where R 1 in general formula (1) is these. Also, when Ar 2 is 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, specific examples are the same as the case where Ar 1 in general formula (1) is these.

[0054] A preferred embodiment of general formula (2) is formula (8). In formula (8), n is an integer from 1 to 5, p is an integer from 0 to 1, preferably, n is an integer from 1 to 2, and p is 0. L 8represents a group derived from benzene, dibenzofuran, or dibenzothiophene. R 81 represents hydrogen, or a group derived from benzene, dibenzofuran or dibenzothiophene.

[0055] Specific examples of the compound represented by the general formula (2) are shown below, but the compound is not limited to these exemplified compounds.

[0056] [Chemical formula] [Chemical formula] [Chemical formula]

[0057] [Chemical formula] [Chemical formula] [Chemical formula]

[0058] [Chemical formula] [Chemical formula]

[0059] The compound represented by the general formula (3) will be described. In the general formula (3), Z 3 is an indolocarbazole ring-containing group represented by the formula (3a), and * is the bonding position with L 3 . Ring A is a heterocyclic ring represented by the formula (3b), and this heterocyclic ring is condensed with an adjacent ring at an arbitrary position. f represents an integer from 1 to 3, preferably 1. g represents an integer from 0 to 3, and j represents an integer from 0 to 3. Preferably, g is an integer from 0 to 2, and j is an integer from 0 to 2.

[0060] Preferred general formula (3) includes the following formula (9) or formula (10).

Chemical formula

[0061] L 3 and L 31 each independently represent 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. Preferably, it represents an aromatic hydrocarbon group having 6 to 20 carbon atoms, or an aromatic heterocyclic group having 3 to 15 carbon atoms. More preferably, it is a group derived from benzene, naphthalene, pyridine, triazine, dibenzofuran, or carbazole.

[0062] Ar 3 and Ar 31 each independently represent 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 formed by linking 2 to 8 of them. Preferably, it is a substituted or unsubstituted aromatic hydrocarbon group having 6 to 20 carbon atoms, a substituted or unsubstituted aromatic heterocyclic group having 3 to 17 carbon atoms, or a substituted or unsubstituted linked aromatic group formed by linking 2 to 4 of these aromatic rings. More preferably, it is 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 formed by linking 2 to 3 of them. Ar 3 and Ar 31is preferably a phenyl group, a biphenyl group, or a terphenyl group. The terphenyl group may be linearly linked or branched. Also, benzene, carbazole, and a linked aromatic group formed by linking 2 to 3 of these aromatic rings are preferred.

[0063] L 3 and L 31 or Ar 3 and Ar 31 When they are an unsubstituted aromatic hydrocarbon group having 6 to 30 carbon atoms or an aromatic heterocyclic group having 3 to 17 carbon atoms, specific examples include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene, tetracene, pentacene, hexacene, coronene, heptacene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazole, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, or a group derived from carbazole. However, L 3 and L 31 are a group having a g + f valence or a j + 1 valence. Ar 3 and Ar 31 can be a linked aromatic group. For the linked aromatic group, in the general formula (1), Ar 1 is the same as the case where Ar is a linked aromatic group, except that the number of carbon atoms of the aromatic hydrocarbon group constituting the linked aromatic group is 6 to 30. Regarding the substituents when these have substituents, in the general formula (1), Ar 1 is the same as the explanation when Ar has substituents.

[0064] R 3 each independently represents 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. Preferably, it is an aliphatic hydrocarbon group having 1 to 8 carbon atoms, a substituted or unsubstituted 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 a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms. h independently represents an integer from 0 to 4, and i represents an integer from 0 to 2. Preferably, h is an integer from 0 to 1, and i is an integer from 0 to 1.

[0065] R 3 Specific examples where is an aliphatic hydrocarbon group having 1 to 10 carbon atoms are the same as in the case of R 1 , and specific examples in the case of being 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 are the same as the cases where Ar 1 is these in the general formula (1).

[0066] Specific examples of the compound represented by the general formula (3) are shown below, but are not limited to these exemplified compounds.

[0067]

Chemical formula

Chemical formula

Chemical formula

[0068]

Chemical formula

Chemical formula

Chemical formula

[0069]

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Chem.

Chem.

[0070]

Chem.

Chem.

Chem.

[0071]

Chem.

Chem.

Chem.

[0072]

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Chem.

[0073]

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[0074] [Chemistry] [Chemistry] [Chemistry]

[0075] [Chemistry] [Chemistry]

[0076] The luminescent dopant used in the organic EL element of the present invention is a polycyclic aromatic compound represented by the general formula (4) or a polycyclic aromatic compound having the structure represented by the general formula (4) as a partial structure. A polycyclic aromatic compound having the structure represented by the general formula (4) as a partial structure is also referred to as a partial structure type polycyclic aromatic compound. As this partial structure type polycyclic aromatic compound, preferably, it is a polycyclic aromatic compound represented by the formula (5), and more preferably, it is a boron-containing polycyclic aromatic compound represented by the formula (6).

[0077] In the general formula (4) and the general formula (5), the C ring, D ring, E ring, F ring, G ring, H ring, I ring and J ring are each independently an aromatic hydrocarbon ring having 6 to 24 carbon atoms or an aromatic heterocyclic ring having 3 to 17 carbon atoms, and preferably, they represent an aromatic hydrocarbon ring having 6 to 20 carbon atoms or an aromatic heterocyclic ring having 3 to 15 carbon atoms. Since the C ring to the J ring are aromatic hydrocarbon rings or aromatic heterocyclic rings as described above, they are also referred to as aromatic rings.

[0078] Specific examples of the aromatic ring include benzene, naphthalene, acenaphthene, acenaphthylene, azulene, anthracene, chrysene, pyrene, phenanthrene, triphenylene, fluorene, benzo[a]anthracene pyridine, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazole, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, or a ring composed of carbazole. More preferably, it is a benzene ring, naphthalene ring, anthracene ring, triphenylene ring, phenanthrene ring, pyrene ring, pyridine ring, dibenzofuran ring, dibenzothiophene ring, or carbazole ring.

[0079] In the general formula (4), Y 4 is B, P, P=O, P=S, Al, Ga, As, Si-R 4 or Ge-R 41 and is preferably B, P, P=O or P=S, and more preferably B.

[0080] R 4 and R 41 represent 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. Preferably, it is an aliphatic hydrocarbon group having 1 to 8 carbon atoms, a substituted or unsubstituted 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 a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms.

[0081] R 4and R 41 When 41 is 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, specific examples are the same as those of R in general formula (1). 1 When 1 is these groups, it is the same as the above cases.

[0082] X 4 is each independently O, N-Ar 4 , S or Se, preferably O, N-Ar 4 or S, more preferably O or N-Ar 4 .

[0083] Ar 4 is each 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 formed by linking 2 to 8 of them. Preferably, it represents a substituted or unsubstituted aromatic hydrocarbon 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 formed by linking 2 to 6 of these aromatic rings. More preferably, it represents a substituted or unsubstituted aromatic hydrocarbon 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 formed by linking 2 to 4 of these aromatic rings. More preferably, it is a phenyl group, a biphenyl group, or a terphenyl group.

[0084] Ar 4 When 4 is 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 formed by linking 2 to 8 of them, specific examples are the same as those of Ar in general formula (1). 1 When 1 is these groups, it is the same as the above cases.

[0085] N-Ar 4 may combine with an aromatic ring selected from ring C, ring D, or ring E to form a heterocyclic ring containing N. Also, ring C, ring D, ring E, R4 、 R 41 、 R 42 、 and Ar 4 at least one hydrogen in may be substituted with a halogen or deuterium.

[0086] R 42 represents a substituent of ring C, ring D, and ring E, and each independently represents a cyano group, deuterium, a diarylamino group having 12 to 44 carbon atoms, an arylheteroarylamino group having 12 to 44 carbon atoms, a diheteroarylamino group having 12 to 44 carbon atoms, 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. Preferably, it is a diarylamino group having 12 to 36 carbon atoms, an arylheteroarylamino group having 12 to 36 carbon atoms, a diheteroarylamino group having 12 to 36 carbon atoms, a substituted or unsubstituted 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 a diarylamino group having 12 to 24 carbon atoms, an arylheteroarylamino group having 12 to 24 carbon atoms, a diheteroarylamino group having 12 to 24 carbon atoms, a substituted or unsubstituted aromatic hydrocarbon group having 6 to 10 carbon atoms, or a substituted or unsubstituted aromatic heterocyclic group having 3 to 12 carbon atoms.

[0087] R 42 When represents an aliphatic hydrocarbon group having 1 to 10 carbon atoms, specific examples are the same as those in the case of R 1 in the case of.

[0088] R 42 When represents 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, specific examples are Ar 1This is the same as the case of. Preferably, a group derived from benzene, naphthalene, acenaphthene, acenaphthylene, azulene, pyridine, pyrimidine, triazine, thiophene, isothiazole, thiazole, pyridazine, pyrrole, pyrazole, imidazole, triazole, thiadiazole, pyrazine, furan, isoxazole, quinoline, isoquinoline, quinoxaline, quinazoline, thiadiazole, phthalazine, tetrazole, indole, benzofuran, benzothiophene, benzoxazole, benzothiazole, indazole, benzimidazole, benzotriazole, benzoisothiazole, benzothiadiazole, purine, pyranone, coumarin, isocoumarin, chromone, dibenzofuran, dibenzothiophene, dibenzoselenophene, or carbazole is mentioned. More preferably, a group derived from benzene or naphthalene is mentioned.

[0089] R 42When it represents a diarylamino group having 12 to 44 carbon atoms, an arylheteroarylamino group having 12 to 44 carbon atoms, a diheteroarylamino group having 12 to 44 carbon atoms, or an aliphatic hydrocarbon group having 1 to 10 carbon atoms, specific examples include diphenylamino, dibiphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthranylamino, diphenanthrenylamino, dipyrenylamino, dibenzofuranylphenylamino, dibenzofuranylbiphenylamino, dibenzofuranylnaphthylamino, dibenzofuranylanthranylamino, dibenzofuranylphenanthrenylamino, dibenzofuranylpirenylamino, bisdibenzofuranylamino, carbazolylphenylamino, carbazolylnaphthylamino, carbazolylanthranylamino, carbazolylphenanthrenylamino, carbazolylpirenylamino, dicarbazolylamino, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, or nonyl. Preferably, diphenylamino, dibiphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dianthranylamino, diphenanthrenylamino, or dipyrenylamino is mentioned. More preferably, diphenylamino, dibiphenylamino, phenylbiphenylamino, naphthylphenylamino, dinaphthylamino, dibenzofuranylphenylamino, or carbazolylphenylamino is mentioned.

[0090] v each independently represents an integer from 0 to 4, preferably an integer from 0 to 2, and more preferably an integer from 0 to 1. x represents an integer from 0 to 3, preferably an integer from 0 to 2, and more preferably an integer from 0 to 1

[0091] The polycyclic aromatic compound having the structure represented by the general formula (4) as a partial structure will be described. Since the polycyclic aromatic compound having the structure represented by the general formula (4) as a partial structure can be regarded as a condensate of the compound represented by the general formula (4) or its analog, it is also referred to as a partial structure type polycyclic aromatic compound. Examples of this partial structure type polycyclic aromatic compound include the compounds represented by the above formula (5) or formula (6).

[0092] In General Formulas (4), (5), and (6), common symbols have the same meaning. In Formula (5), 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.

[0093] In Formula (5), the F ring to the J ring are as described above. The F ring and the G ring are the same as the C ring and the D ring in General Formula (4), the H ring and the J ring are the same as the E ring, and the I ring has a shared structure and thus is a tetravalent group (when z = 0).

[0094] In Formula (6), X 6 independently represents N-Ar 6 , O, or S, but at least one X 6 represents N-Ar 6 . Preferably, it represents O or N-Ar 5 , and more preferably represents N-Ar 5 . Ar 6 is the same as Ar 4 in General Formula (4). N-Ar 6 may combine with the above aromatic ring to form a heterocyclic ring containing N. In this case, Ar 3 may be directly bonded to the above aromatic ring or may be bonded via a linking group.

[0095] R 6 independently represents a cyano group, deuterium, a diarylamino group having 12 to 44 carbon atoms, 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. Specific examples thereof are the same as those when R 42 is these.

[0096] k independently represents an integer from 0 to 4, l independently represents an integer from 0 to 3, and m independently represents an integer from 0 to 2. Preferably, k independently represents an integer from 0 to 2, l represents an integer from 0 to 2, and m represents an integer from 0 to 1.

[0097] The partial structure type polycyclic aromatic compounds will be described below with reference to Formula (5) and Formula (6). Formula (5) consists of the structure represented by General Formula (4) and a partial structure thereof. From another perspective, there are two structures represented by General Formula (4), but they are structures sharing Ring I. That is, the structure represented by General Formula (4) is used as a partial structure. The same applies to Formula (6). It has a structure in which the central benzene ring is shared, and it can be understood that it consists of the structure represented by General Formula (4) and a partial structure thereof. The partial structure type polycyclic aromatic compound referred to in the present invention has the structure represented by General Formula (4) as a partial structure. Those having a structure in which any one of Rings C to E in General Formula (4) is missing as another partial structure are suitable. And those having one structure represented by General Formula (4) as a partial structure and 1 to 3 of the above-mentioned other partial structures are preferred. The connection between the structure represented by General Formula (4) and the other partial structure may be a connection by condensation or formation of one or more rings, or a connection by one or more bonds.

[0098] Preferred embodiments of the above General Formula (4), General Formula (5) or Formula (6), or the partial structure type polycyclic aromatic compound include the following Formulas (4-a) to (4-h). [Chemical formula]

[0099] The partial structure type polycyclic aromatic compound represented by the above Formula (4-a) corresponds to, for example, a compound represented by Formula (4-64) described later. That is, Formula (4-a) is a structure in which two structures of General Formula (4) are shared by the central benzene ring, and it is understood that it is a compound containing the structural unit of General Formula (4) and including one of its partial structures.

[0100] The partial-structured polycyclic aromatic compound represented by the formula (4-b) corresponds to, for example, a compound represented by the formula (4-65) described later. That is, the formula (4-b) has a structure in which two structures of the general formula (4) are shared by the central benzene ring, and it is understood that it is a compound containing the structural unit of the general formula (4) and including one of its partial structures. In terms of the general formula (4), X 4 One of them is NAr 4 and this forms a ring structure (condensed ring structure) by bonding to the other aromatic ring.

[0101] The partial-structured polycyclic aromatic compound represented by the formula (4-c) corresponds to, for example, a compound represented by the formula (4-66) described later. That is, in terms of the general formula (4), it has a structure having three unit structures represented by the general formula (4) by sharing the benzene ring which is the E ring. That is, it is understood that it is a compound having the unit structure represented by the general formula (4) as a partial structure and including two of its partial structures which are structures obtained by removing one benzene ring from the general formula (4). Also, X 4 is N-Ar 4 and this forms a ring structure by bonding to the other adjacent ring.

[0102]

Chemical formula

[0103] Also, the partial-structured polycyclic aromatic compounds represented by the formula (4-d), the formula (4-e), the formula (4-f), and the formula (4-g) correspond to, for example, compounds represented by the formula (4-67), the formula (4-68), the formula (4-69), and the formula (4-70) described later. That is, it is a compound having two or three unit structures represented by the general formula (4) in one compound by sharing the benzene ring which is the C ring (or D ring). That is, it is understood that it is a compound having the unit structure represented by the general formula (4) as a partial structure and including one of its partial structures which are structures obtained by removing one benzene ring from the general formula (4).

[0104] The partial structure type polycyclic aromatic compound represented by formula (4-h) corresponds to compounds represented by, for example, formula (4-71), formula (4-72), formula (4-73), formula (4-74), and formula (4-75) described later. That is, explained by the general formula (4), it is a partial structure type polycyclic aromatic compound in which the C ring is a naphthalene ring and two unit structures represented by the general formula (4) are contained in one compound so as to share the ring. That is, it is understood that it is a compound having a unit structure represented by the general formula (4) as a partial structure and containing one or two of its partial structures having a structure in which one C ring (naphthalene ring) is removed from the general formula (4).

[0105] In formulas (4-a) to (4-h), X 4 and Y 4 are the same as in the general formula (4), and R 6 , k, l, and m are the same as in formula (6). s is 0 to 1, preferably 0.

[0106] The partial structure type polycyclic aromatic compound of the present invention can be said to have a structure in which a plurality of compounds of the general formula (4) are linked by sharing one or two of the rings (C ring to E ring) in the structural unit of the general formula (4) and contains at least one structural unit of the general formula (4). The number of compounds of the general formula (4) forming the above structure is 2 to 5, preferably 2 to 3. The sharing of the above rings (C ring to E ring) may be one, two, or three rings may be shared.

[0107] Specific examples of the polycyclic aromatic compound represented by the general formula (4), the general formula (5), or the formula (6) and other partial structure type polycyclic aromatic compounds are shown below, but the present invention is not limited to these exemplified compounds.

[0108]

Chemical formula

Chemical formula

Chemical formula

[0109]

Chem.

Chem.

Chem.

[0110]

Chem.

Chem.

Chem.

[0111]

Chem.

Chem.

Chem.

[0112]

Chem.

Chem.

Chem.

[0113]

Chem.

Chem.

Chem.

[0114] The organic light-emitting material used as a light-emitting dopant in the organic EL element of the present invention preferably has ΔEST of 0.20 eV. More preferably, it is 0.15 eV or less, and still more preferably 0.10 eV.

[0115] ΔEST represents the difference between the singlet excitation energy (S1) and the triplet excitation energy (T1). Here, the measurement conditions for S1 and T1 are according to the method described in the examples.

[0116] By using a material selected from the polycyclic aromatic compounds or partially structured polycyclic aromatic compounds represented by the general formula (3) (hereinafter also referred to as polycyclic aromatic compound materials) as a light-emitting dopant, a material selected from the compounds represented by the general formula (1) or general formula (2) as a first host, and a material selected from the compounds represented by the general formula (3) as a second host, an excellent organic EL element can be provided.

[0117] In another aspect of the present invention, together with the above first host and second host, a compound having ΔEST of 0.20 eV or less is used as a light-emitting dopant. In this case, the compound as the light-emitting dopant does not necessarily have to be the above polycyclic aromatic compound material, and any compound having ΔEST of 0.20 eV or less, preferably 0.15 eV or less, and more preferably 0.10 eV may be used. Such compounds are known as delayed fluorescence emitting materials (TADF) in many documents such as Patent Document 2, and thus can be selected from them.

[0118] Next, the structure of the organic EL element of the present invention will be described with reference to the drawings, but the structure of the organic EL element of the present invention is not limited thereto.

[0119] FIG. 1 is a cross-sectional view showing an example of the structure of a general organic EL element used in the present invention, where 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, 5 is a light-emitting layer, 6 is an electron transport layer, and 7 is a cathode. The organic EL element of the present invention may have an exciton blocking layer adjacent to the light-emitting layer, or may have an electron blocking layer between the light-emitting layer and the hole injection layer. The exciton blocking layer can be inserted on either the anode side or the cathode side of the light-emitting layer, or both can be inserted simultaneously. In the organic EL element of the present invention, the anode, the light-emitting layer, and the cathode are essential layers, but in addition to the essential layers, it is preferable to have a hole injection / transport layer and an electron injection / transport layer, and it is also preferable to have a hole blocking layer between the light-emitting layer and the electron injection / transport layer. Note that the hole injection / transport layer means either the hole injection layer or the hole transport layer, or both, and the electron injection / transport layer means either the electron injection layer or the electron transport layer, or both.

[0120] A structure reverse to that of FIG. 1, that is, the cathode 7, the electron transport layer 6, the light-emitting layer 5, the hole transport layer 4, and the anode 2 can be laminated in this order on the substrate 1. In this case, layers can also be added or omitted as necessary.

[0121] - Substrate - The organic EL element of the present invention is preferably supported by a substrate. There are no particular restrictions on this substrate, and any substrate that has been conventionally used for organic EL elements can be used. For example, a substrate made of glass, transparent plastic, quartz, etc. can be used.

[0122] - Anode - As the anode material in the organic EL element, a material composed of a metal, alloy, electrically conductive compound, or a mixture thereof having a large work function (4 eV or more) is preferably used. Specific examples of such electrode materials include metals such as Au, CuI, indium tin oxide (ITO), SnO 2 , ZnO and other conductive transparent materials. Also, IDIXO (In 2 O 3It is also possible to use an amorphous material such as ZnO that can form a transparent conductive film. The anode may be formed by depositing these electrode materials by methods such as evaporation or sputtering to form a thin film, and then forming a pattern of a desired shape by photolithography. Alternatively, when the pattern accuracy is not required much (about 100 μm or more), a pattern may be formed through a mask of a desired shape during the evaporation or sputtering of the above electrode materials. Alternatively, when a coatable substance such as an organic conductive compound is used, wet film-forming methods such as printing and coating methods can also be used. When extracting light emission from this anode, it is desirable to make the transmittance greater than 10%, and the sheet resistance as an anode is preferably several hundred Ω / sq or less. The film thickness is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm, although it depends on the material.

[0123] - Cathode - On the other hand, as the cathode material, a material composed of a metal with a small work function (4 eV or less) (referred to as an electron-injecting metal), an alloy, an electrically conductive compound, or a mixture thereof is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al 2 O 3 ) mixture, indium, lithium / aluminum mixture, rare earth metals, and the like. Among these, from the viewpoints of electron injection property and durability against oxidation and the like, a mixture of an electron-injecting metal and a second metal that is a metal with a larger and more stable work function value than this, for example, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al 2 O 3)Mixtures, lithium / aluminum mixtures, aluminum, etc. are suitable. The cathode can be fabricated by forming a thin film of these cathode materials by methods such as evaporation or sputtering. Also, as the cathode, a sheet resistance of several hundred Ω / sq or less is preferable, and the film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm. Note that in order to transmit the emitted light, it is advantageous for either the anode or the cathode of the organic EL element to be transparent or translucent, as this improves the emission luminance.

[0124] Also, after forming the above metal on the cathode with a film thickness of 1 to 20 nm, a conductive transparent material mentioned in the description of the anode is formed thereon, whereby a transparent or translucent cathode can be fabricated, and by applying this, an element in which both the anode and the cathode have permeability can be fabricated.

[0125] - Emission layer - The emission layer is a layer that emits light after excitons are generated by the recombination of holes and electrons injected from the anode and the cathode, respectively. The emission layer contains a light-emitting dopant and a host. The light-emitting dopant and the host can be used, for example, such that the light-emitting dopant is 0.10 to 10% and the host is 99.9 to 90%. Preferably, the light-emitting dopant is 1.0 to 5.0%, the host is 99 to 95%, and more preferably, the light-emitting dopant is 1.0 to 3.0%, the host is 99 to 97%. In this specification, % is mass % unless otherwise specified.

[0126] As the host in the emission layer, a first host represented by general formula (1) or general formula (2) and a second host represented by general formula (3) are used. The first host and the second host can be used, for example, such that the first host is 10 to 90% and the second host is 90 to 10%. Preferably, the first host is 30 to 70%, the second host is 70 to 30%, and more preferably, the first host is 40 to 60%, the second host is 60 to 40%. Furthermore, as other hosts in addition to the above, one or more known hosts may be used in combination, but the amount used is preferably 50% or less, more preferably 25% or less, based on the total host material.

[0127] The host is a compound having a hole transporting ability, an electron transporting ability, and a high glass transition temperature, and preferably has a T1 larger than that of the luminescent dopant. Specifically, the T1 of the host is preferably 0.010 eV or more higher than the T1 of the luminescent dopant, more preferably 0.030 eV or more higher, and even more preferably 0.10 eV or more higher. Further, a TADF-active compound may be used as the host material, and this compound preferably has a difference (ΔEST) between the singlet excitation energy (S1) and the triplet excitation energy (T1) of 0.20 eV or less.

[0128] Known hosts as the other hosts described above are known from a number of patent documents and the like, and can be selected from them. Specific examples of the host are not particularly limited, but include indole derivatives, carbazole derivatives, indolocarbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, phenylenediamine derivatives, arylamine derivatives, styrylanthracene derivatives, fluorenone derivatives, stilbene derivatives, triphenylene derivatives, carborane derivatives, porphyrin derivatives, phthalocyanine derivatives, metal complexes of 8-quinolinol derivatives and metal phthalocyanines, various metal complexes typified by metal complexes of benzoxazole and benzothiazole derivatives, poly(N-vinylcarbazole) derivatives, aniline-based copolymers, thiophene oligomers, polythiophene derivatives, polyphenylene derivatives, polyphenylene vinylene derivatives, polyfluorene derivatives and other polymer compounds.

[0129] When using a plurality of hosts, each host can be vapor-deposited from different vapor-deposition sources, or a plurality of hosts can be vapor-deposited simultaneously from one vapor-deposition source by premixing before vapor-deposition to form a premixed mixture.

[0130] As a preliminary mixing method, a method that can mix as uniformly as possible is desirable, and examples include pulverization mixing, heating and melting under reduced pressure or in an inert gas atmosphere such as nitrogen, sublimation, etc., but it is not limited to these methods.

[0131] As the light-emitting dopant in the light-emitting layer, the above polycyclic aromatic compound material or an organic light-emitting material with ΔEST of 0.20 eV or less can be used. Preferably, it is the above polycyclic aromatic compound material that satisfies ΔEST of 0.20 eV or less.

[0132] As the light-emitting dopant in the light-emitting layer, it is preferable to use the above polycyclic aromatic compound material. Preferably, it is a partial structure type polycyclic aromatic compound represented by the above formula (5), and more preferably, it is a boron-containing partial structure type polycyclic aromatic compound represented by the above formula (6). The ΔEST of the above polycyclic aromatic compound material is preferably 0.20 eV or less.

[0133] The light-emitting layer can contain two or more types of light-emitting dopants. For example, it may be a light-emitting dopant composed of the above polycyclic aromatic compound material and other compounds. In this case, the light-emitting dopant composed of the above other compounds preferably has ΔEST of 0.20 eV or less, but is not limited thereto.

[0134] When two or more types of light-emitting dopants are contained in the light-emitting layer, the first dopant can be the above polycyclic aromatic compound material, and a known compound can be used in combination with other light-emitting dopants as the second dopant. As the content, preferably, the first dopant is 0.05 to 50% with respect to the host material, and the second dopant is 0.050 to 50% with respect to the host material, and the total content of the first dopant and the second dopant does not exceed 50% with respect to the host material.

[0135] Such other luminescent dopants are known from a number of patent documents and the like, and can be selected from them. Specific examples of the dopant are not particularly limited, but condensed ring derivatives such as phenanthrene, anthracene, pyrene, tetracene, pentacene, perylene, naphthopyrene, dibenzopyrene, rubrene and chrysene, 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, bisstyryl derivatives such as bisstyrylanthracene derivatives and distyrylbenzene derivatives, bisstyrylarylene derivatives, diazaindacene derivatives, furan derivatives, benzofuran derivatives, isobenzofuran derivatives, dibenzofuran derivatives, coumarin derivatives, dicyanomethylene pyran derivatives, dicyanomethylene thiopyran derivatives, polymethine derivatives, cyanine derivatives, oxobenzoanthracene derivatives, xanthene derivatives, rhodamine derivatives, fluorescein derivatives, pyrylium derivatives, carbostyryl derivatives, acridine derivatives, oxazine derivatives, phenylene oxide derivatives, quinacridone derivatives, quinazoline derivatives, pyrrolopyridine derivatives, furopyridine derivatives, 1,2,5-thiadiazolopyrene derivatives, pyrromethene derivatives, perinone derivatives, pyrrolopyrrole derivatives, squarylium derivatives, violanthrone derivatives, phenazine derivatives, acridone derivatives, deazaflavin derivatives, fluorene derivatives and benzofluorene derivatives, etc. can be mentioned.

[0136] The organic luminescent dopant and the first host, or the second host, can be vapor-deposited from different vapor-deposition sources respectively, or can be vapor-deposited simultaneously from one vapor-deposition source by premixing them before vapor-deposition to form a premixed mixture of the luminescent dopant and the first host, or the second host.

[0137] - Injection layer - The injection layer refers to a layer provided between the electrode and the organic layer for reducing the driving voltage and improving the emission luminance. There are a hole injection layer and an electron injection layer, which may be present between the anode and the light-emitting layer or the hole transport layer, and between the cathode and the light-emitting layer or the electron transport layer. The injection layer can be provided as needed.

[0138] -Hole blocking layer- In a broad sense, the hole blocking layer has the function of an electron transport layer. It is made of a hole blocking material that has the ability to transport electrons while having extremely low ability to transport holes, and can improve the recombination probability of electrons and holes in the light-emitting layer by transporting electrons while blocking holes. Known hole blocking materials can be used for the hole blocking layer. In order to bring out the characteristics of the light-emitting dopant, the material used as the second host can also be used as the material of the hole blocking layer. Also, multiple types of hole blocking materials can be used in combination.

[0139] -Electron blocking layer- In a broad sense, the electron blocking layer has the function of a hole transport layer, and can improve the probability of recombination of electrons and holes in the light-emitting layer by transporting holes while blocking electrons. As the material of the electron blocking layer, known electron blocking layer materials can be used. In order to bring out the characteristics of the light-emitting dopant, the material used as the first host can also be used as the material of the electron blocking layer. The film thickness of the electron blocking layer is preferably 3 to 100 nm, more preferably 5 to 30 nm.

[0140] -Exciton blocking layer- The exciton blocking layer is a layer for preventing 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 confined within the light-emitting layer, and the light-emitting efficiency of the device can be improved. The exciton blocking layer can be inserted between two adjacent light-emitting layers in a device where two or more light-emitting layers are adjacent. As the material of the exciton blocking layer, known exciton blocking layer materials can be used.

[0141] As the layer adjacent to the light-emitting layer, there are a hole-blocking layer, an electron-blocking layer, an exciton-blocking layer, etc. When these layers are not provided, a hole-transporting layer, an electron-transporting layer, etc. become the adjacent layers.

[0142] -Hole-transporting layer- The hole-transporting layer is made of a hole-transporting material having a function of transporting holes, and the hole-transporting layer can be provided as a single layer or multiple layers.

[0143] The hole-transporting material has either a function of injecting or transporting holes or a function of blocking electrons, and can be either an organic or inorganic material. Any material known in the art can be selected and used for the hole-transporting layer. Examples of such hole-transporting materials include porphyrin derivatives, arylamine derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, and conductive polymer oligomers, particularly thiophene oligomers. Among them, porphyrin derivatives, arylamine derivatives, and styrylamine derivatives are preferably used, and arylamine compounds are more preferably used.

[0144] -Electron-transporting layer- The electron-transporting layer is made of a material having a function of transporting electrons, and the electron-transporting layer can be provided as a single layer or multiple layers.

[0145] As the electron transport material (which may also serve as a hole blocking material), it only needs to have the function of transmitting the electrons injected from the cathode to the light emitting layer. For the electron transport layer, any one can be selected from conventionally known compounds and used. For example, polycyclic aromatic derivatives such as naphthalene, anthracene, phenanthroline, tris(8-quinolinolato)aluminum(III) derivatives, phosphine oxide derivatives, nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimide, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, bipyridine derivatives, quinoline derivatives, oxadiazole derivatives, benzimidazole derivatives, benzothiazole derivatives, indolocarbazole derivatives, etc. can be mentioned. Furthermore, polymer materials in which these materials are introduced into the polymer chain or these materials are used as the main chain of the polymer can also be used.

[0146] When fabricating the organic EL element of the present invention, the film forming method of each layer is not particularly limited, and it may be fabricated by either a dry process or a wet process.

Examples

[0147] Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0148] The compounds used in the examples and comparative examples are shown below.

Chemical formula

[0149] S1 and T1 of the compounds (4-2) and (4-110) were measured. S1 and T1 were measured as follows. On a quartz substrate by vacuum evaporation method, the degree of vacuum is 10 -4Under the condition of Pa or less, the compound (2 - 30) as the host and the compound (4 - 2) or (4 - 110) as the luminescent dopant were co-evaporated from different evaporation sources, and an evaporation film was formed with a thickness of 100 nm. At this time, co-evaporation was carried out under the evaporation conditions where the concentration of the compound (4 - 2) or (4 - 110) was 3%. S1 measures the emission spectrum of this evaporation film, draws a tangent to the rising edge on the short-wavelength side of this emission spectrum, and substitutes the wavelength value λedge [nm] at the intersection of the tangent and the horizontal axis into the following formula (i) to calculate S1. S1 [eV] = 1239.85 / λedge (i) T1 measures the phosphorescence spectrum of the above evaporation film, draws a tangent to the rising edge on the short-wavelength side of this phosphorescence spectrum, and substitutes the wavelength value λedge [nm] at the intersection of the tangent and the horizontal axis into formula (ii) to calculate T1. T1 [eV] = 1239.85 / λedge (ii)

[0150] The measurement results are shown in Table 1.

Table 1

[0151] Example 1 On a glass substrate on which an anode made of ITO with a film thickness of 70 nm was formed, each thin film was formed by vacuum evaporation method with a vacuum degree of 4.0×10 -5They were laminated at Pa. First, HAT-CN was formed as a hole injection layer on ITO with a thickness of 10 nm, and then HT-1 was formed as a hole transport layer with a thickness of 25 nm. Next, compound (1-77) was formed as an electron blocking layer with a thickness of 5 nm. Next, compound (1-77) was co-evaporated as the first host, compound (3-3) was co-evaporated as the second host, and compound (4-110) was co-evaporated as the light-emitting dopant from different evaporation sources to form a light-emitting layer with a thickness of 30 nm. At this time, co-evaporation was carried out under evaporation conditions where the concentration of compound (4-110) was 2% and the weight ratio of the first host to the second host was 50:50. Next, compound (HB1) was formed as a hole blocking layer with a thickness of 5 nm. Next, ET-1 was formed as an electron transport layer with a thickness of 40 nm. Further, lithium fluoride (LiF) was formed as an electron injection layer on the electron transport layer with a thickness of 1 nm. Finally, aluminum (Al) was formed as a cathode with a thickness of 70 nm on the electron injection layer to fabricate an organic EL element.

[0152] Examples 2 to 16 An organic EL element was fabricated in the same manner as in Example 1, except that the light-emitting dopant, the first host, the second host, and the compound shown in Table 2 for the weight ratio of the first host to the second host were used. Note that Example 9 is a reference example.

[0153] Comparative Example 1 On a glass substrate on which an anode made of ITO with a film thickness of 70 nm was formed, each thin film was formed by vacuum evaporation at a vacuum degree of 4.0×10 -5It was laminated at Pa. First, HAT-CN was formed on ITO as a hole injection layer with a thickness of 10 nm, and then HT-1 was formed as a hole transport layer with a thickness of 25 nm. Next, compound (2-30) was formed as an electron blocking layer with a thickness of 5 nm. Next, compound (1-77) was co-evaporated from different evaporation sources as the first host and compound (4-110) as the light-emitting dopant to form a light-emitting layer with a thickness of 30 nm. At this time, it was co-evaporated under the evaporation conditions where the concentration of compound (4-110) was 2%. Next, compound (HB1) was formed as a hole blocking layer with a thickness of 5 nm. Next, ET-1 was formed as an electron transport layer with a thickness of 40 nm. Further, lithium fluoride (LiF) was formed as an electron injection layer on the electron transport layer with a thickness of 1 nm. Finally, aluminum (Al) was formed as a cathode with a thickness of 70 nm on the electron injection layer to fabricate an organic EL element.

[0154] Comparative Examples 2, 3, 4, 7, 8, 9 An organic EL element was fabricated in the same manner as in Comparative Example 1, except that the light-emitting dopant and the first host (without the second host) were the compounds shown in Table 2.

[0155] Comparative Examples 5, 6, 10 An organic EL element was fabricated in the same manner as in Example 1, except that the light-emitting dopant, the first host, and the second host were the compounds shown in Table 2.

[0156]

Table 2

[0157] Table 3 shows the voltage, the maximum emission wavelength of the emission spectrum, the external quantum efficiency, and the lifetime of the organic EL elements fabricated in the examples and comparative examples. The voltage, the maximum emission wavelength, and the external quantum efficiency are the values at a luminance of 500 cd / m 2 and are the initial characteristics. The lifetime was measured as the time until the luminance decayed to 50% of the initial luminance at an initial luminance of 500 cd / m 2 .

[0158]

Table 3

[0159] It can be seen from Table 3 that the organic EL element of the example of the present invention has characteristics of high efficiency and long life, and it can be seen that the emission is blue light from the maximum emission wavelength.

Explanation of symbols

[0160] 1 Substrate, 2 Anode, 3 Hole injection layer, 4 Hole transport layer, 5 Light emitting layer, 6 Electron transport layer, 7 Cathode

Claims

1. In an organic electroluminescent device including one or more light-emitting layers between opposing anodes and cathodes, at least one light-emitting layer includes a host and a light-emitting dopant, the host includes a first host represented by General Formula (1) or General Formula (2), and a second host represented by General Formula (3), and the light-emitting dopant includes a polycyclic aromatic compound represented by the following Formula (5) having a structure represented by General Formula (4) as a partial structure. An organic electroluminescent device characterized by including the same. 【Chemical 1】 (Here, Y １ represents O, S, or N—Ar １ . Ar １ 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 formed by linking 2 to 8 of these aromatic rings. R １ independently represents deuterium, 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. a independently represents an integer of 0 to 4, and b independently represents an integer of 0 to 3.) [Chemical Formula 2] (Here, c independently is an integer of 0 to 5, d independently is an integer of 0 to 2, and at least one d is 1 or more. e independently is an integer of 0 to 2. R ２ is independently a cyano group, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms, L ２ is 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. However, L ２ is not a biphenylene group represented by -Ph-Ph- (where Ph is a phenylene group). Ar ２ is hydrogen, a cyano group, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, 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 formed by linking 2 to 3 of these.) However, a compound represented by the following Formula H1 is excluded. 【Chemical Formula 3】 【Chemical Formula 4】 (Here, Z ３ is an indolocarbazole ring-containing group represented by formula (3a), * is the bonding position with L ３ which is the bonding position with Ring A is a heterocyclic ring represented by Formula (3b), and is condensed with an adjacent ring at an arbitrary position. L ３ and L ３１ each independently represents 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 ３ and Ar ３１ is each 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 formed by linking 2 to 8 of these groups. R ３ is 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. f represents an integer of 1 to 3, g represents an integer of 0 to 3, h independently represents an integer of 0 to 4, i represents an integer of 0 to 2, and j represents an integer of 0 to 3.) [Chemical Formula 5] (Here, Ring C, Ring D, and Ring E are each independently an aromatic hydrocarbon ring having 6 to 24 carbon atoms or an aromatic heterocyclic ring having 3 to 17 carbon atoms, Y ４ is B, P, P=O, P=S, Al, Ga, As, Si-R ４ or Ge-R ４１ and X ４ is independently O, N—Ar ４ , S, or Se, and R ４ and R ４１ are each 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, Ar ４ 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 formed by linking 2 to 8 of them, and N-Ar ４ may combine with any one of Ring C, Ring D, or Ring E to form a heterocyclic ring containing N, R ４２ each independently represents a cyano group, deuterium, a diarylamino group having 12 to 44 carbon atoms, an arylheteroarylamino group having 12 to 44 carbon atoms, a diheteroarylamino group having 12 to 44 carbon atoms, 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, v each independently represents an integer of 0 to 4, and x represents an integer of 0 to 3. Ring C, Ring D, Ring E, R ４ , R ４１ , R ４２ , and Ar ４ in which at least one hydrogen may be substituted with a halogen or deuterium.) 【Chemical Formula 6】 (Here, Ring F, Ring G, Ring H, Ring I, and Ring J are each independently an aromatic hydrocarbon ring having 6 to 24 carbon atoms, or an aromatic heterocyclic ring having 3 to 17 carbon atoms, At least one hydrogen in Ring F, Ring G, Ring H, Ring I, and Ring J may be substituted with a halogen or deuterium. X4, Y4, R42, x, and v are the same as in General Formula (4), w represents an integer of 0 to 4, y represents an integer of 0 to 3, and z represents an integer of 0 to 2.)

2. The organic electroluminescent device according to Claim 1, wherein the polycyclic aromatic compound having a structure represented by General Formula (4) as a partial structure is a boron-containing polycyclic aromatic compound represented by the following Formula (6). 【Chemical Formula 7】 (Here, X ６ independently represents N-Ar ６ , O, or S, provided that at least one X ６ represents N-Ar ６ . Ar ６ 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 formed by linking 2 to 8 of these aromatic rings, and N-Ar ６ may form a heterocyclic ring containing N by bonding to the aromatic ring to which X ６ is bonded. R ６ independently represents a cyano group, deuterium, a diarylamino group having 12 to 44 carbon atoms, 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. k independently represents an integer of 0 to 4, l independently represents an integer of 0 to 3, and m represents an integer of 0 to 2.)

3. The organic electroluminescent device according to Claim 1 or 2, characterized by containing the first host represented by General Formula (1).

4. Y in the general formula (1) １ is N-Ar １ The organic electroluminescent element according to any one of claims 1 to 3, characterized in that.

5. The organic electroluminescent device according to Claim 4, wherein the General Formula (1) is the following Formula (7). 【Chemical Formula 8】 (Here, Ar １ is synonymous with the general formula (1).)

6. The organic electroluminescent device according to claim 1 or 2, wherein the light-emitting layer contains a first host represented by the general formula (2) and a second host represented by the general formula (3). **Claim 7**: In an organic electroluminescent device including one or more light-emitting layers between a pair of opposing anode and cathode, at least one light-emitting layer contains a host and a light-emitting dopant, the host includes a first host represented by the general formula (2) and a second host represented by the general formula (3), the light-emitting dopant includes a polycyclic aromatic compound represented by the general formula (4) or a polycyclic aromatic compound having a structure represented by the general formula (4) as a partial structure, and the organic electroluminescent device is characterized in that the general formula (2) is the following formula (8). 【Chemical Formula 9】 (Here, c is independently an integer of 0 to 5, d is independently an integer of 0 to 2, and at least one d is 1 or more. e is independently an integer of 0 to 2.) R 2 is independently a cyano group, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, or a substituted or unsubstituted aromatic hydrocarbon group having 6 to 18 carbon atoms. L 2 is 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. However, L 2 is not a biphenylene group represented by -Ph-Ph- (where Ph is a phenylene group). Ar 2 is hydrogen, a cyano group, an aliphatic hydrocarbon group having 1 to 10 carbon atoms, 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 formed by linking 2 to 3 of these.) However, a compound represented by the following formula H1 is excluded. 【Chemical Formula 10】 【Chemical 11】 (Here, Z 3 is an indolocarbazole ring-containing group represented by the formula (3a). * is the bonding position with L 3. Ring A is a heterocyclic ring represented by the formula (3b) and is condensed with an adjacent ring at an arbitrary position. L 3 and L 31 are each 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 3 and Ar 31 are each 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 formed by linking 2 to 8 of these. R3 is 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. f represents an integer of 1 to 3, g represents an integer of 0 to 3, h independently represents an integer of 0 to 4, i represents an integer of 0 to 2, and j represents an integer of 0 to 3. ) 【Chemical Formula 12】 (Here, the C ring, D ring, and E ring are each independently an aromatic hydrocarbon ring having 6 to 24 carbon atoms or an aromatic heterocyclic ring having 3 to 17 carbon atoms, Y4 is B, P, P=O, P=S, Al, Ga, As, Si-R4, or Ge-R41, X4 is independently O, N-Ar4, S, or Se, R4 and R41 are each 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, Ar4 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 formed by linking 2 to 8 of them, and N-Ar4 may combine with any of the C ring, D ring, or E ring to form a heterocyclic ring containing N, R42 is each independently a cyano group, deuterium, a diarylamino group having 12 to 44 carbon atoms, an arylheteroaryl amino group having 12 to 44 carbon atoms, a diheteroaryl amino group having 12 to 44 carbon atoms, 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, v each independently represents an integer of 0 to 4, and x represents an integer of 0 to 3. At least one hydrogen in the C ring, D ring, E ring, R4, R41, R42, and Ar4 may be substituted with a halogen or deuterium. ) 【Chemical 13】 (Here, n is an integer of 1 to 5, p is an integer of 0 to 1, L ８ represents a group derived from benzene, dibenzofuran, or dibenzothiophene. R ８１ is derived from hydrogen, benzene, dibenzofuran, or dibenzothiophene represents a group. )

8. The organic electroluminescent device according to claim 7, wherein the polycyclic aromatic compound having the structure represented by the general formula (4) as a partial structure is a boron-containing polycyclic aromatic compound represented by the following formula (6). 【Chemical Formula 14】 (Here, X6 independently represents N-Ar6, O, or S, but at least one X6 represents N-Ar6. Ar 6 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 formed by linking 2 to 8 of these aromatic rings, and N-Ar 6 may combine with the aromatic ring to which X 6 is bonded to form a heterocyclic ring containing N. R 6 independently represents a cyano group, deuterium, a diarylamino group having 12 to 44 carbon atoms, 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. k independently represents an integer of 0 to 4, l independently represents an integer of 0 to 3, and m represents an integer of 0 to 2. )

9. The organic electroluminescent device according to any one of claims 1 to 8, wherein f in the general formula (3) is 1.

10. The organic electroluminescent device according to any one of claims 1 to 9, wherein the luminescent dopant has a difference (ΔEST) between the singlet excitation energy (S1) and the triplet excitation energy (T1) of 0.20 eV or less.

11. The organic electroluminescent device according to claim 10, wherein the ΔEST is 0.10 eV or less.

12. The organic electroluminescent device according to any one of claims 1 to 11, which contains 0.10 to 10 wt% of a luminescent dopant and 99.9 to 90 wt% of a host, and in the host, 10 to 90 wt% of a first host and 90 to 10 wt% of a second host are contained.

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