JP6855129B2 - Organic electroluminescent device containing a polycyclic aromatic compound as a constituent - Google Patents

Description

The present invention relates to an organic electroluminescent device using a polycyclic aromatic compound.

The organic electroluminescent element has a basic configuration in which a light emitting layer containing a light emitting material is sandwiched between a hole transporting layer and an electron transporting layer, and an anode and a cathode are further attached to the outside thereof, and is injected into the light emitting layer. It is a light emitting element that utilizes the emission of light (fluorescence or phosphorescence) when excitons generated by the recombination of holes and electrons are deactivated. It is already used not only for small displays but also for large TVs and lighting. The hole transporting layer is used for the hole transporting layer and the hole injection layer, the light emitting layer is used for the light emitting host and the light emitting dopant, or the electron blocking layer is used for the electron blocking layer and the light emitting layer and the hole blocking layer. The layer may be divided into an electron transport layer and an electron injection layer. Further, as the carrier transport layer (electron transport layer or hole transport layer) of the organic electroluminescent element, a co-deposited film doped with a metal, an organometallic compound or another organic compound may be used.

Here, in recent years, studies have been actively conducted from general-purpose low-molecular-weight compounds toward bottom-up synthesis of graphenes having a single structure by an organic reaction (for example, Patent Document 1 and Non-Patent Document 1). And 2). The polycyclic aromatic compounds produced in these research processes are expected to be applied as organic semiconductor devices because they have a bandgap that graphene does not have, although the π-conjugated system has a highly expanded structure. it can. However, in the above-mentioned documents, there is no description about a specific usage method and its performance regarding the application of these polycyclic aromatic compounds.

Japanese Patent No. 5988051

Nature Communications, 2015, No. 6, p. 6251. Synlett, 2016, No. 27, p. 2081.

An object of the present invention is to provide a high-performance organic electroluminescence device having excellent drive voltage, luminous efficiency, and device life.

As a result of diligent studies to solve the above problems, the present inventor has shown that the polycyclic aromatic compound represented by the following general formula (1) exhibits excellent charge transport characteristics, and the driving voltage. We have found that we can provide a high-performance organic electroluminescence device with excellent luminous efficiency and device life, and have completed the present invention. That is, the present invention is an organic electroluminescence element having a plurality of organic layers between the anode and the cathode and the anode and the cathode, and at least one of the layers constituting the hole transport region and the light emitting region. The present invention relates to an organic electroluminescence device, which comprises a polycyclic aromatic compound represented by the following formula (1).

(In the formula, A ¹ and A ² are the same or different, and represent a hydrogen atom, a methyl group, an ethyl group, or a linear, cyclic, or branched alkyl group having 3 to 18 carbon atoms, respectively.
B ^{1 to} B ⁴ are the same or different, respectively, of a monocyclic, linked or condensed aromatic hydrocarbon group having 6 to 18 carbon atoms, a monocyclic, linked or condensed ring having 3 to 36 carbon atoms, respectively. Heteroaromatic groups (each of these groups is independently a fluorine atom, a methyl group, an ethyl group, a linear, cyclic or branched alkyl group having 3 to 18 carbon atoms, a methoxy group, an ethoxy group, or a carbon number of carbon atoms. It may have one or more substituents selected from the group consisting of 3-18 linear, cyclic or branched alkoxy groups), methyl group, ethyl group, linear with 3-18 carbon atoms, A cyclic or branched alkyl group, methoxy group, ethoxy group, linear, cyclic or branched alkoxy group having 3 to 18 carbon atoms, or the following general formula (2).

(In the formula, R ¹ and R ² are the same or different, respectively, an aromatic hydrocarbon group having 6 to 18 carbon atoms, a linked or condensed ring, and a monocyclic ring having 3 to 36 carbon atoms, linked. Alternatively, a fused heteroaromatic group (these groups are independently a fluorine atom, a methyl group, an ethyl group, a linear, cyclic or branched alkyl group having 3 to 18 carbon atoms, a methoxy group and an ethoxy group. , Or may have one or more substituents selected from the group consisting of linear, cyclic, or branched alkoxy groups having 3 to 18 carbon atoms), hydrogen atom, methyl group, ethyl group, or carbon. Represents a linear, cyclic, or branched alkyl group of equations 3-18.)
Represents a group represented by.
k ^{1 to k 4} are the same or different, and are integers from 0 to 4, respectively. )

The organic electroluminescence element of the present invention has a stable amorphous layer, high heat resistance, low driving voltage, long life, etc. by using a polycyclic aromatic compound represented by the general formula (1) as a constituent component. realizable. By using the organic electroluminescence element of the present invention, it can be developed in various applications such as displays and lighting fixtures.

The polycyclic aromatic compound represented by the general formula (1) in the present invention has excellent solubility in a general-purpose solvent. Therefore, it is highly soluble not only in halogen-based solvents such as chloroform and chlorobenzene, but also in non-halogen solvents such as toluene and xylene. Therefore, it is suitable not only for film formation by a vapor deposition process but also for a coating process using a solvent.

In addition, by using another material dissolved in a poor solvent for the polycyclic aromatic compound represented by the general formula (1), a layer containing the polycyclic aromatic compound represented by the general formula (1). A film of another material can be overcoated without eroding. Therefore, the present invention can also provide an organic electroluminescence device produced by a continuous coating film formation process using a polycyclic aromatic compound represented by the general formula (1).

Hereinafter, the present invention will be described in more detail.

In the polycyclic aromatic compound represented by the general formula (1), A ¹ and A ² are the same or different, respectively, and are a hydrogen atom, a methyl group, an ethyl group, or a linear chain having 3 to 18 carbon atoms, respectively. , Cyclic, or branched alkyl groups.

The linear, cyclic, or branched alkyl group having 3 to 18 carbon atoms is not particularly limited, but for example, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, and the like. Examples thereof include a tert-butyl group, an i-butyl group, an n-hexyl group, a cyclohexyl group, a cyclohexadienyl group, an octyl group, a trifluoromethyl group, a benzyl group, a phenethyl group and the like.

As A ¹ and A ² , a hydrogen atom, a methyl group, a tert-butyl group, or an n-butyl group is preferable, and a hydrogen atom or a methyl group is more preferable, from the viewpoint of raw material availability.

In the polycyclic aromatic compound represented by the general formula (1), B ^{1 to} B ⁴ are the same or different, and are monocyclic, linked, or condensed aromatic charcoal having 6 to 18 carbon atoms, respectively. Hydrogen group, monocyclic, linked or condensed heteroaromatic group with 3 to 36 carbon atoms (these groups are independently fluorine atoms, methyl groups, ethyl groups and linear chains with 3 to 18 carbon atoms. , A cyclic or branched alkyl group, a methoxy group, an ethoxy group, or one or more substituents selected from the group consisting of a linear, cyclic or branched alkoxy group having 3 to 18 carbon atoms. Good), methyl group, ethyl group, linear, cyclic or branched alkyl group with 3-18 carbon atoms, methoxy group, ethoxy group, linear, cyclic or branched alkoxy group with 3-18 carbon atoms, or It represents a group represented by the general formula (2).

The linear, cyclic, or branched alkyl group having 3 to 18 carbon atoms in ^{B 1 to} B ⁴ is the linear, cyclic, or branched alkyl group having 3 to 18 carbon atoms in ^{A 1} and A ^2. It is the same as the definition of.

The ^{linear, cyclic, or branched alkoxy groups of B 1 to} B ⁴ having 3 to 18 carbon atoms are not particularly limited, but are n-propoxy group, isopropoxy group, cyclopentyloxy group, cyclohexyloxy group. , Or a cycloheptyloxy group and the like.

The ^{monocyclic, linked, or condensed ring aromatic hydrocarbon groups of B 1 to} B ⁴ having 6 to 18 carbon atoms are not particularly limited, but are phenyl group, biphenylyl group, terphenylyl group, and naphthyl group. , A fluorenyl group, a phenanthryl group, a benzofluorenyl group, a pyrenyl group, a triphenylenyl group and the like.

The ^{monocyclic, linked, or condensed ring heteroaromatic group having 3 to 36 carbon atoms of B 1 to} B ⁴ is not particularly limited, but is, for example, at least one oxygen atom, nitrogen atom, or, for example. A heteroaromatic group containing a sulfur atom and having 3 to 36 carbon atoms which may be linked or condensed can be mentioned, and more preferably, an atom selected from the group consisting of an oxygen atom, a nitrogen atom and a sulfur atom is selected. Examples thereof include a heteroaromatic group having at least one of 3 to 36 carbon atoms contained on the aromatic ring, which may be linked or condensed, and is not particularly limited, but for example, a pyrrolyl group, a thienyl group, or a frill. Group, imidazolyl group, pyrazolyl group, thiazolyl group, isothiazolyl group, oxazolyl group, isooxazolyl group, pyridyl group, phenylpyridyl group, pyridylphenyl group, pyrimidyl group, pyrazil group, 1,3,5-triazyl group, indolyl group, benzo Thienyl group, benzofuranyl group, benzoimidazolyl group, indazolyl group, benzothiazolyl group, benzoisothiazolyl group, 2,1,3-benzothiazolyl group, benzoxazolyl group, benzoisooxazolyl group, 2,1, Examples thereof include 3-benzoxaziazolyl group, quinolyl group, isoquinolyl group, quinoxalyl group, quinazolyl group, carbazolyl group, dibenzothienyl group, dibenzofuranyl group, phenoxadinyl group, phenothiazinyl group, phenazine group, thianthrenyl group and the like.

Further, as described above, the above B ^{1 to} B ⁴ can also be used as a group represented by the above general formula (2).

^{In R 1} and R ² of the above general formula (2), a linear, cyclic or branched alkyl group having 3 to 18 carbon atoms, a linear, cyclic or branched alkoxy group having 3 to 18 carbon atoms, or a branched alkyl group has a carbon number of carbons. 6-18 monocyclic, linked, or aromatic hydrocarbon group having condensed, monocyclic 3 to 36 carbon atoms, linking, or the definition of heteroaromatic groups condensed, in each of the above a ¹ and a ² Same as definition.

Specific examples of B ^{1 to} B ⁴ include methyl group, ethyl group, tert-butyl group, n-butyl group, phenyl group, 4-methylphenyl group, 3-methylphenyl group, 2-methylphenyl group, 2, 4-Dimethylphenyl group, 2,5-dimethylphenyl group, 3,4-dimethylphenyl group, 3,5-dimethylphenyl group, 2,6-dimethylphenyl group, 2,3,5-trimethylphenyl group, 2, 3,6-trimethylphenyl group, 3,4,5-trimethylphenyl group, 4-biphenyl group, 3-biphenyl group, 2-biphenyl group, 2-methyl-1,1'-biphenyl-4-yl group, 3 -Methyl-1,1'-biphenyl-4-yl group, 2'-methyl-1,1'-biphenyl-4-yl group, 3'-methyl-1,1'-biphenyl-4-yl group, 4 '-Methyl-1,1'-biphenyl-4-yl group, 2,6-dimethyl-1,1'-biphenyl-4-yl group, 2,2'-dimethyl-1,1'-biphenyl-4- Il group, 2,3'-dimethyl-1,1'-biphenyl-4-yl group, 2,4'-dimethyl-1,1'-biphenyl-4-yl group, 3,2'-dimethyl-1, 1'-biphenyl-4-yl group, 2', 3'-dimethyl-1,1'-biphenyl-4-yl group, 2', 4'-dimethyl-1,1'-biphenyl-4-yl group, 2', 5'-dimethyl-1,1'-biphenyl-4-yl group, 2', 6'-dimethyl-1,1'-biphenyl-4-yl group, 4-phenylbiphenyl group, 2-phenylbiphenyl Group, 1-naphthyl group, 2-naphthyl group, 2-methylnaphthalene-1-yl group, 4-methylnaphthalene-1-yl group, 6-methylnaphthalene-2-yl group, 4- (1-naphthyl) phenyl Group, 4- (2-naphthyl) phenyl group, 3- (1-naphthyl) phenyl group, 3- (2-naphthyl) phenyl group, 3-methyl-4- (1-naphthyl) phenyl group, 3-methyl- 4- (2-naphthyl) phenyl group, 4- (2-methylnaphthalen-1-yl) phenyl group, 3- (2-methylnaphthalen-1-yl) phenyl group, 4-phenylnaphthalene-1-yl group, 4- (2-Methylphenyl) naphthalene-1-yl group, 4- (3-methylphenyl) naphthalene-1-yl group, 4- (4-methylphenyl) naphthalene-1-yl group, 6-phenylnaphthalene- 2-yl group, 4- (2-methylphenyl) naphthalene-2-yl group, 4- (3-methylphenyl) naphthalene -2-yl group, 4- (4-methylphenyl) naphthalene-2-yl group, 2-fluorenyl group, 9,9-dimethyl-2-fluorenyl group, 9,9'-spirobifluorenyl group, 9 -Phenantril group, 2-phenanthryl group, 11,11'-dimethylbenzo [a] fluorene-9-yl group, 11,11'-dimethylbenzo [a] fluorene-3-yl group, 11,11'-dimethylbenzo [B] Fluoren-9-yl group, 11,11'-dimethylbenzo [b] fluoren-3-yl group, 11,11'-dimethylbenzo [c] fluoren-9-yl group, 11,11'-dimethyl Benzo [c] Fluoren-2-yl group, 3-fluoranthenyl group, 8-fluoranthenyl group, 1-imidazolyl group, 2-phenyl-1-imidazolyl group, 2-phenyl-3,4-dimethyl-1 -Imidazolyl group, 2,3,4-triphenyl-1-imidazolyl group, 2- (2-naphthyl) -3,4-dimethyl-1-imidazolyl group, 2- (2-naphthyl) -3,4-diphenyl -1-imidazolyl group, 1-methyl-2-imidazolyl group, 1-ethyl-2-imidazolyl group, 1-phenyl-2-imidazolyl group, 1-methyl-4-phenyl-2-imidazolyl group, 1-methyl- 4,5-Dimethyl-2-imidazolyl group, 1-methyl-4,5-diphenyl-2-imidazolyl group, 1-phenyl-4,5-dimethyl-2-imidazolyl group, 1-phenyl-4,5-diphenyl -2-imidazolyl group, 1-phenyl-4,5-dibiphenylyl-2-imidazolyl group, 1-methyl-3-pyrazolyl group, 1-phenyl-3-pyrazolyl group, 1-methyl-4-pyrazolyl group, 1- Phenyl-4-pyrazolyl group, 1-methyl-5-pyrazolyl group, 1-phenyl-5-pyrazolyl group, 2-thiazolyl group, 4-thiazolyl group, 5-thiazolyl group, 3-isothiazolyl group, 4-isothiazolyl group, 5-isothiazolyl group, 2-oxazolyl group, 4-oxazolyl group, 5-oxazolyl group, 3-isooxazolyl group, 4-isoxazolyl group, 5-isooxazolyl group, 2-pyridyl group, 3-methyl-2-pyridyl group, 4 -Methyl-2-pyridyl group, 5-methyl-2-pyridyl group, 6-methyl-2-pyridyl group, 3-pyridyl group, 4-methyl-3-pyridyl group, 4-pyridyl group, 2-pyrimidyl group, 2,2'-bipyridine-3-yl group, 2,2'-bipyridine-4-yl group, 2,2' -Bipylene-5-yl group, 2,3'-bipyridine-3-yl group, 2,3'-bipyridine-4-yl group, 2,3'-bipyridine-5-yl group, 5-pyrimidyl group, pyragil Group, 1,3,5-triazyl group, 4,6-diphenyl-1,3,5-triazine-2-yl group, 1-benzoimidazolyl group, 2-methyl-1-benzoimidazolyl group, 2-phenyl-1- Benzoimidazolyl group, 1-methyl-2-benzoimidazolyl group, 1-phenyl-2-benzoimidazolyl group, 1-methyl-5-benzoimidazolyl group, 1,2-dimethyl-5-benzoimidazolyl group, 1-methyl-2-phenyl-5 -Benzoimidazolyl group, 1-phenyl-5-benzoimidazolyl group, 1,2-diphenyl-5-benzoimidazolyl group, 1-methyl-6-benzoimidazolyl group, 1,2-dimethyl-6-benzoimidazolyl group, 1-methyl-2- Phenyl-6-benzoimidazolyl group, 1-phenyl-6-benzoimidazolyl group, 1,2-diphenyl-6-benzoimidazolyl group, 1-methyl-3-indazolyl group, 1-phenyl-3-indazolyl group,
2-benzothiazolyl group, 4-benzothiazolyl group, 5-benzothiazolyl group, 6-benzothiazolyl group, 7-benzothiazolyl group, 3-benzoisothiazolic group, 4-benzoisothiazolic group, 5-benzoisothiazolic group, 6 -Benzoisothiazolyl group, 7-benzoisothiazolyl group, 2,1,3-benzothiazol-4-yl group, 2,1,3-benzothiazol-5-yl group, 2-benzoxazolyl group , 4-benzoxazolyl group, 5-benzoxazolyl group, 6-benzoxazolyl group, 7-benzoxazolyl group, 3-benzoisoxazolyl group, 4-benzoisooxazolyl group , 5-benzoisoxazolyl group, 6-benzoisoxazolyl group, 7-benzoisoxazolyl group, 2,1,3-benzoxadiazolyl-4-yl group, 2,1,3- Benoxadiazolyl-5-yl group, 2-quinolyl group, 3-quinolyl group, 5-quinolyl group, 6-quinolyl group, 1-isoquinolyl group, 4-isoquinolyl group, 5-isoquinolyl group, 2-quinoxalyl group, 3-Phenyl-2-quinoxalyl group, 6-quinoxalyl group, 2,3-dimethyl-6-quinoxalyl group, 2,3-diphenyl-6-quinoxalyl group, 2-quinazolyl group, 4-quinazolyl group, 2-acrydinyl group , 9-Acridinyl group, 1,10-phenanthroline-3-yl group, 1,10-phenanthroline-5-yl group, 2-thienyl group, 3-thienyl group, 2-benzothienyl group, 3-benzothienyl group, 2-Dibenzothienyl group, 4-dibenzothienyl group, 2-furanyl group, 3-furanyl group, 2-benzofuranyl group, 3-benzofuranyl group, 2-dibenzofuranyl group, 4-dibenzofuranyl group, 9-methylcarbazole -2-yl group, 9-methylcarbazole-3-yl group, 9-methylcarbazole-4-yl group, 9-phenylcarbazole-2-yl group, 9-phenylcarbazole-3-yl group, 9-phenylcarbazole group -4-yl group, 9-biphenylcarbazole-2-yl group, 9-biphenylcarbazole-3-yl group, 9-biphenylcarbazole-4-yl group, 2-thiantolyl group, 10-phenylphenothiazine-3-yl group 10,-Phenylphenothiazine-2-yl group, 10-phenylphenoxazine-3-yl group, 10-phenylphenoxadin-2-yl group, 1-methylindole-2-yl group, 1-phenylindole-2- Il group, 9-Phenylcarbazole-4-yl group, 1-methylindole-2-yl group, 1-phenylindole-2-yl group, 4- (2-pyridyl) phenyl group, 4- (3-pyridyl) Phenyl group, 4- (4-pyridyl) phenyl group, 3- (2-pyridyl) phenyl group, 3- (3-pyridyl) phenyl group, 3- (4-pyridyl) phenyl group, 4- (2-phenylimidazole) -1-yl) phenyl group, 4- (1-phenylimidazol-2-yl) phenyl group, 4- (2,3,4-triphenylimidazol-1-yl) phenyl group, 4- (1-methyl-) 4,5-Diphenylimidazol-2-yl) phenyl group, 4- (2-methylbenzoimidazole-1-yl) phenyl group, 4- (2-phenylbenzoimidazol-1-yl) phenyl group, 4- (1) -Methylbenzoimidazole-2-yl) phenyl group, 4- (2-phenylbenzoimidazole-1-yl) phenyl group, 3- (2-methylbenzoimidazole-1-yl) phenyl group, 3- (2-phenyl) Benzoimidazole-1-yl) phenyl group, 3- (1-methylbenzoimidazol-2-yl) phenyl group, 3- (2-phenylbenzoimidazole-1-yl) phenyl group, 4- (3,5-diphenyl) Triazine-1-yl) phenyl group, 4- (2-thienyl) phenyl group, 4- (2-furanyl) phenyl group, 5-phenylthiophen-2-yl group, 5-phenylfuran-2-yl group, 4 -(5-Phenylthiophen-2-yl) phenyl group, 4- (5-phenylfuran-2-yl) phenyl group, 3- (5-phenylthiophen-2-yl) phenyl group, 3- (5-phenyl) Fran-2-yl) phenyl group, 4- (2-benzothienyl) phenyl group, 4- (3-benzothienyl) phenyl group, 3- (2-benzothienyl) phenyl group, 3- (3-benzothienyl) Phenyl group, 4- (2-dibenzothienyl) phenyl group, 4- (4-dibenzothienyl) phenyl group, 3- (2-dibenzothienyl) phenyl group, 3- (4-dibenzothienyl) phenyl group, 4-( 2-Dibenzofuranyl) phenyl group, 4- (4-dibenzofuranyl) phenyl group, 3- (2-dibenzofuranyl) phenyl group, 3- (4-dibenzofuranyl) phenyl group, 5-phenylpyridine- 2-yl group, 4-phenylpyridine-2-yl group, 5-phenylpyridine-3-yl group, 4- (9-) Carbazolyl) phenyl group, or 3- (9-carbazolyl) phenyl group, N, N'-dimethylamino group, N, N'-diphenylamino group, N, N'-bisbiphenylamino group, N- (4-biphenyl) ) -4-p-Terphenylamino group, N- [4- (carbazole-9-yl) phenyl] -4-biphenylamino group, and the like can be exemplified, but the present invention is not limited thereto.

In the polycyclic aromatic compound represented by the general formula (1), from the viewpoint of raw material availability, B ^{1 to} B ⁴ are independently methyl group, tert-butyl group, n-butyl group, respectively. It is preferably a phenyl group, a biphenylyl group, a tertphenylyl group, a naphthyl group, a fluorenyl group, or a phenanthryl group, and more preferably a methyl group or a phenyl group.

k ^{1 to k 4} are the same or different, and are integers of 0 to 4, respectively. From the viewpoint of raw material availability and the production of the polycyclic aromatic compound represented by the general formula (1) in good yield, ^{k 1 to k 4 are preferably the same integer, and are all 0 or all 1.} Is more preferable.

The polycyclic aromatic compounds represented by the general formula (1) contained in the organic electroluminescence element of the present invention are described below from the viewpoints of low drive voltage, high luminous efficiency, and long life of the organic electroluminescence element. Preferred compounds are exemplified, but the present invention is not limited to these compounds.

The polycyclic aromatic compound represented by the general formula (1) uses an unsubstituted or substituted condensed ring compound and an unsubstituted or substituted silol compound as raw materials, and is known by a known method (for example, Nature Communications). , 2015, No. 6, p. 6251.).

For example, it can be synthesized by the following route.

A siror compound represented by the general formula (3), (3') or (3 ″) and a condensed ring compound represented by the general formula (4), (4 ′) or (4 ″). , In the presence of an oxidizing agent, the reaction is carried out using a palladium catalyst. The general formulas (3) and (3'), and (4') and (4 ") may be the same or different. The general formulas (3) and (3'), and (4') and (4 ″) are reacted simultaneously even if they are reacted stepwise with the general formulas (4) and (3 ″), respectively. However, from the viewpoint of reaction selectivity, it is preferable to react in stages.

(In the formula, A ¹ and A ² , B ^{1 to} B ⁴ , and k ^{1 to k 4} represent the same definition as the general formula (1).

The compounds represented by the general formulas (3), (3'), (3 ″), (4), (4 ′), and (4 ″) can be synthesized by a generally known method. It is possible, or commercially available compounds can be used (eg, Nature Communications, 2015, No. 6, p. 6251.).

The polycyclic aromatic compound represented by the general formula (1) of the present invention can be used as a material for an organic electroluminescence device. The polycyclic aromatic compound represented by the general formula (1) is preferably highly pure in terms of charge transport characteristics and device life. Specifically, it is preferable that impurities such as halogen atoms and transition metal elements and impurities such as manufacturing raw materials and by-products are as small as possible.

The present invention is an organic electroluminescence element having a plurality of organic layers between an anode and a cathode and the anode and the cathode, and is a hole transport region (for example, specifically, a hole injection layer and a hole). At least one of the layers constituting the transport layer, the electron blocking layer, etc.) and the light emitting region (for example, specifically composed of the light emitting layer, etc.) is represented by the following formula (1). It is an organic electroluminescence element characterized by containing a polycyclic aromatic compound.

In the present invention, the holes constituting the hole transport region and the light emitting region have a hole injection layer, a hole transport layer, an electron blocking layer, and a light emitting layer, and the holes are excellent. The injection layer, the hole transport layer, the electron blocking layer, or the light emitting layer preferably contains the compound (1), and the hole transport region and the layer constituting the light emitting region are the hole injection layer and the hole transport. It is more preferable that the hole injection layer, the hole transport layer, or the electron blocking layer has a layer, an electron blocking layer, and a light emitting layer, and the hole transporting layer or the electron blocking layer is a single layer of the compound (1).

The polycyclic aromatic compound represented by the general formula (1) is applied to the hole transport region (for example, specifically, the hole injection layer, the hole transport layer, the electron blocking layer, etc.) of the organic electroluminescence element. A known fluorescent light emitting material, a phosphorescent light emitting material, which has been conventionally used, is used as a light emitting layer when used as a light emitting region (for example, specifically composed of a light emitting layer or the like). Alternatively, a thermally activated delayed fluorescent material can be used. The light emitting layer may be formed of only one kind of light emitting material, or may be doped with one or more kinds of light emitting materials in the host material.

A hole transport region containing a polycyclic aromatic compound represented by the general formula (1) (specifically, it is composed of a hole injection layer, a hole transport layer, an electron blocking layer, etc.). When forming, it may be a single layer, or may contain or laminate another single or a plurality of known materials, and the known materials include, for example, an oxide such as molybdenum oxide, 7 , 7,8,8-Tetracyanoquinodimethane, 2,3,5,6-Tetrafluoro-7,7,8,8-Tetracyanoquinodimethane, Hexacyanohexazatriphenylene and other known electron-accepting materials May be contained or laminated.

When the polycyclic aromatic compound represented by the general formula (1) is used as the light emitting layer of the organic electroluminescence device, it may be used alone or doped with a known light emitting host material. It may be used by doping with a known light emitting dopant.

The polycyclic aromatic compound represented by the general formula (1) is used in an electron transport region (specifically, it is composed of an electron injection layer, an electron transport layer, a hole blocking layer, etc.). You can also do it. An electron transport region (for example, specifically composed of an electron injection layer, an electron transport layer, a hole blocking layer, etc.) containing a polycyclic aromatic compound represented by the general formula (1) is formed. In some cases, it may be a single layer, or may contain or laminate other one or more known materials, and the known materials include, for example, an alkali metal complex, an alkaline earth metal complex, and the like. Examples include earth metal complexes. Examples of the alkali metal complex, alkaline earth metal complex, or earth metal complex include 8-hydroxyquinolinate lithium (Liq), bis (8-hydroxyquinolinate) zinc, and bis (8-hydroxyquinolinate). Copper, bis (8-hydroxyquinolinate) manganese, tris (8-hydroxyquinolinate) aluminum, tris (2-methyl-8-hydroxyquinolinate) aluminum, tris (8-hydroxyquinolinate) gallium, Bis (10-hydroxybenzo [h] quinolinate) berylium, bis (10-hydroxybenzo [h] quinolinate) zinc, bis (2-methyl-8-quinolinate) chlorogallium, bis (2-methyl-8-quinolinate) ( Known electron-accepting materials such as o-cresolate) gallium, bis (2-methyl-8-quinolinate) -1-naphtholate aluminum, bis (2-methyl-8-quinolinate) -2-naphtholate gallium can be mentioned. , These may be contained or laminated.

A hole injection layer, a hole transport layer, an electron blocking layer, a light emitting layer, a hole blocking layer, an electron transport layer, or an electron injection layer containing a polycyclic aromatic compound represented by the general formula (1). As a method for forming, for example, a known method such as a vacuum deposition method, a spin coating method, or a casting method can be applied.

The basic structure of the organic electroluminescence device from which the effects of the present invention can be obtained preferably includes a substrate, an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode. Layer may be omitted or vice versa.

The anode and cathode of the organic electroluminescence device are connected to a power source via an electric conductor. By applying an electric potential between the anode and the cathode, the organic electroluminescence element operates and emits light.

Holes are injected into the organic electroluminescence device from the anode, and electrons are injected into the organic electroluminescence device at the cathode.

The organic electroluminescence device is typically overlaid on the substrate and the anode or cathode can be in contact with the substrate. The electrodes that come into contact with the substrate are called lower electrodes for convenience. Generally, the lower electrode is an anode, but the organic electroluminescence device of the present invention is not limited to such a form.

The substrate may be light transmissive or opaque, depending on the intended emission direction. The light transmission characteristics can be confirmed by electroluminescence emission through the substrate. Generally, transparent glass or plastic is adopted as a substrate in such a case. The substrate may have a composite structure including multiple material layers.

When the electroluminescence emission is confirmed through the anode, the anode is formed by passing or substantially passing the emission.

The general transparent anode material used in the present invention is not particularly limited, and examples thereof include indium-tin oxide (ITO), indium-zinc oxide (IZO), and tin oxide. .. Other metal oxides such as aluminum or indium-doped tin oxide, magnesium-indium oxide, or nickel-tungsten oxide can also be used. In addition to these oxides, metal nitrides such as gallium nitride, metal selenides such as zinc selenide, or metal sulfides such as zinc sulfide can be used as the anode.

The anode can be modified with plasma-deposited fluorocarbons. If electroluminescence emission is confirmed only through the cathode, the transmission properties of the anode are not important and any transparent, opaque or reflective conductive material can be used. Examples of conductors for this application include gold, iridium, molybdenum, palladium, platinum and the like.

A plurality of hole-transporting layers such as a hole-injecting layer, a hole-transporting layer, and an electron-blocking layer can be provided between the anode and the light-emitting layer. The hole injection layer and the hole transport layer have a function of transmitting holes injected from the anode to the light emitting layer, and by interposing these layers between the anode and the light emitting layer, many holes are generated at a lower electric field. Holes can be injected into the light emitting layer.

The known hole transporting material (including the hole injecting material, the hole transporting material, the electron blocking material, etc.) is not particularly limited, and is, for example, a triazole derivative, an oxadiazole derivative, an imidazole derivative, and a polyaryl. Alcan derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stillben derivatives, silazane derivatives, aniline copolymers, and conductivity Examples thereof include sex polymer oligomers, especially thiophene oligomers. Of these, porphyrin compounds, aromatic tertiary amine compounds and styrylamine compounds, particularly aromatic tertiary amine compounds are preferred.

Typical examples of the above aromatic tertiary amine compound and styrylamine compound are N, N, N', N'-tetraphenyl-4,4'-diaminophenyl, N, N'-diphenyl-N, N'. -Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (TPD), 2,2-bis (4-di-p-tolylaminophenyl) propane, 1,1- Bis (4-di-p-tolylaminophenyl) cyclohexane, N, N, N', N'-tetra-p-tolyl-4,4'-diaminobiphenyl, 1,1-bis (4-di-p-) Trillaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N'-diphenyl-N, N '-Di (4-methoxyphenyl) -4,4'-diaminobiphenyl, N, N, N', N'-tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis (diphenylamino) Audriphenyl, N, N, N-tri (p-tolyl) amine, 4- (di-p-tolylamino) -4'-[4- (di-p-tolylamino) styryl] stilben, 4-N, N- Diphenylamino- (2-diphenylvinyl) benzene, 3-methoxy-4'-N, N-diphenylaminostillbenzene, N-phenylcarbazole, 4,4'-bis [N- (1-naphthyl) -N-phenyl Examples thereof include amino] biphenyl (NPD), 4,4', 4''-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) and the like.

Inorganic compounds such as p-type-Si and p-type-SiC can also be used as hole injection materials and hole transport materials. The hole injection layer and the hole transport layer may have a one-layer structure composed of one or more of the above materials, or may have a laminated structure composed of a plurality of layers having the same composition or a different composition.

The light emitting layer of the organic electroluminescence element contains a phosphorescent light emitting material, a fluorescent light emitting material, or a thermal activated delayed fluorescent light emitting material, and emits light as a result of the recombination of electron-hole pairs in this region.

The light emitting layer may consist of a single material containing both small molecules and polymers, but more generally it consists of a host material doped with a guest compound, the emission of which originates primarily from dopants and is optional. Can have a color.

Examples of the host material of the light emitting layer include compounds having a biphenyl group, a fluorenyl group, a triphenylsilyl group, a carbazole group, a pyrenyl group, or an anthranyl group. For example, DPVBi (4,4'-bis (2,2-diphenylvinyl) -1,1'-biphenyl), BCzVBi (4,4'-bis (9-ethyl-3-carbazobinylene) 1,1'-biphenyl. ), TBADN (2-talshalbutyl-9,10-di (2-naphthyl) anthracene), ADN (9,10-di (2-naphthyl) anthracene), CBP (4,4'-bis (carbazole-9) -Il) biphenyl), CDBP (4,4'-bis (carbazole-9-yl) -2,2'-dimethylbiphenyl), 9,10-bis (biphenyl) anthracene and the like.

The host material in the light emitting layer may be an electron transport material as defined below, a hole transport material as defined above, another material that assists (supports) hole / electron recombination, or a combination of these materials. Good.

Examples of fluorescent dopants include anthracene, pyrene, tetracene, xanthene, perylene, rubrene, coumarin, rhodamine, quinacridone, dicyanomethylenepyrane compound, thiopyrene compound, polymethine compound, pyrylium or thiapyrylium compound, fluorene derivative, perifrantene derivative, indenoperylene Derivatives, bis (azinyl) amine boron compounds, bis (azinyl) methane compounds, carbostyryl compounds and the like can be mentioned.

Examples of phosphorescent dopants include organometallic complexes of transition metals such as iridium, platinum, palladium and osmium.

Examples of dopants are Alq ₃ (tris (8-hydroxyquinoline) aluminum)), DPAVBi (4,4'-bis [4- (di-p-tolylamino) styryl] biphenyl), perylene, Ir (PPy) ₃ ( Examples thereof include tris (2-phenylpyridine) iridium (III), FlrPic (bis (3,5-difluoro-2- (2-pyridyl) phenyl- (2-carboxypyridyl) iridium (III)) and the like.

Examples of the electron-transporting material include the known electron-accepting materials described above.

A hole blocking layer may be provided between the light emitting layer and the electron transporting layer for the purpose of improving the carrier balance. Desirable compounds for the hole blocking layer are BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), Bphenyl (4,7-diphenyl-1,10-phenanthroline), BAlq (bis (2). −Methyl-8-quinolinolate) -4- (phenylphenanthroline) aluminum), bis (10-hydroxybenzo [h] quinolinate) berylium) and the like.

In the organic electroluminescence device of the present invention, an electron injection layer may be provided for the purpose of improving the electron injection property and the device characteristics (for example, luminous efficiency, constant voltage drive, or high durability).

Desirable compounds for the electron injection layer include fluorenone, anthraquinodimethane, diphenoquinone, thiopyrandioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, fleolenilidenemethane, anthraquinodimethane, anthron and the like. Can be mentioned. In addition, the metal complexes, alkali metal oxides, alkaline earth oxides, rare earth oxides, alkali metal halides, alkaline earth halides, rare earth halides, SiO ₂ , AlO, SiN, SiON, AlON, as described above, Various oxides such as GeO, LiO, LiON, TiO, TiON, TaO, TaON, TaN, and C, nitrides, and inorganic compounds such as oxide nitrides can also be used.

The cathode used in the present invention can be formed from any conductive material if the emission is confirmed only through the anode. Desirable cathode 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.

It is sectional drawing of the cross section of the organic electroluminescence device produced in Example 1 or 2. FIG. 5 is a schematic cross-sectional view of the organic electroluminescence device produced in Example 3.

Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not construed as being limited to these Examples.

The analytical instruments and measurement methods used in this example are listed below.

[Material purity measurement (HPLC analysis)]
Measuring device: Tosoh Multi-Station LC-8020
Measurement conditions: Column Inertsil ODS-3V
(4.6 mmΦ x 250 mm)
Detector UV detection (wavelength 254 nm)
Eluent Methanol / tetrahydrofuran = 9/1 (v / v ratio)
[Emission characteristics of organic electroluminescence device]
Measuring device: LUMINANCEMETER (BM-9) manufactured by TOPCON
The structural formulas and abbreviations of the compounds used for device evaluation are shown below.

Element Example 1
As the substrate, a glass substrate with an ITO transparent electrode in which a 2 mm wide indium tin oxide (ITO) film (thickness 110 nm) was patterned in a stripe shape was used. After washing this substrate with isopropyl alcohol, the surface was treated by ozone ultraviolet washing. A spin-coated coating film was formed on the washed substrate, and then each layer was vapor-deposited by a vacuum vapor deposition method to produce an organic electroluminescent device having ^{a light emitting area of 4 mm 2 as shown in FIG. 1 in a schematic cross-sectional view.} In the vacuum vapor deposition method, each organic material was formed by a resistance heating method.

First, the first hole injection layer 2 was formed as an organic compound layer on the glass substrate with the ITO transparent electrode shown in FIG. As the first hole injection layer 2, Cleviоs (manufactured by Heleus) was spin-coated under the conditions of 1000 rpm and 120 seconds to obtain a film-forming substrate having a 70 nm film formation.

Next, the film-forming substrate was introduced into the vacuum vapor deposition tank, and the pressure was reduced to ^{1.0 × 10 -4 Pa.}

After that, on the first hole injection layer 2 shown in FIG. 1-2, as an organic compound layer, a second hole injection layer 3, a hole transport layer 4, a light emitting layer 5, an electron transport layer 6, and an electron injection layer 7 , And the cathode layer 8 were laminated in this order, and all of them were formed by vacuum deposition.

As the second hole injection layer 3, a sublimation-purified compound (H1) (HPLC purity 99.69%) was formed into a 10 nm film at a rate of 0.15 nm / sec.

As the hole transport layer 4, HTL was formed at a rate of 0.15 nm / sec to 10 nm.

As the light emitting layer 5, EML-1 and EML-2 were formed into a film at a ratio of 93: 7 (weight ratio) at 40 nm (film formation rate 0.16 nm / sec).

As the electron transport layer 6, ETL-1 was formed into a film at a rate of 0.15 nm / sec at 10 nm.

As the electron injection layer 7, LiF was formed into a film at a rate of 0.01 nm / sec at 1 nm.

Finally, a metal mask was arranged so as to be orthogonal to the ITO stripe, and the cathode layer 8 was formed into a film. The cathode layer 8 was formed by forming 100 nm of aluminum at a rate of 0.30 nm / sec.

Each film thickness was measured with a stylus type film thickness measuring meter (DEKTAK).

Further, this element was sealed in a nitrogen atmosphere glove box having an oxygen and water concentration of 1 ppm or less. For sealing, a glass sealing cap and the film-forming substrate epoxy type ultraviolet curable resin (manufactured by Nagase ChemteX Corporation) were used.

A direct current was applied to the organic electroluminescent device produced as described above, and the light emission characteristics were evaluated using a luminance meter of LUMINANCE METER (BM-9) manufactured by TOPCON. As the light emission characteristics, the voltage (V) and the current efficiency (cd / A) when a current density of 10 mA / cm ² was passed were measured, and the element life (h) at the time of continuous lighting was measured. Incidentally, Table 1 of element lifetime (h) measures the luminance decay time at the time of continuous lighting when driving was prepared device at an initial luminance 1000 cd / ^{m 2,} to the luminance (cd / ^{m 2)} is reduced by 10% The time required for was measured. The voltage, current efficiency, and device life are shown as relative values using the result in device comparative example 1 described later as a reference value (100). The results are shown in Table 1.

Element comparison example 1
An organic electroluminescent device was produced and evaluated in the same manner as in Device Example 1 except that compound (X1) was used instead of compound (H1) in Device Example 1. The results are shown in Table 1. Regarding the voltage, current efficiency, and device life, the result of this device comparative example 1 was used as a reference value (100).

Element Example 2
In device example 1, compound (X1) was used for the second hole injection layer 3, compound (H1) was used for the hole transport layer 4, and the thickness of the electron transport layer 6 (ETL-1) was set to 40 nm. An organic electroluminescent device was produced and evaluated by the same method as in Example 1 of the device except for the above. The voltage and current efficiency are shown as relative values using the result in Element Comparative Example 2 described later as a reference value (100). The results are shown in Table 2.

Element comparison example 2
In the device example 2, an organic electroluminescent device was produced and evaluated by the same method as in the device example 2 except that the compound (X1) was used for the second hole injection layer 3 and the hole transport layer 4. The results are shown in Table 2. Regarding the voltage and current efficiency, the result of Comparative Example 2 of this element was used as a reference value (100).

Element Example 3
The substrate, cleaning, and surface treatment steps used were carried out in the same manner as in Example 1.

The first hole injection layer 2 was formed as an organic compound layer on the glass substrate with the ITO transparent electrode shown in FIG. As the first hole injection layer 2, Cleviоs (manufactured by Heleus) was spin-coated at 4000 rpm for 120 seconds to form a 35 nm film.

Next, the film-forming substrate was introduced into the vacuum vapor deposition tank, and the pressure was reduced to ^{1.0 × 10 -4 Pa.}

After that, the hole transport layer 4, the light emitting layer 5, the electron transport layer 6, the electron injection layer 7, and the cathode layer 8 are laminated in this order on the hole injection layer 2 shown in FIG. 2-2 as an organic compound layer. All of them were formed by vacuum vapor deposition.

As the hole transport layer 4, NPD was formed into a 50 nm film at a rate of 0.15 nm / sec.

As the light emitting layer 5, compound (H1) and EML-2 were formed into a film at a ratio of 90:10 (weight ratio) at 40 nm (film formation rate 0.16 nm / sec).

As the electron transport layer 6, ETL-2 was formed into a 20 nm film at a rate of 0.15 nm / sec.

As the electron injection layer 7, LiF was formed into a film at a rate of 0.01 nm / sec at 1 nm.

Finally, a metal mask was arranged so as to be orthogonal to the ITO stripe, and the cathode layer 8 was formed into a film. The cathode layer 8 was formed by forming 100 nm of aluminum at a rate of 0.30 nm / sec.

The film thickness measurement, the sealing step, and the light emission characteristics were carried out in the same manner as in Example 1. The voltage and current efficiency are shown as relative values using the result in Element Comparative Example 3 described later as a reference value (100). The results are shown in Table 3.

Element comparison example 3
An organic electroluminescent device was produced and evaluated in the same manner as in Device Example 3 except that EML-1 was used instead of compound (H1) in Device Example 3. The results are shown in Table 3. Regarding the voltage and current efficiency, the result of Comparative Example 3 of this element was used as a reference value (100).

The organic electroluminescence device of this name has a polycyclic aromatic compound represented by the general formula (1) as a constituent component, so that the driving voltage is higher than that of an organic electroluminescence device using a conventionally known material. Or, the element life is excellent.

1. 1. Glass substrate with ITO transparent electrode 2. First hole injection layer 3. Second hole injection layer 4. Hole transport layer 5. Light emitting layer 6. Electron transport layer 7. Electron injection layer 8. Cathode layer

Claims (3)

An organic electroluminescence element having a plurality of organic layers between the anode and the cathode and the anode and the cathode, and at least one of the layers constituting the hole transport region and the light emitting region is the following formula (1). An organic electroluminescence element, which comprises a polycyclic aromatic compound represented by.

(Wherein, ^{A 1} and ^{A 2} are the same or different, each represent a hydrogen atom, a methyl group, an ethyl group, or a straight-chain carbon atoms 3 to 18, ^.B 1 ~ showing cyclic, or branched alkyl group B ⁴ is the same or different, and is a monocyclic, linked, or condensed aromatic hydrocarbon group having 6 to 18 carbon atoms, and a monocyclic, linked, or condensed ring heteroaromatic group having 3 to 36 carbon atoms, respectively. Groups (each of these groups is independently a hydrogen atom, a methyl group, an ethyl group, a linear, cyclic or branched alkyl group having 3 to 18 carbon atoms, a methoxy group, an ethoxy group, or a group having 3 to 18 carbon atoms. It may have one or more substituents selected from the group consisting of linear, cyclic, or branched alkoxy groups), methyl groups, ethyl groups, linear, cyclic, or cyclic groups having 3 to 18 carbon atoms. A branched alkyl group, a methoxy group, an ethoxy group, a linear, cyclic or branched alkoxy group having 3 to 18 carbon atoms, or the following general formula (2).

(In the formula, R ¹ and R ² are the same or different, respectively, an aromatic hydrocarbon group having 6 to 18 carbon atoms, a linked or condensed ring, and a monocyclic ring having 3 to 36 carbon atoms, linked. Alternatively, a fused heteroaromatic group (these groups are independently a fluorine atom, a methyl group, an ethyl group, a linear, cyclic or branched alkyl group having 3 to 18 carbon atoms, a methoxy group and an ethoxy group. , Or may have one or more substituents selected from the group consisting of linear, cyclic, or branched alkoxy groups having 3 to 18 carbon atoms), hydrogen atom, methyl group, ethyl group, or carbon. Represents a linear, cyclic, or branched alkyl group of equations 3-18.)
Represents a group represented by.
k ^{1 to k 4} are the same or different, and are integers from 0 to 4, respectively. ) The holes constituting the hole transport region and the light emitting region have a hole injection layer, a hole transport layer, or an electron blocking layer, and a light emitting layer, and the hole injection layer, the hole transport layer, and the electron blocking layer are provided. The organic electroluminescence device according to claim 1, wherein the light emitting layer contains the compound (1). The holes constituting the hole transport region and the light emitting region have a hole injection layer, a hole transport layer, or an electron blocking layer, and a light emitting layer, and the hole injection layer, the hole transport layer, or an electron blocking layer is provided. The organic electroluminescence device according to claim 1 or 2, wherein the layer is a single layer of the compound (1).

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