JP2010126480A - Benzodithiophene-based compound, and composition and organic electroluminescent device containing the same compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compound which has high amorphousness and solubility in solvents, and allows maintenance of high performances in an organic electroluminescent device obtained even by using the compound in an organic layer formed according to a wet film-forming method. <P>SOLUTION: A benzodithiophene-based compound is represented by formula (1) (wherein, R<SP>1</SP>to R<SP>6</SP>represent each independently a hydrogen atom or substituent, with the proviso that any of R<SP>1</SP>and R<SP>6</SP>, R<SP>2</SP>and R<SP>5</SP>, and R<SP>3</SP>and R<SP>4</SP>are not the same). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel benzodithiophene compound used for a light emitting layer or the like of an organic electroluminescent device, a composition containing the compound, and an organic electroluminescent device containing the compound.

  In recent years, as a thin film type electroluminescent element, an organic electroluminescent element using an organic thin film has been developed instead of using an inorganic material. The organic electroluminescent device usually has a hole injection layer, a hole transport layer, an organic light emitting layer, an electron transport layer, etc. between the anode and the cathode, and suitable for each layer such as red, green, blue, etc. Development of light emitting devices is progressing. However, blue light-emitting elements are not satisfactory in terms of efficiency, life, and heat resistance, and there is a problem that application to full-color displays is limited.

  In addition, as a method for forming each layer of the organic electroluminescent element, there are a vapor deposition film forming method and a wet film forming method. The vapor deposition method has a problem in terms of yield when manufacturing a medium or large full color panel for a television or a monitor. Therefore, the wet film-forming method is suitable for these large area applications.

  However, in order to form each layer of the organic electroluminescent element by the wet film forming method, it has been desired that the material for forming each layer is dissolved in a solvent and has high performance as an element even after the wet film formation. However, many materials that have been used in the conventionally developed vapor deposition method are not suitable for the wet film formation method (see Patent Document 1).

That is, in Patent Document 1, as a light emitting layer material of an organic electroluminescent element by a vapor deposition film forming method, in formula (1) according to the present invention, R ¹ and R ⁶ are hydrogen atoms, R ^{2 to} R ⁵ Any one of a hydrogen atom, an alkyl group and an aryl group, in which R ⁴ and R ³ are the same, and R ² and R ⁵ are the same, A benzodithiophene compound having a molecular structure has been proposed, but this compound has a poor solubility in a solvent due to its symmetrical molecular structure, as shown in Comparative Examples 1 and 2 to be described later. It was not suitable for a film, and it was low in amorphousness, so that it could not be said to have high performance as an element even after wet film formation.
JP 2007-145833 A

  This invention is made | formed in view of the said conventional actual condition, Comprising: It makes it a subject to provide the compound suitable for wet film-formings, such as high amorphous property and high solubility to a solvent. It is another object of the present invention to provide a compound that can maintain high performance even when used in an organic layer formed by a wet film formation method.

  As a result of intensive studies by the present inventors, it has been found that the above problem can be solved by using a specific compound, and the present invention has been achieved.

That is, the present invention resides in a benzodithiophene compound characterized by being represented by the following formula (1).

(In formula (1), R ^{1 to} R ⁶ each independently represents a hydrogen atom or a substituent, provided that R ¹ and R ⁶ , R ² and R ^5, and R ³ and R ⁴ are the same. Never.)

  The present invention also includes a composition comprising the benzodithiophene compound and a solvent, and an organic material having an anode and a cathode, and an organic layer provided between the anode and the cathode. The electroluminescent element is an organic electroluminescent element characterized in that the organic layer contains the benzodithiophene compound.

  The benzodithiophene compound of the present invention is a compound suitable for wet film formation because of its high amorphous property, high solubility in a solvent, and a small difference in emission spectrum between a solid state and a solution state. In addition, the organic electroluminescence device having an organic layer using the benzodithiophene compound of the present invention has a luminous efficiency and luminance even when the formation method of the organic layer is not only a vapor deposition method but also a wet film formation method. High performance in terms of life and the like.

  Embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention does not exceed the gist thereof. The content of is not specified.

[Benzodithiophene compounds]
The benzodithiophene compound of the present invention is represented by the following formula (1).

(In formula (1), R ^{1 to} R ⁶ each independently represents a hydrogen atom or a substituent, provided that R ¹ and R ⁶ , R ² and R ^5, and R ³ and R ⁴ are the same. Never.)

Here, R ¹ and R ⁶ , R ² and R ^5, and R ³ and R ⁴ are not the same, meaning that the following (a) to (c) are not satisfied. means.
(a) R ¹ and R ⁶ are the same
(b) R ² and R ⁵ are the same
(c) R ³ and R ⁴ are the same

That is, even if R ¹ and R ⁶ are the same, and R ² and R ⁵ are the same, the conditions of the present invention are satisfied as long as R ³ and R ⁴ are different. Of the three combinations of R ¹ and R ⁶ , R ² and R ⁵ , and R ³ and R ⁴ , at least one of them may be different from each other.
Here, “different” means, for example, when R ¹ and R ⁶ are taken as an example, when R ¹ is a hydrogen atom and R ⁶ is a substituent; both R ¹ and R ⁶ Is a substituent but the type of the substituent is different; For example, when the substituent is a “phenyl group substituted with a methyl group”, those having different methyl substitution positions relative to the phenyl group are also included as different substituent types.

{Structural features}
The benzodithiophene compound represented by the above formula (1) (hereinafter sometimes referred to as the benzodithiophene compound of the present invention) is thus R ¹ and R ⁶ , R ² and R ^5, and R ³ . Since R ⁴ is not the same, the molecule has an asymmetric structure and is amorphous, so that it is presumed that the solubility in a solvent is good.

  In addition, when the benzodithiophene compound of the present invention is used in an organic layer of an organic electroluminescence device formed by a wet film formation method, the amorphous property is high, so that molecules crystallize during driving and dark spots (not lighted) It is possible to obtain an organic electroluminescent element having a long life and less prone to deterioration such as forming a point).

{Substituent}
Specific examples in the case where R ^{1 to} R ⁶ are substituents include groups described in the following substituent group Q. Among these, alkyl groups and substituents which may have a substituent An aromatic hydrocarbon group that may have a substituent, an aromatic heterocyclic group that may have a substituent, or an aromatic hydrocarbon group and a substituent that may have this substituent. A group formed by connecting two or more aromatic heterocyclic groups which may be used is preferable. Among them, a group derived from a benzene ring or a naphthalene ring or a group formed by connecting two or more of these is particularly preferable.

<Substituent group Q>
An alkyl group which may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms, for example, a methyl group, an ethyl group, an n-propyl group, a 2-propyl group; , Isopropyl group, n-butyl group, isobutyl group, tert-butyl group, octyl group, etc.).
An alkenyl group which may have a substituent (preferably an alkenyl group having 2 to 8 carbon atoms, and examples thereof include a vinyl group and a 1-butenyl group);
An alkynyl group which may have a substituent (preferably an alkynyl group having 2 to 8 carbon atoms, and examples thereof include an ethynyl group and a propargyl group);
An aralkyl group which may have a substituent (preferably an aralkyl group having 6 to 10 carbon atoms, such as a benzyl group);
An alkoxy group which may have a substituent (preferably an alkoxy group having 1 to 8 carbon atoms which may have a substituent, such as a methoxy group, an ethoxy group and a butoxy group) ),
An amino group which may have a substituent (preferably an amino group having at least one alkyl group having 1 to 8 carbon atoms (this alkyl group may further have a substituent) in the substituent; And examples thereof include a methylamino group, a dimethylamino group, a diethylamino group, and a dibenzylamino group).
An arylamino group which may have a substituent (for example, a phenylamino group, a diphenylamino group, a ditolylamino group, etc.);
A heteroarylamino group which may have a substituent (for example, a pyridylamino group, a thienylamino group, a dithienylamino group, etc.);
An acylamino group which may have a substituent (for example, acetylamino group, benzoylamino group and the like),
A cycloalkyl group optionally having a substituent (for example, an adamantyl group, etc.),
An aryloxy group which may have a substituent (preferably an aryloxy group having an aromatic hydrocarbon group or an aromatic heterocyclic group, such as a phenyloxy group, a 1-naphthyloxy group, 2- Naphthyloxy group, pyridyloxy group, thienyloxy group, etc.),
An acyl group which may have a substituent (preferably an acyl group having 1 to 8 carbon atoms which may have a substituent, such as a formyl group, an acetyl group, a benzoyl group, etc. ),
An alkoxycarbonyl group which may have a substituent (preferably an alkoxycarbonyl group having 2 to 13 carbon atoms which may have a substituent, such as a methoxycarbonyl group, an ethoxycarbonyl group, etc. ),
An aryloxycarbonyl group which may have a substituent (preferably an aryloxycarbonyl group having 6 to 13 carbon atoms which may have a substituent);
A carboxy group,
A cyano group,
Hydroxyl group,
Thiol groups,
An alkylthio group which may have a substituent (preferably an alkylthio group having 1 to 8 carbon atoms, for example, a methylthio group, an ethylthio group, etc.),
An arylthio group which may have a substituent (preferably an arylthio group having 1 to 10 carbon atoms, such as a phenylthio group and a 1-naphthylthio group);
A sulfonyl group which may have a substituent (for example, mesyl group, tosyl group and the like),
A silyl group which may have a substituent (for example, a trimethylsilyl group, a triphenylsilyl group, etc.),
An optionally substituted boryl group (for example, a dimesitylboryl group),
A phosphino group which may have a substituent (for example, a diphenylphosphino group);
An aromatic hydrocarbon group which may have a substituent (for example, benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring, etc. Derived from aromatic hydrocarbon groups),
An aromatic heterocyclic group which may have a substituent (for example, furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, Pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring , An aromatic hydrocarbon group derived from a pyrimidine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a sinoline ring, a quinoxaline ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, an azulene ring, and the like.
A group formed by linking two or more aromatic hydrocarbon groups which may have a substituent and an aromatic heterocyclic group which may have a substituent (for example, biphenyl group and terphenyl group) .)

  In addition, examples of the substituent that the group of the substituent group Q may have include an alkyl group, an arylamino group, an aromatic hydrocarbon group, and an aromatic heterocyclic group, and specific examples thereof include The thing of the said substituent group Q is mentioned.

{Molecular weight}
The molecular weight of the benzodithiophene compound of the present invention represented by the formula (1) is usually 2000 or less, preferably 1500 or less. If the molecular weight exceeds this upper limit, purification may become difficult due to the high molecular weight of impurities.

{Solvent solubility}
The benzodithiophene compound of the present invention represented by the formula (1) is excellent in solvent solubility, and preferably has a solubility of 0.9% by weight or more at 25 ° C. with respect to toluene.

{Preferred structure}
Among the benzodithiophene compounds of the present invention represented by the formula (1), those in which R ² and R ⁵ are different are improved in solubility in organic solvents, and the crystallinity is lowered. However, it is preferable in that crystallization hardly occurs in the formed thin film. Especially, it is preferable that it is a compound represented by a following formula (1-1).

(In formula (1-1), R ^{12 to} R ¹⁵ each independently represents a hydrogen atom or a substituent. However, R ¹² and R ¹⁵ are not the same.)

Specific examples and preferred examples of the substituent when R ^{12 to} R ¹⁵ are substituents are the same as those in the case where R ^{1 to} R ⁶ in the above formula (1) are substituents.

In the compound represented by the formula (1-1), R ^{12 to} R ¹⁵ are each independently an aromatic hydrocarbon group which may have a substituent or an aromatic complex which may have a substituent. It is preferably a cyclic group, more preferably an aromatic hydrocarbon group which may have a substituent, and in particular, a group derived from a benzene ring which may have a substituent, or a benzene ring An aromatic hydrocarbon group formed by condensation of 2 to 5 rings, more preferably 2 to 3 rings is more preferable.

In the compound represented by formula (1-1), R ¹² and R ¹⁵ are different from each other, but R ¹³ and R ¹⁴ are preferably the same, and in particular, R ¹³ and R ¹⁴ are either Is preferably an aromatic hydrocarbon group which may have a substituent, and more preferably a group derived from a benzene ring which may have a substituent (phenyl group).

Among the benzodithiophene compounds of the present invention represented by the aforementioned formula (1), a compound wherein R ¹ is a substituent, an emission spectrum in which R ¹ for compounds not a substituent, measured in a solution state The difference in emission spectrum measured in the solid state is small, that is, the material is uniformly dispersed in the solid state as well as in the dilute solution, and it is possible to prevent the decrease in color purity and the emission efficiency due to association, etc. It is particularly useful as a material used for organic electroluminescence devices. Among these, a compound represented by the formula (1-2) is preferable because the effect is obtained.

(In formula (1-2), R ²¹ represents a substituent. R ^{22 to} R ²⁵ each independently represents a hydrogen atom or a substituent.)

Specific examples and preferred examples of the substituent when R ²¹ and R ^{22 to} R ²⁵ are substituents are the same as those in the case where R ^{1 to} R ⁶ in the above formula (1) are substituents.

In the compound represented by the formula (1-2), R ^{21 to} R ²⁵ are each independently an aromatic hydrocarbon group which may have a substituent or an aromatic complex which may have a substituent. It is preferably a cyclic group, and more preferably an aromatic hydrocarbon group which may have a substituent.

In the compound represented by the formula (1-2), R ²¹ is preferably an aromatic hydrocarbon group which may have a substituent, and particularly derived from a benzene ring which may have a substituent. It is more preferable that the group is a phenyl group.
R ^{22 to} R ²⁵ are preferably each independently an aromatic hydrocarbon group which may have a substituent, and particularly a group derived from a benzene ring which may have a substituent (phenyl group). ) Is more preferable.

{Concrete example}
Specific examples of the benzodithiophene compound of the present invention are given below, but the benzodithiophene compound of the present invention is not limited to the following compounds 1 to 107.

{Synthesis method}
The benzodithiophene compound of the present invention can be synthesized, for example, by the following method.

  First, a benzodithiophene derivative is synthesized by a method described in JP 2007-145833 A or the like.

  Thereafter, the benzodithiophene compound of the present invention can be obtained by repeating an aryl-aryl bond reaction such as Suzuki coupling and a halogenation reaction to lead to various derivatives.

  The product at each stage can be purified by sublimation purification, distillation, column chromatography, crystallization, or other purification methods.

{Usage}
The benzodithiophene compound of the present invention can be used alone, but because of its good solubility in various solvents, the composition containing the benzodithiophene compound of the present invention and the solvent, ie, the present invention It is also preferable to use it as a composition in which the benzodithiophene compound of the invention is dissolved or dispersed in a solvent (hereinafter sometimes referred to as the composition of the present invention).

  The benzodithiophene compound of the present invention is preferably used as a light emitting material, but may be used as a charge transport material such as a hole transport material. In particular, it is preferably used as a material for a light emitting layer or a hole transport layer of an organic electroluminescence device, more preferably used as a material for a light emitting layer, and particularly preferably used as a light emitting material for a light emitting layer. Further, the benzodithiophene compound of the present invention may be used in combination with another material for a light emitting layer of a white organic electroluminescent device such as white illumination.

The benzodithiophene compound of the present invention is preferably used for forming a light emitting layer by a wet film-forming method, particularly as a composition of the present invention containing a solvent.
However, the benzodithiophene compound of the present invention can also be used effectively for the formation of a light emitting layer by vacuum deposition.

[Composition]
The composition of the present invention comprises the benzodithiophene compound of the present invention and a solvent.

  The composition of this invention may contain only 1 type of the benzodithiophene type compound of this invention, and may contain 2 or more types. The benzodithiophene compound of the present invention is contained in the composition of the present invention in an amount of usually 1 part by weight or more, usually 50 parts by weight or less, preferably 30 parts by weight or less, based on 100 parts by weight of the composition. The When the content of the benzodithiophene compound of the present invention in the composition of the present invention exceeds this range, the luminous efficiency of the organic electroluminescence device formed using this composition is decreased, the driving life is decreased, the light emission There is a possibility that the spectrum becomes broad. On the other hand, below this range, there is a possibility that the light emission life, the drive life, and the drive voltage of the organic electroluminescence device formed using this composition are lowered.

In addition, the solvent contained in the composition of the present invention is not particularly limited as long as the solute benzodithiophene compound dissolves well, but as a preferable solvent, for example,
alkanes such as n-decane, cyclohexane, ethylcyclohexane, decalin, bicyclohexane;
Aromatic hydrocarbons such as toluene, xylene, methicylene, cyclohexylbenzene, tetralin;
Halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene and trichlorobenzene;
1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, diphenyl ether, etc. Aromatic ethers;
Aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, ethyl benzoate, propyl benzoate, n-butyl benzoate;
Cycloaliphatic ketones such as cyclohexanone, cyclooctanone, and fenkon;
Cycloaliphatic alcohols such as cyclohexanol and cyclooctanol;
Aliphatic ketones such as methyl ethyl ketone and dibutyl ketone;
Aliphatic alcohols such as butanol and hexanol;
Aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA);
Etc.

  Of these, alkanes and aromatic hydrocarbons are preferable. One of these solvents may be used alone, or two or more thereof may be used in any combination and ratio.

  In order to obtain a more uniform film, it is preferable that the solvent evaporates from the liquid film immediately after the film formation at an appropriate rate. For this reason, the boiling point of the solvent used is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 120 ° C. or higher, and usually 270 ° C. or lower, preferably 250 ° C. or lower, more preferably 230 ° C. or lower.

  The composition of the present invention may contain other compounds in addition to the benzodithiophene compound and the solvent of the present invention. For example, when the composition is used for forming an organic layer of an organic electroluminescence device, it preferably contains another material that matches the layer to be formed, and contains a charge transport material or the like used for each layer. It is more preferable.

  When the benzodithiophene compound of the present invention is used as a light emitting material for a light emitting layer, the benzodithiophene compound of the present invention may be used as a dopant material in combination with a host material composed of other compounds. A benzodithiophene compound as a host material may be combined with a dopant material (light-emitting material) made of another compound. Of course, the benzodithiophene compound of the present invention may be used alone as the light emitting material of the light emitting layer.

  Arbitrary well-known materials are applicable as a luminescent material which consists of another compound. For example, a fluorescent material or a phosphorescent material may be used, but a phosphorescent material is preferable from the viewpoint of internal quantum efficiency.

  For the purpose of improving the solubility in a solvent, it is preferable to reduce the symmetry and rigidity of the molecules of the luminescent material, or to introduce a lipophilic substituent such as an alkyl group.

Hereinafter, examples of the fluorescent light emitting material among the light emitting materials will be described, but the fluorescent light emitting material is not limited to the following examples.
Examples of the fluorescent light emitting material (blue fluorescent dye) that emits blue light include naphthalene, perylene, pyrene, chrysene, anthracene, coumarin, p-bis (2-phenylethenyl) benzene, and derivatives thereof.
Examples of the fluorescent light emitting material (green fluorescent dye) that gives green light emission include quinacridone derivatives, coumarin derivatives, and aluminum complexes such as Al (C ₉ H ₆ NO) ₃ .
Examples of the fluorescent light emitting material (yellow fluorescent dye) that gives yellow light include rubrene, perimidone derivatives, and the like.
Examples of the fluorescent light-emitting material (red fluorescent dye) that emits red light include, for example, DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) -based compounds, benzopyran derivatives, rhodamine derivatives, Examples thereof include benzothioxanthene derivatives and azabenzothioxanthene.

As the phosphorescent material, for example, a long-period type periodic table (hereinafter referred to as a long-period type periodic table when referred to as “periodic table” unless otherwise specified) is selected from the seventh to eleventh groups. And an organometallic complex containing a metal.
Preferred examples of the metal selected from Groups 7 to 11 of the periodic table include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold.
The ligand of the complex is preferably a ligand in which a (hetero) aryl group such as a (hetero) arylpyridine ligand or (hetero) arylpyrazole ligand is linked to pyridine, pyrazole, phenanthroline, etc. A pyridine ligand and a phenylpyrazole ligand are preferable. Here, (hetero) aryl represents an aryl group or a heteroaryl group.

  Specific examples of the phosphorescent material include tris (2-phenylpyridine) iridium, tris (2-phenylpyridine) ruthenium, tris (2-phenylpyridine) palladium, bis (2-phenylpyridine) platinum, tris (2- Phenylpyridine) osmium, tris (2-phenylpyridine) rhenium, octaethyl platinum porphyrin, octaphenyl platinum porphyrin, octaethyl palladium porphyrin, octaphenyl palladium porphyrin, and the like.

  The molecular weight of the compound used as the light emitting material is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, Preferably it is 200 or more, More preferably, it is 300 or more, More preferably, it is the range of 400 or more. If the molecular weight of the luminescent material is too small, the heat resistance will be significantly reduced, gas generation will be caused, the film quality will be reduced when the film is formed, or the morphology of the organic electroluminescent element will be changed due to migration, etc. Sometimes come. On the other hand, if the molecular weight of the luminescent material is too large, it tends to be difficult to purify the organic compound, or it may take time to dissolve in the solvent.

  In addition, only 1 type may be used for the luminescent material mentioned above, and 2 or more types may be used together by arbitrary combinations and a ratio.

  Examples of the host material composed of other compounds include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked by a fluorene group, hydrazone derivatives, Silazane derivatives, silanamine derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, phenanthroline derivatives, oxadiazole derivatives, carbazole derivatives, anthracene derivatives, pyrene Derivatives, fluorene derivatives, naphthalene derivatives, pyridine derivatives, carbon and the like.

  Specific examples include, for example, two or more condensed aromatic rings containing two or more tertiary amines represented by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl. Aromatic amine compounds having a starburst structure such as aromatic diamines substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine ( Journal of Luminescence, 1997, Vol. 72-74, pp. 985), aromatic amine derivatives such as aromatic amine compounds consisting of tetramers of triphenylamine (Chemical Communications, 1996, pp. 2175), 2 , 2 ', 7,7'-tetrakis- (diphenylamino) -9,9'-spirobifluore Fluorene derivatives (Synthetic Metals, 1997, Vol. 91, pp. 209), etc. In addition, 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND) and the like Oxadiazole derivatives such as 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 2,5-bis (6 ′-( 2 ', 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy) and other pyridine derivatives, bathophenanthroline (BPhen) and 2,9-dimethyl-4,7-diphenyl-1 , 10-phenanthroline (BCP, bathocuproin) and other phenanthroline derivatives, 4,4′-bis (9-carbazole) -biphenyl (CB ) Carbazole derivatives, and the like, such as.

  In addition, the composition of the present invention may contain another solvent in addition to the above-described solvents, if necessary. Examples of such a solvent include amides such as N, N-dimethylformamide and N, N-dimethylacetamide, and dimethyl sulfoxide. One of these may be used alone, or two or more may be used in any combination and ratio. Moreover, various additives, such as a leveling agent and an antifoamer, may be contained for the purpose of improving film formability.

[Organic electroluminescence device]
The organic electroluminescent element of the present invention is an organic electroluminescent element having an anode and a cathode, and an organic layer provided between the anode and the cathode, and the benzodithiophene compound of the present invention is applied to the organic layer. It is characterized by containing.

Below, the layer structure of the organic electroluminescent element of this invention, its general formation method, etc. are demonstrated with reference to FIG.
FIG. 7 is a schematic cross-sectional view showing a structural example of the organic electroluminescent device according to the present invention. In FIG. 7, 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, Represents a light-emitting layer, 6 represents a hole blocking layer, 7 represents an electron transport layer, 8 represents an electron injection layer, and 9 represents a cathode.
In the present invention, the wet film forming method includes, for example, spin coating method, dip coating method, die coating method, bar coating method, blade coating method, roll coating method, spray coating method, capillary coating method, ink jet method, screen printing. This method is a wet film formation method such as a method, a gravure printing method, or a flexographic printing method. Among these film forming methods, a spin coating method, a spray coating method, and an ink jet method are preferable. This is because the liquid property specific to the coating composition used for the organic electroluminescent element is matched.

{substrate}
The substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, polysulfone or the like is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too small, the organic electroluminescent element may be deteriorated by the outside air that has passed through the substrate, which is not preferable. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

{anode}
The anode 2 serves to inject holes into the layer on the light emitting layer side.
This anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, carbon black, or It is composed of a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.

In general, the anode 2 is often formed by a sputtering method, a vacuum deposition method, or the like. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution The anode 2 can also be formed by being dispersed on the substrate 1 and being coated on the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).
The anode 2 usually has a single-layer structure, but it can also have a laminated structure made of a plurality of materials if desired.
The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more, and is usually 1000 nm or less, preferably about 500 nm or less. When it may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.

  For the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the surface of the anode 2 is treated with ultraviolet (UV) / ozone, or with oxygen plasma or argon plasma. It is preferable to do.

{Hole injection layer}
The hole injection layer 3 is a layer that transports holes from the anode 2 to the light emitting layer 5, and is usually formed on the anode 2.

The method for forming the hole injection layer 3 according to the present invention may be a vacuum deposition method or a wet film formation method, and is not particularly limited, but the hole injection layer 3 is formed by a wet film formation method from the viewpoint of reducing dark spots. It is preferable.
The thickness of the hole injection layer 3 is usually 5 nm or more, preferably 10 nm or more, and usually 1000 nm or less, preferably 500 nm or less.

<Formation of hole injection layer by wet film formation method>
When forming the hole injection layer 3 by wet film formation, the material for forming the hole injection layer 3 is usually mixed with an appropriate solvent (hole injection layer solvent) to form a film-forming composition (positive A composition for forming a hole injection layer), and applying the composition for forming a hole injection layer on a layer (usually an anode) corresponding to the lower layer of the hole injection layer 3 by an appropriate technique. The hole injection layer 3 is formed by coating and drying.

(Hole transporting compound)
The composition for forming a hole injection layer usually contains a hole transporting compound and a solvent as constituent materials of the hole injection layer.
As long as the hole transporting compound is a compound having a hole transporting property, which is usually used in a hole injection layer of an organic electroluminescence device, a monomer or the like may be a polymer compound or the like. Although it may be a low molecular weight compound, it is preferably a high molecular weight compound.

  The hole transporting compound is preferably a compound having an ionization potential of 4.5 eV to 6.0 eV from the viewpoint of a charge injection barrier from the anode 2 to the hole injection layer 3. Examples of hole transporting compounds include aromatic amine derivatives, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, polythiophene derivatives, benzylphenyl derivatives, compounds in which tertiary amines are linked by a fluorene group, hydrazone derivatives, silazane derivatives, silanamines Derivatives, phosphamine derivatives, quinacridone derivatives, polyaniline derivatives, polypyrrole derivatives, polyphenylene vinylene derivatives, polythienylene vinylene derivatives, polyquinoline derivatives, polyquinoxaline derivatives, carbon and the like.

  In the present invention, a derivative includes, for example, an aromatic amine derivative, and includes an aromatic amine itself and a compound having an aromatic amine as a main skeleton. It may be a mer.

  The hole transporting compound used as the material for the hole injection layer 3 may contain any one of these compounds alone, or may contain two or more. When two or more hole transporting compounds are contained, the combination thereof is arbitrary, but one or more aromatic tertiary amine polymer compounds and one or two other hole transporting compounds are used. It is preferable to use the above in combination.

  Among the above examples, an aromatic amine compound is preferable from the viewpoint of amorphousness and visible light transmittance, and an aromatic tertiary amine compound is particularly preferable. Here, the aromatic tertiary amine compound is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.

  The type of the aromatic tertiary amine compound is not particularly limited, but from the viewpoint of uniform light emission due to the surface smoothing effect, a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less (a polymerizable compound in which repeating units are linked) is further included. preferable. Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (I).

(In Formula (I), Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Ar ^{3 to} Ar ⁵ each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Represents a linking group selected from the group of linking groups, and among Ar ^{1 to} Ar ⁵ , two groups bonded to the same N atom may be bonded to each other to form a ring.

（上記各式中、Ａｒ^６〜Ａｒ^１６は、それぞれ独立して、置換基を有していてもよい芳香族炭化水素基または置換基を有していてもよい芳香族複素環基を表す。Ｒ^３１およびＲ^３２は、それぞれ独立して、水素原子または任意の置換基を表す。））

(In said each formula, Ar < ⁶ > -Ar < ¹⁶ > represents each independently the aromatic hydrocarbon group which may have a substituent, or the aromatic heterocyclic group which may have a substituent. R ³¹ and R ³² each independently represents a hydrogen atom or an arbitrary substituent.))

As the aromatic hydrocarbon group and the aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ , a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene from the viewpoint of the solubility, heat resistance, hole injection / transport property of the polymer compound A group derived from a ring or a pyridine ring is preferred, and a group derived from a benzene ring or a naphthalene ring is more preferred.

The aromatic hydrocarbon group and aromatic heterocyclic group of Ar ^{1 to} Ar ¹⁶ may further have a substituent. The molecular weight of the substituent is usually 400 or less, preferably about 250 or less. As the substituent, an alkyl group, an alkenyl group, an alkoxy group, an aromatic hydrocarbon group, an aromatic heterocyclic group and the like are preferable.

When R ³¹ and R ³² are optional substituents, examples of the substituent include alkyl groups, alkenyl groups, alkoxy groups, silyl groups, siloxy groups, aromatic hydrocarbon groups, aromatic heterocyclic groups, and the like. .

  Specific examples of the aromatic tertiary amine polymer compound having a repeating unit represented by the formula (I) include those described in International Publication No. 2005/089024.

  In addition, as a hole transporting compound, a conductive polymer (PEDOT / PSS) obtained by polymerizing 3,4-ethylenedioxythiophene (3,4-ethylenedioxythiophene), a polythiophene derivative, in high molecular weight polystyrene sulfonic acid. Is also preferred. Moreover, the end of this polymer may be capped with methacrylate or the like.

  The concentration of the hole transporting compound in the composition for forming a hole injection layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably in terms of film thickness uniformity. Is 0.1% by weight or more, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If this concentration is too high, film thickness unevenness may occur, and if it is too low, defects may occur in the formed hole injection layer.

(Electron-accepting compound)
The composition for forming a hole injection layer preferably contains an electron accepting compound as a constituent material of the hole injection layer.
The electron-accepting compound is preferably a compound having an oxidizing power and the ability to accept one electron from the above-described hole transporting compound, specifically, a compound having an electron affinity of 4 eV or more is preferable, and 5 eV or more. The compound which is the compound of these is further more preferable.

  Examples of such electron-accepting compounds include triarylboron compounds, metal halides, Lewis acids, organic acids, onium salts, salts of arylamines and metal halides, and salts of arylamines and Lewis acids. Examples thereof include one or more compounds selected from the group. More specifically, an onium salt substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate and triphenylsulfonium tetrafluoroborate (International Publication No. WO 2005/089024); High valent inorganic compounds such as iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene, tris (pendafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365) Aromatic boron compounds such as); fullerene derivatives; iodine; sulfonate ions such as polystyrene sulfonate ions, alkylbenzene sulfonate ions, camphor sulfonate ions, and the like.

  These electron accepting compounds can improve the conductivity of the hole injection layer by oxidizing the hole transporting compound.

  The content of the electron-accepting compound in the hole-injecting layer or the composition for forming a hole-injecting layer with respect to the hole-transporting compound is usually 0.1 mol% or more, preferably 1 mol% or more. However, it is usually 100 mol% or less, preferably 40 mol% or less.

(Other components)
As a material for the hole injection layer, other components may be further contained in addition to the above-described hole transporting compound and electron accepting compound as long as the effects of the present invention are not significantly impaired. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, and coating property improving agents. In addition, only 1 type may be used for another component and it may use 2 or more types together by arbitrary combinations and a ratio.

(solvent)
At least one of the solvents of the composition for forming a hole injection layer used in the wet film formation method is preferably a compound that can dissolve the constituent material of the hole injection layer. The boiling point of this solvent is usually 110 ° C. or higher, preferably 140 ° C. or higher, particularly 200 ° C. or higher, usually 400 ° C. or lower, and preferably 300 ° C. or lower. If the boiling point of the solvent is too low, the drying speed is too high and the film quality may be deteriorated. Further, if the boiling point of the solvent is too high, it is necessary to increase the temperature of the drying step, which may adversely affect other layers and the substrate.

Examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents, and the like.
Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, aromatic ethers such as 2,4-dimethylanisole, and the like.
Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.
Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylpropylphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene. Can be mentioned.
Examples of the amide solvent include N, N-dimethylformamide, N, N-dimethylacetamide, and the like.
In addition, dimethyl sulfoxide and the like can also be used.
These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.

(Film formation method)
After preparing the composition for forming a hole injection layer, the composition is wet-formed on a layer corresponding to the lower layer of the hole-injection layer 3 (usually the anode 2) by wet film formation and dried. The hole injection layer 3 is formed.
The temperature in the film forming step is preferably 10 ° C. or higher, and preferably 50 ° C. or lower, in order to prevent film loss due to the formation of crystals in the composition.
Although the relative humidity in a film-forming process is not limited unless the effect of this invention is impaired remarkably, it is 0.01 ppm or more normally and 80% or less normally.

  After the film formation, the film of the composition for forming a hole injection layer is usually dried by heating or the like. Examples of the heating means used in the heating step include a clean oven, a hot plate, infrared rays, a halogen heater, microwave irradiation and the like. Among them, a clean oven and a hot plate are preferable in order to uniformly apply heat to the entire film.

  The heating temperature in the heating step is preferably heated at a temperature equal to or higher than the boiling point of the solvent used in the composition for forming a hole injection layer as long as the effects of the present invention are not significantly impaired. In the case of a mixed solvent containing two or more types of solvents used in the hole injection layer, at least one type is preferably heated at a temperature equal to or higher than the boiling point of the solvent. In consideration of an increase in the boiling point of the solvent, the heating step is preferably performed at 120 ° C. or higher, preferably 410 ° C. or lower.

  In the heating step, the heating time is not limited as long as the heating temperature is not lower than the boiling point of the solvent of the composition for forming a hole injection layer and sufficient insolubilization of the coating film does not occur. Is less than a minute. If the heating time is too long, the components of the other layers tend to diffuse, and if it is too short, the hole injection layer tends to be inhomogeneous. Heating may be performed in two steps.

<Formation of hole injection layer by vacuum deposition>
When the hole injection layer 3 is formed by vacuum deposition, one or more of the constituent materials of the hole injection layer 3 (the aforementioned hole transporting compound, electron accepting compound, etc.) are placed in a vacuum container. Put in crucibles installed (in case of using two or more materials, put them in each crucible), evacuate the inside of the vacuum vessel to about 10 ⁻⁴ Pa with a suitable vacuum pump, and then heat the crucible (two types When using the above materials, heat each crucible) and evaporate by controlling the amount of evaporation (when using two or more materials, evaporate by independently controlling the amount of evaporation) and face the crucible Then, the hole injection layer 3 is formed on the anode 2 of the substrate placed on the substrate. In addition, when using 2 or more types of materials, the hole injection layer 3 can also be formed by putting those mixtures into a crucible, heating and evaporating.

The degree of vacuum at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 × 10 ⁻⁶ Torr (0.13 × 10 ⁻⁴ Pa) or more, usually 9.0 × 10 ⁻⁶ Torr. (12.0 × 10 ⁻⁴ Pa) or less. The deposition rate is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.1 Å / second or more and usually 5.0 Å / second or less. The film forming temperature at the time of vapor deposition is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C. or higher, preferably 50 ° C. or lower.

{Hole transport layer}
The hole transport layer 4 has a function of injecting holes injected in the order of the anode 2 and the hole injection layer 3 into the light emitting layer 5, and emits light when electrons are injected from the light emitting layer 5 to the anode 2 side. It has a function to suppress a decrease in efficiency.
The hole transport layer 4 can be formed on the hole injection layer 3 when there is a hole injection layer and on the anode 2 when there is no hole injection layer 3. The organic electroluminescent device of the present invention may have a configuration in which the hole transport layer is omitted.

  The formation method of the hole transport layer 4 may be a vacuum deposition method or a wet film formation method, and is not particularly limited. However, from the viewpoint of reducing dark spots, the hole transport layer 4 is preferably formed by a wet film formation method.

  The material for forming the hole transport layer 4 is preferably a material having high hole transportability and capable of efficiently transporting injected holes. Therefore, it is preferable that the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is high, and impurities that become traps are not easily generated during manufacturing or use. In many cases, it is preferable not to quench the light emitted from the light emitting layer 5 or to form an exciplex with the light emitting layer 5 to reduce the efficiency because it is in contact with the light emitting layer 5.

Such a material for the hole transport layer 4 may be any material conventionally used as a constituent material for the hole transport layer. For example, the hole transport property used for the hole injection layer 3 described above. What was illustrated as a compound is mentioned. In addition, arylamine derivatives, fluorene derivatives, spiro derivatives, carbazole derivatives, pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, phthalocyanine derivatives, porphyrin derivatives, silole derivatives, oligothiophene derivatives, condensed polycyclic aromatics Group derivatives and metal complexes.
Also, for example, polyvinylcarbazole derivatives, polyarylamine derivatives, polyvinyltriphenylamine derivatives, polyfluorene derivatives, polyarylene derivatives, polyarylene ether sulfone derivatives containing tetraphenylbenzidine, polyarylene vinylene derivatives, polysiloxane derivatives, polythiophenes Derivatives, poly (p-phenylene vinylene) derivatives, and the like. These may be any of an alternating copolymer, a random polymer, a block polymer, or a graft copolymer. Further, it may be a polymer having a branched main chain and three or more terminal portions, or a so-called dendrimer.
Of these, polyarylamine derivatives and polyarylene derivatives are preferred.

The polyarylamine derivative is preferably a polymer containing a repeating unit represented by the following formula (II). In particular, a polymer composed of a repeating unit represented by the following formula (II) is preferable. In this case, Ar ^a or Ar ^b may be different in each repeating unit.

(In formula (II), Ar ^a and Ar ^b each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.)

Examples of the aromatic hydrocarbon group optionally having a substituent for Ar ^a and Ar ^b include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene A group derived from a 6-membered monocyclic ring or a 2-5 condensed ring, such as a ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, a fluorene ring, and a group formed by connecting these rings by two or more direct bonds. .

Examples of the aromatic heterocyclic group optionally having a substituent for Ar ^a and Ar ^b include a furan ring, a benzofuran ring, a thiophene ring, a benzothiophene ring, a pyrrole ring, a pyrazole ring, an imidazole ring, and an oxadiazole ring. , Indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine Ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring, etc. Include groups groups and the rings from monocyclic or 2-4 fused 5- or 6-membered ring is formed by connecting a direct bond or two or more rings.

From the viewpoint of solubility and heat resistance, Ar ^a and Ar ^b are each independently a group consisting of a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a triphenylene ring, a pyrene ring, a thiophene ring, a pyridine ring, and a fluorene ring. A group derived from a selected ring or a group formed by linking two or more benzene rings (for example, a biphenyl group or a terphenyl group) is preferable.
Among these, a group derived from a benzene ring (phenyl group), a group formed by connecting two benzene rings (biphenyl group), and a group derived from a fluorene ring (fluorenyl group) are preferable.

When the aromatic hydrocarbon group and the aromatic heterocyclic group of Ar ^a and Ar ^b have a substituent, examples of the substituent include an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an alkoxycarbonyl group, Examples thereof include a dialkylamino group, a diarylamino group, an acyl group, a halogen atom, a haloalkyl group, an alkylthio group, an arylthio group, a silyl group, a siloxy group, a cyano group, an aromatic hydrocarbon ring group, and an aromatic heterocyclic group.

As the polyarylene derivative, an arylene group such as an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent, exemplified as Ar ^a or Ar ^b in the formula (II), is ^a repeating unit. The polymer which has in is mentioned.

As the polyarylene derivative, a polymer having a repeating unit of the following formula (III-1) and / or the following formula (III-2) is preferable.

(In the formula (III-1), R ^a , R ^b , R ^c and R ^d are each independently an alkyl group, an alkoxy group, a phenylalkyl group, a phenylalkoxy group, a phenyl group, a phenoxy group, an alkylphenyl group, Represents an alkoxyphenyl group, an alkylcarbonyl group, an alkoxycarbonyl group, or a carboxy group, and t and s each independently represent an integer of 0 to 3. When t or s is 2 or more, they are contained in one molecule. A plurality of R ^a or R ^b may be the same or different, and adjacent R ^a or R ^b may form a ring.)

(In the formula (III-2), R ^e and R ^f are each independently synonymous with R ^a , R ^b , R ^c or R ^d in the formula (III-1). Independently, it represents an integer of 0 to 3. When r or u is 2 or more, a plurality of R ^e and R ^f contained in one molecule may be the same or different, and adjacent R ^e or R ^f may form a ring, and X represents an atom or a group of atoms constituting a 5-membered ring or a 6-membered ring.)

  Specific examples of X include an oxygen atom, a boron atom which may have a substituent, a nitrogen atom which may have a substituent, a silicon atom which may have a substituent, and a substituent. A phosphorus atom which may be substituted, a sulfur atom which may have a substituent, a carbon atom which may have a substituent, or a group formed by bonding these.

  Further, the polyarylene derivative has a repeating unit represented by the following formula (III-3) in addition to the repeating unit represented by the above formula (III-1) and / or the above formula (III-2). Is preferred.

(In the formula (III-3), Ar ^{c to} Ar ⁱ each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. Independently represents 0 or 1.)

Specific examples of Ar ^{c to} Ar ⁱ are the same as Ar ^a and Ar ^b in the formula (II).

  Specific examples of the above formulas (III-1) to (III-3) and specific examples of polyarylene derivatives include those described in JP-A-2008-98619.

In the case of forming the hole transport layer 4 by a wet film formation method, a composition for forming a hole transport layer is prepared in the same manner as the formation of the hole injection layer 3 and then heated and dried after the wet film formation. .
The composition for forming a hole transport layer contains a solvent in addition to the above hole transport compound. The solvent used is the same as that used for the hole injection layer forming composition. The film forming conditions, heat drying conditions, and the like are the same as in the case of forming the hole injection layer 3.

  In the case where the hole transport layer is formed by the vacuum deposition method, the film forming conditions are the same as those in the case of forming the hole injection layer 3.

  The hole transport layer 4 may contain various light emitting materials, electron transport compounds, binder resins, coating property improving agents, and the like in addition to the hole transport compound.

The hole transport layer 4 may also be a layer formed by crosslinking a crosslinkable compound. The crosslinkable compound is a compound having a crosslinkable group, and forms a network polymer compound by crosslinking.
Examples of this crosslinkable group include groups derived from cyclic ethers such as oxetane and epoxy; groups derived from unsaturated double bonds such as vinyl, trifluorovinyl, styryl, acrylic, methacryloyl and cinnamoyl; benzo Examples include groups derived from cyclobutene.

  The crosslinkable compound may be any of a monomer, an oligomer, and a polymer. The crosslinkable compound may have only one type of crosslinkable group, or may have two or more types in any combination and ratio.

  As the crosslinkable compound, a hole transporting compound having a crosslinkable group is preferably used. Examples of the hole transporting compound include nitrogen-containing aromatic compound derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives, phthalocyanine derivatives, porphyrin derivatives; Derivatives; silole derivatives; oligothiophene derivatives, condensed polycyclic aromatic derivatives, metal complexes and the like. Among them, nitrogen-containing aromatic derivatives such as pyridine derivatives, pyrazine derivatives, pyrimidine derivatives, triazine derivatives, quinoline derivatives, phenanthroline derivatives, carbazole derivatives; triphenylamine derivatives, silole derivatives, condensed polycyclic aromatic derivatives, metal complexes, etc. Particularly preferred are triphenylamine derivatives. Examples of the hole transporting compound having a crosslinkable group include those in which the crosslinkable group is bonded to the main chain or the side chain with respect to these hole transportable compounds. In particular, the crosslinkable group is preferably bonded to the main chain via a linking group such as an alkylene group. In particular, the hole transporting compound is preferably a polymer containing a repeating unit having a crosslinkable group, and the above formula (II) or formulas (III-1) to (III-3) can be used as a crosslinkable group. Is preferably a polymer having a repeating unit bonded directly or via a linking group.

  In order to form the hole transport layer 4 by crosslinking the crosslinkable compound, a composition for forming a hole transport layer in which the crosslinkable compound is dissolved or dispersed in a solvent is usually prepared and deposited by wet film formation. To crosslink.

The composition for forming a hole transport layer may contain an additive for promoting a crosslinking reaction in addition to the crosslinking compound. Examples of additives that accelerate the crosslinking reaction include polymerization initiators and polymerization accelerators such as alkylphenone compounds, acylphosphine oxide compounds, metallocene compounds, oxime ester compounds, azo compounds, onium salts; condensed polycyclic hydrocarbons, And photosensitizers such as porphyrin compounds and diaryl ketone compounds.
Further, it may contain a coating property improving agent such as a leveling agent and an antifoaming agent; an electron accepting compound; a binder resin;

In the composition for forming a hole transport layer, the crosslinkable compound is usually 0.01% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, usually 50% by weight or less, preferably 20%. It is contained by weight% or less, more preferably 10% by weight or less.
After forming a composition for forming a hole transport layer containing a crosslinkable compound at such a concentration on the lower layer (usually the hole injection layer 3), the composition is crosslinked by heating and / or irradiation with electromagnetic energy such as light. Are crosslinked to form a network polymer compound.

Conditions such as temperature and humidity during film formation are the same as those during the wet film formation of the hole injection layer 3.
The heating method after film formation is not particularly limited. As heating temperature conditions, it is 120 degreeC or more normally, Preferably it is 400 degrees C or less.
The heating time is usually 1 minute or longer, preferably 24 hours or shorter. The heating means is not particularly limited, and means such as placing a laminated body having a formed layer on a hot plate or heating in an oven is used. For example, conditions such as heating on a hot plate at 120 ° C. or more for 1 minute or more can be used.

  In the case of cross-linking by irradiation of electromagnetic energy such as light, a method of direct irradiation using an ultraviolet, visible or infrared light source such as an ultra high pressure mercury lamp, a high pressure mercury lamp, a halogen lamp, an infrared lamp, or the above-mentioned light source is used. Examples include a mask aligner incorporated and a method of irradiation using a conveyor type light irradiation device. In electromagnetic energy irradiation other than light, for example, there is a method of irradiation using a device that irradiates a microwave generated by a magnetron, a so-called microwave oven. As the irradiation time, it is preferable to set conditions necessary for reducing the solubility of the film, but irradiation is usually performed for 0.1 seconds or longer, preferably 10 hours or shorter.

  Heating and irradiation of electromagnetic energy such as light may be performed individually or in combination. When combined, the order of implementation is not particularly limited.

  The film thickness of the hole transport layer 4 thus formed is usually 5 nm or more, preferably 10 nm or more, and usually 300 nm or less, preferably 100 nm or less.

{Light emitting layer}
When the hole injection layer 3 or the hole transport layer 4 is provided, the light emitting layer 5 is provided on the hole transport layer 4. The light emitting layer 5 is a layer that is excited by recombination of holes injected from the anode 2 and electrons injected from the cathode 9 between electrodes to which an electric field is applied, and becomes a main light emitting source.

  The molecular weight of the compound used as the light emitting material of the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, Usually, it is 100 or more, preferably 200 or more, more preferably 300 or more, and still more preferably 400 or more. Only one of the luminescent materials may be used, or two or more of the luminescent materials may be used in any combination and ratio.

  When the benzodithiophene compound of the present invention is used as a light emitting material for a light emitting layer, as described above, the benzodithiophene compound of the present invention may be used as a dopant material in combination with a host material composed of another compound. The benzodithiophene compound of the present invention may be used as a host material in combination with a dopant material (light emitting material) made of another compound. Of course, the benzodithiophene compound of the present invention may be used alone as the light emitting material of the light emitting layer. Host materials and luminescent materials made of other compounds are as described above.

  The ratio of the light emitting material in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.05% by weight or more and usually 35% by weight or less. If the amount of the light emitting material is too small, uneven light emission may occur. If the amount is too large, the light emission efficiency may be reduced. In addition, when using together 2 or more types of luminescent material, it is made for the total content of these to be contained in the said range.

  Although the ratio of the host material in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, it is usually 0.1% by weight or more and usually 65% by weight or less. If the amount of the hole transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using 2 or more types of host materials together, it is made for the total content of these to be contained in the said range.

<Formation of light emitting layer>
In the case of forming the light emitting layer 5 by a wet film forming method, the above material is dissolved in an appropriate solvent to prepare a light emitting layer forming composition, which is then formed by wet film forming.

  As the luminescent layer solvent to be contained in the luminescent layer forming composition for forming the luminescent layer 5 by the wet film forming method according to the present invention, any solvent can be used as long as the luminescent layer can be formed. . Suitable examples of the solvent for the light emitting layer are the same as those described for the composition for forming a hole injection layer.

  The ratio of the solvent for the light emitting layer to the composition for forming the light emitting layer for forming the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more and usually 70% by weight or less. It is. In addition, when mixing and using 2 or more types of solvents as a solvent for light emitting layers, it is made for the sum total of these solvents to satisfy | fill this range.

  The solid content concentration of the light emitting material, hole transporting compound, electron transporting compound and the like in the composition for forming a light emitting layer is usually 0.01% by weight or more and usually 70% by weight or less. If this concentration is too large, film thickness unevenness may occur, and if it is too small, defects may occur in the film.

  After wet-deposition of the composition for forming a light emitting layer, the resulting coating film is dried and the solvent is removed to form a light emitting layer. Specifically, it is the same as the method described in the formation of the hole injection layer. The method of the wet film forming method is not limited as long as the effect of the present invention is not significantly impaired, and any of the methods described above can be used.

  The thickness of the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. If the thickness of the light emitting layer 5 is too thin, defects may occur in the film, and if it is too thick, the driving voltage may increase.

{Hole blocking layer}
A hole blocking layer 6 may be provided between the light emitting layer 5 and an electron injection layer 8 described later. The hole blocking layer 6 is a layer laminated on the light emitting layer 5 so as to be in contact with the interface of the light emitting layer 5 on the cathode 9 side.

  The hole blocking layer 6 has a role of blocking holes moving from the anode 2 from reaching the cathode 9 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5. Have

  The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high. Examples of the material of the hole blocking layer 6 that satisfies such conditions include bis (2-methyl-8-quinolinolato) (phenolato) aluminum, bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum. Mixed ligand complexes such as, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolato) aluminum binuclear metal complexes, distyrylbiphenyl derivatives, etc. Of styryl compounds (JP-A-11-242996), triazole derivatives such as 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole 7-41759), phenanthroline derivatives such as bathocuproine (JP-A-10-79297), and the like. It is. Further, a compound having at least one pyridine ring substituted at the 2,4,6-position described in International Publication No. 2005-022962 is also preferable as the material for the hole blocking layer 6.

  In addition, the material of the hole-blocking layer 6 may use only 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  There is no restriction | limiting in the formation method of the hole-blocking layer 6. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

  The thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less.

{Electron transport layer}
An electron transport layer 7 may be provided between the light emitting layer 5 and an electron injection layer 8 described later.
The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the device, and efficiently transports electrons injected from the cathode 9 between the electrodes to which an electric field is applied in the direction of the light emitting layer 5. Formed from a compound capable of

  As an electron transport compound used for the electron transport layer 7, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons are transported efficiently with high electron mobility. The compound which can be used is used. Examples of the compound satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives , Distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compounds ( JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide , N-type zinc sulfide, n-type Sele Zinc oxide and the like.

  In addition, the material of the electron carrying layer 7 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of the electron carrying layer 7. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

  The thickness of the electron transport layer 7 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

{Electron injection layer}
The electron injection layer 8 plays a role of efficiently injecting electrons injected from the cathode 9 into the light emitting layer 5. In order to perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, alkaline earth metals such as barium and calcium, and the film thickness is preferably from 0.1 nm to 5 nm.

  Furthermore, an organic electron transport compound represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium, or rubidium ( (As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.), it is possible to improve the electron injection / transport properties and achieve excellent film quality. preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.

  In addition, the material of the electron injection layer 8 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of the electron injection layer 8. FIG. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

{cathode}
The cathode 9 plays a role of injecting electrons into a layer (such as the electron injection layer 8 or the light emitting layer 5) on the light emitting layer 5 side.

As the material of the cathode 9, the material used for the anode 2 can be used. However, a metal having a low work function is preferable for efficient electron injection. For example, tin, magnesium, indium, A suitable metal such as calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.

  In addition, the material of the cathode 9 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The film thickness of the cathode 9 is usually the same as that of the anode 2.

  Further, for the purpose of protecting the cathode 9 made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the device is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

{Other layers}
The organic electroluminescent element according to the present invention may have another configuration without departing from the gist thereof. For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and an arbitrary layer may be omitted. . For example, as shown in FIG. 8, the hole injection layer 3 and the hole blocking layer 6 may be omitted. The electron transport layer 7 and the hole blocking layer 6 may be appropriately provided as necessary. 1) Only the electron transport layer, 2) Only the hole block layer, and 3) The hole block layer / electron transport layer There are usages such as lamination, 4) not using, etc.

Examples of the layer that may be included in addition to the constituent layers shown in FIG. 7 include an electron blocking layer.
The electron blocking layer is provided between the hole injection layer 3 or the hole transport layer 4 and the light emitting layer 5 and prevents electrons moving from the light emitting layer 5 from reaching the hole injection layer 3. Thus, the probability of recombination of holes and electrons in the light emitting layer 5 is increased, the excitons generated are confined in the light emitting layer 5, and the holes injected from the hole injection layer 3 are efficiently collected. There is a role to transport in the direction of. In particular, when a phosphorescent material or a blue light emitting material is used as the light emitting material, it is effective to provide an electron blocking layer.

  The characteristics required for the electron blocking layer include high hole transportability, a large energy gap (difference between HOMO and LUMO), and a high excited triplet level (T1). Furthermore, in the present invention, when the light emitting layer 5 is produced by a wet film formation method, the electron blocking layer is also required to be compatible with the wet film formation. Examples of the material used for such an electron blocking layer include a copolymer of dioctylfluorene and triphenylamine typified by F8-TFB (International Publication No. 2004/084260).

  In addition, the material of an electron blocking layer may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of an electron blocking layer. Therefore, it can be formed by a wet film forming method, a vapor deposition method, or other methods.

Further, at the interface between the cathode 9 and the light emitting layer 5 or the electron transport layer 7, for example, lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), lithium oxide (Li ₂ O), cesium carbonate (II) (CsCO ₃ ). It is also an effective method to improve the efficiency of the device (Applied Physics Letters, 1997, Vol. 70, pp. 152; No. 10-74586; IEEE Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154, etc.).

Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than a board | substrate in reverse order. For example, in the case of the layer configuration of FIG. 7, the other components on the substrate 1 are the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6, the light emitting layer 5, the hole transport layer 4, the positive layer. The hole injection layer 3 and the anode 2 may be provided in this order.
Furthermore, it is also possible to constitute the organic electroluminescent element according to the present invention by laminating components other than the substrate between two substrates, at least one of which is transparent.

Further, a structure in which a plurality of components (light emitting units) other than the substrate are stacked in a plurality of layers (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, (when the anode is ITO, the cathode is Al, these two layers) interfacial layer between the respective stages (between emission units) Alternatively, for example, a charge consisting of five vanadium oxide (V 2 _{O 5),} etc. When a generation layer (Carrier Generation Layer: CGL) is provided, a barrier between steps is reduced, which is more preferable from the viewpoint of light emission efficiency and driving voltage.

Furthermore, the organic electroluminescent device according to the present invention may be configured as a single organic electroluminescent device, or may be applied to a configuration in which a plurality of organic electroluminescent devices are arranged in an array. You may apply to the structure by which the cathode is arrange | positioned at XY matrix form.
In addition, each layer described above may contain components other than those described as the constituent materials unless the effects of the present invention are significantly impaired.

  The organic electroluminescent element of the present invention is suitably used for an organic EL display. The organic electroluminescent device obtained by the present invention is described in, for example, “Organic EL Display” (Ohm Co., issued on August 20, 2004, Shizushi Tokito, Chiba Adachi, Hideyuki Murata). An organic EL display can be formed by the method.

  Examples The present invention will be described more specifically with reference to examples. However, the present invention is not limited to the description of the following examples unless it exceeds the gist.

一口ナスフラスコに4,5-ジフェニルベンゾ[1,2-b:4,3-b´]ジチオフェン(1)(1.20ｇ，3.45mmol)を乾燥CH_２Cl_２(40mL)に溶かし、0℃に冷却した後にNBS(N-ブロモスクシンイミド）（0.68ｇ，3.80mmol)を加え、アルゴン雰囲気下、0℃で10分間、その後、室温にて12時間攪拌した。反応終了後、炭酸水素ナトリウム水溶液とチオ硫酸ナトリウム水溶液を加え、有機層を分離し、水層をCH_２Cl_２で抽出した。これを食塩水で洗浄し、硫酸ナトリウムを加えて乾燥した後、濃縮した。この混合物を展開溶液にヘキサンを用いたシリカゲルクロマトグラフィーにより精製し、白色の固体として2-ブロモ-4,5-ジフェニルベンゾ[1,2-b:4,3-b´]ジチオフェン(2)(1.26ｇ，収率87％)を得た。 [Synthesis example]
(a) Synthesis of 2-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (2)

Dissolve 4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (1) (1.20 g, 3.45 mmol) in dry CH ₂ Cl ₂ (40 mL) in a one-necked eggplant flask and bring it to 0 ° C. After cooling, NBS (N-bromosuccinimide) (0.68 g, 3.80 mmol) was added, and the mixture was stirred at 0 ° C. for 10 minutes in an argon atmosphere and then at room temperature for 12 hours. After completion of the reaction, an aqueous sodium hydrogen carbonate solution and an aqueous sodium thiosulfate solution were added, the organic layer was separated, and the aqueous layer was extracted with CH ₂ Cl ₂ . This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using hexane as a developing solution to give 2-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (2) as a white solid ( 1.26 g, yield 87%).

mp: 180-182 ° C
¹ HNMR (CDCl ₃ ): δ7.25-7.34 (m, 10H), 7.55 (d, J5.7, 1H), 7.68 (d, J5.7, 1H), 7.77 (s, 1H)
¹³ C NMR (CDCl ₃ ): δ 116.5, 124.7, 127.7, 128.3, 129.9, 130.7, 132.4, 138.4, 140.8
Anal.Calcd.for C ₂₂ H ₁₃ BrS ₂ : C = 62.71, H = 3.11
Found: C = 62.56, H = 3.12

(b) Synthesis of 2-iodo-7-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (3)

  2-Bromo-4,5-diphenylbenzo [1,2-b: 4,3-b '] dithiophene (2) (1.0 g, 2.37 mmol) and potassium iodide (0.50 g, 3.08 mmol) in a one-necked eggplant flask Was dissolved in acetic acid (100 ml) and distilled water (10 ml) and refluxed at 110 ° C. for 1 hour under an argon atmosphere. Thereafter, potassium iodate (0.66 g, 3.08 mmol) was added, and the mixture was stirred at 110 ° C. for 17 hours under an argon atmosphere. After completion of the reaction, the reaction mixture was cooled to room temperature, water was added to precipitate a solid, the solid was separated by filtration, and then dissolved in benzene. A sodium sulfite aqueous solution was added to the solution, the organic layer was separated, and the aqueous layer was extracted with benzene. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using hexane as a developing solution, and 2-iodo-7-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene as a white solid. (3) (0.64 g, yield 49%) was obtained.

mp: 252-254 ° C
¹ HNMR (CDCl ₃ ): δ7.25-7.30 (m, 10H), 7.67 (s, 1H), 7.85 (s, 1H)
¹³ C NMR (CDCl ₃ ): δ 97.1, 116.5, 124.2, 124.8, 127.7, 128.3, 129.9, 130.1, 130.5, 130.6,
131.8,132.0,133.7,138.3,138.5,140.7,144.5,145.2

(C) 7-bromo-2,4,5-triphenylbenzo [1,2-b: 4,3-b ′] dithiophene and 2,4,5,7-tetraphenylbenzo [1,2-b: Synthesis of 4,3-b´] dithiophene (6) (BDT-1)

  Toluene (10 mL) and distilled water (3 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.63 g) was added, and the solution was degassed at 90 ° C. for 2 hours under an argon atmosphere. After cooling to room temperature, 2-iodo-7-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (3) (0.50 g, 0.91 mmol), phenylboronic acid (0.12 g, 1.01 mmol) and tetrakis (triphenylphosphine) palladium (0) (63 mg, 0.055 mmol) were added, and the mixture was stirred at 75 ° C. for 72 hours under an argon atmosphere. After completion of the reaction, the mixture was cooled to room temperature, filtered through celite, and 10% by weight diluted hydrochloric acid was added.

  After separating the organic layer, the aqueous layer was extracted with toluene. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using hexane: chloroform (5: 1) as a developing solution, and 7-bromo-2,4,5-triphenylbenzo [1,2-b: 4 as a pale yellow solid. , 3-b ′] dithiophene (5) (0.29 g, 63% yield) and 2,4,5,7-tetraphenylbenzo [1,2-b: 4,3-b ′ as a pale yellow solid Dithiophene (6) (54 mg, 12% yield) was obtained.

<7-bromo-2,4,5-triphenylbenzo [1,2-b: 4,3-b ′] dithiophene (5)>
mp: 192-195 ℃
¹ HNMR (CDCl ₃ ): δ 7.25-7.35 (m, 10H), 7.37-7.43 (m, 3H), 7.69-7.73 (m, 2H), 7.76 (s, 1H),
7.87 (s, 1H)
¹³ C NMR (CDCl ₃ ): δ 116.0, 117.3, 125.0, 126.3, 127.5, 127.6, 128.2, 128.3, 129.0, 130.0,
130.1,130.5,131.4,133.3,133.7,134.1,138.7,138.8,139.2,140.7,145.6
Anal.Calcd.for C ₂₈ H ₁₇ BrS ₂ : C = 67.60, H = 3.44
Found: C = 67.05, H = 3.83

<2,4,5,7-tetraphenylbenzo [1,2-b: 4,3-b ′] dithiophene (6)>
mp: 288 ° C
¹ HNMR (CDCl ₃ ): δ 7.25-7.45 (m, 16H), 7.74 (d, J = 7.2, 4H), 8.02 (s, 2H)
¹³ C NMR (CDCl ₃ ): δ 118.0, 125.4, 126.6, 127.2, 127.5, 128.2, 129.1, 130.5, 133.2
133.9,138.2,144.0
Anal.Calcd.for C ₃₄ H ₂₂ S ₂ : C = 82.55, H = 4.48
Found: C = 82.56, H = 4.50

(d) 2- (2-naphthyl) -7-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene and 2,7-di (2-naphthyl) -4, Synthesis of 5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (9) (BDT-2)

  Toluene (2 mL) and distilled water (1.5 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.32 g) was added, and the solution was degassed at 90 ° C. for 2 hours under an argon atmosphere. After cooling to room temperature, 2-iodo-7-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (3) (0.10 g, 0.18 mmol), 2-naphthyl Boronic acid (32 mg, 0.18 mmol) and tetrakis (triphenylphosphine) palladium (0) (10 mg, 0.009 mmol) were added, and the mixture was stirred at 75 ° C. for 16 hours under an argon atmosphere. After completion of the reaction, the mixture was cooled to room temperature, filtered through celite, and 10% by weight diluted hydrochloric acid was added. After the organic layer was separated, the aqueous layer was extracted with ethyl acetate. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using hexane: chloroform (5: 1) as a developing solution to give 2- (2-naphthyl) -7-bromo-4,5-diphenylbenzo [1, as a pale yellow solid. 2-b: 4,3-b ′] dithiophene (8) (69 mg, 69% yield) and 2,7-di (2-naphthyl) -4,5-diphenylbenzo [1,2 as a yellow solid -b: 4,3-b ′] dithiophene (9) (7 mg, yield 7%) was obtained.

<2- (2-naphthyl) -7-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (8)>
mp: 263-265 ℃
¹ HNMR (CDCl ₃ ): δ 7.25-7.40 (m, 8H), 7.48-7.52 (m, 2H), 7.82-7.89 (m, 7H), 8.02 (s, 1H),
8.15 (s, 1H)
¹³ C NMR (CDCl ₃ ): δ 116.1, 117.7, 124.1, 125.0, 125.2, 126.4, 126.7, 127.5, 127.6, 127.7,
128.1,128.2,128.3,128.6,130.0,130.1,130.6,131.4,133.1,133.4,
133.5,133.8,138.8,138.9,139.3,140.7,145.6
Anal.Calcd.for C ₃₂ H ₁₉ BrS ₂ : C = 70.20, H = 3.50
Found: C = 69.97, H = 3.67

<2,7-di (2-naphthyl) -4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (9)>
¹ HNMR (CDCl ₃ ): δ 7.27-7.41 (m, 12H), 7.45-7.52 (m, 4H), 7.80-7.94 (m, 8H), 8.17 (s, 2H)
¹³ C NMR (CDCl ₃ ): δ 118.1, 124.2, 125.1, 126.3, 126.7, 127.4, 127.7, 128.1, 128.2, 128.6,
130.3,131.4,131.6,133.1,133.6,134.7,139.2,145.2
Anal.Calcd.for C ₄₂ H ₂₆ S ₂ : C = 84.81, H = 4.41
Found: C = 84.54, H = 4.31

(e) Synthesis of 2- (2-naphthyl) -4,5,7-triphenylbenzo [1,2-b: 4,3-b ′] dithiophene (10) (BDT-3)

  Toluene (3 mL) and distilled water (1.5 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.32 g) was added, and the solution was degassed at 90 ° C. for 2 hours under an argon atmosphere. After cooling to room temperature, 2- (2-naphthyl) -7-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (8) (0.16 g, 0.29 mmol) Phenylboronic acid (67 mg, 0.55 mmol) and tetrakis (triphenylphosphine) palladium (0) (19 mg, 0.016 mmol) were added, and the mixture was stirred at 90 ° C. for 19 hours in an argon atmosphere. After completion of the reaction, the mixture was cooled to room temperature, filtered through celite, and 10% by weight diluted hydrochloric acid was added. After separating the organic layer, the aqueous layer was extracted with toluene. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using hexane: chloroform (10: 1) as a developing solution, and 2- (2-naphthyl) -4,5,7-triphenylbenzo [1,2- b: 4,3-b ′] dithiophene (10) (0.15 g, yield 93%) was obtained.

mp: 263-265 ℃
¹ HNMR (CDCl ₃ ): δ 7.25-7.40 (m, 8H), 7.48-7.52 (m, 2H), 7.82-7.89 (m, 7H), 8.02 (s, 1H),
8.15 (s, 1H)
¹³ C NMR (CDCl ₃ ): δ 116.1, 117.7, 124.1, 125.0, 125.2, 126.4, 126.7, 127.5, 127.6, 127.7,
128.1,128.2,128.3,128.6,130.0,130.1,130.6,131.4,133.1,133.4,
133.5,133.8,138.8,138.9,139.3,140.7,145.6
Anal.Calcd.for C ₃₂ H ₁₉ BrS ₂ : C = 70.20, H = 3.50
Found: C = 69.97, H = 3.67

(f) Synthesis of 2- (9-phenanthryl) -7- (2-naphthyl) -4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (12) (BDT-4)

  Toluene (12 mL) and distilled water (1.5 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.32 g) was added, and the solution was degassed at 90 ° C. for 2 hours under an argon atmosphere. After cooling to room temperature, 2- (2-naphthyl) -7-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (8) (0.18 g, 0.33 mmol) 9-phenanthrylboronic acid (0.26 g, 1.15 mmol) and tetrakis (triphenylphosphine) palladium (0) (23 mg, 0.020 mmol) were added, and the mixture was stirred at 90 ° C. for 12 hours under an argon atmosphere. After completion of the reaction, the mixture was cooled to room temperature, filtered through celite, and 10% by weight diluted hydrochloric acid was added. After the organic layer was separated, the aqueous layer was extracted with ethyl acetate. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using hexane: chloroform (5: 1) as a developing solution, and 2- (9-phenanthryl) -7- (2-naphthyl) -4,5-diphenylbenzoic acid as a yellow solid. [1,2-b: 4,3-b ′] dithiophene (12) (0.19 g, yield 88%) was obtained.

mp: 263-265 ℃
¹ HNMR (CDCl ₃ ): δ 7.25-7.40 (m, 8H), 7.48-7.52 (m, 2H), 7.82-7.89 (m, 7H), 8.02 (s, 1H),
8.15 (s, 1H)
¹³ C NMR (CDCl ₃ ): δ 116.1, 117.7, 124.1, 125.0, 125.2, 126.4, 126.7, 127.5, 127.6,
127.7,128.1,128.2,128.3,128.6,130.0,130.1,130.6,131.4,133.1,
133.4,133.5,133.8,138.8,138.9,139.3,140.7,145.6
Anal.Calcd.for C ₃₂ H ₁₉ BrS ₂ : C = 70.20, H = 3.50
Found: C = 69.97, H = 3.67

(g) Synthesis of 2- (tributyltin) -1,3,5-trimethylbenzene (14)

  2-Bromomesitylene (13) (0.29 ml, 1.91 mmol) was dissolved in dry THF (tetrahydrofuran) (10 mL) in a one-necked eggplant flask, and n-BuLi (n-butyllithium) (2.88 mmol) at −78 ° C. under an argon atmosphere. 1.55 M hexane solution 1.86 ml) was added dropwise. After stirring this at -78 ° C for 2 hours, tributyltin (IV) chloride (0.78ml, 2.88mmol) was added dropwise and stirred at -78 ° C for 2 hours. After completion of the reaction, the mixture was filtered through silica gel to remove inorganic salts and concentrated. This was dried to obtain 2- (tributyltin) -1,3,5-trimethylbenzene (14) as a pale yellow liquid. This product was used in the next reaction without further purification.

(h) Synthesis of 2-mesityl-7- (2-naphthyl) -4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (15) (BDT-5)

  Put toluene (15 ml) into a one-necked eggplant flask and add 2- (tributyltin) -1,3,5-trimethylbenzene (14) (crude), 2- (2-naphthyl) -7-bromo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (8) (0.35 g, 0.64 mmol), tetrakis (triphenylphosphine) palladium (0) (44 mg, 0.038 mmol) and copper oxide (50 mg, 0.70 mmol) And stirred at 110 ° C. for 66 hours under an argon atmosphere. After completion of the reaction, the mixture was cooled to room temperature, filtered through celite, and 10% by weight diluted hydrochloric acid was added. After separating the organic layer, the aqueous layer was extracted with toluene. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using hexane: chloroform (5: 1) as a developing solution to give 2-mesityl-7- (2-naphthyl) -4,5-diphenylbenzo [1,2 as a yellow solid. -b: 4,3-b '] dithiophene (15) (0.23 g, 63% yield) was obtained.

mp: 151-153 ° C
¹ HNMR (CDCl ₃ ): δ 2.22 (s, 6H), 2.34, (s, 3H), 6.95, (s, 2H), 7.25-7.50 (m, 12H),
7.54 (s, 1H), 7.80-7.91 (m, 4H), 8.07, (s, 1H), 8.15 (s, 1H)
¹³ C NMR (CDCl ₃ ): δ 20.7, 21.1, 118.1, 121.4, 124.2, 125.1, 126.3, 126.6, 127.3, 127.4,
127.7,128.0,128.1,128.2,128.5,130.2,130.3,130.7,130.8,131.3,
131.7,133.0,133.5,134.2,134.5,137.9,138.1,138.9,139.3,139.4,
140.2,144.0,145.0
Anal.Calcd.for C ₄₁ H ₃₀ S ₂ : C = 83.92, H = 5.15
Found: C = 83.70, H = 5.42

(i) Synthesis of 2,7-diiodo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (16)

  Dissolve 4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (1) (1.00 g, 2.92 mmol) in dry THF (40 mL) in a one-necked eggplant flask, and add −78 N-BuLi (7.30 mmol, 1.87 M hexane solution 4.87 mL) was added dropwise at ° C. This was stirred at -78 ° C for 2 hours. Iodine (2.22 g, 8.75 mmol) dissolved in dry THF (5 mL) was added thereto, and the mixture was gradually returned to room temperature under an argon atmosphere and stirred for 2 hours 30 minutes. After completion of the reaction, an aqueous sodium hydrogen carbonate solution and an aqueous sodium thiosulfate solution were added, the organic layer was separated, and the aqueous layer was extracted with ethyl acetate. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using hexane as a developing solution, and 2,7-diiodo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (16) was obtained as a white solid. (1.74 g, yield 98%) was obtained.

mp: 235-237 ° C
¹ HNMR (CDCl ₃ ): δ7.26-7.40 (m, 10H), 7.88 (s, 2H)
¹³ C NMR (CDCl ₃ ): δ 127.7, 128.3, 129.9, 131.9, 133.3, 138.5
IR (KBr): 3051, 2348, 1472, 1362, 1029, 808, 695cm ^-1
Anal.Calcd.for C ₂₂ H ₁₂ I ₂ S ₂ : C = 44.46, H = 2.04
Found: C = 44.21, H = 2.15

(j) Synthesis of 2,4,5,7-tetraphenylbenzo [1,2-b: 4,3-b´] dithiophene (17)

  Toluene (15 mL) and distilled water (2 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.41 g) was added, and the solution was degassed at 90 ° C. for 2 hours under an argon atmosphere. After cooling to room temperature, 2,7-diiodo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (16) (1.00 g, 1.68 mmol), phenylboronic acid (0.62 g, 5.04 mmol) and tetrakis (triphenylphosphine) palladium (0) (0.12 g, 0.10 mmol) were added, and the mixture was stirred at 90 ° C. for 20 hours under an argon atmosphere. After completion of the reaction, the mixture was cooled to room temperature, filtered through celite, and 10% by weight diluted hydrochloric acid was added. After the organic layer was separated, the aqueous layer was extracted with ethyl acetate. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using chloroform as a developing solution, and 2,4,5,7-tetraphenylbenzo [1,2-b: 4,3-b ′] dithiophene (17) as a yellow solid. (0.75 g, yield 90%) was obtained.

mp: 288 ° C
¹ HNMR (CDCl ₃ ): δ 7.25-7.45 (m, 16H), 7.74 (d, J = 7.2, 4H), 8.02 (s, 2H)
¹³ C NMR (CDCl ₃ ): δ 118.0, 125.4, 126.6, 127.2, 127.5, 128.2, 129.1, 130.5, 133.2, 133.9,
138.2,144.0
IR (KBr): 3057,2312,1958,1596,1482,1072,702cm ^-1
Anal.Calcd.for C ₃₄ H ₂₂ S ₂ : C = 82.55, H = 4.48
Found: C = 82.56, H = 4.50

(k) Synthesis of 2,4,5,7-tetraphenyl-1-bromobenzo [1,2-b: 4,3-b ′] dithiophene (18)

  Dissolve 2,4,5,7-tetraphenylbenzo [1,2-b: 4,3-b ′] dithiophene (17) (1.48 g, 3.0 mmol) in dry methylene chloride (100 mL) in a single-necked eggplant flask, NBS (0.53 g, 3.0 mmol) was added thereto, and the mixture was stirred at room temperature for 20 hours under an argon atmosphere. After completion of the reaction, an aqueous sodium hydrogen carbonate solution and an aqueous sodium thiosulfate solution were added, the organic layer was separated, and the aqueous layer was extracted with methylene chloride. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using benzene as a developing solution, and almost quantitatively as a yellow solid 2,4,5,7-tetraphenyl-1-bromobenzo [1,2-b: 4,3- b ′] dithiophene (18) (1.72 g) was obtained.

mp: 239 ° C
¹ HNMR (CDCl ₃ ): δ7.25-7.78 (m, 20H), 9.10 (s, 1H)

(l) Synthesis of 1,2,4,5,7-pentaphenylbenzo [1,2-b: 4,3-b´] dithiophene (19) (BDT-6)

  Toluene (12 mL) and distilled water (2 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.42 g) was added, and the solution was degassed at 90 ° C. for 2 hours under an argon atmosphere. Then, it was cooled to room temperature, 2,4,5,7-tetraphenyl-1-bromobenzo [1,2-b: 4,3-b ′] dithiophene (18) (1.72 g, 3.00 mmol), phenylboronic acid (0.55 g, 4.50 mmol) and tetrakis (triphenylphosphine) palladium (0) (0.10 g, 0.09 mmol) were added, and the mixture was stirred at 90 ° C. for 20 hours under an argon atmosphere. After completion of the reaction, the mixture was cooled to room temperature, filtered through celite, and 10% by weight diluted hydrochloric acid was added. After the organic layer was separated, the aqueous layer was extracted with ethyl acetate. This was washed with brine, dried by adding sodium sulfate, and concentrated. The mixture was purified by silica gel chromatography using benzene as the developing solution, and 1,2,4,5,7-pentaphenylbenzo [1,2-b: 4,3-b´] dithiophene as a pale yellow solid (19) (1.20 g, yield 70%) was obtained.

mp: 257 ° C
¹ HNMR (CDCl ₃ ): δ 6.80 (s, 1H), 7.13-7.41 (m, 20H), 7.49-7.55 (m, 5H)

(m) Synthesis of 2,7-di (4-t-butylphenyl) -4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (21)

  Toluene (6 mL) and distilled water (1.5 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.32 g) was added, and the solution was degassed at 90 ° C. for 2 hours under an argon atmosphere. After cooling to room temperature, 2,7-diiodo-4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (16) (0.40 g, 0.67 mmol), 4-t-butyl Phenylboronic acid (20) (0.42 g, 2.36 mmol) and tetrakis (triphenylphosphine) palladium (0) (0.06 g, 0.05 mmol) were added, and the mixture was stirred at 90 ° C. for 18 hours in an argon atmosphere. After completion of the reaction, the mixture was cooled to room temperature, filtered through celite, and 10% by weight diluted hydrochloric acid was added. After the organic layer was separated, the aqueous layer was extracted with ethyl acetate. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using chloroform as a developing solution, and 2,7-di (4-t-butylphenyl) -4,5-diphenylbenzo [1,2-b: 4, 3-b ′] dithiophene (21) (0.38 g, yield 89%) was obtained.

mp: 287 ° C
¹ HNMR (CDCl ₃ ): 1.36 (s, 18H), 7.31-7.38 (m, 10H), 7.44 (dt, J8.4, 2.04H),
7.70 (dt, J8.4,2.04H), 7.98 (s, 2H)
¹³ C NMR (CDCl ₃ ): -31.2, 34.7, 117.1, 127.3, 125.9, 126.0, 127.3, 128.1, 130.3, 131.0,
131.5,134.6,138.8,139.3,145.2,151.4
IR (KBr): 3027,2960,2864,2363,1601,1494,815,696cm ^-1
Anal.Calcd for C ₄₂ H ₃₈ S ₂ : C = 83.12, H = 6.31
Found: C = 83.38, H = 6.30

Synthesis of (n) 2,7-di (4-t-butylphenyl) -4,5-diphenyl-1-bromobenzo [1,2-b: 4,3-b ′] dithiophene (22)

  Add 2,7-di (4-t-butylphenyl) -4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene (21) (0.37 g, 0.61 mmol) to a one-necked eggplant flask. It melt | dissolved in dry DMF (17 mL), NBS (0.13 g, 0.73 mmol) was added there, and it stirred at room temperature for 20 hours under argon atmosphere. After completion of the reaction, an aqueous sodium hydrogen carbonate solution and an aqueous sodium thiosulfate solution were added, the organic layer was separated, and the aqueous layer was extracted with methylene chloride. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using benzene as the developing solution, and almost quantitatively as a yellow solid 2,7-di (4-t-butylphenyl) -4,5-diphenyl-1-bromobenzo [1 , 2-b: 4,3-b ′] dithiophene (22) (0.42 g) was obtained.

(o) 2,7-di (4-t-butylphenyl) -1,4,5-triphenylbenzo [1,2-b: 4,3-b ′] dithiophene (23) (BDT-7) Composition

  Toluene (5 mL) and distilled water (1.5 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.32 g) was added, and the solution was degassed at 90 ° C. for 1 hour in an argon atmosphere. Then, it was cooled to room temperature and 2,7-di (4-t-butylphenyl) -4,5-diphenyl-1-bromobenzo [1,2-b: 4,3-b ′] dithiophene (22) (0.42 g, 0.61 mmol), phenylboronic acid (0.097 g, 0.79 mmol) and tetrakis (triphenylphosphine) palladium (0) (0.042 g, 0.037 mmol) were added, and the mixture was stirred at 90 ° C. for 48 hours under an argon atmosphere. After completion of the reaction, the mixture was cooled to room temperature, filtered through celite, and 10% by weight diluted hydrochloric acid was added. After the organic layer was separated, the aqueous layer was extracted with ethyl acetate. This was washed with brine, dried by adding sodium sulfate, and concentrated. This mixture was purified by silica gel chromatography using benzene as a developing solution to obtain 2,7-di (4-t-butylphenyl) -1,4,5-triphenylbenzo [1,2-b as a white solid. : 4,3-b ′] dithiophene (23) (0.29 g, yield 69%) was obtained.

mp:> 300 ° C
¹ HNMR (CDCl ₃ ): 1.36 (s, 18H), 7.18-7.53 (m, 20H), 7.68-7.74 (m, 3H), 7.98 (s, 1H)

[Example 1]
The solubility of the obtained BDT-4 (2- (9-phenanthryl) -7- (2-naphthyl) -4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene) in toluene When measured at 25 ° C., the solubility in toluene was 53.6% by weight.

[Examples 2 to 4, Comparative Examples 1 and 2]
In place of BDT-4, the solubility in toluene at 25 ° C. was measured in the same manner as in Example 1 except that the compounds shown in Table 2 below were used. The results are shown in Table 2.

[Example 5]
Solution and thin film of the obtained BDT-4 (2- (9-phenanthryl) -7- (2-naphthyl) -4,5-diphenylbenzo [1,2-b: 4,3-b ′] dithiophene) The inside emission spectrum (PL spectrum) was measured as follows.

First, for the measurement of the emission spectrum in the solution, BDT-4 was dissolved in CHCl ₃ to prepare a 1 × 10 ⁻⁵ mol / L solution. In addition, for the measurement of the emission spectrum in a thin film, a BDT-4 solution in CHCl ₃ (1.5 wt%) was prepared, and the solution was formed into a film by spin coating (1800 rpm, 60 s) to produce a film did.
Using FP-6200 manufactured by JASCO Corporation, the emission spectra of the emission spectrum measurement solution in the solution and the emission spectrum measurement film in the thin film were measured.
The emission spectrum (PL spectrum) had a maximum wavelength at 417 nm in the solution and a maximum wavelength at 460 nm in the thin film. The shift of the maximum wavelength of the emission spectrum (PL spectrum) between the solution and the thin film was small. This indicates that BDT-4 is very uniformly dispersed in the thin film. The emission spectrum (PL spectrum) is shown in FIG.

[Examples 6 to 8, Comparative Examples 3 and 4]
An emission spectrum (PL spectrum) in the solution and in the thin film was measured in the same manner as in Example 5 except that the compounds shown in Table 3 below were used instead of BDT-4. The results are shown in Table 3. Moreover, the emission spectrum (PL spectrum) is shown in FIGS.

[Example 9]
The organic electroluminescent element shown in FIG. 8 was produced.
On glass substrate 1, anode 2 made of ITO (indium tin oxide) transparent electrode, hole transport layer 4 made of bis [N- (1-naphthyl) -N-phenyl] benzidine and having a thickness of 50 nm, BDT- 40 nm-thick emission layer 5 made of 6 (1,2,4,5,7-pentaphenylbenzo [1,2-b: 4,3-b ′] dithiophene), tris (8-hydroxyquinolinate) A 4 nm-thickness electron transport layer 7 made of aluminum (III), a 0.5 nm-thickness electron injection layer 8 made of lithium fluoride, and a 100-nm-thick metal electrode cathode 9 made of aluminum fluoride are vacuum-deposited in this order. The organic electroluminescent element laminated | stacked by the method was produced. This organic electroluminescent element emitted blue light with a maximum luminance of 6070 cd / m ² at 13 V in the atmosphere. In FIG. 3, the emission spectrum (EL spectrum) of this organic electroluminescent element is shown.

It is a chart which shows the emission spectrum (PL spectrum) in the solution of BDT-4 of Example 5, and a thin film. It is a chart which shows the emission spectrum (PL spectrum) in the solution of BDT-5 of Example 6, and a thin film. It is a chart which shows the emission spectrum (PL spectrum) in the solution of BDT-6 of Example 7, and a thin film, and the emission spectrum (EL spectrum) of the organic electroluminescent element of Example 9. It is a chart which shows the emission spectrum (PL spectrum) in the solution of BDT-7 of Example 8, and a thin film. It is a chart which shows the emission spectrum (PL spectrum) in the solution of BDT-1 of the comparative example 3, and a thin film. It is a chart which shows the emission spectrum (PL spectrum) in the solution of BDT-2 of the comparative example 4, and a thin film. It is a schematic diagram of the cross section which shows the structural example of the organic electroluminescent element of this invention. It is a schematic diagram of the cross section which shows the other structural example of the organic electroluminescent element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode

Claims (6)

A benzodithiophene compound represented by the following formula (1):

(In formula (1), R ^{1 to} R ⁶ each independently represents a hydrogen atom or a substituent, provided that R ¹ and R ⁶ , R ² and R ^5, and R ³ and R ⁴ are the same. Never.) The benzodithiophene compound according to claim 1, wherein R ¹ is a substituent. R ^{1 to} R ⁶ may each independently have a hydrogen atom, an alkyl group that may have a substituent, an aromatic hydrocarbon group that may have a substituent, or a substituent. The benzodithiophene compound according to claim 1 or 2, which is selected from good aromatic heterocyclic groups. The benzodithiophene compound according to any one of claims 1 to 3, wherein R ² and R ⁵ are different.   A composition comprising the benzodithiophene compound according to any one of claims 1 to 4 and a solvent.   5. The benzodithiophene compound according to claim 1, wherein the organic layer has an anode and a cathode, and an organic layer provided between the anode and the cathode. An organic electroluminescent element comprising:

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