JP5322091B2 - Polymer for organic electroluminescence device, organic electroluminescence device and organic EL display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polymer for an organic electrolytic light emitting element which is capable of exhibiting white light emission by itself, in organic electrolytic light emitting elements. <P>SOLUTION: The polymer for the organic electrolytic light emitting element has a structure represented by formula (I). Since it is a compound capable of obtaining light emission from both the excitation states of fluorescent light emission (singlet) and phosphorescent light emission (triplet) regardless of a single compound, white light emission is performed with high efficiency. In the formula, Ar<SP>1</SP>and Ar<SP>2</SP>are each independently an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, and R<SP>1</SP>and R<SP>2</SP>are each independently a substituent. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

The present invention relates to a polymer for an organic electroluminescent element used for an organic electroluminescent element.
The present invention also provides a composition for an organic electroluminescent element containing the polymer for organic electroluminescent elements, an organic electroluminescent element having an organic layer containing the polymer for organic electroluminescent elements, and the organic electroluminescent element. The present invention relates to an organic EL display using the element.

  As a thin film type electroluminescent device, an organic electroluminescent (organic EL) device using an organic material instead of an inorganic material has been developed. Organic electroluminescent devices usually have each layer such as a hole injection layer, a hole transport layer, an organic light emitting layer, and an electron transport layer between an anode and a cathode, and materials suitable for these layers have been developed. Yes. In addition, the emission colors include red, green, and blue, and materials that match the emission colors are also being developed.

  When such an organic electroluminescent element is used for white illumination or the like, white is obtained by mixing materials that develop colors such as red, green, and blue, or white is obtained by laminating materials of these colors, Alternatively, a method of combining pixels that emit light for each color is performed (for example, see Patent Document 1).

However, there is a problem that combining a plurality of color elements in this way is very complicated in manufacturing.
JP 2006-324016 A

  This invention makes it a subject to provide the polymer for organic electroluminescent elements which can show single and white light emission in an organic electroluminescent element.

  As a result of intensive studies by the present inventors, it has been found that the above problem can be solved by using a polymer containing a structure represented by the following formula (I), and the present invention has been achieved.

（式（Ｉ）中、Ａｒ^１およびＡｒ^２は、それぞれ独立に、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^１およびＲ^２は、それぞれ独立に置換基を表す。）

（式（II）中、Ｒ ^３ 〜Ｒ ^５ は、それぞれ独立に置換基を表す。ａは０〜４の整数を表し、ｂは０〜５の整数を表し、ｃは０〜４の整数を表す。Ａｒ ^１ 、Ａｒ ^２ 、Ｒ ^１ およびＲ ^２ は、それぞれ式（Ｉ）におけるものと同義である。）

（式（III）中、Ｒ ^６ 〜Ｒ ^９ は、それぞれ独立に置換基を表す。ｄおよびｅはそれぞれ独立に０〜４の整数を表す。Ａｒ ^１ 、Ａｒ ^２ 、Ｒ ^１ およびＲ ^２ は、それぞれ式（Ｉ）におけるものと同義である。） That is, the gist of the present invention is a polymer for an organic electroluminescence device including a structure represented by the following formula (I), which is represented by the structure represented by the following formula (II) or the following formula (III). A polymer for an organic electroluminescent device comprising the structure .

(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. R ¹ and R ² each independently represent a substituent.)

(In formula (II), R ^{3 to} R ⁵ each independently represents a substituent. A represents an integer of 0 to 4, b represents an integer of 0 to 5, and c represents an integer of 0 to 4. ^{.Ar 1,} Ar ^{2, R} 1 and ^{R 2} representing have the same meanings as those in each of formulas (I).)

(In formula (III), R ^{6 to} R ⁹ each independently represents a substituent . D and e each independently represent an integer of 0 to 4. Ar ¹ , Ar ² , R ¹ and R ² are Each having the same meaning as in formula (I).)

  Another gist of the present invention resides in a composition for an organic electroluminescence device containing such a polymer for an organic electroluminescence device and a solvent.

  Another gist of the present invention is an organic electroluminescence device having an anode, a cathode, and an organic layer between the anode and the cathode, wherein the organic layer contains the polymer for organic electroluminescence device in the organic layer. Element.

  Still another subject matter of the present invention resides in an organic EL display using the organic electroluminescent element.

  According to the polymer of the present invention, white light emission can be obtained with a single compound, and using such a polymer of the present invention, an organic electroluminescent element and an organic EL display with high luminous efficiency can be obtained. it can.

Hereinafter, embodiments of the present invention will be described in detail.
The description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not specified in these contents unless it exceeds the gist.

[Polymer for organic electroluminescence device]
The polymer for an organic electroluminescence device of the present invention (hereinafter sometimes referred to as “the polymer of the present invention”) has a structure represented by the following formula (I) (hereinafter referred to as “structure (I)”). Preferably, a structure represented by the following formula (II) (hereinafter sometimes referred to as “structure (II)”) or a structure represented by the formula (III) (hereinafter “structure (III)”) In some cases).

(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. R ¹ and R ² each independently represent a substituent.)

The reason why the polymer of the present invention usually emits white light and high efficiency is not clear, but it is fluorescent (singlet) even though the polymer of the present invention is a single compound. It is presumed that it is a compound that can emit light from both excited states of phosphorescence and phosphorescence (triplet). The polymer of the present invention has a steric hindrance between Ar ¹ and “the moiety bonded to the carbon between Ar ¹ and S”, and the steric hindrance between Ar ² and “the moiety bonded to the carbon between Ar ² and S”. From the steric hindrance between Ar ¹ and Ar ² , it is presumed that a unique three-dimensional structure is formed, and this unique three-dimensional structure can obtain fluorescence emission and phosphorescence emission.

The polymer of the present invention includes the structure (I), preferably the structure (II) or the structure (III) (which may include the structure (II) and the structure (III)). The polymer of the present invention is a polymer containing the structure (I), preferably the structure (II) or the structure (III) as a repeating unit. In this case, the polymer of the present invention may be a homopolymer comprising the structure (I), preferably the structure (II) or the structure (III), and the structure (I), preferably the structure (II) and / or Alternatively, it may be a copolymer containing the structure (III) and other repeating units.
In addition, when the polymer of the present invention is a copolymer, the structure (I), preferably the structure (II) and / or the structure (III) may be included, even if it is a random copolymer, It may be a block copolymer.

{Molecular weight}
The weight average molecular weight of the polymer of the present invention is usually 3,000 or more, preferably 4,000 or more, usually 400,000 or less, preferably 150,000 or less. This molecular weight is measured by the GPC method, and the measurement conditions are obtained by comparison with a calibration curve prepared with a polystyrene standard sample of known weight by gel permeation chromatography.
The number average molecular weight of the polymer of the present invention is usually 2,000 or more, preferably 3,000 or more, usually 300,000 or less, preferably 100,000 or less. This molecular weight is measured by the GPC method.

  In the case where the polymer of the present invention has the structure (I), preferably the structure (II) or the structure (III) (which may contain the structure (II) and the structure (III)) as a repeating unit. The number n of repeating units of these structures (I) to (III) in the polymer of the present invention is about 3 to 300.

{Formula (I)}
<Ar ¹ and Ar ² >
In formula (I), Ar ¹ and Ar ² are each independently an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent, preferably a substituent An aromatic hydrocarbon group which may have a group.

  The aromatic hydrocarbon group is preferably a 6-membered monocyclic ring or an aromatic hydrocarbon group derived from 2 to 5 condensed rings.

Examples thereof include groups derived from aromatic hydrocarbon rings such as benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, fluoranthene ring and the like.
A group formed by connecting a plurality of the above-described single rings or 2 to 5 condensed rings is also preferable. For example, a biphenyl group, a terphenyl group, etc. are mentioned.
Among these, a group derived from a benzene ring or a naphthalene ring or a group formed by linking a plurality of these groups (for example, a biphenylene group, a terphenylene group, etc.) is preferable.

  Examples of the aromatic heterocyclic group include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, and pyrrolo. Pyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyrazine ring, pyrimidine ring, triazine And a group derived from an aromatic heterocycle such as a 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 and an azulene ring.

Examples of the substituent that each of the aromatic hydrocarbon groups or aromatic heterocyclic groups of Ar ¹ and Ar ² may have include the substituents described in the following substituent group Q. As for these substituents, one type of substituent may be substituted independently per one aromatic hydrocarbon group or aromatic heterocyclic group, or two or more types of substituents may be combined in any combination and ratio. May be substituted.

(Substituent group Q)
An alkyl group which may have a substituent (preferably a linear or branched alkyl group having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, a 2-propyl group, an n-butyl group, an isobutyl group, a tert-butyl group, etc.).
A cycloalkyl group which may have a substituent (for example, an adamantyl group and the like);
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, an allyl 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 7 to 20 carbon atoms, such as a benzyl group);
An amino group which may have a substituent (preferably an amino group having one or more alkyl groups having 1 to 8 carbon atoms in the substituent, for example, a methylamino group, a dimethylamino group, a diethylamino group A dibenzylamino group, etc.);
An arylamino group which may have a substituent (for example, phenylamino group, diphenylamino group, ditolylamino group and the like);
A heteroarylamino group which may have a substituent (for example, pyridylamino group, thienylamino group, dithienylamino group and the like);
An acylamino group which may have a substituent (for example, acetylamino group, benzoylamino group and the like);
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 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- A naphthyloxy group, a pyridyloxy group, a 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 2 to 13 carbon atoms which may have a substituent, such as an acetoxy group);
A carboxy group;
A cyano group;
Hydroxyl group;
A thiol group;
An alkylthio group which may have a substituent (preferably an alkylthio group having 1 to 8 carbon atoms, such as a methylthio group and an ethylthio group);
An arylthio group which may have a substituent (preferably an arylthio group having 6 to 20 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);
An optionally substituted phosphino group (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. A group derived from aromatic hydrocarbons of
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 And groups derived from aromatic heterocyclic rings such as pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, sinoline ring, quinoxaline ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, and azulene ring.

  In addition, when the substituent listed in the above substituent group Q further has a substituent, the substituent includes a linear, branched, or cyclic alkyl group, an arylamino group, an aromatic hydrocarbon group, or An aromatic heterocyclic group etc. are mentioned, As the specific example, what was illustrated to the said substituent group Q is mentioned.

Of the substituent group Q, the substituent that the aromatic hydrocarbon group or aromatic heterocyclic group of Ar ¹ and Ar ² may have is preferably a linear, branched or cyclic alkyl group, An arylamino group, an aromatic hydrocarbon group, an aromatic heterocyclic group, etc. are mentioned, As a specific example, what was illustrated to the said substituent group Q is mentioned.

<R ¹ and R ² >
R ¹ and R ² each independently represent a substituent. Examples of the substituent include the groups described in the above-mentioned substituent group Q. In order to improve durability, solubility, film quality, and the like, an alkyl group, an arylamino group, a silyl group, and an aromatic hydrocarbon group are preferable. And aromatic heterocyclic groups.

<Formula (II)>
The polymer of the present invention is preferably a polymer having a structure represented by the following formula (II).

(In formula (II), R ^{3 to} R ⁵ each independently represents a substituent. A represents an integer of 0 to 4, b represents an integer of 0 to 5, and c represents an integer of 0 to 4. Ar ¹ , Ar ² , R ¹ and R ² have the same meanings as in formula (I).

^(R 3 ~R 5)
R ^{3 to} R ⁵ each independently represents a substituent. Examples of the substituent include the groups described in the above substituent group Q.
R ^{3 to} R ⁵ are preferably each independently an alkyl group which may have a substituent, a silyl group which may have a substituent, and an aromatic hydrocarbon group which may have a substituent. , An aromatic heterocyclic group which may have a substituent.

(A)
Although a represents the integer of 0-4, Preferably it is 0-2.

(B)
Although b represents the integer of 0-5, Preferably it is 0-2.

(C)
c represents an integer of 0 to 4, preferably 0 to 2.

When a is 2 or more, a plurality of R ³ may be the same or different. In addition, when a is 1, the substitution position of R ³ is preferably the meta position with respect to the position to which N is bonded, and when a is 2, the meta position and ortho are relative to the position to which N is bonded. It is preferable that when a is 3, it is preferably a 2-substitution position at the meta position and a 1-substitution position at the ortho position relative to the position where N is bonded.

Similarly, when b is 2 or more, a plurality of R ⁴ may be the same or different. In addition, when b is 1, the substitution position of R ⁴ is preferably the meta position or the para position with respect to the position to which N is bonded, and when b is 2, the substitution position is meta with respect to the position to which N is bonded. It is preferably a 2-substitution position selected from the position and the para-position. When b is 3, it is preferably a meta-position and a para-position with respect to the position to which N is bonded, and when b is 4, N Is preferably a 1-substitution position selected from a meta position, a para position and an ortho position with respect to the position at which is bonded.

Similarly, when c is 2 or more, a plurality of R ⁵ may be the same or different. In addition, when b is 1, the substitution position of R ⁵ is preferably the meta position with respect to the position to which N is bonded, and when c is 2, the meta position or ortho to the position to which N is bonded. It is preferable that when c is 3, it is preferably a 2-substitution position in the meta position and an ortho position with respect to the position to which N is bonded.

<Formula (III)>
The polymer of the present invention is preferably a polymer having a structure represented by the following formula (III).

(In formula (III), R ^{6 to} R ⁹ each independently represents a substituent. D and e each independently represent an integer of 0 to 4. Ar ¹ , Ar ² , R ¹ and R ² are Each having the same meaning as in formula (I).)

^(R 6 ~R 9)
R ^{6 to} R ⁹ each independently represents a substituent. Examples of the substituent include the groups described in the substituent group Q.
R ^{6 to} R ⁹ are preferably each independently an alkyl group which may have a substituent, a silyl group which may have a substituent, and an aromatic hydrocarbon group which may have a substituent. And an aromatic heterocyclic group which may have a substituent.

(D)
d represents an integer of 0 to 4, preferably 0 to 2.

(E)
Although e represents the integer of 0-4, Preferably it is 0-2.

<Other repeating units>
The polymer of the present invention has the structure (I), preferably the structure (II) or the structure (III) (which may contain the structure (II) and the structure (III)), and other repetitions. Units may be included. Examples of the other repeating unit that may be contained in the polymer of the present invention include the following structures.

(In the formula, Ar ^{31 to} Ar ⁵⁸ each independently represents an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Ar ⁶¹ to Ar ⁷⁴ represents an aromatic hydrocarbon group that may have a substituent or a group that includes an aromatic heterocyclic group that may have a substituent, and R ^{21 to} R ²⁴ each independently represents: Represents a hydrogen atom or a substituent.)

Specific examples of Ar ^{31 to} Ar ⁵⁸ include the monovalent aromatic hydrocarbon groups and aromatic heterocyclic groups exemplified in the substituent group Q, and the substituents that may be included are also substituents. This is the same as those exemplified as the substituent that the aromatic hydrocarbon group and aromatic heterocyclic group listed in Group Q may have.
Specific examples of Ar ^{61 to} Ar ⁷⁴ include the divalent aromatic hydrocarbon groups and aromatic heterocyclic groups exemplified in the substituent group Q, and the substituents that may be included are also substituents. This is the same as those exemplified as the substituent that the aromatic hydrocarbon group and aromatic heterocyclic group listed in Group Q may have.
Moreover, as a substituent of R < ²¹ > -R < ²⁴ >, the thing as described in the substituent group Q is mentioned each independently.

  When the polymer of the present invention contains a repeating unit other than the structure (I), preferably the structure (II) and / or the structure (III), the structure (I) according to the present invention, preferably the structure (II) In addition, in order to obtain the effects of the present invention by including the structure (III), the ratio of other repeating units in the total repeating units of the polymer of the present invention is 50 mol% or less, particularly 30 mol% or less. Preferably there is.

<Exemplary compound>
Specific examples of the structure (I), preferably the structures (II) and (III) are shown below, but the present invention is not limited thereto.

{Singlet and triplet excitation}
The polymer of the present invention is also characterized in that it emits white light by light emission from both singlet and triplet excited states.
As described above, the polymer that emits white light by emitting light from both singlet and triplet excited states may have the above formula structure (I), preferably structure (II) or structure (III) ( And a polymer containing the structure (II) and the structure (III).

{Usage}
Since the polymer of the present invention can emit white light, it can be used as a material for a light emitting layer of an organic electroluminescence device. Moreover, the polymer of this invention can improve the performance of an organic electroluminescent element by making it contain in layers other than a light emitting layer. For example, the polymer of the present invention can be used as a material for a hole transport layer, and can also be used as a material for an electron transport layer. Of course, you may use for another layer.

[Composition for organic electroluminescence device]
The composition for an organic electroluminescent device of the present invention contains the polymer of the present invention and a solvent, and usually forms an organic layer of the organic electroluminescent device of the present invention described later by a wet film forming method. Used when
Only 1 type of the polymer of this invention may be contained in the composition for organic electroluminescent elements of this invention, and 2 or more types may be contained.

<Solvent>
Examples of the solvent contained in the composition for an organic electroluminescence device of the present invention include aromatic hydrocarbons such as toluene, xylene, mesitylene, cyclohexylbenzene, and tetralin; halogenated aromatic carbonizations such as chlorobenzene, dichlorobenzene, and trichlorobenzene. Hydrogen; 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole, phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, 2,4-dimethylanisole, etc. Aromatic ethers; Aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate and n-butyl benzoate; ketones having an alicyclic ring such as cyclohexanone and cyclooctanone; methyl ethyl ketone and dibutyl ketone Aliphatic alcohols such as methyl ethyl ketone, cyclohexanol, cyclooctanol and other alicyclic alcohols; butanol, hexanol and other aliphatic alcohols; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate ( PGMEA) and the like; aliphatic esters such as ethyl acetate, n-butyl acetate, ethyl lactate, and n-butyl lactate. These solvents may be used alone or in combination of two or more.

<Other ingredients>
In the composition for organic electroluminescent elements of the present invention, in addition to the above-described solvents, various other solvents may be included as necessary. Examples of such other solvents include amides such as N, N-dimethylformamide and N, N-dimethylacetamide; dimethyl sulfoxide and the like.
Furthermore, in the composition for organic electroluminescent elements of the present invention, various additives such as a leveling agent and an antifoaming agent may be included.
Moreover, when forming the organic layer of the organic electroluminescent element of this invention mentioned later, the other compound contained in the said organic layer may be included.

<Composition>
The solid content concentration of the polymer of the present invention contained in the composition for organic electroluminescent elements of the present invention and components (for example, leveling agents) that can be added as necessary is usually 0.01% by weight or more, Preferably it is 0.05 weight% or more, More preferably, it is 0.1 weight% or more, More preferably, it is 0.5 weight% or more, Most preferably, it is 1 weight% or more. However, it is usually 80% by weight or less, preferably 50% by weight or less, more preferably 40% by weight or less, still more preferably 30% by weight or less, and most preferably 20% by weight or less. When the solid content concentration of the polymer of the present invention contained in the composition for organic electroluminescent elements is excessively low, it tends to be difficult to form a film having a predetermined thickness when forming the organic layer. . When the solid content concentration of the composition for organic electroluminescent elements is excessively high, it tends to be difficult to form a thin film.

[Organic electroluminescence device]
The organic electroluminescent element of the present invention has an anode and a cathode, and an organic layer between the anode and the cathode, and the above-described polymer of the present invention is contained in this organic layer.
As described above, since the polymer of the present invention can emit white light, it is suitably used as a material for the light emitting layer of the organic electroluminescent device. Other layers other than the light emitting layer, for example, a hole transport layer, an electron Although it is effective for improving the performance of the organic electroluminescence device by using it for the transport layer and other layers, in the organic electroluminescence device of the present invention, the organic layer containing the polymer of the present invention is a hole transport layer. Or a light emitting layer is preferable and a light emitting layer is more preferable.

In the organic electroluminescent element of the present invention, the organic layer containing the polymer of the present invention is usually formed by a vacuum deposition method or a wet film forming method as described later.
In this case, the composition used when forming the organic layer includes, for example, a composition containing the polymer of the present invention and another compound contained in the organic layer containing the polymer of the present invention, and the composition of the present invention. Examples include a composition containing a coalescence and a solvent. For the formation of the organic layer by a wet film-forming method, the above-described composition for an organic electroluminescence device of the present invention is preferably used.

Hereinafter, the structure of the organic electroluminescent element of the present invention will be described with reference to the drawings. The drawings to be used are for explaining an example of the embodiment of the present invention and do not represent the actual size.
1 and 2 are schematic cross-sectional views showing an example of an organic electroluminescent element to which the exemplary embodiment is applied.
As shown in FIG. 1, the organic electroluminescent element 10 includes a substrate 1 as a support, an anode 2, a hole transport layer 4, a light emitting layer 5, a hole blocking layer 6, and a cathode that are sequentially stacked on the substrate 1. 8.
As shown in FIG. 2, the organic electroluminescent element 20 includes a substrate 1 as a support, an anode 2, a hole injection layer 3, a hole transport layer 4, and a light emitting layer 5 that are sequentially stacked on the substrate 1. , A hole blocking layer 6, an electron transport layer 7, and a cathode 8.

  First, the components of the organic electroluminescent element 10 shown in FIG. 1 will be described.

<Board>
The substrate 1 serves as a support for the organic electroluminescent element. Examples of the material of the substrate 1 include quartz and glass plates, metal plates and metal foils, and transparent plastic films and sheets. In particular, glass plates, plastic films and sheets are preferred. Here, examples of the synthetic resin used for the plastic film include a polyester resin, a polymethacrylate resin, a polycarbonate resin, and a polysulfone resin.
When a plastic film or sheet is used, a dense silicon oxide film or the like may be provided on at least one surface to ensure gas barrier properties.

<Anode>
The anode 2 provided on the substrate 1 plays a role of hole injection into the hole transport layer 4. The anode 2 is made of a conductive material. Examples of such conductive materials usually include metals such as aluminum, gold, silver, nickel, palladium, and platinum; metal oxides such as oxides of indium and / or tin; metal halides such as copper iodide; carbon Black; Examples thereof include conductive polymers such as poly (3-methylthiophene), polypyrrole, and polyaniline.

As a method for forming the anode 2, a sputtering method, a vacuum deposition method, or the like is usually used. In addition, when using metal fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, these are dispersed in an appropriate binder resin solution. The anode 2 can also be formed by coating on the substrate 1.
Further, when a conductive polymer is used, 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 (for example, Appl.Phys.Lett., 60, 2711, 1992). The anode 2 can be formed by stacking different materials.

The thickness of the anode 2 is appropriately selected depending on the required transparency and is not particularly limited. For example, when transparency is required, it is desirable that the visible light transmittance be 60% or more, preferably 80% or more, and therefore the thickness of the anode 2 is usually 5 nm to 1,000 nm. The thickness is preferably about 10 nm to 500 nm.
In addition, when transparency is not required, the thickness of the anode 2 may be the same as that of the substrate 1. Furthermore, other different conductive materials can be laminated on the anode 2.

<Hole transport layer>
As a material (hole transport material) constituting the hole transport layer 4 provided on the anode 2, the hole injection efficiency from the anode 2 is high and the injected holes can be efficiently transported. It must be a material that can be made. For this purpose, the ionization potential is small, the transparency to visible light is high, the hole mobility is high, the stability is high, and impurities that become traps are less likely to be generated during manufacturing and use. Required.
Further, in order to contact the light emitting layer 5, it is required 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. Furthermore, in addition to such general requirements, for example, when considering uses such as in-vehicle display, the element is required to have further heat resistance. Accordingly, a material having a glass transition temperature (Tg) of 85 ° C. or higher is desirable.

  Examples of such a hole transport material include two or more tertiary amines represented by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl, and two or more A starburst structure such as an aromatic diamine in which a condensed aromatic ring is substituted with a nitrogen atom (for example, JP-A No. 5-234681); 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine Aromatic amine compounds having a tetramer of triphenylamine (e.g. Chem. Commun., 2175, 1996) having aromatic amine compounds (e.g. J. Lumin., 72-74, 985, 1997); Years); spiro compounds such as 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene (Synth. Metals) 91, 209, 1997), poly (3,4-ethylenedioxythiophene) (PEDOT), poly (3-hexylthiophene), etc. These compounds may be used alone, You may mix and use each as needed.

  As the hole transport material, the polymer of the present invention may be used. Further, for example, polyvinyl carbazole, polyvinyl triphenylamine (for example, JP-A-7-53953), polyarylene ether sulfone containing tetraphenylbenzidine (for example, Polym. Adv. Tech., 7, page 33, (1996) may be used.

The hole transport layer 4 can be formed by a wet film formation method or a vacuum deposition method. For example, in the case of a wet film-forming method, one or two or more hole transport materials and, if necessary, additives such as binder resins and coating property improvers that do not trap holes are dissolved in a solvent to form a coating solution. Is applied onto the anode 2 by a method such as spin coating, and dried to form the hole transport layer 4. At this time, when a compound having a crosslinking group is used, it is formed by crosslinking with light or heat after application.
Examples of the binder resin include polycarbonate resin, polyarylate resin, and polyester resin. In addition, the addition amount of the binder resin is usually preferably 50% by weight or less in terms of the content in the hole transport layer 4. When the amount of the binder resin added is excessively large, the hole mobility tends to be lowered.

When the hole transport layer 4 is formed by vacuum deposition, the hole transport material is put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is exhausted to about 10 ⁻⁴ Pa with an appropriate vacuum pump. The crucible is heated to evaporate the hole transport material, and the hole transport layer 4 is formed on the substrate 1 on which the anode 2 is formed, which is placed facing the crucible. The thickness of the hole transport layer 4 is usually 5 nm to 300 nm, preferably 10 nm to 100 nm.

<Light emitting layer>
The light emitting layer 5 provided on the hole transport layer 4 usually preferably contains the above-described polymer of the present invention. The light-emitting layer 5 is formed by reusing holes injected from the anode 2 to move through the hole transport layer 4 and electrons injected from the cathode 8 and moved through the hole blocking layer 6 between electrodes to which an electric field is applied. Excited by the bond, it emits strong light.
The light emitting layer 5 is preferably formed by a wet film forming method using the above-described composition for organic electroluminescent elements of the present invention.
The thickness of the light emitting layer 5 is usually 10 nm or more, preferably 20 nm or more. However, it is usually 200 nm or less, preferably 100 nm or less.

<Hole blocking layer>
The hole blocking layer 6 laminated on the light emitting layer 5 has a role of blocking holes moving from the hole transport layer 4 from reaching the cathode 8 and an efficiency of electrons injected from the cathode 8. It is formed from a compound that can be transported in the direction of the light emitting layer 5 well. The physical properties required for the material constituting the hole blocking layer 6 are required to have high electron mobility and low hole mobility. The hole blocking layer 6 has a function of confining holes and electrons in the light emitting layer 5 and improving luminous efficiency.
Examples of the material constituting the hole blocking layer 6 include an aluminum hydroxyquinoline complex, a triazole compound, a phenanthroline compound, and a pyridine compound. The thickness of the hole blocking layer 6 is usually 0.3 nm to 100 nm, preferably 0.5 nm to 50 nm. The hole blocking layer 6 can be formed by the same method as the hole transport layer 4 described above, and a vacuum deposition method is usually used.

<Cathode 8>
The cathode 8 serves to inject electrons into the light emitting layer 5 through the hole blocking layer 6. The material used for the cathode 8 can be the material used for the anode 2 described above. For efficient electron injection, a metal having a low work function is preferable. For example, a metal such as tin, magnesium, indium, calcium, aluminum, silver, or an alloy thereof is used.
Specific examples of the alloy used as the cathode 8 include a low work function alloy electrode such as a magnesium-silver alloy, a magnesium-indium alloy, and an aluminum-lithium alloy.
The thickness of the cathode 8 is usually in the same range as the thickness of the anode 2 described above.

<Hole injection layer>
The organic electroluminescent element 20 in FIG. 2 is provided with a hole injection layer 3 between the anode 2 and the hole transport layer 4 in the organic electroluminescent element in FIG. The hole injection layer 3 is provided between the hole transport layer 4 and the anode 2 in order to further improve the efficiency of hole injection and improve the adhesion of the whole organic layer to the anode 2.
By inserting the hole injection layer 3, the driving voltage of the initial element is lowered, and at the same time, an increase in voltage when the element is continuously driven with a constant current is suppressed. Conditions required for the material used for the hole injection layer 3 include that the contact with the anode 2 is good and a uniform thin film can be formed, and that the material is thermally stable, that is, the melting point and the glass transition temperature are high. The melting point is required to be 300 ° C. or higher, and the glass transition temperature is required to be 100 ° C. or higher. Furthermore, the ionization potential is low, hole injection from the anode 2 is easy, and the hole mobility is high.

  Examples of materials satisfying such conditions include phthalocyanine compounds such as copper phthalocyanine (Japanese Patent Laid-Open No. 63-295695), polyaniline (Appl. Phys. Lett., 64, 1245, 1994), polythiophene ( Organic Materials, Vol. 9, 125, 1998), etc .; sputtered carbon films (Synth. Met., 91, 73, 1997), vanadium oxide, ruthenium oxide, molybdenum oxide, etc. Metal oxides (J. Phys. D, 29, 2750, 1996) have been reported. Moreover, hole injection can be facilitated by doping an aromatic diamine-containing polyether with an electron-accepting group such as 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ). .

A hole transporting polymer can also be used as the hole injection layer 3. When a hole transporting polymer is used, the hole injection layer 3 preferably further contains an electron accepting compound.
Examples of such hole transporting polymers include aromatic amine compounds, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, and the like. Of these, aromatic amine compounds are preferred from the viewpoints of amorphousness, solubility in solvents, and visible light transmittance.
Further, among aromatic amine compounds, aromatic tertiary amine compounds are particularly preferable. In addition, the aromatic tertiary amine compound here 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, and among them, a polymer compound having a weight average molecular weight of 1,000 or more and 1,000,000 or less is more preferable from the viewpoint of the surface smoothing effect.
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 ^a and Ar ^b each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. Ar ^{c to} Ar ^e each independently represents a divalent aromatic hydrocarbon group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent. X represents a linking group selected from the following linking group group Z.)

(Linking group Z)

(In the formula, Ar ^{11 to} Ar ²⁸ each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. R ¹¹ and R ¹² each independently represent Represents a hydrogen atom or an arbitrary substituent.

  Examples of the aromatic hydrocarbon group include a group derived from a 5- or 6-membered monocyclic ring or a 2-5 condensed ring. Specific examples thereof include groups derived from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, fluorene ring and the like. It is done.

  Examples of the aromatic heterocyclic group include a group derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples thereof include 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, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline And a group derived from a ring, a cinnoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, an azulene ring, and the like.

In addition, as Ar ^{c to} Ar ^e , Ar ^{11 to} Ar ¹⁵ , Ar ^{17 to} Ar ²⁰ , Ar ^{22 to} Ar ²⁵ , Ar ²⁷ , Ar ²⁸ , one type or two or more types of aromatic hydrocarbon groups exemplified above are used. And / or two or more divalent groups derived from an aromatic heterocyclic group may be used in combination.

The molecular weight of the hole transporting polymer used as the material of the hole injection layer 3 is appropriately selected and is not particularly limited, but is usually 1,000 or more, preferably 2,000 or more, and more preferably 3,000. That's it. However, the weight average molecular weight is usually 500,000 or less, preferably 200,000 or less, more preferably 100,000 or less.
The ratio of the hole transporting polymer in the hole injection layer 3 is appropriately selected and is not particularly limited, but is usually 10% by weight or more, preferably 30% by weight or more in terms of the weight ratio with respect to the whole hole injection layer 3. is there. However, it is usually 99.9% by weight or less, preferably 99% by weight or less. In addition, when using 2 or more types of polymers together, it is preferable that these total content is contained in said range.

The type of the electron-accepting compound used as the material for the hole injection layer 3 is appropriately selected and is not particularly limited. For example, 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pentafluorophenyl) borate, triphenylsulfonium tetra An onium salt substituted with an organic group such as fluoroborate; an inorganic compound having a high valence such as iron (III) chloride (Japanese Patent Laid-Open No. 11-251067), ammonium peroxodisulfate; a cyano compound such as tetracyanoethylene; Aromatic boron compounds such as Pendafluorophenyl) borane (Japanese Patent Laid-Open No. 2003-31365); fullerene derivatives; iodine and the like.
Among these compounds, an onium salt substituted with an organic group is preferable in terms of having strong oxidizing power, and an inorganic compound having a high valence is preferable, and an onium salt substituted with an organic group in terms of being soluble in various solvents, A cyano compound and an aromatic boron compound are preferable.

In the case of the hole injection layer 3, a thin film can be formed by the same method as that for the hole transport layer 4. Further, when an inorganic material is used, a sputtering method, an electron beam evaporation method, or a plasma CVD method is further used.
The thickness of the hole injection layer 3 formed as described above is usually 3 nm to 100 nm, preferably 5 nm to 50 nm.

<Electron transport layer>
The organic electroluminescent element 20 of FIG. 2 is further provided with an electron transport layer 7 between the hole blocking layer 6 and the cathode 8 in the organic electroluminescent element of FIG. The electron transport layer 7 is provided between the hole blocking layer 6 and the cathode 8 in order to further improve the light emission efficiency of an element in which a metal such as aluminum, silver, copper, nickel, chromium, gold, or platinum is used. .
The electron transport layer 7 is formed of a compound that can efficiently transport electrons injected from the cathode 8 between electrodes to which an electric field is applied in the direction of the hole blocking layer 6. The electron transporting compound used for the electron transporting layer 7 is a compound that has high electron injection efficiency from the cathode 8 and that can efficiently transport injected electrons with high electron mobility. is necessary.

As a material satisfying such conditions as an electron transporting compound, for example, a metal complex such as an aluminum complex of 8-hydroxyquinoline (Japanese Patent Laid-Open No. 59-194393), a metal complex of 10-hydroxybenzo [h] quinoline Oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3- or 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), Quinoxaline compounds (JP-A-6-207169), phenanthroline derivatives (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous Silicon carbide, n-type zinc sulfide, n-type selenide Lead etc. are mentioned. Electron transport with enhanced electron transport capability by doping alkali metals into phenanthroline derivatives and metal complexes, or by doping organic substances with high electron transport properties such as oxadiazole derivatives, quinoxaline compounds, and phenanthroline derivatives. Layer 7 can also be formed.
The thickness of the electron transport layer 7 is usually 5 nm to 200 nm, preferably 10 nm to 100 nm.

  1 and 2 show an example of an organic electroluminescent element to which the present embodiment is applied. The organic electroluminescent element of the present invention is not limited to the layer structure shown in FIGS. Further, any other layer may be inserted as necessary, and any layer may be omitted as long as the effects of the present invention are not impaired.

For example, it is also possible to insert a very thin insulating film (thickness of about 0.1 to 5 nm) such as LiF, MgF ₂ , or Li ₂ O at the interface between the cathode 8 and the light emitting layer 5 or the electron transport layer 7. (For example, Appl. Phys. Lett., 70, 152, 1997; Japanese Patent Laid-Open No. 10-74586; IEEE Trans. Electron. Devices, 44, 1245, 1997) .
Further, by laminating a metal layer having a high work function and stable to the atmosphere on the cathode 8, the cathode 8 made of a low work function metal can be protected and the stability of the device can be increased.

1 and 2, the structure opposite to that of the organic electroluminescent elements 10 and 20, that is, for example, a cathode 8, an electron transport layer 7, a hole blocking layer 6, a light emitting layer 5 on the substrate 1, It is also possible to laminate the hole transport layer 4, the hole injection layer 3, and the anode 2 in this order. Further, as described above, an organic electroluminescent element can be provided between two substrates, at least one of which is highly transparent.
The organic electroluminescent element of the present invention can be applied to any of a single element, an element having a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an XY matrix.

[Organic EL display]
The organic EL display of the present invention uses the above-described organic electroluminescent element of the present invention.
The organic EL display to which the present embodiment is applied has at least a transparent support substrate and an organic electroluminescent element laminated on the transparent support substrate, and the organic electroluminescent element of the present invention described above is used as the organic electroluminescent element. By using an organic electroluminescent device comprising an organic layer formed using a polymer for polymer or a composition for organic electroluminescent device, for example, “Organic EL Display” (Ohm, August 20, 2004) , Shizushi Tokito, Chiba Adachi, and Hideyuki Murata), an organic EL display can be formed.

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

<Synthesis Example 1: Synthesis of raw material compound>
(1) Synthesis of 2,3,7,8-tetrabromo-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene

  Dissolve 4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene (1) (1.00 g, 2.79 mmol) in dry dimethylformamide (DMF) (3 mL) in a one-necked eggplant flask. Bromine (2.23 g, 13.9 mmol) was added, and the mixture was stirred at 60 ° C. for 18 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 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 solvent, and 2,3,7,8-tetrabromo-4,5-dihexylbenzo [1,2-b: 4,3-b was obtained as a pale yellow solid. '] Dithiophene (2) (1.57 g, 84% yield) was obtained.

mp: 56-58 ° C
¹ H NMR (CDCl ₃ ): 0.88-0.93 (m, 6H), 1.31-1.39 (m, 8H), 1.41-1.51 (m, 4H),
1.59-1.70 (m, 4H), 2.83-2.89 (m, 4H)
¹³ C NMR (CDCl ₃ ): 14.1, 22.6, 29.5, 29.7, 31.3, 31.5, 109.5, 116.3, 129.3,
130.8,141.1
_{Anal.Calcd.FOR C 22 H 26 Br 4 S} 2: C = 39.19, H = 3.89
Found: C = 39.09, H = 4.07

(2) Synthesis of 3,8-dibromo-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene

  2,3,7,8-Tetrabromo-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene (2) (0.50 g, 0.74 mmol) was dried in dry tetrahydrofuran (THF) ) (7 mL), and n-BuLi (1.5 mmol, 1.1 mL of 1.39 M hexane solution) was added dropwise at −78 ° C. under an argon atmosphere. This was stirred at -78 ° C for 30 minutes. After completion of the reaction, water was 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. The mixture was purified by silica gel chromatography using hexane as a developing solvent, and 3,8-dibromo-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene ( 3) (0.30 g, yield 78%) was obtained.

mp: 56-58 ° C
¹ H NMR (CDCl ₃ ): 0.91 (t, J = 7.1 Hz, 6H), 1.31-1.38 (m, 8H), 1.44-1.53 (m, 4H),
1.63-1.74 (m, 4H), 2.96 (t, J = 7.8Hz, 4H), 7.26 (s, 2H)

(3) Synthesis of 3,8-diphenyl-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene

  Toluene (8 mL) and distilled water (2 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.41 g) was added, and the solvent was degassed at 90 ° C. for 2 hours under an argon atmosphere. After cooling to room temperature, 3,8-dibromo-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene (3) (0.50 g, 0.97 mmol), phenylboronic acid (4 ) (0.47 g, 3.87 mmol) and tetrakis (triphenylphosphine) palladium (0) (68 mg, 0.058 mmol) were added, and the mixture was stirred at 80 ° 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% dilute 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 as a developing solvent, and 3,8-diphenyl-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene (5 ) (0.45 g, yield 90%).

¹ H NMR (CDCl ₃ ): 0.88 (t, J = 6.9 Hz, 3H), 0.94 (t, J = 6.9 Hz, 3H), 1.36-1.46 (m, 8H),
1.52-1.59 (m, 4H), 1.77-1.84 (m, 4H), 3.04 (t, J = 8.2Hz, 4H),
6.89-6.92 (m, 6H), 6.92-6.96 (m, 4H), 7.12 (s, 2H)
¹³ C NMR (CDCl ₃ ): 14.1, 22.7, 29.8, 29.9, 31.6, 31.9, 124.1, 126.0, 127.8,
127.9,130.3,130.8,139.1,140.5,141.7;
Anal.Calcd.FOR C ₃₄ H ₃₈ Br ₄ S ₂ : C = 79.95, H = 7.50
Found: C = 80.16, H = 7.63

(4) Synthesis of 2,7-bis [tributyltin] -3,8-diphenyl-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene

  3,8-diphenyl-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene (5) (0.10 g, 0.20 mmol) was dissolved in dry THF (15 mL) in a single-necked eggplant flask, Under an argon atmosphere, n-BuLi (0.49 mmol, 0.32 ml of 1.5 M hexane solution) was added dropwise at −10 ° C. After stirring this at -10 ° C for 1 hour, tributyltin chloride (IV) was added dropwise and stirred at -10 ° C for 1 hour. After completion of the reaction, the mixture was filtered through silica gel to remove inorganic salts and concentrated. This is dried and 2,7-bis [tributyltin] -3,8-diphenyl-4,5-dihexylbenzo [1,2-b: 4,3-b´] dithiophene (6) is used as a pale yellow liquid. Obtained. This product was used in the next reaction without further purification.

(5) Synthesis of N- (4-bromo-2,5-dimethylphenyl) amino-4-hexylbenzene

Toluene (8 mL) was placed in a one-necked eggplant flask, and the solvent was degassed at 120 ^° C. for 2 hours. After cooling to room temperature, tris (dibenzylideneacetone) dipalladium (0) (65 mg, 0.07 mmol), 1,1′-bis (diphenylphosphino) ferrocene (66 mg, 0.12 mmol) and 2,5-dibromo- p-Xylene (8) (1.5 g, 5.7 mmol) was added, and the mixture was stirred at room temperature for 10 minutes under an argon atmosphere. Then, NaO-t-Bu (0.57 g, 5.9 mmol) and 4-hexylaniline (7) (0.46 ml, 2.4 mmol) were added and stirred at 90 ° C. for 24 hours. After completion of the reaction, water was added to separate the organic layer, 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: ethyl acetate (20: 1) as a developing solvent, and N- (4-bromo-2,5-dimethylphenyl) amino-4-hexylbenzene as a wine red liquid. (9) (0.71 g, yield 83%) was obtained.

¹ H NMR (CDCl ₃ ): 0.89 (t, J = 6.9 Hz, 3H), 1.26-1.37 (m, 6H), 1.55-1.64 (m, 2H),
2.18 (s, 3H), 2.28 (s, 3H), 2.55 (t, J = 7.9Hz, 2H), 5.21 (s, 1H),
6.90 (d, J = 8.4Hz, 2H), 7.03 (s, 1H), 7.09 (d, J = 8.4Hz, 2H),
7.30 (s, 1H)

(6) Synthesis of N, N-bis (4-bromo-2,5-dimethylphenyl) amino-4-hexylbenzene

  Toluene (5 mL) was placed in a one-necked eggplant flask, and the solvent was deaerated at 120 ° C. for 2 hours. After cooling to room temperature, tris (dibenzylideneacetone) dipalladium (0) (54 mg, 0.06 mmol), 1,1′-bis (diphenylphosphino) ferrocene (55 mg, 0.10 mmol) and 2,5-dibromo- p-Xylene (8) (2.1 g, 7.9 mmol) was added, and the mixture was stirred at room temperature for 10 minutes under an argon atmosphere. Thereafter, NaO-t-Bu (0.38 g, 3.9 mmol) and N- (4-bromo-2,5-dimethylphenyl) amino-4-hexylbenzene (9) (0.71 g, 2.0 mmol) were added, and 90 ° C was added. For 24 hours. After completion of the reaction, water was added to separate the organic layer, 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 solvent, and N, N-bis (4-bromo-2,5-dimethylphenyl) amino-4-hexylbenzene (10) (0.25 g) was obtained as a colorless liquid. Yield 23%).

¹ H NMR (CDCl ₃ ): 0.85-0.90 (m, 3H), 1.27-1.34 (m, 6H), 1.55-1.63 (m, 2H),
1.89 (s, 6H), 2.25 (s, 6H), 2.52 (t, J = 7.5Hz, 2H),
6.58 (d, J = 8.4Hz, 2H), 6.76 (s, 2H), 6.96 (d, J = 8.4Hz, 2H),
7.33 (s, 2H)

<Synthesis Example 2: Synthesis of a polymer composed of a repeating unit represented by the formula (II-A)>

  Dry toluene (1.5 mL) was placed in a one-necked eggplant flask, and the solvent was degassed at 120 ° C. for 2 hours under an argon atmosphere. Thereafter, the mixture was cooled to room temperature, and N, N-bis (4-bromo-2,5-dimethylphenyl) amino-4-hexylbenzene (10) (0.10 g, 0.19 mmol) synthesized in (6) of Synthesis Example 1 was used. 2,7-bistributyltin-3,6-diphenyl-4,5-dihexylbenzo [1,2-b: 4,3-b ′] dithiophene (6) (0.20 mmol) and tetrakis synthesized in (4) (Triphenylphosphine) palladium (0) (13 mg, 0.011 mmol) and copper (II) oxide (33 mg, 0.41 mmol) were added, and the mixture was stirred at 120 ° C. for 20 hours under an argon atmosphere. After completion of the reaction, the reaction solution was cooled to room temperature, chloroform and dilute hydrochloric acid were added, the organic layer was neutralized with sodium bicarbonate water, and sodium sulfate was added. The solution was passed through a short silica gel chromatography and concentrated. A small amount of chloroform was added thereto, and it was added dropwise to a solution of methanol: ethanol: acetone (230: 115: 60 mL). Suction filtration was performed, and the solid was collected by washing with ethanol and acetone and dried to obtain a pale yellow solid copolymer in a yield of 63% (0.11 g, 0.12 mmol). Further, the solid was dissolved in chloroform (150 mL), a metal remover (Deloxan MP (manufactured by Wako Chemical)) (0.5 g) was added, and the mixture was stirred at 70 ° C. for 1 day. Suction filtration was performed again, and after concentration, a small amount of chloroform was added, and this was added dropwise to a solution of methanol: ethanol: acetone (100: 200: 100 mL). Suction filtration was performed again, and the solid was recovered by washing with ethanol and acetone and dried to obtain a very light yellow solid copolymer. The molecular weight and the degree of polymerization of this copolymer examined by the following GPC measurement apparatus and measurement conditions are as follows.

<GPC measurement equipment and measurement conditions>
-HPLC apparatus name: JASCO Corporation pump: PU-980
UV detector: PU-970 (detection wavelength: 254 nm)
Column oven: CO-1565
Degasser: DG-1580-53
・ GPC column name: Tosoh TSKgel MultiporeHXL-M
(Column inner diameter: 7.8 mm, column length: 300 mm x 2)
・ GPC solvent: THF
・ Measurement temperature: 40 ℃
・ Analysis software name: Borwin

Weight average molecular weight: 8100
Number average molecular weight: 4000
Degree of polymerization: 4.48

<Synthesis Example 3: Synthesis of a polymer composed of repeating units represented by the formula (III-A)>

Toluene (2 mL) and distilled water (1 mL) were placed in a one-necked eggplant flask, sodium carbonate (0.21 g) was added, and the solvent was degassed at 90 ^° C. for 2 hours under an argon atmosphere. Thereafter, the mixture was cooled to room temperature and 2,7-bistributyltin-3,8-diphenyl-4,5-dihexylbenzo [1,2-b: 4,3-b ′] synthesized in (4) of Synthesis Example 1 was used. Dithiophene (6) (0.16 mmol), 2,2-bis [4- (4,4,5,5-tetramethyl-1,3,5,-) synthesized by the method described in JP-A-2004-224766 Dioxaborolan-4-yl) phenyl] propane (72 mg, 0.16 mmol) and tetrakis (triphenylphosphine) palladium (0) (11 mg, 0.01 mmol) were added, and the mixture was stirred at 90 ^° C. for 7 days under an argon atmosphere. After completion of the reaction, the reaction solution was cooled to room temperature, chloroform and dilute hydrochloric acid were added, the organic layer was neutralized with sodium bicarbonate water, and sodium sulfate was added. The solution was passed through a short silica gel chromatography, concentrated, and low molecular weight by-products were removed using gel permeation chromatography. The solution was concentrated and dissolved in chloroform (150 mL), a metal removing agent (0.5 g) was added, and the mixture was stirred at 70 ° C. for 1 day. After suction filtration and concentration, a small amount of chloroform was added, and this was added dropwise to a solution of methanol: ethanol (250: 50 mL). The solution was suction filtered again, washed with ethanol, and the dried solid was once again dissolved in a small amount of chloroform and added dropwise to a solution of methanol: ethanol: acetone (100: 100: 100 mL). Suction filtration was performed again, and the solid was recovered by washing with ethanol and acetone and dried to obtain a very light yellow solid copolymer. The molecular weight and degree of polymerization of this copolymer examined by the same GPC measurement apparatus and measurement conditions as in Synthesis Example 2 are as follows.

Weight average molecular weight: 20000
Number average molecular weight: 11000
Degree of polymerization: 16

<Example 1>
The UV absorption and PL spectrum of the polymer (hereinafter referred to as “copolymer P-BPTx”) composed of the repeating unit represented by the formula (II-A) obtained in Synthesis Example 2 was measured with the following measuring apparatus and measurement conditions. It was measured. UV absorption and PL spectra were measured on both solution and film.
Method for preparing measurement solution: Copolymer P-BPTx was dissolved in toluene to prepare a solution having a concentration of 1 × 10 ⁻⁵ mol / L.
Film production method: The copolymer P-BPTx was dissolved in toluene at a concentration of 1.5% by weight, and the glass substrate (Clinical Test Ware, manufactured by Iwaki Glass Co., Ltd. Code: 2918, Cover24-40) by spin coating (1800 rpm, 60 s). , Thickness: 0.13-0.16 mm).

<UV absorption measuring device and measurement conditions>
・ UV device: Model name V-530 (manufactured by JASCO)
・ UV measurement conditions:
(solution)
Band width: 2.0nm
Response: Medium
Measurement range: 550-300nm
Data capture interval: 1nm
Scanning speed: 100nm / min
(the film)
Band width: 2.0nm
Response: Medium
Measurement range: 550-300nm
Data capture interval: 1nm
Scanning speed: 100nm / min

<PL spectrum measurement device and measurement conditions>
・ PL equipment: Model name FP-6200 (manufactured by JASCO)
・ PL measurement conditions:
(solution)
Measurement mode: Fluorescence spectrum Excitation side bandwidth: 5nm
Fluorescent side bandwidth: 5nm
Response: Medium
Sensitivity: Medium
Measurement range: 300-650nm
Data capture interval: 1nm
Excitation wavelength: 339.0nm
Scanning speed: 125nm / min
(the film)
Measurement mode: Fluorescence spectrum Excitation side bandwidth: 5nm
Fluorescent side bandwidth: 5nm
Response: Medium
Sensitivity: low
Measurement range: 350-600nm
Data capture interval: 1nm
Excitation wavelength: 320.0 nm
Scanning speed: 125nm / min

The measurement results are shown in FIG. Both the solution and the film exhibited similar UV and PL behavior. In PL, a light emission maximum was observed around a wavelength of 450 nm. From the tangent of the UV curve of the film, it was estimated that Eg = 3.25 eV (382 nm).
In addition, only fluorescence was observed in both the solution and the film.
Using the T1 level calculation formula described in Phys. Rev. Lett. 2001, 86, 1358 (T1 = (1.13 × S1-1.43) ± 0.25 (eV)), triplet energy band gap Was calculated. Since S1 = 3.25 eV from the above Eg value, it was found that T1 was 2.24 ± 0.25 (eV).
From this, if phosphorescence was observed, it was estimated that the emission maximum was observed at a wavelength of 545 to 560 nm.

<Example 2>
A glass substrate with an ITO (indium tin oxide) transparent electrode was washed in isopropyl alcohol and subjected to UV ozone treatment for 60 minutes. On the substrate, PEDOT: PSS was applied by spin coating (3000 rpm, 180 seconds), and annealed at 130 ° C. for 10 minutes to form a 40 nm-thick hole transport layer. Next, a 1.5 wt% toluene solution of the copolymer P-BPTx was applied onto the hole transport layer by spin coating (1800 rpm, 60 s) and annealed at 130 ° C. for 10 minutes to form a light emitting layer. Further, Ca (30 nm) and Al (120 nm) were sequentially laminated by a vacuum deposition method, and an organic electroluminescent element sample 1 was produced.
For the obtained sample, an IV plot (current value with respect to voltage), an IL plot (luminance with respect to voltage), and an EL spectrum with respect to voltage were measured in the atmosphere. The results are shown in FIGS.
White light emission was obtained. Light emission was observed near a wavelength of 560 nm under a low voltage, light emission at a wavelength of 560 nm disappeared under a high voltage, and fluorescence at a wavelength of 450 nm was observed. From the above calculation, light emission at a wavelength of 560 nm was attributed to phosphorescence.

<Example 3>
In Example 2, a device was prepared and measured in the same manner as in Example 2 except that the toluene solution of copolymer P-BPTx was changed to a 10 mg / mL chloroform solution of copolymer P-BPTx. The results are shown in FIG.
White light emission was obtained, fluorescence having a wavelength of 450 nm was observed, and phosphorescence was observed at a wavelength of 560 nm.

<Example 4>
A device was prepared and measured in the same manner as in Example 2 except that 10% by weight of the toluene solution of the copolymer P-BPTx was changed to a 10 mg / mL chloroform solution of PBD shown below.

The results are shown in FIGS.
Fluorescence was observed at a wavelength of 450 nm and phosphorescence was observed at a wavelength of 560 nm. In this case, the emission peak at 450 nm gave a main emission peak.

<Example 5>
A device was prepared and measured in the same manner as in Example 2 except that 30% by weight of the toluene solution of the copolymer P-BPTx was changed to a 10 mg / mL chloroform solution of polymethyl methacrylate (PMMA).
The results are shown in FIGS.
Only a peak at a wavelength of 560 nm was observed.

<Example 6>
Example 1 except that instead of the copolymer P-BPTx, a polymer comprising a repeating unit represented by the formula (III-A) obtained in Synthesis Example 3 (hereinafter referred to as “copolymer P-BPBP”) was used. The emission spectrum of P-BPBP was measured in the same manner as described above. The results are shown in FIG.
The light emission behavior was measured by changing the temperature from 5K to 280K.

From the UV spectrum, Eg = S1 = 3.17 eV and T1 = 2.12 eV was calculated.
White light emission was obtained, and from the emission spectrum, light emission with a wavelength of 585 nm and light emission with a wavelength of 420 to 430 nm corresponding to 2.12 eV were observed at low temperature, and light emission with a wavelength of 585 nm disappeared with increasing temperature. From this, it was concluded that the light emission at a wavelength of 585 nm was phosphorescent similarly to the copolymer P-BPTx.

It is typical sectional drawing which shows an example of the organic electroluminescent element to which this Embodiment is applied. It is typical sectional drawing which shows the other example of the organic electroluminescent element to which this Embodiment is applied. 2 is a chart showing measurement results of UV absorption and PL spectrum of copolymer P-BPTx in Example 1. FIG. It is a chart which shows the measurement result of the IV plot of the element formed from the toluene solution and chloroform solution of copolymer P-BPTx in Example 2, 3. 6 is a chart showing measurement results of EL spectrum with respect to voltage of a toluene solution of a copolymer P-BPTx in Example 2. FIG. It is a chart which shows the measurement result of the IV plot of the copolymer P-BPTx / PBD solution in Example 4, and IL plot. 6 is a chart showing measurement results of EL spectrum with respect to voltage of a copolymer P-BPTx / PBD solution in Example 4. 6 is a chart showing measurement results of IV plot and IL plot of a copolymer P-BPTx / PMMA solution in Example 5. FIG. 6 is a chart showing measurement results of EL spectrum with respect to voltage of a copolymer P-BPTx / PMMA solution in Example 5. FIG. 7 is a chart showing an emission spectrum of copolymer P-BPBP in Example 6. FIG.

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 Cathode 10,20 Copolymer

Claims (5)

The polymer for organic electroluminescent elements containing the structure represented by following formula (I), Comprising: The polymer for organic electroluminescent elements containing the structure represented by following formula (II).

(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. R ¹ and R ² each independently represent a substituent.)

(In formula (II), R ^{3 to} R ⁵ each independently represents a substituent. A represents an integer of 0 to 4, b represents an integer of 0 to 5, and c represents an integer of 0 to 4. ^{.Ar 1,} Ar ^{2, R} 1 and ^{R 2} representing have the same meanings as those in each of formulas (I).) The polymer for organic electroluminescent elements containing the structure represented by following formula (I), Comprising: The polymer for organic electroluminescent elements containing the structure represented by following formula (III).

(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. R ¹ and R ² each independently represent a substituent.)

(In formula (III), R ^{6 to} R ⁹ each independently represents a substituent . D and e each independently represent an integer of 0 to 4. Ar ¹ , Ar ² , R ¹ and R ² are Each having the same meaning as in formula (I).) An organic electroluminescent element composition comprising the polymer for an organic electroluminescent element according to claim 1 or 2 and a solvent. An organic electroluminescent device having an anode, a cathode, and an organic layer between the anode and the cathode, wherein the organic layer contains the polymer for an organic electroluminescent device according to claim 1 or 2. Organic electroluminescent device. The organic electroluminescent display using the organic electroluminescent element of Claim 4 .

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