JP2011116805A - Copolymer and organic light-emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copolymer which is a charge-transporting polymer containing both a triarylamine structure and an electron-transporting structure in the same molecule, wherein light emission with energy lower than that derived from each structure is suppressed; and to enhance light-emitting efficiency of an organic light-emitting element using the same. <P>SOLUTION: The copolymer is obtained by radical polymerization of a composition containing polymerizable compounds represented by formulae (1), (2) and (3). In formula (1), Ar<SP>1</SP>and Ar<SP>2</SP>respectively represent an aromatic group. In formula (2), A represents an electron-transporting group. In formula (3), R<SP>2</SP>represents an alkyl group or an aromatic group. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a copolymer having a hole transporting property and an electron transporting property, and an organic light emitting device including the same in a light emitting layer.

  In recent years, materials having high luminous efficiency and durability have been actively developed in order to expand the applications of organic light emitting devices. However, in order to develop organic light-emitting elements for display and lighting applications, it is essential to develop materials that have higher luminous efficiency and maintain stable driving of the elements. Among them, a phosphorescent material that emits light from a triplet excited state generated by the combination of holes and electrons is expected as a material that can greatly improve the light emission efficiency of an organic light emitting device. (Non-Patent Document 1)

  An organic light emitting element generally has a configuration including one or more organic layers sandwiched between a pair of electrodes. When a polymer compound or a mixture of a polymer compound and a non-polymer compound is used as a material for forming these layers, it is possible to easily form a film by applying a solution in which the polymer compound is dissolved, and the device can have a large area and can be mass-produced. Become. As such a polymer compound, a charge transporting polymer having a charge transporting structure in its side chain is known, and as disclosed in Patent Documents 1 and 2, triarylamine derivatives have high hole mobility. Therefore, it is preferable as a side chain structure of the charge transporting polymer.

  However, if the charge-transporting polymer has both a hole-transporting triarylamine structure and an electron-transporting structure in the side chain, when the polymer is photoexcited, in addition to the light emission of the triarylamine structure and the electron-transporting structure alone A lower energy emission is observed. This emission energy is often lower than the excitation energy of the phosphor dispersed in the charge transporting polymer, causing the emission from the phosphor to decrease, especially in the case of phosphorescent emitters with high excitation energy. The luminous efficiency of the device is greatly reduced.

JP-A-7-53953 JP-A-8-269133

Applied Physics Letters 75, 4-6, 1999

  The present invention provides a copolymer having a triarylamine structure and an electron transporting structure simultaneously containing in the same molecule, and suppressing the emission of energy lower than the light emission derived from each structure. It is an object to increase the light emission efficiency of the organic light emitting device used.

  As a result of intensive studies to solve the above problems, the present inventor is obtained by copolymerizing a triarylamine derivative having a vinyl group and an electron transporter having a vinyl group with a polymerizable compound having a specific structure. In the copolymer, the above-mentioned low-energy light emission is suppressed, and it has been found that the use of this as a material for the light-emitting layer improves the light-emitting efficiency of the organic light-emitting device, thereby completing the present invention.

That is, the present invention relates to the following [1] to [6].
[1]
A copolymer obtained by radical polymerization of a composition containing a polymerizable compound represented by the following formulas (1), (2) and (3).

（式（１）中、Ａｒ¹およびＡｒ²はそれぞれ独立に、フェニル基、ビフェニル基、ターフェニル基、ナフチル基またはジアリールアミノフェニル基を表し、ｎ１は１または２を表し、ｎ１が２の場合には二つの｛Ｎ（Ａｒ¹）（Ａｒ²）｝基はそれぞれ同一でも異なっていてもよい。Ｒ¹は炭素数１〜２０のアルキル基または炭素数１〜２０のアルコキシ基を表し、ｎ２は０〜４の整数を表し、ｎ２が２以上の場合には複数のＲ¹はそれぞれ同一でも異なっていてもよく、ｎ１とｎ２の和は５以下である。）

(In Formula (1), Ar ¹ and Ar ² each independently represent a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group or a diarylaminophenyl group, n1 represents 1 or 2, and n1 is 2) The two {N (Ar ¹ ) (Ar ² )} groups may be the same or different, and R ¹ represents an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, and n 2 Represents an integer of 0 to 4, and when n2 is 2 or more, a plurality of R ^{1 s} may be the same or different, and the sum of n1 and n2 is 5 or less.)

（式（２）中、Ａは電子輸送性を有する基を表す。）

(In formula (2), A represents a group having an electron transporting property.)

（式（３）中、Ｒ²は炭素数１〜２０のアルキル基、置換基を有してもよいフェニル基、置換基を有してもよいビフェニル基または置換基を有してもよいターフェニル基を表す。）
［２］
前記組成物が前記式（１）、（２）および（３）で表される重合性化合物をそれぞれｘ ｍｏｌ、ｙ ｍｏｌおよびｚ ｍｏｌ含み、ｚがｘとｙの和に等しいかそれよりも大きい、上記［１］に記載の共重合体。

(In Formula (3), R ² is an alkyl group having 1 to 20 carbon atoms, a phenyl group that may have a substituent, a biphenyl group that may have a substituent, or a ter that may have a substituent. Represents a phenyl group.)
[2]
The composition contains x mol, y mol and z mol of polymerizable compounds represented by the formulas (1), (2) and (3), respectively, and z is equal to or greater than the sum of x and y The copolymer according to [1] above.

[3]
The copolymer according to the above [1] or [2], wherein A in the formula (2) is a heteroaromatic compound derivative or a triarylborane derivative.

[4]
The copolymer according to the above [1] or [2], wherein A in the formula (2) is selected from the following formulas (A-1) to (A-8).
(In formulas (A-1) to (A-8), the broken line represents binding to a vinyl group.)

（式（Ａ−１）中、Ｒ¹¹はフッ素原子、シアノ基、アルキル基、アリール基、アルコキシ基またはシリル基を表し、ｎ１１は０〜４の整数を表し、ｎ１１が２以上の場合には２つ以上のＲ¹¹はそれぞれ同一でも異なっていてもよい。Ａｒ¹¹はベンゼンの二価基を表す。）

(In the formula (A-1), R ¹¹ represents a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, n11 represents an integer of 0 to 4, and when n11 is 2 or more, Two or more R ^{11 s} may be the same or different, and Ar ¹¹ represents a divalent group of benzene.)

（式（Ａ−２）中、Ａｒ¹²はアリール基を表し、ｎ１２は１〜４の整数を表し、ｎ１２が２以上の場合には２つ以上のＲ¹²はそれぞれ同一でも異なっていてもよい。）

(In Formula (A-2), Ar ¹² represents an aryl group, n12 represents an integer of 1 to 4, and when n12 is 2 or more, two or more R ^{12 s} may be the same or different. .)

（式（Ａ−３）中、Ａｒ¹²はベンゼンの二価基を表し、Ａｒ¹³はアリール基を表し、ｎ１３は０〜３の整数を表し、ｎ１３が２以上の場合には２つ以上のＡｒ¹³はそれぞれ同一でも異なっていてもよい。）

(In the formula (A-3), Ar ¹² represents a divalent group of benzene, Ar ¹³ represents an aryl group, n13 represents an integer of 0 to 3, and when n13 is 2 or more, two or more Ar ¹³ may be the same or different.

（式（Ａ−４）中、Ａｒ¹⁴はベンゼンの二価基を表し、Ａｒ¹⁵はアリール基を表し、ｎ１５は０〜２の整数を表し、ｎ１５が２以上の場合には２つ以上のＡｒ¹⁵はそれぞれ同一でも異なっていてもよい。）

(In the formula (A-4), Ar ¹⁴ represents a divalent group of benzene, Ar ¹⁵ represents an aryl group, n15 represents an integer of 0 to 2, and when n15 is 2 or more, two or more Ar ¹⁵ may be the same or different.

（式（Ａ−５）中、Ｒ¹⁶はフッ素原子、シアノ基、アルキル基、アリール基、アルコキシ基またはシリル基を表し、ｎ１６は０〜５の整数を表し、ｎ１６が２以上の場合には２つ以上のＲ¹⁶はそれぞれ同一でも異なっていてもよい。Ａｒ¹⁶はベンゼンの二価基を表す。）

(In the formula (A-5), R ¹⁶ represents a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, n16 represents an integer of 0 to 5, and when n16 is 2 or more, Two or more R ^{16 s} may be the same or different, and Ar ¹⁶ represents a divalent group of benzene.)

（式（Ａ−６）中、Ｒ¹⁷はフッ素原子、シアノ基、アルキル基、アリール基、アルコキシ基またはシリル基を表し、ｎ１７は０〜５の整数を表し、ｎ１７が２以上の場合にはＲ¹⁷はそれぞれ同一でも異なっていてもよい。Ａｒ¹⁷はベンゼンの二価基を表し、Ａｒ¹⁸はアリール基を表す。）

(In the formula (A-6), R ¹⁷ represents a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, n17 represents an integer of 0 to 5, and when n17 is 2 or more, R ¹⁷ may be the same or different, Ar ¹⁷ represents a divalent group of benzene, and Ar ¹⁸ represents an aryl group.

（式（Ａ−７）中、Ｒ¹⁹およびＲ²⁰はそれぞれ独立にフッ素原子、シアノ基、アルキル基、アリール基、アルコキシ基またはシリル基を表し、ｎ１９およびｎ２０はそれぞれ独立に０〜４の整数を表し、ｎ１９またはｎ２０が２以上の場合には２つ以上のＲ¹⁹またはＲ²⁰はそれぞれ同一でも異なっていてもよい。Ａｒ¹⁹はアリール基を表す。）

(In the formula (A-7), R ¹⁹ and R ²⁰ each independently represent a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, and n19 and n20 each independently represents an integer of 0 to 4) the expressed, more than one R ¹⁹ or R ²⁰ may .Ar ¹⁹ be different also in each identical if the n19 or n20 is 2 or more represents an aryl group.)

（式（Ａ−８）中、Ｒ²¹およびＲ²²はそれぞれ独立にフッ素原子、シアノ基、アルキル基、アリール基、アルコキシ基またはシリル基を表し、ｎ２１およびｎ２２はそれぞれ独立に０〜５の整数を表し、ｎが２以上の場合には２つ以上のＲはそれぞれ同一でも異なっていてもよい。Ａｒ²¹はベンゼンの二価基を表す。）
［５］
一対の電極および、発光層を含む一層以上の有機化合物層を有し、前記一対の電極間に電圧を印加することにより発光する有機発光素子であって、前記発光層が上記［１］〜［４］のいずれか一つに記載の共重合体を含むことを特徴とする有機発光素子。

(In formula (A-8), R ²¹ and R ²² each independently represent a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, and n ²¹ and n ²² are each independently an integer of 0 to 5) In the case where n is 2 or more, two or more Rs may be the same or different, and Ar ²¹ represents a divalent group of benzene.)
[5]
An organic light emitting device having a pair of electrodes and one or more organic compound layers including a light emitting layer and emitting light by applying a voltage between the pair of electrodes, wherein the light emitting layer is the above [1] to [ 4] The organic light emitting element characterized by including the copolymer as described in any one of 4.

[6]
The organic light-emitting device according to the above [5], wherein the light-emitting layer contains a phosphorescent compound.

  The organic light emitting device of the present invention includes a charge transporting polymer (copolymer) that can be formed by coating in a light emitting layer, and is high by suppressing a decrease in luminous efficiency of the light emitting body due to the charge transporting polymer (copolymer). It has luminous efficiency.

Next, the present invention will be specifically described.
The copolymer of the present invention is obtained by radical polymerization of a composition containing a polymerizable compound represented by the above formulas (1), (2) and (3).

The polymerizable compound represented by the above formula (1) is a triarylamine derivative having a vinyl group as a polymerizable functional group. Ar ¹ and Ar ² each independently represent a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group, or a diarylaminophenyl group, which may have a substituent such as an alkyl group or an alkoxy group.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, an amyl group, a hexyl group, an octyl group, and a decyl group.

  Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a t-butoxy group, a hexyloxy group, a 2-ethylhexyloxy group, and a decyloxy group.

Ar ¹ and Ar ² further have a diarylamino group or diarylaminophenyl group as a substituent, so that the polymerizable compound represented by formula (1) forms a structure containing two or more triarylamine structures. You may do it.

R ¹ in the above formula (1) represents an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, and a butyl group. , Isobutyl group, t-butyl group, amyl group, hexyl group, octyl group, decyl group and the like. Examples of the alkoxy group include methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group. Group, t-butoxy group, hexyloxy group, 2-ethylhexyloxy group, decyloxy group and the like.

  Specific examples of the polymerizable compound represented by the above formula (1) are shown below.

上記式（２）で表される重合性化合物におけるＡは電子輸送性を有する基を表す。電子輸送性を有する基としては、例えば、ヘテロ芳香族化合物誘導体やトリアリールボラン誘導体を挙げることができ、これらは上記式（Ａ−１）〜（Ａ−８）で表される構造であることが好ましい。

A in the polymerizable compound represented by the above formula (2) represents a group having an electron transporting property. Examples of the group having an electron transporting property include heteroaromatic compound derivatives and triarylborane derivatives, and these are structures represented by the above formulas (A-1) to (A-8). Is preferred.

In formulas (A-1) to (A-8), R ¹¹ , R ¹⁶ , R ¹⁷ and R ^{19 to} R ²² are each independently a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group. Represents. Here, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, an amyl group, a hexyl group, an octyl group, and a decyl group. Examples of the group include phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, biphenyl group, terphenyl group and pyridyl group, pyrazyl group, quinolyl group, isoquinolyl group, pyrrolyl group, imidazolyl group, pyrazolyl group, oxazolyl group. Groups, oxadiazolyl groups, toazolyl groups, benzoxazolyl groups, benzthiazolyl groups, thienyl groups, furyl groups, tetrazole groups, carbazolyl groups, carbazolylphenyl groups and the like heteroaryl groups. Examples of alkoxy groups include Methoxy group, ethoxy group, propoxy group, Examples include propoxy group, butoxy group, isobutoxy group, t-butoxy group, hexyloxy group, 2-ethylhexyloxy group, decyloxy group, etc. Examples of the silyl group include trimethylsilyl group, triethylsilyl group, t-butyldimethylsilyl group. Group, trimethoxysilyl group and the like. Among these substituents, an alkyl group, an aryl group, and an alkoxy group are preferable, and a methyl group, a t-butyl group, a phenyl group, a tolyl group, a biphenyl group, a carbazolyl group, and a carbazolylphenyl group are more preferable.

In the above formulas (A-1) to (A-8), Ar ^{11 to} Ar ¹⁹ and Ar ²¹ each represent an aryl group. For example, phenyl group, tolyl group, xylyl group, mesityl group, naphthyl group, biphenyl group, ter Examples thereof include a phenyl group, a carbazolyl group, a carbazolylphenyl group, and the like, preferably a phenyl group, a tolyl group, a xylyl group, a biphenyl group, a carbazolyl group, and a carbazolylphenyl group. These groups may be further substituted with an aryl group.

  Specific examples of the polymerizable compound represented by the above formula (2) are shown below.

上記式（３）で表される重合性化合物はマレイミド誘導体である。式（３）におけるＲ²は炭素数１〜２０のアルキル基、置換基を有してもよいフェニル基、置換基を有してもよいビフェニル基または置換基を有してもよいターフェニル基を表す。該アルキル基としては例えば、メチル基、エチル基、プロピル基、イソプロピル基、ブチル基、イソブチル基、ｔ−ブチル基、アミル基、ヘキシル基、オクチル基、デシル基などが挙げられ、該アルコキシ基としては、例えば、メトキシ基、エトキシ基、プロポキシ基、イソプロポキシ基、ブトキシ基、イソブトキシ基、ｔ−ブトキシ基、ヘキシルオキシ基、２−エチルヘキシルオキシ基、デシルオキシ基などが挙げられる。上記置換基を有してもよいフェニル基、置換基を有してもよいビフェニル基または置換基を有してもよいターフェニル基における置換基としては、上記のアルキル基やアルコキシ基などが挙げられる。

The polymerizable compound represented by the above formula (3) is a maleimide derivative. R ² in Formula (3) is an alkyl group having 1 to 20 carbon atoms, a phenyl group that may have a substituent, a biphenyl group that may have a substituent, or a terphenyl group that may have a substituent. Represents. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, an amyl group, a hexyl group, an octyl group, and a decyl group. Examples include methoxy group, ethoxy group, propoxy group, isopropoxy group, butoxy group, isobutoxy group, t-butoxy group, hexyloxy group, 2-ethylhexyloxy group, decyloxy group and the like. Examples of the substituent in the phenyl group which may have a substituent, the biphenyl group which may have a substituent or the terphenyl group which may have a substituent include the above-described alkyl group and alkoxy group. It is done.

  The polymerizable compound represented by the above formula (3) has a larger band gap than the polymerizable compound represented by the above formula (1) and the polymerizable compound represented by the above formula (2). The copolymer of the present invention can suppress the above low energy emission.

  When the number of moles of the polymerizable compound represented by the formulas (1), (2) and (3) contained in the composition in the present invention is x mol, y mol and z mol, respectively (x, y and z is larger than 0), z is preferably 0.75 times or more of the sum of x and y, and more preferably 1.00 times or more. When z is less than 0.75 times the sum of x and y, the light-emitting efficiency of the organic light-emitting element is high because the effect of suppressing light emission at a lower energy than the above triarylamine structure and electron-transporting structure is small. Don't be. In addition, when z exceeds 1.25 times the sum of x and y, the effect of suppressing the low-energy emission does not increase with increasing z.

The ratio of the polymerizable compounds represented by the above formulas (1) and (2) in the composition, that is, the optimum value of x / y is determined by the charge transporting ability, concentration, etc. of each repeating unit, but is usually It is preferably in the range of 0.05 to 20, and more preferably in the range of 0.25 to 4. Moreover, the ratio of each repeating unit contained in the copolymer of this invention obtained by superposing | polymerizing the said composition is estimated by < ¹³ > C-NMR measurement.

  The composition has two or more types of polymerizable compounds represented by the above formula (1) having different structures, two or more types of polymerizable compounds represented by the above formula (2) and / or different structures. Two or more kinds of polymerizable compounds represented by the above formula (3) may be included. In this case, said x, y, and z are defined as the sum total of the mol number of the polymeric compound represented by Formula (1), (2) and (3), respectively.

  The weight average molecular weight of the copolymer of the present invention is usually 1,000 to 2,000,000, and preferably 5,000 to 1,000,000. When the weight average molecular weight is in this range, the copolymer is soluble in an organic solvent, and a uniform thin film can be obtained. Here, the weight average molecular weight is a value measured at 40 ° C. using tetrahydrofuran as a solvent by gel permeation chromatography (GPC).

  The copolymer of the present invention can be obtained by radical polymerization of a composition containing a polymerizable compound represented by the above formulas (1), (2) and (3). For example, cationic polymerization, anionic polymerization, etc. In the copolymer obtained by polymerization methods other than radical polymerization, the effect of suppressing the low energy emission is small.

  As an example of the configuration of the organic light-emitting device according to the present invention, a configuration in which a hole transport layer, a light-emitting layer, and an electron transport layer are laminated in this order between an anode and a cathode provided on a transparent substrate can be given. In the configuration of another organic light emitting device, for example, either 1) a hole transport layer / light emitting layer or 2) a light emitting layer / electron transport layer may be provided between the anode and the cathode of the organic light emitting device. 3) a layer containing a hole transport material, a light emitting material, an electron transport material, 4) a layer containing a hole transport material, a light emitting material, 5) a layer containing a light emitting material, an electron transport material, 6) Any one of the layers may be provided. Further, two or more light emitting layers may be stacked. The organic layer may be formed inside pores (cavities) provided in the electrode surface on the substrate.

The organic light-emitting device of the present invention preferably contains 30 to 99% by weight, more preferably 60 to 99% by weight of the above-described copolymer in the light-emitting layer.
The light-emitting layer preferably contains a phosphorescent compound. Examples of the phosphorescent compound include iridium complexes having a ligand such as arylpyridine and carbene, platinum complexes, and osmium complexes. More specific examples of the iridium complex include the following compounds (E1-1) to (E1-39).

上記発光層は、本発明の共重合体１００重量部に対して、上記燐光発光性化合物を、好ましくは１〜５０重量部、より好ましくは５〜２０重量部の量で含むことが望ましい。また、上記発光性化合物は、本発明の共重合体の側鎖構造として含まれていてもよい。また、この発光層がさらに電荷輸送性の化合物を含むときは、本発明の共重合体１００重量部に対して、上記電荷輸送性の化合物を、好ましくは５〜９５重量部、より好ましくは２０〜８０重量部の量で含むことが望ましい。

The light emitting layer preferably contains the phosphorescent compound in an amount of 1 to 50 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the copolymer of the present invention. Moreover, the said luminescent compound may be contained as a side chain structure of the copolymer of this invention. When the light emitting layer further contains a charge transporting compound, the charge transporting compound is preferably 5 to 95 parts by weight, more preferably 20 parts by weight based on 100 parts by weight of the copolymer of the present invention. It is desirable to include it in an amount of ˜80 parts by weight.

  The hole transport material and the electron transport material used for each of the above layers may be formed independently, or may be formed by mixing materials having different functions. Also in the light emitting layer in the organic light emitting device according to the present invention, in addition to the copolymer according to the present invention and the phosphorescent compound, other known hole transport materials and / or for the purpose of supplementing the carrier transport property. An electron transport material may be included. Such a hole transport material and an electron transport material may be a low molecular compound or a high molecular compound, and preferably 5 to 95 weights with respect to 100 parts by weight of the copolymer of the present invention. Part, more preferably 20 to 80 parts by weight.

  The method for forming the light emitting layer is not particularly limited, and for example, the light emitting layer can be formed as follows. First, a solution in which the copolymer of the present invention and, if necessary, the phosphorescent compound and the charge transporting compound are dissolved is prepared. The solvent used for the preparation of the solution is not particularly limited. Ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate are used. Next, the solution thus prepared is subjected to spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, and screen printing. The film is formed on the substrate by a wet film forming method such as a flexographic printing method, an offset printing method, or an ink jet printing method. Depending on the compound used and the film formation conditions, for example, in the case of a spin coating method or a dip coating method, the above solution contains a mixture of the copolymer of the present invention, the phosphorescent compound and the charge transporting compound. It is preferably contained in an amount of 0.5 to 5% by weight.

  As the substrate of the organic light emitting device of the present invention, an insulating substrate transparent to the emission wavelength of the light emitting material is preferably used. Specifically, in addition to glass, transparent materials such as PET (polyethylene terephthalate) and polycarbonate are used. Plastic or the like is used.

  A hole injection layer may be provided between the anode and the light emitting layer in order to relax the injection barrier in hole injection. In order to form the hole injection layer, a known material such as copper phthalocyanine, a mixture of polyethylene dioxythiophene (PEDOT) and polystyrene sulfonic acid (PSS), fluorocarbon, silicon dioxide or the like is used.

  An insulating layer having a thickness of 0.1 to 10 nm is provided between the cathode and the electron transport layer or between the cathode and the organic compound layer laminated adjacent to the cathode in order to improve electron injection efficiency. It may be done. In order to form the insulating layer, known materials such as lithium fluoride, sodium fluoride, magnesium fluoride, magnesium oxide, and alumina are used.

  As a hole transport material for forming the hole transport layer or a hole transport material mixed in the light emitting layer, for example, TPD (N, N′-dimethyl-N, N ′-(3-methylphenyl)- 1,1′-biphenyl-4,4′diamine); α-NPD (4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl); m-MTDATA (4,4 ′, Low molecular weight triphenylamine derivatives such as 4 ″ -tris (3-methylphenylphenylamino) triphenylamine), low molecular weight such as 4,4′-dicarbazolylbiphenyl, 1,3-dicarbazolylbiphenyl And carbazole derivatives. The above hole transport materials may be used singly or in combination of two or more, or different hole transport materials may be laminated and used. Since the thickness of the hole transport layer depends on the conductivity of the hole transport layer and the like, it cannot be unconditionally limited, but is preferably 1 nm to 5 μm, more preferably 5 nm to 1 μm, and particularly preferably 10 nm to 500 nm. Is desirable.

  Examples of the electron transport material for forming the electron transport layer or the electron transport material mixed in the light emitting layer include quinolinol derivative metal complexes such as Alq3 (aluminum trisquinolinolate), oxadiazole derivatives, triazole derivatives, imidazole. Examples include known compounds such as derivatives, triazine derivatives, and triarylborane derivatives. The electron transport materials may be used singly or in combination of two or more, or different electron transport materials may be laminated and used. The thickness of the electron transport layer depends on the conductivity of the electron transport layer and cannot be generally limited, but is preferably 1 nm to 5 μm, more preferably 5 nm to 1 μm, and particularly preferably 10 nm to 500 nm. .

  In addition, a hole blocking layer is provided adjacent to the cathode side of the light emitting layer for the purpose of preventing holes from passing through the light emitting layer and efficiently recombining holes and electrons in the light emitting layer. May be. In order to form the hole blocking layer, a known material such as a triazole derivative, an oxadiazole derivative, or a phenanthroline derivative is used.

  Examples of film formation methods for the light-emitting layer, the hole transport layer, and the electron transport layer include dry coating methods such as resistance heating evaporation, electron beam evaporation, and sputtering, as well as spin coating, casting, and microgravure. Wet film forming methods such as coating methods, gravure coating methods, bar coating methods, roll coating methods, wire bar coating methods, dip coating methods, spray coating methods, screen printing methods, flexographic printing methods, offset printing methods, and inkjet printing methods ( Application method) can be used. The layer containing the compound of the present invention has an advantage that it can be formed by a coating method capable of suppressing the manufacturing cost of the organic light emitting device.

  As an anode material used for the organic light emitting device of the present invention, for example, a known transparent conductive material such as ITO (indium tin oxide), tin oxide, zinc oxide, polythiophene, polypyrrole, polyaniline or the like is preferably used. It is done. The surface resistance of the electrode formed of the transparent conductive material is preferably 1 to 50Ω / □ (ohm / square). The thickness of the anode is preferably 50 to 300 nm.

  Examples of the cathode material used in the organic EL device of the present invention include alkali metals such as Li, Na, K, and Cs; alkaline earth metals such as Mg, Ca, and Ba; Al; MgAg alloys; Al such as AlLi and AlCa A known cathode material such as an alloy of alkali metal or alkaline earth metal is preferably used. The thickness of the cathode is preferably 10 nm to 1 μm, more preferably 50 to 500 nm. When a highly active metal such as an alkali metal or alkaline earth metal is used, the thickness of the cathode is preferably 0.1 to 100 nm, more preferably 0.5 to 50 nm. In this case, a metal layer that is stable to the atmosphere is laminated on the cathode for the purpose of protecting the cathode metal. Examples of the metal forming the metal layer include Al, Ag, Au, Pt, Cu, Ni, and Cr. The thickness of the metal layer is preferably 10 nm to 1 μm, more preferably 50 to 500 nm.

  In addition, as a method for forming the anode material, for example, an electron beam evaporation method, a sputtering method, a chemical reaction method, a coating method, or the like is used. As a method for forming the cathode material, for example, a resistance heating evaporation method, An electron beam evaporation method, a sputtering method, an ion plating method, or the like is used.

  The organic light-emitting element of the present invention is suitably used in an image display device as a matrix-type or segment-type pixel by a known method. The organic EL element is also suitably used as a surface light source without forming pixels.

  Specifically, the organic light-emitting device of the present invention is suitably used for displays, backlights, electrophotography, illumination light sources, recording light sources, exposure light sources, reading light sources, signs, signboards, interiors, optical communications, and the like.

Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited by these.
Example 1
A copolymer (1-1) was synthesized by copolymerizing the following polymerizable compounds (M-1), (M-2) and (M-3). The compounds (M-1) and (M-2) were synthesized according to the method described in JP-A-2005-200508, and (M-3) was purchased from Tokyo Chemical Industry Co., Ltd. as it was.

密閉容器に重合性化合物（Ｍ−１）２５０ｍｇ（０．４２ｍｍｏｌ）、重合性化合物（Ｍ−２）２５０ｍｇ（０．４３ｍｍｏｌ）および重合性化合物（Ｍ−３）１５５ｍｇ（９０ｍｍｏｌ）を入れ、脱水トルエン（５．０ｍＬ）を加えた。次いで、Ｖ−６０１（和光純薬工業（株）製）のトルエン溶液（０．１Ｍ、０．１０ｍＬ）を加え、凍結脱気操作を５回繰り返した。真空のまま密閉し、６０℃で６０時間撹拌した。反応後、反応液をアセトン２００ｍＬ中に滴下し、沈殿を得た。さらにトルエン−アセトンでの再沈殿精製を２回繰り返した後、５０℃で一晩真空乾燥して、共重合体（１−１）を得た。共重合体（１−１）の重量平均分子量（Ｍｗ）は４５６００、分子量分布指数（Ｍｗ／Ｍｎ）は２．１１であった。¹³Ｃ−ＮＭＲ測定の結果から見積もった共重合体（１−１）におけるｘ／ｙの値は１．００であり、ｚ／（ｘ＋ｙ）は１．０１であった。共重合体（１−１）をジクロロメタンに溶解し、発光スペクトルを測定したところ、４１０ｎｍ付近に重合性化合物（Ｍ−１）および重合性化合物（Ｍ−２）から誘導される繰り返し単位に由来する発光が観察されたが、それ以外の発光は観察されなかった。

In a closed container, 250 mg (0.42 mmol) of the polymerizable compound (M-1), 250 mg (0.43 mmol) of the polymerizable compound (M-2) and 155 mg (90 mmol) of the polymerizable compound (M-3) were added and dehydrated toluene. (5.0 mL) was added. Next, a toluene solution (0.1 M, 0.10 mL) of V-601 (manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the freeze degassing operation was repeated 5 times. It sealed in vacuum and stirred at 60 ° C. for 60 hours. After the reaction, the reaction solution was dropped into 200 mL of acetone to obtain a precipitate. Further, reprecipitation purification with toluene-acetone was repeated twice, followed by vacuum drying at 50 ° C. overnight to obtain a copolymer (1-1). The weight average molecular weight (Mw) of the copolymer (1-1) was 45600, and the molecular weight distribution index (Mw / Mn) was 2.11. The value of x / y in the copolymer (1-1) estimated from the result of ¹³ C-NMR measurement was 1.00, and z / (x + y) was 1.01. When the copolymer (1-1) was dissolved in dichloromethane and the emission spectrum was measured, it was derived from a repeating unit derived from the polymerizable compound (M-1) and the polymerizable compound (M-2) at around 410 nm. Luminescence was observed, but no other luminescence was observed.

(Example 2)
Polymerization was conducted in the same manner as in Synthesis Example 1 except that the amount of the polymerizable compound (M-3) used for the polymerization was 110 mg (0.63 mmol) to obtain a copolymer (1-2). The weight average molecular weight (Mw) of the copolymer (1-2) was 40700, and the molecular weight distribution index (Mw / Mn) was 2.24. The value of x / y in the copolymer (1-2) estimated from the result of ¹³ C-NMR measurement was 1.00, and z / (x + y) was 0.75. When copolymer (1-2) was dissolved in dichloromethane and the emission spectrum was measured, it was derived from a repeating unit derived from polymerizable compound (M-1) and polymerizable compound (M-2) at around 410 nm. Luminescence was observed, but no other luminescence was observed.

(Comparative Example 1)
Polymerization was carried out in the same manner as in Synthesis Example 1 except that the amount of the polymerizable compound (M-3) used for the polymerization was 80 mg (0.46 mmol) to obtain a copolymer (C1-1). The weight average molecular weight (Mw) of the copolymer (C1-1) was 47700, and the molecular weight distribution index (Mw / Mn) was 2.21. The value of x / y in the copolymer (C1-1) estimated from the result of ¹³ C-NMR measurement was 0.99, and z / (x + y) was 0.54. When the copolymer (C1-1) was dissolved in dichloromethane and the emission spectrum was measured, it was derived from a repeating unit derived from the polymerizable compound (M-1) and the polymerizable compound (M-2) at around 410 nm. In addition to the observed light emission, light emission was observed near 505 nm in the lower energy wavelength region.

(Comparative Example 2)
Polymerization was performed in the same manner as in Synthesis Example 1 except that the polymerizable compound (M-3) was not added, to obtain a copolymer (C1-2). The weight average molecular weight (Mw) of the copolymer (C1-2) was 34600, and the molecular weight distribution index (Mw / Mn) was 2.10. The value of x / y in the copolymer (C1-2) estimated from the result of ¹³ C-NMR measurement was 0.98, and z / (x + y) was 0. When the copolymer (C1-1) was dissolved in dichloromethane and the emission spectrum was measured, it was derived from a repeating unit derived from the polymerizable compound (M-1) and the polymerizable compound (M-2) at around 410 nm. In addition to the observed light emission, light emission was observed near 505 nm in the lower energy wavelength region.

(Example 3)
A substrate with ITO (manufactured by Nippon Electric Co., Ltd.) was used. This was a substrate in which two ITO (indium tin oxide) electrodes (anodes) having a width of 4 mm were formed in one stripe on one surface of a 25 mm square glass substrate.

First, on the substrate with ITO, N, N′-di (1-naphthyl) -N, N′-diphenyl-4,4′-diaminobiphenyl (manufactured by Sigma-Aldrich, sublimation purified product, purity 99%) A hole transport layer was formed to a thickness of about 50 nm at a rate of 0.2 nm / sec by resistance heating vapor deposition under a reduced pressure of 8.5 × 10 ⁻⁵ Pa. Next, a mixture of 82 mg of copolymer (1-1) and 8 mg of phosphorescent emitter (E1-4) was dissolved in 2910 mg of toluene (special grade, manufactured by Wako Pure Chemical Industries, Ltd.), and this solution was dissolved in a pore size of 0.2 μm. The solution was filtered to prepare a coating solution. Next, the coating solution was coated on the hole transport layer by a spin coating method under the conditions of a rotation speed of 3000 rpm and a coating time of 30 seconds. After the application, it was dried at room temperature (25 ° C.) for 30 minutes to form a light emitting layer. The film thickness of the obtained light emitting layer was about 50 nm.

Next, 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (manufactured by Sigma-Aldrich, sublimation purified product, purity 99.99%) and Alq3 (manufactured by Tokyo Chemical Industry Co., Ltd.) are formed on the light emitting layer. , Sublimation refined product, purity 98%) under reduced pressure of 8.5 × 10 ⁻⁵ Pa by resistance heating vapor deposition method to a film thickness of 20 nm and 30 nm respectively at a rate of 0.2 nm / sec. An electron transport layer was formed. Next, barium and aluminum were co-evaporated at a weight ratio of 1:10 under a reduced pressure of 8.5 × 10 ⁻⁵ Pa, and a cathode having a width of 3 mm was striped in a shape of 2 so as to be orthogonal to the extending direction of the anode. The book was formed. The film thickness of the obtained cathode was about 50 nm.

Finally, in an argon atmosphere, lead wires (wirings) were attached to the anode and the cathode to produce four organic light emitting elements having a length of 4 mm and a width of 3 mm. A voltage was applied to the organic EL element to emit light using a programmable DC voltage / current source (TR6143, manufactured by Advantest Corporation).
The produced organic light emitting device had an emission external quantum efficiency of 10.3%.

(Example 2)
An organic light emitting device was produced in the same manner as in Example 1 except that the copolymer (1-2) was used instead of the copolymer (1-1). The light emitting external quantum efficiency of the produced organic light emitting device was 9.5%.

(Comparative Example 1)
An organic light emitting device was produced in the same manner as in Example 1 except that the copolymer (C1-1) was used instead of the copolymer (1-1). The light-emitting external quantum efficiency of the produced organic light-emitting device was 6.9%.

(Comparative Example 2)
An organic light emitting device was produced in the same manner as in Example 1 except that the copolymer (C1-2) was used instead of the copolymer (1-1). The produced organic light emitting device had a light emission external quantum efficiency of 5.5%.

  Specifically, the organic light-emitting device of the present invention is suitably used for displays, backlights, electrophotography, illumination light sources, recording light sources, exposure light sources, reading light sources, signs, signboards, interiors, optical communications, and the like.

Claims (6)

A copolymer obtained by radical polymerization of a composition containing a polymerizable compound represented by the following formulas (1), (2) and (3).

(In Formula (1), Ar ¹ and Ar ² each independently represent a phenyl group, a biphenyl group, a terphenyl group, a naphthyl group or a diarylaminophenyl group, n1 represents 1 or 2, and n1 is 2) The two {N (Ar ¹ ) (Ar ² )} groups may be the same or different, and R ¹ represents an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, and n 2 Represents an integer of 0 to 4, and when n2 is 2 or more, a plurality of R ^{1 s} may be the same or different, and the sum of n1 and n2 is 5 or less.)

(In formula (2), A represents a group having an electron transporting property.)

(In Formula (3), R ² is an alkyl group having 1 to 20 carbon atoms, a phenyl group that may have a substituent, a biphenyl group that may have a substituent, or a ter that may have a substituent. Represents a phenyl group.)   The composition contains x mol, y mol and z mol of polymerizable compounds represented by the formulas (1), (2) and (3), respectively, and z is equal to or greater than the sum of x and y The copolymer according to claim 1.   The copolymer according to claim 1 or 2, wherein A in the formula (2) is a heteroaromatic compound derivative or a triarylborane derivative. The copolymer according to claim 1 or 2, wherein one A in the formula (2) is selected from the following formulas (A-1) to (A-8).
(In formulas (A-1) to (A-8), the broken line represents bonding to a vinyl group.)

(In the formula (A-1), R ¹¹ represents a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, n11 represents an integer of 0 to 4, and when n11 is 2 or more, Two or more R ^{11 s} may be the same or different, and Ar ¹¹ represents a divalent group of benzene.)

(In Formula (A-2), Ar ¹² represents an aryl group, n12 represents an integer of 1 to 4, and when n12 is 2 or more, two or more R ^{12 s} may be the same or different. .)

(In the formula (A-3), Ar ¹² represents a divalent group of benzene, Ar ¹³ represents an aryl group, n13 represents an integer of 0 to 3, and when n13 is 2 or more, two or more Ar ¹³ may be the same or different.

(In the formula (A-4), Ar ¹⁴ represents a divalent group of benzene, Ar ¹⁵ represents an aryl group, n15 represents an integer of 0 to 2, and when n15 is 2 or more, two or more Ar ¹⁵ may be the same or different.

(In the formula (A-5), R ¹⁶ represents a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, n16 represents an integer of 0 to 5, and when n16 is 2 or more, Two or more R ^{16 s} may be the same or different, and Ar ¹⁶ represents a divalent group of benzene.)

(In the formula (A-6), R ¹⁷ represents a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, n17 represents an integer of 0 to 5, and when n17 is 2 or more, R ¹⁷ may be the same or different, and Ar ¹⁷ represents a divalent group of benzene and represents an Ar ¹⁸ aryl group.

(In the formula (A-7), R ¹⁹ and R ²⁰ each independently represent a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, and n19 and n20 each independently represents an integer of 0 to 4) the expressed, more than one R ¹⁹ or R ²⁰ may .Ar ¹⁹ be different also in each identical if the n19 or n20 is 2 or more represents an aryl group.)

(In formula (A-8), R ²¹ and R ²² each independently represent a fluorine atom, a cyano group, an alkyl group, an aryl group, an alkoxy group or a silyl group, and n ²¹ and n ²² are each independently an integer of 0 to 5) In the case where n is 2 or more, two or more Rs may be the same or different, and Ar ²¹ represents a divalent group of benzene.   An organic light emitting device having a pair of electrodes and one or more organic compound layers including a light emitting layer and emitting light by applying a voltage between the pair of electrodes, wherein the light emitting layer is as defined in claims 1 to 4. The organic light emitting element characterized by including the copolymer as described in any one.   The organic light emitting device according to claim 5, wherein the light emitting layer contains a phosphorescent compound.