JP4569997B2 - Polymer charge transport material, method for producing the same, and electroluminescence device using the same - Google Patents

Description

式中、ｎは重合度を表す正の整数、ｍは芳香族三級アミンの数を表す正の整数（ただしｍ＝１を除く）、Ｒ_１およびＲ_２は置換基を有していてもよいアリーレン基、Ｒ_３は置換基を有していてもよいアリール基、Ｒ_４は置換基を有していてもよいアリーレン基またはアルキル基、あるいは蛍光性を有する化合物を示す。前記の置換基は、アルキル基、アルコキシ基、エステル基、シアノ基からなる群から選ばれる。Ｒ_５およびＲ_６はアルキレン基またはカルボニル基を示す。
【００１２】
請求項２の発明は、芳香族第三アミンとハロゲン化有機化合物とのフリーデル・クラフツ反応により得られることを特徴とする、下記一般式（５）で示される高分子電荷輸送材料の製造方法である。
【化５】

【００１３】
請求項３の発明は、芳香族第三アミンとハロゲン化有機化合物とのフリーデル・クラフツ反応により得られることを特徴とする、下記一般式（６）で示される高分子電荷輸送材料の製造方法である。
【化６】

【００１４】
請求項４の発明は請求項１記載の高分子電荷輸送材料を用いることを特徴とするエレクトロルミネッセンス素子である。
【００１５】
【発明の実施の形態】
以下に、本発明を詳細に説明する。
本発明の高分子電荷輸送材料は、芳香族三級アミンとハロゲン化有機化合物との重縮合（例えばフリーデル−クラフツ反応）により得られるものである。例えば、ほぼ等モルの芳香族三級アミンとハロゲン化有機化合物とを、クロロベンゼン溶媒中で触媒に塩化すずを用いて反応させることにより、容易に合成することが可能である。
【００１６】
フリーデル−クラフツ反応は塩化アルミニウムのような触媒の存在下において、芳香族あるいはオレフィン化合物とハロゲン化アルキルまたはハロゲン化アリール化合物を反応させてアルキル化合物またはアシル化合物を得るものであり、有機合成に広く利用されている。本発明は、このフリーデル−クラフツ反応を用いて容易に電荷輸送性能を有する高分子材料を得ることができることを特徴としている。
【００１７】
本発明の高分子電荷輸送材料は、数平均分子量が１，０００〜５，０００，０００であることが好ましく、特に１０，０００〜５００，０００がより好ましい。芳香族三級アミン化合物を主鎖骨格に導入することで高い正孔輸送性能を維持することができ、さらに高分子材料とすることで結晶性を抑制し、ガラス転移温度を低分子化合物よりも高くすることが可能となり、薄膜の作製も湿式法などで容易に行うことができる。
【００１８】
上記一般式（４）〜（６）で示される本発明の高分子電荷輸送材料において、Ｒ_１と、Ｒ_２はアリーレン基、Ｒ_３はアリール基を示す。ここでアリーレン基およびアリール基は、フェニル基、ナフチル基、ビフニレン基、トリフェニレン基などの芳香族化合物やピリジン環、キノリン環、チオフェン環等に代表される酸素原子や窒素原子および硫黄原子等のヘテロ原子を一つあるいは複数含む芳香族化合物を具体例として挙げることができる。さらに、上記のアリーレン基及びアリール基は、フッ素、塩素、臭素、ヨウ素のハロゲン原子、メチル基、エチル基、イソプロピル基、ターシャリーブチル基、シクロヘキシル基、トリフルオロメチル基等に代表されるアルキル基（ここで飽和環状炭化水素基もアルキル基に含む）、メトキシ基、エトキシ基、イソプロポキシ基、ターシャリーブトキシ基等に代表されるアルコキシ基、シアノ基等の置換基を有していてもよい。Ｒ_１〜 Ｒ_３は互いに同一でも異なっていても良い。
【００１９】
Ｒ_４としては、メチル基、エチル基、イソプロピル基、ターシャリーブチル基、シクロヘキシル基等に代表されるアルキル基（ここで飽和環状炭化水素基もアルキル基に含む）またはフェニレン基、ナフチレン基、ビフニレン基、トリフェニレン基などの芳香族化合物やピリジン環、キノリン環、チオフェン環等に代表される酸素原子や窒素原子および硫黄原子等のヘテロ原子を一つあるいは複数含む芳香族化合物を具体例として挙げることができる。また、蛍光性を有する化合物としては特に限定するものではないが、フリーデル・クラフツ反応により容易に導入するにはハロゲン化アルキルを有する蛍光性化合物が好ましく、例えば、アントラセン、ベンゾアントラセン、フルオレン等に代表される蛍光性を有する芳香族化合物やカルバゾール、アクリドン等に代表される酸素原子や窒素原子および硫黄原子等のヘテロ原子を一つあるいは複数含む芳香族化合物を具体例として挙げることができ、さらにはクマリンやＤＣＭ等に代表されるレーザー色素およびＥＬ素子に用いられているＡｌｑやジスチリルアリーレン誘導体等も具体例として挙げることができる。上記のＲ_４は、フッ素、塩素、臭素、ヨウ素のハロゲン原子、メチル基、エチル基、イソプロピル基、ターシャリーブチル基、トリフルオロメチル基、シクロヘキシル基等のアルキル基、メトキシ基やエトキシ基、イソプロポキシ基等に代表されるアルコキシ基、シアノ基、またはフェニル基やトリル基、ナフチル基等に代表されるアリール基を置換基として有していてもよい。
【００２０】
Ｒ_５およびＲ_６としては、メチレン基、エチレン基、イソプロピレン基、ターシャリーブチレン基等に代表されるアルキレン基（ここで飽和環状炭化水素基もアルキレン基に含む）またはカルボニル基を具体例として挙げることができる。
【００２１】
Ｒ_７としては、メチレン基、エチレン基、イソプロピレン基、ターシャリーブチレン基に代表されるアルキレン基（ここで飽和環状炭化水素基もアルキル基に含む）またはフェニレン基、ナフチレン基、ビフニレン基、トリフェニレン基などの芳香族化合物やピリジン環、キノリン環、チオフェン環等に代表される酸素原子や窒素原子および硫黄原子等のヘテロ原子を一つあるいは複数含む芳香族化合物を具体例として挙げることができる。上記のＲ7は、フッ素、塩素、臭素、ヨウ素のハロゲン原子、メチル基、エチル基、イソプロピル基、ターシャリーブチル基、トリフルオロメチル基、シクロヘキシル基等のアルキル基、メトキシ基やエトキシ基、イソプロポキシ基等に代表されるアルコキシ基、シアノ基、またはフェニル基やトリル基、ナフチル基等に代表されるアリール基を置換基として有していてもよい。
【００２２】
以上示した本発明の高分子電荷輸送性材料は、有機薄膜ＥＬ素子および電子写真感光体の電荷輸送層に適用でき、その適用方法としては他の電荷輸送材料や発光材料等と混合して用いることも可能である。また、薄膜形成としてはスピンコート法、キャスト法、印刷等の一般的な方法により可能である。
【００２３】
これまでに示してきた芳香族三級アミンとハロゲン化有機化合物との重縮合（フリーデル−クラフツ反応）により得られる電荷輸送材料または発光材料を用いた有機ＥＬ素子について述べる。透明あるいは半透明の陽極付き透明基板上に、正孔注入輸送材料として銅フタロシアニンに代表されるフタロシアニン誘導体の薄膜を、蒸着法あるいはスピンコート法で作製する。次に、フリーデル・クラフツ反応により合成した高分子材料の薄膜をスピンコート方法に代表されるウエットプロセスにより積層する。最後に、電子注入・輸送層としてＡｌｑに代表される有機金属錯体やオキサジアゾール誘導体などの薄膜を形成する。この有機層の上に、仕事関数が低く電気伝導性の高い金属、あるいはアルミニウム：リチウム（Ａｌ：Ｌｉ）、マグネシウム：銀（Ｍｇ：Ａｇ）等の合金、さらにはフッ化リチウムなどの仕事関数の低い金属からなる化合物を数Å蒸着した後に上記のような仕事関数が低く電気伝導性の高い金属を蒸着することで形成される陰極を蒸着方法などで形成する。
【００２４】
本発明における高分子電荷輸送材料は、単独あるいは他の機能性を有する低分子および高分子材料と積層または混合させて用いることも可能である。
【００２５】
【実施例】
以下、本発明の実施例について説明する。
（実施例１）
不活性ガス雰囲気中で、Ｎ，Ｎ’−ジフェニル− Ｎ，Ｎ’−ジ（パラ−トリル）ベンジジン１．０ｍＭとa、a’−ジクロロ−パラ−キシレン１．０ｍＭにクロロベンゼン３．０ｍｌを加え、これに８．０ｍｏｌ％の四塩化すずを加えて、８０℃で１２時間反応させた。これを、良溶媒にクロロホルム、貧溶媒としてアセトンを用いた再沈殿法で精製することにより、下記化学式（９）に示す、白色粉末状の高分子電荷輸送材料を得た。
【００２６】
【化７】

【００２７】
図１に、上述のようにして得られた高分子電荷輸送材料の^１Ｈ−ＮＭＲスペクトル（日本電子（株）社製 ＪＥＯＬ Ａ−５００を使用、重クロロホルム溶媒）を示す。
^１Ｈ−ＮＭＲ（ＣＤＣｌ３、ＴＭＳ） σ（ｐｐｍ）：２．０〜２．４（６Ｈ、ＣＨ_３）、３．４〜３．９（４Ｈ、ＣＨ_２）、６．５〜７．５（２８Ｈ、ＣＨ）
また、この高分子電荷輸送材料について、ポンプとして日本分光工業社製の８８０−ＰＵを用い、検出器として日本分光工業社製の示差屈折計８３０−ＲＩを用い、スチレンゲルを固定相、クロロホルムを移動相としてＧＰＣ測定を行ったところ、重量平均分子量は２１０，０００（昭和電工社製 標準ポリスチレン換算）であることが分かった。
次に、この高分子電荷輸送材料について、セイコー電子工業社製のＤＳＣ２２０を用い、窒素雰囲気下、昇温速度１０℃／ｍｉｎでガラス転移点（Ｔｇ）を測定したところ、１２１℃であることが分かった。さらに、この高分子電荷輸送材料からなるキャスト膜を白金電極上に形成し、窒素雰囲気下、アセトニトリル中で、参照電極にＡｇ／ＡｇＣｌを用い、東方技研製ＰＳ−０６により、この高分子電荷輸送材料の酸化電位を測定した結果、酸化電位は１．０３Ｖであることが分かった。また、このキャスト膜は掃引を繰り返し行っても同様な酸化還元波がみられた。
【００２８】
（実施例２）
不活性ガス雰囲気中で、Ｎ，Ｎ’−ジフェニル− Ｎ，Ｎ’−ジ（パラ−トリル）ベンジジン１．０ｍＭと９，１０−ビスクロロメチルアントラセン１．０ｍＭにクロロベンゼン９．０ｍｌを加え、これに８．０ｍｏｌ％の四塩化すずを加えて、４０℃で２時間反応させた。これを、良溶媒にクロロホルム、貧溶媒としてアセトンを用いた再沈殿法で精製することにより、下記化学式（１０）に示す、黄色粉末状の高分子電荷輸送材料を得た。
【００２９】
【化８】

【００３０】
上述のようにして得られた高分子電荷輸送材料について、^１Ｈ−ＮＭＲスペクトル（日本電子（株）社製 ＪＥＯＬ Ａ−５００を使用、重クロロホルム溶媒）の測定を行った。その結果を図２に示す。
^１Ｈ−ＮＭＲ（ＣＤＣｌ３， ＴＭＳ） s（ｐｐｍ）：０．７〜０．９（６Ｈ、ＣＨ_２）、１．１〜１．６（６Ｈ、ＣＨ_２）、２．２〜２．６（４Ｈ、ＣＨ_２）、４．４〜５．０（４Ｈ、ＣＨ_２）、６．６〜８．３（３２Ｈ、ＣＨ）
また、この高分子電荷輸送材料についてＧＰＣ測定を行ったところ、分子量が２９０，０００であることが分かった。次に、この高分子電荷輸送材料についてガラス転移点（Ｔｇ）を測定したところ１４４℃であることが分かった。さらに、この高分子電荷輸送材料の酸化電位を測定した結果、酸化電位は０．８７Ｖ、０．９９Ｖであることが分かった。また、このキャスト膜は掃引を繰り返し行っても同様な酸化還元波がみられた。
この高分子電荷輸送材料の蛍光測定を行ったところ、極大波長が４８０ｎｍの青緑色の発光がみられた。
【００３１】
上記実施例の高分子電荷輸送材料は、主鎖に導入した芳香族三級アミン化合物の低分子材料に比べてガラス転移点が高くなり、高い耐熱性が期待できる。また、酸化電位も導入した芳香族三級アミン化合物の低分子材料と同程度の値を示すことから、高分子に導入してもその電荷輸送性能は維持されていることが分かる。また、蛍光特性を有する材料を主鎖に導入することで、電荷輸送性および蛍光特性を同時に示す高分子材料を得ることができる。
【００３２】
（実施例３）
フリーデル・クラフツ反応で得られた高分子材料を用いた有機ＥＬ素子の作製を以下に述べる。洗浄したＩＴＯ付きガラス基板上に、実施例１において合成した高分子材料のトルエン溶液からスピンコート法により厚さ５０ｎｍの薄膜を積層した。さらに、発光および電子注入・輸送層としてＡｌｑを５０ｎｍの厚さに蒸着した。最後に、マグネシウムと銀を共蒸着して陰極を作製した。作製した素子からは、Ａｌｑによる輝度８、３００ｃｄ／ｍ^２の緑色発光が得られた。さらに、ポリマー層と発光層の界面に、トリフェニルジアミン誘導体を１０ｎｍ挟んだ素子からは、輝度２０、０００ｃｄ／ｍ^２の緑色の発光が得られた。
【００３３】
本発明で得られた高分子電荷輸送材料を用いた素子は、低分子材料のみを用いた素子と同程度の発光特性を示し、低分子素子が破壊する印過電圧においても安定な発光がみられ、素子の高い耐久性を確認することができた。
【００３４】
【発明の効果】
以上のように、芳香族三級アミンを主鎖とし、電荷輸送性、蛍光特性を有する、高耐熱性、高耐久性の高分子電荷輸送材料を提供できる。また、芳香族三級アミンとハロゲン化有機化合物のフリーデル・クラフツ反応により容易に高分子電荷輸送材料の製造方法を提供することができる。また、該高分子電荷輸送材料を用いて高い耐久性を有するＥＬ素子を提供することができる
【００３５】
【図面の簡単な説明】
【図１】 本発明の実施例１に係わる高分子電荷輸送材料の^１Ｈ−ＮＭＲスペクトルを示す図。
【図２】 本発明の実施例２に係わる高分子電荷輸送材料の^１Ｈ−ＮＭＲスペクトルを示す図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a charge transport material, and is a polymer charge transport material applicable to an organic electroluminescence element and an electrophotographic photosensitive member.
[0002]
[Prior art]
BACKGROUND ART An organic electroluminescent (electroluminescence; hereinafter referred to as EL) element is a light emitting element made of an organic material utilizing an organic electroluminescence phenomenon, and has attracted attention as a self-luminous type flat display element or a flat light source. This organic EL device started from research on anthracene single crystals in the 1960s, and was manufactured by C.E. W. Tang et al. Developed a thin film laminated element, and disclosed in Japanese Patent Application Laid-Open No. 59-194393, Japanese Patent Application Laid-Open No. 63-264692, Japanese Patent Application Laid-Open No. 63-295695, Applied Physics Letter Vol. 51 No. 12 913 (1987), Journal of Applied Physics, Vol. 65, No. 9, 3610 (1989), and the like. Even now, research and development has been conducted on a wide range of thin-film stacked organic EL elements.
[0003]
In general, an organic thin film EL element has a structure in which an anode, a hole injection transport layer, an organic light emitting layer, and a cathode are laminated in this order, and is manufactured as follows. First, a transparent conductive film mainly composed of a composite oxide of indium and tin (hereinafter referred to as ITO) is formed as an anode on a transparent insulating substrate such as glass or a resin film by an evaporation method or a sputtering method. Next, a single layer film or a multilayer film made of an organic hole injection / transport material typified by copper phthalocyanine or an aromatic amine compound is formed on the anode with a thickness of about 100 nm or less by vapor deposition. Further, an organic phosphor film such as tris (8-quinolinol) aluminum (hereinafter referred to as Alq) is formed as an organic light emitting layer on the hole injecting and transporting layer by a vapor deposition method with a thickness of about 100 nm or less. An organic thin-film EL element is produced by forming an alloy such as Mg: Ag or a laminated cathode such as LiF / Al on the organic light emitting layer with a thickness of about 200 nm by vapor deposition.
[0004]
By applying a DC low voltage between the electrodes of the organic thin-film EL element fabricated as described above, holes (positive charge) from the anode and electrons (negative charge) from the cathode are injected into the organic layer. The applied electric field causes the holes and electrons to move inside the organic layer and recombine in the organic light emitting layer to form excitons. The formed excitons emit light from the organic phosphor that is the organic light emitting layer and return to the ground state. The element using this light emission is an organic thin film EL element, and the direct current voltage applied to this element is usually 20 V or less, and the EL element using Alq for the light emitting layer and LiF / Al alloy for the cathode is 50,000 cd. A luminance of at least / m ² is obtained.
[0005]
However, most of the charge transport materials used in the above organic thin film EL devices are mostly low molecular compounds so far, and when a charge transport film is formed with these low molecular compounds, the low molecular compounds are low. Due to heat resistance and high crystallinity, it has been difficult to obtain an organic thin film EL element having excellent thermal stability. For this reason, a charge transport material excellent in thermal stability is desired.
[0006]
These charge transport materials are also used for photoreceptors in electrophotographic technology as described below. In the electrophotographic technology, since an electrophotographic copying machine using an amorphous selenium photoreceptor has been put into practical use, many inorganic and organic photoreceptor materials have been developed. As the photoreceptor material of this electrophotographic photoreceptor, inorganic photoreceptor materials such as selenium, zinc oxide and cadmium sulfide have been conventionally used.Some of these inorganic photoreceptor materials have toxicity, The possibility of causing environmental problems has been pointed out, and instead, development of a low-pollution organic photoreceptor material with high sensitivity and durability is rapidly progressing.
[0007]
An electrophotographic photoreceptor using an organic photoreceptor material generally has a structure in which a charge generation layer and a charge transport layer are sequentially laminated on a conductive support. Here, the charge generation layer is a layer having a function of generating charges by absorbing light, and the charge transport layer has a function of allowing charges generated in the charge generation layer to move in the photoconductor. Is a layer. Thus, when an organic photoreceptor material is used for an electrophotographic photoreceptor, there is little risk of causing the above-mentioned environmental problems, but since there are few materials having high charge generation properties and charge transport properties at the same time, the normal charge generation layer and A two-layer structure in which a charge transport layer is laminated is required.
[0008]
In the electrophotographic process using the electrophotographic photosensitive member configured as described above, the electrophotographic photosensitive member is charged by corona discharge, and an electrostatic latent image is formed on the surface of the photosensitive member by exposing the image. The electrostatic latent image is developed using a toner charged opposite to the charge of the latent image, and this is transferred to a plain paper and fixed to perform printing. In this process, the electrophotographic photosensitive member is required to be able to hold a charge on the surface in a dark place, and to be excellent in photoconductivity that reduces the electrical resistance by light irradiation and quickly releases the surface charge. In addition, since this photoreceptor is reused by cleaning, excellent durability that can withstand repeated use is also required.
[0009]
[Problems to be solved by the invention]
As described above, materials that have been used as charge transport materials in organic thin film EL elements or electrophotographic photoreceptors do not necessarily satisfy the required characteristics, and have excellent hole transport properties. Development of highly durable charge transport materials is expected.
[0010]
Attempts have been made to use polymer materials as a means of suppressing the crystallinity of the thin film and improving heat resistance and mechanical strength. One is a low molecular weight organic material dispersed in a polymer, such as charge transport or light emission, and the other is a polymer material that has a functional molecule in the main chain or side chain. is there. An object of the present invention is to provide a charge transport material having excellent hole transport properties, heat resistance and mechanical strength, a method for producing the same, and an electroluminescence device using the same.
[0011]
[Means for Solving the Problems]
The invention of claim 1 is a polymer charge transporting material having an aromatic tertiary amine as a main chain skeleton and represented by the following general formula ( 4 ).
[Formula 4]

In the formula, n is a positive integer representing the degree of polymerization, m is a positive integer representing the number of aromatic tertiary amines (except for m = 1), and R ₁ and R ₂ may have a substituent. A good arylene group, R ₃ represents an aryl group which may have a substituent, R ₄ represents an arylene group or an alkyl group which may have a substituent, or a compound having fluorescence. The substituent is selected from the group consisting of an alkyl group, an alkoxy group, an ester group, and a cyano group. R ₅ and R _{6 each} represents an alkylene group or a carbonyl group.
[0012]
Invention of Claim 2 is obtained by Friedel-Crafts reaction of aromatic tertiary amine and halogenated organic compound, The manufacturing method of the polymeric charge transport material shown by following General formula ( 5 ) characterized by the above-mentioned It is.
[Chemical formula 5]

[0013]
The invention of claim 3 is obtained by a Friedel-Crafts reaction between an aromatic tertiary amine and a halogenated organic compound, and a method for producing a polymer charge transporting material represented by the following general formula ( 6 ) It is.
[Chemical 6]

[0014]
The invention of claim 4 is the electroluminescent device which comprises using a polymeric charge transport material according to claim 1, wherein.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is described in detail below.
The polymer charge transport material of the present invention is obtained by polycondensation (for example, Friedel-Crafts reaction) of an aromatic tertiary amine and a halogenated organic compound. For example, it can be easily synthesized by reacting approximately equimolar amounts of an aromatic tertiary amine and a halogenated organic compound in a chlorobenzene solvent using tin chloride as a catalyst.
[0016]
The Friedel-Crafts reaction is an alkyl compound or acyl compound obtained by reacting an aromatic or olefin compound with an alkyl halide or aryl halide compound in the presence of a catalyst such as aluminum chloride. It's being used. The present invention is characterized in that a polymer material having charge transport performance can be easily obtained using this Friedel-Crafts reaction.
[0017]
The polymer charge transport material of the present invention preferably has a number average molecular weight of 1,000 to 5,000,000, more preferably 10,000 to 500,000. By introducing an aromatic tertiary amine compound into the main chain skeleton, high hole transport performance can be maintained, and by using a polymer material, crystallinity is suppressed and the glass transition temperature is lower than that of a low molecular compound. The film thickness can be increased, and the thin film can be easily manufactured by a wet method or the like.
[0018]
In the polymer charge-transporting material of the present invention represented by the general formula (4) to (6), and _{R 1, R 2} is an arylene group, _{R 3} represents an aryl group. Here, the arylene group and the aryl group are an aromatic compound such as a phenyl group, a naphthyl group, a bifunylene group, or a triphenylene group, or a hetero atom such as an oxygen atom, a nitrogen atom, or a sulfur atom typified by a pyridine ring, a quinoline ring, or a thiophene ring. Specific examples include aromatic compounds containing one or more atoms. Further, the arylene group and aryl group are alkyl groups represented by fluorine, chlorine, bromine, iodine halogen atoms, methyl group, ethyl group, isopropyl group, tertiary butyl group, cyclohexyl group, trifluoromethyl group and the like. It may have a substituent such as a cyano group (including a saturated cyclic hydrocarbon group in the alkyl group), an alkoxy group represented by a methoxy group, an ethoxy group, an isopropoxy group, a tertiary butoxy group, and the like. . R ₁ to R ₃ may be the same as or different from each other.
[0019]
R ₄ is an alkyl group represented by a methyl group, an ethyl group, an isopropyl group, a tertiary butyl group, a cyclohexyl group or the like (where a saturated cyclic hydrocarbon group is also included in the alkyl group), a phenylene group, a naphthylene group, a bifunylene. Specific examples include aromatic compounds such as a group, a triphenylene group, and aromatic compounds containing one or more heteroatoms such as oxygen, nitrogen and sulfur atoms represented by pyridine ring, quinoline ring, thiophene ring, etc. Can do. Further, the fluorescent compound is not particularly limited, but a fluorescent compound having an alkyl halide is preferable for easy introduction by Friedel-Crafts reaction. For example, anthracene, benzoanthracene, fluorene, etc. Specific examples include aromatic compounds represented by fluorescence and aromatic compounds containing one or more hetero atoms such as oxygen atoms, nitrogen atoms and sulfur atoms represented by carbazole, acridone, and the like. Specific examples include laser dyes such as coumarin and DCM, and Alq and distyrylarylene derivatives used in EL elements. The above R ₄ represents fluorine, chlorine, bromine, iodine halogen atoms, methyl groups, ethyl groups, isopropyl groups, tertiary butyl groups, trifluoromethyl groups, cyclohexyl groups and other alkyl groups, methoxy groups, ethoxy groups, An alkoxy group typified by a propoxy group or the like, a cyano group, or an aryl group typified by a phenyl group, a tolyl group, a naphthyl group or the like may be used as a substituent.
[0020]
Specific examples of R ₅ and R ₆ include an alkylene group represented by a methylene group, an ethylene group, an isopropylene group, a tertiary butylene group, etc. (here, a saturated cyclic hydrocarbon group is also included in the alkylene group) or a carbonyl group. Can be mentioned.
[0021]
R ₇ includes an alkylene group represented by a methylene group, an ethylene group, an isopropylene group, a tertiary butylene group (here, a saturated cyclic hydrocarbon group is also included in the alkyl group), a phenylene group, a naphthylene group, a bifunylene group, a triphenylene group. Specific examples include aromatic compounds such as groups, and aromatic compounds containing one or more heteroatoms such as oxygen, nitrogen and sulfur atoms represented by pyridine ring, quinoline ring, thiophene ring and the like. The above R7 is fluorine, chlorine, bromine, iodine halogen atom, methyl group, ethyl group, isopropyl group, tertiary butyl group, trifluoromethyl group, cyclohexyl group or other alkyl group, methoxy group, ethoxy group, isopropoxy An alkoxy group typified by a group or the like, a cyano group, or an aryl group typified by a phenyl group, a tolyl group, a naphthyl group or the like may be used as a substituent.
[0022]
The polymer charge transporting material of the present invention described above can be applied to an organic thin film EL device and a charge transporting layer of an electrophotographic photosensitive member, and the application method is used by mixing with other charge transporting materials or light emitting materials. It is also possible. The thin film can be formed by a general method such as spin coating, casting, or printing.
[0023]
An organic EL device using a charge transporting material or a light emitting material obtained by polycondensation (Friedel-Crafts reaction) of an aromatic tertiary amine and a halogenated organic compound as described above will be described. A thin film of a phthalocyanine derivative typified by copper phthalocyanine as a hole injection / transport material is formed on a transparent or translucent transparent substrate with an anode by a vapor deposition method or a spin coating method. Next, a thin film of a polymer material synthesized by the Friedel-Crafts reaction is laminated by a wet process typified by a spin coating method. Finally, a thin film such as an organometallic complex represented by Alq or an oxadiazole derivative is formed as an electron injection / transport layer. On this organic layer, a metal having a low work function and high electrical conductivity, an alloy such as aluminum: lithium (Al: Li), magnesium: silver (Mg: Ag), or a work function such as lithium fluoride. A cathode formed by depositing a metal composed of a low metal and depositing a metal having a low work function and high electrical conductivity as described above is formed by a vapor deposition method or the like.
[0024]
The polymer charge transport material in the present invention can be used alone or laminated or mixed with a low molecular weight polymer material having other functionality and a polymer material.
[0025]
【Example】
Examples of the present invention will be described below.
Example 1
In an inert gas atmosphere, add 3.0 ml of chlorobenzene to 1.0 mM of N, N′-diphenyl-N, N′-di (para-tolyl) benzidine and 1.0 mM of a, a′-dichloro-para-xylene. 8.0 mol% tin tetrachloride was added thereto and reacted at 80 ° C. for 12 hours. This was purified by a reprecipitation method using chloroform as a good solvent and acetone as a poor solvent, to obtain a white powdery polymer charge transport material represented by the following chemical formula ( 9 ).
[0026]
[Chemical 7 ]

[0027]
FIG. 1 shows a ¹ H-NMR spectrum (using JEOL A-500 manufactured by JEOL Ltd., deuterated chloroform solvent) of the polymer charge transport material obtained as described above.
¹ H-NMR (CDCl 3, TMS) σ (ppm): 2.0 to 2.4 (6H, CH ₃ ), 3.4 to 3.9 (4H, CH ₂ ), 6.5 to 7.5 ( 28H, CH)
Further, for this polymer charge transport material, 880-PU manufactured by JASCO Corporation was used as a pump, a differential refractometer 830-RI manufactured by JASCO Corporation was used as a detector, styrene gel was used as a stationary phase, and chloroform was used. When GPC measurement was performed as the mobile phase, it was found that the weight average molecular weight was 210,000 (standard polystyrene conversion, manufactured by Showa Denko KK).
Next, when the glass transition point (Tg) of this polymer charge transporting material was measured at a heating rate of 10 ° C./min in a nitrogen atmosphere using a DSC220 manufactured by Seiko Instruments Inc., it was found to be 121 ° C. I understood. Further, a cast film made of this polymer charge transport material is formed on a platinum electrode, and this polymer charge transport is performed with Toyo Giken PS-06 using Ag / AgCl as a reference electrode in acetonitrile in a nitrogen atmosphere. As a result of measuring the oxidation potential of the material, it was found that the oxidation potential was 1.03V. The cast film showed similar oxidation-reduction waves even after repeated sweeps.
[0028]
(Example 2)
In an inert gas atmosphere, 9.0 ml of chlorobenzene was added to 1.0 mM of N, N′-diphenyl-N, N′-di (para-tolyl) benzidine and 1.0 mM of 9,10-bischloromethylanthracene. 8.0 mol% tin tetrachloride was added to the reaction mixture, and reacted at 40 ° C. for 2 hours. This was purified by a reprecipitation method using chloroform as a good solvent and acetone as a poor solvent, thereby obtaining a yellow powdery polymer charge transport material represented by the following chemical formula ( 10 ).
[0029]
[Chemical 8]

[0030]
About the polymeric charge transport material obtained as mentioned above, the < ¹ > H-NMR spectrum (JEOL A-500 made by JEOL Co., Ltd., deuterated chloroform solvent) was measured. The result is shown in FIG.
¹ H-NMR (CDCl 3, TMS) s (ppm): 0.7 to 0.9 (6H, CH ₂ ), 1.1 to 1.6 (6H, CH ₂ ), 2.2 to 2.6 ( _{4H, CH 2), 4.4~5.0 (} 4H, CH 2), 6.6~8.3 (32H, CH)
Further, when GPC measurement was performed on this polymer charge transport material, it was found that the molecular weight was 290,000. Next, when the glass transition point (Tg) of this polymer charge transport material was measured, it was found to be 144 ° C. Furthermore, as a result of measuring the oxidation potential of the polymer charge transporting material, it was found that the oxidation potential was 0.87V and 0.99V. The cast film showed similar oxidation-reduction waves even after repeated sweeps.
When this polymer charge transport material was measured for fluorescence, blue-green light having a maximum wavelength of 480 nm was observed.
[0031]
The polymer charge transporting material of the above example has a higher glass transition point than the low molecular weight material of the aromatic tertiary amine compound introduced into the main chain, and high heat resistance can be expected. Moreover, since it shows the same value as the low molecular weight material of the aromatic tertiary amine compound into which the oxidation potential is also introduced, it can be understood that the charge transport performance is maintained even when introduced into the polymer. In addition, by introducing a material having fluorescence characteristics into the main chain, a polymer material that exhibits both charge transport properties and fluorescence characteristics can be obtained.
[0032]
(Example 3)
The production of an organic EL device using a polymer material obtained by the Friedel-Crafts reaction will be described below. On the cleaned glass substrate with ITO, a thin film having a thickness of 50 nm was laminated from the toluene solution of the polymer material synthesized in Example 1 by spin coating. Further, Alq was deposited to a thickness of 50 nm as a light emitting and electron injecting / transporting layer. Finally, magnesium and silver were co-evaporated to produce a cathode. From the fabricated element, green light emission with a luminance of 8,300 cd / m ² was obtained by Alq. Furthermore, green light emission with a luminance of 20,000 cd / m ² was obtained from an element in which a triphenyldiamine derivative was sandwiched by 10 nm at the interface between the polymer layer and the light emitting layer.
[0033]
The device using the polymer charge transport material obtained in the present invention exhibits the same light emission characteristics as the device using only the low molecular weight material, and stable light emission can be seen even at the printing voltage at which the low molecular weight device breaks down. The high durability of the device could be confirmed.
[0034]
【The invention's effect】
As described above, it is possible to provide a highly heat-resistant and highly durable polymer charge transport material having an aromatic tertiary amine as a main chain and having charge transport properties and fluorescence characteristics. In addition, a method for producing a polymer charge transport material can be easily provided by Friedel-Crafts reaction of an aromatic tertiary amine and a halogenated organic compound. In addition, an EL device having high durability can be provided by using the polymer charge transport material.
[Brief description of the drawings]
FIG. 1 shows a ¹ H-NMR spectrum of a polymer charge transport material according to Example 1 of the present invention.
FIG. 2 is a diagram showing a ¹ H-NMR spectrum of a polymer charge transport material according to Example 2 of the present invention.

Claims (4)

A polymer charge transporting material having an aromatic amine as a main chain skeleton and represented by the following general formula (1).

(In the formula, n is a positive integer representing the degree of polymerization, m is a positive integer representing the number of aromatic tertiary amines (excluding m = 1), R ₁ and R ₂ have a substituent. R ₃ represents an aryl group which may have a substituent, R ₄ represents an arylene group or an alkyl group which may have a substituent, or a fluorescent compound. The group is selected from the group consisting of an alkyl group, an alkoxy group, an ester group, and a cyano group, and R ₅ and R ₆ represent an alkylene group or a carbonyl group.) A method for producing a polymer charge transporting material represented by the following general formula ( 2 ), which is obtained by a Friedel-Crafts reaction between an aromatic tertiary amine and a halogenated organic compound.

Wherein n is a positive integer representing the degree of polymerization, m is a positive integer representing the number of aromatic tertiary amines, R ₁ and R ₂ are arylene groups which may have a substituent, and R ₃ is An aryl group which may have a substituent, R ₄ is an arylene group or an alkyl group which may have a substituent, or a compound having fluorescence, R ₇ is an arylene which may have a substituent And the substituent is selected from the group consisting of an alkyl group, an alkoxy group, an ester group, and a cyano group, and R ₅ and R ₆ represent an alkylene group or a carbonyl group.) A method for producing a polymer charge transporting material represented by the following general formula ( 3 ), which is obtained by a Friedel-Crafts reaction between an aromatic tertiary amine and a halogenated organic compound.

Wherein n is a positive integer representing the degree of polymerization, m is a positive integer representing the number of aromatic tertiary amines, R ₁ and R ₂ are arylene groups which may have a substituent, and R ₃ is An aryl group which may have a substituent, R ₄ is an arylene group or an alkyl group which may have a substituent, or a compound having fluorescence, R ₇ is an arylene which may have a substituent And the substituent is selected from the group consisting of an alkyl group, an alkoxy group, an ester group, and a cyano group, and R ₅ and R ₆ represent an alkylene group or a carbonyl group.) An electronic luminescence device using the polymer charge transport material according to claim 1 .

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