JP4396115B2 - Polymer compound, 1,4-phenylenediamine derivative, charge transport material, organic electroluminescent element material, and organic electroluminescent element - Google Patents

Description

（式中、環Ａ１および環Ａ２は各々独立して、ベンゼン環、或いは任意の環が縮合したベンゼン環であり、このベンゼン環または縮合環は、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよい芳香族炭化水素環基、および置換基を有していてもよい芳香族複素環基よりなる群から選ばれる１種または２種以上の置換基で置換されていてもよい。
Ａｒ^１ないしＡｒ^８は各々独立して、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよいアミノ基、置換基を有していてもよいアルコキシカルボニル基、置換基を有していてもよい芳香族炭化水素環基、および置換基を有していてもよい芳香族複素環基よりなる群から選ばれる１種または２種以上の置換基で置換されていてもよい芳香族環を表す。
Ｘ、Ｙ^１およびＹ^２は各々独立して、下記構造式で表される部分構造から選ばれた２価の連結基を表す。）
【化９Ｂ】

（式中、Ａｒ^１１ないしＡｒ ^１７ は各々独立して、置換基を有していてもよい芳香族環を表す。）
【００２４】
本発明の電荷輸送材料は、このような本発明の高分子化合物を含むものである。
【００２５】
本発明の有機電界発光素子材料は、このような本発明の高分子化合物を含むものである。
【００２６】
本発明の有機電界発光素子は、基板上に陽極、陰極、および該両極間に存在する発光層を有する有機電界発光素子において、このような本発明の高分子化合物を含む層を有することを特徴とする。
【００２７】
即ち、本発明者らは、従来の問題点を解決し、高温において安定な発光特性を維持できる有機電界発光素子を提供するべく鋭意検討した結果、基板上に、陽極および陰極により挟持された発光層を有する有機電界発光素子において、陽極と発光層との間に、電子受容性化合物を含有し、かつ、高いＴｇを有する高分子化合物からなる層を設けることで、上記課題を解決することができることを知見し、上記一般式（II）で表される繰り返し単位を有する高分子化合物は、ガラス転移温度Ｔｇ≧ 120℃を容易に達成することができ、このような高いＴｇを有する高分子化合物と電子受容性化合物を混合して用いることで、素子の発光特性と耐熱性を同時に改善することができることを見出し、本発明を完成させた。
【００２８】
本発明の高分子化合物は電子供与性であり、この高分子化合物に電子受容性化合物を混合することにより、電荷移動が起こり、結果としてフリーキャリアである正孔が生成し、この層の電気伝導度が高くなる。このような層を設けることで、発光層と陽極との電気的接合が改善され、駆動電圧が低下すると同時に連続駆動時の安定性も向上する。
【００２９】
しかも、このような高分子化合物を主成分とする層を、塗布プロセスにて陽極上に形成することにより、前述の陽極の表面粗さが緩和され、良好な表面平滑化効果が得られ、素子作製時の短絡欠陥が防止されるという効果も奏される。
【００３０】
また、この高分子化合物はクロスリンク構造を持つため、直鎖型の高分子化合物に比べて高Ｔｇとなる。即ち、本発明の高分子化合物は、クロスリンク構造を有し、好ましくはＴｇが150℃以上であるものである。また、この高分子化合物を含む層を印刷法にて形成する場合には、化合物中のクロスリンクの割合を調整することによって、塗布液（印刷用組成物）の粘度を適切な範囲に調節することができ、膜厚を精密に制御できるため好ましい。
【００３１】
なお、本発明に係る高分子化合物と電子受容性化合物を含む層は、正孔輸送性を示す層であり、陽極と発光層との間であればどこにあっても良く、後掲の図１〜３に示す如く、陽極上に直接設けるものに何ら限定されないが、陽極（無機材料）との電気的接合が良く、耐熱性が高いというこの層の長所を十分に生かすためには、陽極と接する位置に正孔注入層として形成するのが最も有利である。
【００３２】
本発明の有機電界発光素子においては、この高分子化合物のイオン化ポテンシャルから電子受容性化合物の電子親和力を引いた値は0.7eV以下であることが好ましく、また、これらを含有する層中の電子受容性化合物の含有量は、この高分子化合物に対して0.1〜50重量％の範囲であることが好ましい。
【００３３】
本発明の有機電界発光素子において、電子受容性化合物は、下記化合物群から選ばれる化合物の少なくとも１種であることが好ましい。
【００３４】
【化１０】

【００３５】
本発明の１，４−フェニレンジアミン誘導体は、本発明の高分子化合物の合成中間体として有用な単量体であり、下記一般式（IV'）で表される。
【００３６】
【化１１】

（式中、Ｒ^６，Ｒ^７，Ｒ^９，Ｒ^１０は各々独立して、水素原子、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよいアミノ基、置換基を有していてもよいアルコキシカルボニル基、置換基を有していてもよい芳香族炭化水素環基、または置換基を有していてもよい芳香族複素環基を表し、
Ｒ^８は、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよい芳香族炭化水素環基、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。）
【００３７】
【発明の実施の形態】
以下に本発明の実施の形態を詳細に説明する。
まず、本発明の高分子化合物について説明する。
本発明の高分子化合物は、前記一般式（II）で表される繰り返し単位を有するものであり、好ましくは、前記一般式（Ｉ）および（II）で表される繰り返し単位を有するものである。
【００３８】
一般式（Ｉ）の環Ａ１および一般式（II）の環Ａ２は各々独立して、ベンゼン環（フェニレン基）、或いは任意の環が縮合したベンゼン環であり、環Ａ１，Ａ２が縮合環である場合、この縮合環としては、下記のナフタレン環等の２縮合環や、アントラセン環等の３縮合環が挙げられるが、何らこれらに限定されるものではない。
【００３９】
【化１２】

【００４０】
環Ａ１，Ａ２のベンゼン環、或いは環Ａ１，Ａ２の縮合環のベンゼン環部分および／またはベンゼン環に縮合している環は、置換基を有していてもよい。
【００４１】
この環Ａ１，Ａ２が有しうる置換基は、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよい芳香族炭化水素環基、および置換基を有していてもよい芳香族複素環基よりなる群から選ばれる１種または２種以上であり、より具体的には、置換基を有していてもよい、メチル基、エチル基等の炭素数１〜６のアルキル基；置換基を有していてもよい、ビニル基等の炭素数１〜６のアルケニル基；置換基を有していてもよい、エチニル基等の炭素数１〜６のアルキニル基；置換基を有していてもよい、ベンジル基等のアラルキル基；置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基；置換基を有していてもよい、フェニル基、ナフチル基等の芳香族炭化水素環基；置換基を有していてもよい、チエニル基等の芳香族複素環基である。
【００４２】
これらの置換基が有していてもよい置換基としては、例えば、下記の置換基群Ｚの１種または２種以上が挙げられる。
［置換基群Ｚ］
メチル基、エチル基等の炭素数１〜６のアルキル基；ビニル基等の炭素数１〜６のアルケニル基；エチニル基等の炭素数１〜６のアルキニル基；メトキシカルボニル基、エトキシカルボニル基等の炭素数２〜７のアルコキシカルボニル基；ジメチルアミノ基、ジエチルアミノ基等の炭素数１〜１０のジアルキルアミノ基；ジフェニルアミノ基、ジトリルアミノ基、カルバゾリル基等のジアリールアミノ基；フェニルメチルアミノ基等のアリールアルキルアミノ基；アセチル基等の炭素数１〜６のアシル基；フッ素原子等のハロゲン原子；トリフルオロメチル基等のハロアルキル基；フェノキシ基、ベンジルオキシ基等のアリールオキシ基；シアノ基；フェニル基、ナフチル基等の芳香族炭化水素環基
【００４３】
環Ａ１，Ａ２が有する置換基としては、より好ましくは、形成される高分子化合物のイオン化ポテンシャルを過度に低下させることがない基であり、このようなイオン化ポテンシャルの低下の問題のない置換基としてはメトキシカルボニル基、エトキシカルボニル基等の炭素数２〜７のアルコキシカルボニル基；アセチル基等の炭素数１〜６のアシル基；フッ素原子等のハロゲン原子；トリフルオロメチル基等のハロアルキル基が挙げられるが、特に好ましくは水素原子、即ち、環Ａ１，Ａ２は無置換であることが好ましい。
【００４４】
Ａｒ^１ないしＡｒ^８は各々独立して、置換されていてもよい芳香族環であり、この芳香族環としては、好ましくは５または６員環の単環または２〜３縮合環の、芳香族炭化水素環または芳香族複素環、具体的には、ベンゼン環、ナフタレン環、フェナントレン環、アントラセン環、ピリジン環、キノリン環、チオフェン環、ベンゾチオフェン環、フラン環、ピロール環、インドール環、ベンゾフラン環、カルバゾール環が挙げられる。
【００４５】
このＡｒ^１ないしＡｒ^８の芳香族炭化水素環が有しうる置換基としては、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよいアミノ基、置換基を有していてもよいアルコキシカルボニル基、置換基を有していてもよい芳香族炭化水素環基、および置換基を有していてもよい芳香族複素環基よりなる群から選ばれる１種または２種以上であり、より具体的には、置換基を有していてもよい、メチル基、エチル基等の炭素数１〜６のアルキル基；置換基を有していてもよい、ビニル基等の炭素数１〜６のアルケニル基；置換基を有していてもよい、エチニル基等の炭素数１〜６のアルキニル基；置換基を有していてもよい、ベンジル基等のアラルキル基；置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基；置換基を有していてもよいアミノ基、例えばジメチルアミノ基、ジエチルアミノ基等の炭素数１〜１０のジアルキルアミノ基；ジフェニルアミノ基、ジトリルアミノ基、カルバゾリル基等のジアリールアミノ基；フェニルメチルアミノ基等のアリールアルキルアミノ基；置換基を有していてもよい、メトキシカルボニル基；エトキシカルボニル基等の炭素数２〜７のアルコキシカルボニル基；置換基を有していてもよい、フェニル基、ナフチル基等の芳香族炭化水素環基；置換基を有していてもよい、チエニル基等の芳香族複素環基である。
【００４６】
これらの置換基が有していてもよい置換基としては、前述の置換基群Ｚの１種または２種以上が挙げられる。
【００４７】
Ａｒ^１〜Ａｒ^８が有する置換基としては、より好ましくは、形成される高分子化合物のイオン化ポテンシャルを過度に低下させることがない基であり、このようなイオン化ポテンシャルの低下の問題のない置換基としては水素原子、置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基、置換基を有していてもよい、メトキシカルボニル基、エトキシカルボニル基等の炭素数２〜７のアルコキシカルボニル基が挙げられるが、特に好ましくは水素原子、即ち、Ａｒ^１〜Ａｒ^８は無置換であることが好ましい。
【００４８】
１つの繰り返し単位中に含まれるＡｒ^１〜Ａｒ^４、或いはＡｒ^５〜Ａｒ^８は同一であっても異なっていてもよいが、高分子化合物の非晶質性の面からは異なる方が好ましく、合成が容易なことによる生産性の面からは、同一であることが好ましい。
【００４９】
Ｘ，Ｙ^１およびＹ^２は各々独立して、下記構造式で表される部分構造から選ばれた２価の連結基が挙げられる。
【００５０】
【化１３】

【００５１】
上記式中、Ａｒ^１１ないしＡｒ^１８は各々独立して、置換基を有していてもよい芳香族環、好ましくは置換基を有していてもよい、５または６員環の単独または２〜３縮合環の、芳香族炭化水素環または芳香族複素環であり、具体的には、ベンゼン環、ナフタレン環、フェナントレン環、アントラセン環、ピリジン環、キノリン環、チオフェン環、ベンゾチオフェン環、フラン環、ピロール環、インドール環、ベンゾフラン環、カルバゾール環が挙げられる。
【００５２】
このような芳香族環が有しうる置換基としては、以下にＲ^２１，Ｒ^２２として例示するものが挙げられる。
【００５３】
Ｒ^２１およびＲ^２２は各々独立して、水素原子、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアルコキシ基、置換基を有していてもよいアリールオキシ基、置換基を有していてもよいアミノ基、置換基を有していてもよい芳香族炭化水素環基、または置換基を有していてもよい芳香族複素環基を表し、より具体的には、水素原子、メチル基、エチル基等の炭素数１〜６のアルキル基；置換基を有していてもよい、ビニル基等の炭素数１〜６のアルケニル基；置換基を有していてもよい、エチニル基等の炭素数１〜６のアルキニル基；置換基を有していてもよい、ベンジル基等のアラルキル基；置換基を有していてもよい、メトキシ基、エトキシ基等の炭素数１〜６のアルコキシ基；置換基を有していてもよい、フェノキシ基、ベンジルオキシ基等のアリールオキシ基；置換基を有していてもよいアミノ基、例えばジメチルアミノ基、ジエチルアミノ基等の炭素数１〜１０のジアルキルアミノ基；ジフェニルアミノ基、ジトリルアミノ基、カルバゾリル基等のジアリールアミノ基；フェニルメチルアミノ基等のアリールアルキルアミノ基；置換基を有していてもよい、フェニル基、ナフチル基等の芳香族炭化水素環基；置換基を有していてもよい、チエニル基等の芳香族複素環基である。
【００５４】
これらの置換基が有していてもよい置換基としては、前述の置換基群Ｚの１種または２種以上が挙げられる。
【００５５】
Ａｒ^１１〜Ａｒ^１８の置換基、Ｒ^２１，Ｒ^２２として好ましいものは、水素原子（即ち、無置換）、メチル基、エチル基、メトキシ基である。
【００５６】
Ｘ、Ｙ^１、Ｙ^２は、好ましくは
【化１４】

であり、特に、
【化１５】

であることが好ましい。なお、Ｒ^１１〜Ｒ^１７は、Ａｒ^１１〜Ａｒ^１８が有しうる置換基として前述したものであり、好ましい基についても同様である。
【００５７】
前記一般式（Ｉ）で表される繰り返し単位は、下記一般式（Ｉ'）で表されることが好ましく、また、前記一般式（II）で表される繰り返し単位は、下記一般式（II'）で表されることが好ましい。
【００５８】
【化１６】

【００５９】
【化１７】

【００６０】
上記一般式（Ｉ'）中の環Ｂ１，環Ｂ２，環Ｂ４および環Ｂ５並びに上記一般式（II'）中の環Ｂ６，環Ｂ７，環Ｂ９および環Ｂ１０は各々独立して、置換されていてもよいベンゼン環、または置換基を有していてもよいナフタレン環、好ましくはベンゼン環である。このベンゼン環、ナフタレン環が有しうる置換基は、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよいアミノ基、置換基を有していてもよいアルコキシカルボニル基、置換基を有していてもよい芳香族炭化水素環基、および置換基を有していてもよい芳香族複素環基よりなる群から選ばれる１種または２種以上であり、より具体的には、置換基を有していてもよい、メチル基、エチル基等の炭素数１〜６のアルキル基；置換基を有していてもよい、ビニル基等の炭素数１〜６のアルケニル基；置換基を有していてもよい、エチニル基等の炭素数１〜６のアルキニル基；置換基を有していてもよい、ベンジル基等のアラルキル基；置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基；置換基を有していてもよいアミノ基、例えばジメチルアミノ基、ジエチルアミノ基等の炭素数１〜１０のジアルキルアミノ基；ジフェニルアミノ基、ジトリルアミノ基、カルバゾリル基等のジアリールアミノ基；フェニルメチルアミノ基等のアリールアルキルアミノ基；置換基を有していてもよい、メトキシカルボニル基；メトキシカルボニル基等の炭素数２〜７のアルコキシカルボニル基；置換基を有していてもよい、フェニル基、ナフチル基等の芳香族炭化水素環基；置換基を有していてもよい、チエニル基等の芳香族複素環基である。
【００６１】
これらの置換基が有していてもよい置換基としては、前述の置換基群Ｚの１種または２種以上が挙げられる。
【００６２】
環Ｂ１，Ｂ２，Ｂ４，Ｂ５，Ｂ６，Ｂ７，Ｂ９，Ｂ１０が有する置換基としては、より好ましくは、形成される高分子化合物のイオン化ポテンシャルを過度に低下させることがない基であり、このようなイオン化ポテンシャルの低下の問題のない置換基としては水素原子、置換基を有していてもよい、アセチル基等の炭素数２〜７のアシル基、置換基を有していてもよい、メトキシカルボニル基、エトキシカルボニル基等の炭素数２〜７のアルコキシカルボニル基が挙げられるが、特に好ましくは水素原子、即ち、環Ｂ１，Ｂ２，Ｂ４，Ｂ５，Ｂ６，Ｂ７，Ｂ９，Ｂ１０は無置換であることが好ましい。
【００６３】
１つの繰り返し単位中に含まれる環Ｂ１，Ｂ２，Ｂ４，Ｂ５、或いは環Ｂ６，Ｂ７，Ｂ９，Ｂ１０は各々同一であっても異なるものであってもよいが、高分子化合物の非晶質性の点からは互いに異なる方が好ましい。
【００６４】
前記一般式（Ｉ'）中の環Ｂ３および前記一般式（II'）中の環Ｂ８は、置換されていてもよいベンゼン環である。
【００６５】
環Ｂ３，Ｂ８が有しうる置換基としては、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよい芳香族炭化水素環基、および置換基を有していてもよい芳香族複素環基よりなる群から選ばれる１種または２種以上であり、より具体的には、置換基を有していてもよい、メチル基、エチル基等の炭素数１〜６のアルキル基；置換基を有していてもよい、ビニル基等の炭素数１〜６のアルケニル基；置換基を有していてもよい、エチニル基等の炭素数１〜６のアルキニル基；置換基を有していてもよい、ベンジル基等のアラルキル基；置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基；置換基を有していてもよい、フェニル基、ナフチル基等の芳香族炭化水素環基；置換基を有していてもよい、チエニル基等の芳香族複素環基である。
【００６６】
これらの置換基が有していてもよい置換基としては、前述の置換基群Ｚの１種または２種以上が挙げられる。
【００６７】
環Ｂ３，Ｂ８が有する置換基としては、より好ましくは、形成される高分子化合物のイオン化ポテンシャルを過度に低下させることがない基であり、このようなイオン化ポテンシャルの低下の問題のない置換基としては水素原子、置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基が挙げられるが、特に好ましくは水素原子、即ち、環Ｂ３，Ｂ８は無置換であることが好ましい。
【００６８】
このような本発明の高分子化合物は、好ましくは下記一般式（IV）で表される単量体、より好ましくは下記一般式（III）および下記一般式（IV）で表される単量体より合成される。特に好ましくは、下記一般式（IV'）で表される本発明の１，４−フェニレンジアミン誘導体より合成され、とりわけ好ましくは下記一般式（III'）および下記一般式（IV'）で表される１，４−フェニレンジアミン誘導体より合成される。
【００６９】
【化１８】

（上記式中、環Ｂ１ないし環Ｂ１０は前記一般式（Ｉ'）および一般式（II'）におけると同義である。）
【００７０】
【化１９】

【００７１】
【化２０】

【００７２】
上記式中Ｒ^１，Ｒ^２，Ｒ^４，Ｒ^５，Ｒ^６，Ｒ^７，Ｒ^９，Ｒ^１０は各々独立して、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよいアミノ基、置換基を有していてもよいアルコキシカルボニル基、置換基を有していてもよい芳香族炭化水素環基、または置換基を有していてもよい芳香族複素環基であり、より具体的には、置換基を有していてもよい、メチル基、エチル基等の炭素数１〜６のアルキル基；置換基を有していてもよい、ビニル基等の炭素数１〜６のアルケニル基；置換基を有していてもよい、エチニル基等の炭素数１〜６のアルキニル基；置換基を有していてもよい、ベンジル基等のアラルキル基；置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基；置換基を有していてもよいアミノ基、例えばジメチルアミノ基、ジエチルアミノ基等の炭素数１〜１０のジアルキルアミノ基；ジフェニルアミノ基、ジトリルアミノ基、カルバゾリル基等のジアリールアミノ基；フェニルメチルアミノ基等のアリールアルキルアミノ基；置換基を有していてもよい、メトキシカルボニル基；エトキシカルボニル基等の炭素数２〜７のアルコキシカルボニル基；置換基を有していてもよい、フェニル基、ナフチル基等の芳香族炭化水素環基；置換基を有していてもよい、チエニル基等の芳香族複素環基である。
【００７３】
また、Ｒ^３，Ｒ^８は、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよい芳香族炭化水素環基、または置換基を有していてもよい芳香族複素環基であり、より具体的には、置換基を有していてもよい、メチル基、エチル基等の炭素数１〜６のアルキル基；置換基を有していてもよい、ビニル基等の炭素数１〜６のアルケニル基；置換基を有していてもよい、エチニル基等の炭素数１〜６のアルキニル基；置換基を有していてもよい、ベンジル基等のアラルキル基；置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基；置換基を有していてもよい、フェニル基、ナフチル基等の芳香族炭化水素環基；置換基を有していてもよい、チエニル基等の芳香族複素環基である。
【００７４】
これらの置換基が有していてもよい置換基としては、前述の置換基群Ｚの１種または２種以上が挙げられる。
【００７５】
Ｒ^１ないしＲ^５，Ｒ^６ないしＲ^１０としては、好ましくは水素原子（即ち、無置換）、或いは、前述のイオン化ポテンシャルの低下の問題のない、置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基等の置換基が挙げられ、特に好ましくは水素原子（即ち、無置換）である。
【００７６】
以下に本発明の高分子化合物の繰り返し単位の好ましい具体例を示すが、本発明は何らこれらに限定されるものではない。
【００７７】
前記一般式（II'）で表される繰り返し単位としては、次のようなものが好ましい。
【化２１】

【００７８】
前記一般式（Ｉ'）で表される繰り返し単位としては次のようなものが好ましい。
【化２２】

【００７９】
【化２３】

【００８０】
本発明の高分子化合物は、
▲１▼ １種または２種以上の一般式（II）で表される繰り返し単位からなる高分子化合物
および
▲２▼ １種または２種以上の一般式（Ｉ）で表される繰り返し単位と、１種または２種以上の一般式（II）で表される繰り返し単位からなる高分子化合物、
を包含し、好ましくは上記▲２▼に相当する共重合体である。具体的には、一般式（Ｉ）の繰り返し単位に対して0.1〜10モル％の割合で一般式（II）の繰り返し単位を含有する高分子化合物が、有機電界発光素子の製造に特に好ましい。
【００８１】
この一般式（II）で表される繰り返し単位を含む本発明の高分子化合物、すなわちクロスリンク構造を含む本発明の高分子化合物は、前述のように高Ｔｇおよび該高分子化合物を含む塗布液の粘度の点においても、好ましいものである。
【００８２】
更に、本発明の高分子化合物は、その性能を損なわない範囲で、他の種々のモノマー由来の繰り返し単位を含有していてもよい。他のモノマー由来の繰り返し単位としては、例えば前記一般式（Ｉ）で表される繰り返し単位において、
【化２４】

の代わりに
【化２５】

とした繰り返し単位が挙げられるが、有機電界発光素子の製造に有用な化合物としては、前記一般式（Ｉ）および（II）で表される繰り返し単位の含有量が、１分子あたり通常20モル%以上、好ましくは50モル%以上、さらに好ましくは80モル%以上のものである。
【００８３】
なお、上記式中、Ｒ^ａ，Ｒ^ｂ，Ｒ^ｃは、各々独立して、置換基を有していてもよいアルキル基、置換基を有していてもよいアルケニル基、置換基を有していてもよいアルキニル基、置換基を有していてもよいアラルキル基、置換基を有していてもよいアシル基、置換基を有していてもよいアミノ基、置換基を有していてもよいアルコキシカルボニル基、置換基を有していてもよい芳香族炭化水素環基、または置換基を有していてもよい芳香族複素環基であり、より具体的には、置換基を有していてもよい、メチル基、エチル基等の炭素数１〜６のアルキル基；置換基を有していてもよい、ビニル基等の炭素数１〜６のアルケニル基；置換基を有していてもよい、エチニル基等の炭素数１〜６のアルキニル基；置換基を有していてもよい、ベンジル基等のアラルキル基；置換基を有していてもよい、アセチル基等の炭素数１〜６のアシル基；置換基を有していてもよいアミノ基、例えばジメチルアミノ基、ジエチルアミノ基等の炭素数１〜１０のジアルキルアミノ基；ジフェニルアミノ基、ジトリルアミノ基、カルバゾリル基等のジアリールアミノ基；フェニルメチルアミノ基等のアリールアルキルアミノ基；置換基を有していてもよい、メトキシカルボニル基；エトキシカルボニル基等の炭素数２〜７のアルコキシカルボニル基；置換基を有していてもよい、フェニル基、ナフチル基等の芳香族炭化水素環基；置換基を有していてもよい、チエニル基等の芳香族複素環基である。
【００８４】
これらの置換基が有していてもよい置換基としては、前述の置換基群Ｚの１種または２種以上が挙げられる。
【００８５】
これらの高分子化合物のうち、特に重量平均分子量が1,000〜1,000,000のものが有機電界発光素子の製造に有用である。また、この高分子化合物を含む層を、塗布法により形成する場合には、架橋度により差があるが、通常は、溶解性の点から重量平均分子量が10,000〜200,000程度のものが好ましい。
【００８６】
本発明の高分子化合物は、例えば、先ずヒドロキシフェニル基を有する１，４−フェニレンジアミン誘導体を合成し、それと、４，４’−ジフルオロベンゾフェノン、ビス（４−フルオロフェニル）スルホン等の芳香族二フッ化物とを反応させることにより得られる。
【００８７】
本発明の高分子化合物は、高い電荷輸送性を有するため、電荷輸送材料として電子写真感光体、有機電界発光素子、光電変換素子、有機太陽電池、有機整流素子等に好適に使用できる。特に正孔輸送性に優れることから、正孔輸送材料として好適である。
【００８８】
また本発明の高分子化合物を用いることにより、耐熱性に優れ、長期間安定に駆動（発光）する有機電界発光素子が得られるため、有機電界発光素子材料として好適である。
【００８９】
次に、図面を参照して本発明の有機電界発光素子の実施の形態を詳細に説明する。
【００９０】
図１〜３は本発明の有機電界発光素子の実施の形態を示す模式的な断面図であり、１は基板、２は陽極、３は正孔注入層、４は正孔輸送層、５は発光層、６は電子輸送層、７は陰極を各々表わす。
【００９１】
基板１は有機電界発光素子の支持体となるものであり、石英やガラスの板、金属板や金属箔、プラスチックフィルムやシートなどが用いられる。特にガラス板や、ポリエステル、ポリメタクリレート、ポリカーボネート、ポリスルホンなどの透明な合成樹脂の板が好ましい。合成樹脂基板を使用する場合にはガスバリア性に留意する必要がある。基板のガスバリア性が低すぎると、基板を通過する外気により有機電界発光素子が劣化することがあるので好ましくない。このため、合成樹脂基板のどちらか片側もしくは両側に緻密なシリコン酸化膜等を設けてガスバリア性を確保してもよい。
【００９２】
基板１上には陽極２が設けられるが、陽極２は正孔注入層３への正孔注入の役割を果たすものである。この陽極２は、通常、アルミニウム、金、銀、ニッケル、パラジウム、白金等の金属、インジウムおよび／またはスズの酸化物などの金属酸化物、ヨウ化銅などのハロゲン化金属、カーボンブラック等により構成される。陽極２の形成は通常、スパッタリング法、真空蒸着法などにより行われることが多い。また、銀などの金属微粒子、ヨウ化銅などの微粒子、カーボンブラック、導電性の金属酸化物微粒子等を適当なバインダー樹脂溶液に分散し、基板１上に塗布することにより陽極２を形成することもできる。陽極２は異なる物質で積層して形成することも可能である。陽極２の厚みは、必要とされる透明性により異なる。透明性が必要とされる場合は、可視光の透過率を、通常、60％以上、好ましくは80％以上とすることが望ましく、この場合、陽極２の厚みは、通常、1000nm以下、好ましくは 500nm以下であり、下限は10nm程度、好ましくは20nm程度である。不透明でよい場合には陽極２は基板１と同一でもよい。また、さらには上記の陽極２の上に異なる導電材料を積層することも可能である。
【００９３】
本発明では、図１の素子構造においては、陽極２の上に正孔注入層３が設けられる。この正孔注入層３に用いられる材料に要求される条件としては、陽極２からの正孔注入効率が高く、かつ、注入された正孔を効率よく輸送することができる材料であることが挙げられる。そのためには、イオン化ポテンシャルが小さく、可視光の光に対して透明性が高く、しかも正孔移動度が大きく、さらに安定性に優れ、トラップとなる不純物が製造時や使用時に発生しにくいことが要求される。上記の一般的要求以外に、車載表示用の応用を考えた場合、素子にはさらに 120℃以上の耐熱性が要求される。
【００９４】
本発明の有機電界発光素子は、好ましくはこの正孔注入層３が、前記一般式（II）で表される繰り返し単位、或いは、前記一般式（Ｉ）および（II）で表される繰り返し単位を有する本発明の高分子化合物と、電子受容性化合物とを含有するものである。
【００９５】
本発明においては、通常、 120℃以上のＴｇを有する本発明の高分子化合物と電子受容性化合物を混合して用いることで、素子の発光特性と耐熱性を同時に改善することを可能とした。即ち、電子供与性の前記高分子化合物に電子受容性化合物を混合することにより、電荷移動が起こり、結果としてフリーキャリアである正孔が生成し、正孔注入層の電気電導度が高くなる。このため、発光層５と陽極２との電気的接合が、本発明による正孔注入層３を設けることで改善され、駆動電圧が低下すると同時に連続駆動時の安定性も向上する。また、120℃以上のＴｇを有する高分子化合物を正孔注入層３の母体とすることにより、素子の耐熱性も大きく改善される。
【００９６】
しかも、このような本発明の高分子化合物を主成分とする正孔注入層３を、塗布プロセスにて陽極２上に形成することにより、前述の陽極２の表面粗さが緩和され、良好な表面平滑化効果が得られ、素子作製時の短絡欠陥が防止されるという効果も奏される。
【００９７】
正孔注入層３に、本発明の高分子化合物と組み合わせて用いる電子受容性化合物としては、該高分子化合物との間で電荷移動を起こすものであればよいが、本発明者らが鋭意検討した結果、正孔注入層３に用いる本発明の高分子化合物のイオン化ポテンシャル：ＩＰ（本発明の高分子化合物）、と電子受容性化合物（アクセプタ）の電子親和力：ＥＡ（アクセプタ）の２つの物性値が、
ＩＰ（本発明の高分子化合物）−ＥＡ（アクセプタ）≦ 0.7eV、
の関係式で表される時に、本発明の目的に特に有効であることを見出した。
【００９８】
このことを図４のエネルギー準位図を用いて説明する。一般に、イオン化ポテンシャルおよび電子親和力は真空準位を基準として決定される。イオン化ポテンシャルは物質のＨＯＭＯ（最高被占分子軌道）レベルにある電子を真空準位に放出するのに必要なエネルギーで定義され、電子親和力は真空準位にある電子が物質のＬＵＭＯ（最低空分子軌道）レベルに落ちて安定化するエネルギーで定義される。
【００９９】
図４に示す本発明の高分子化合物のＨＯＭＯレベルのイオン化ポテンシャルと、電子受容性化合物のＬＵＭＯレベルの電子親和力の差が 0.7eV以下であることが好ましい。イオン化ポテンシャルは光電子分光法で直接測定されるか、電気化学的に測定した酸化電位を基準電極に対して補正しても求められる。後者の方法の場合は、例えば、飽和甘コウ電極（ＳＣＥ）を基準電極として用いたとき、
イオン化ポテンシャル＝酸化電位（vs.SCE）＋4.3 eV、
で表される（“Molecular Semiconductors”, Springer-Verlag, 1985年、98頁）。電子親和力は、上述のイオン化ポテンシャルから光学的バンドギャップを差し引いて求められるか、電気化学的な還元電位から上記の式で同様に求められる。
【０１００】
前記イオン化ポテンシャルと電子親和力の関係式は、酸化電位と還元電位を用いて、
（本発明の高分子化合物の酸化電位）−（アクセプタの還元電位）≦ 0.7Ｖ、と表現することもできる。
【０１０１】
また、正孔注入層３中の電子受容性化合物の含有量は、本発明の高分子化合物に対して0.1〜50重量％の範囲にあることが好ましい。さらに好ましくは、1〜30重量％の濃度範囲が実用特性上望ましい。
【０１０２】
電子受容性化合物としては、前述の関係を満たすものであれば特に限定はされないが、好ましい例を、以下に省略名とともに示す。
【０１０３】
【化２６】

【０１０４】
本発明の高分子化合物と電子受容性化合物を含有する正孔注入層３は塗布法により前記陽極２上に形成される。即ち、前記一般式（II）で表される繰り返し単位、或いは、前記一般式(Ｉ)および（II）で表される繰り返し単位を有する本発明の高分子化合物と電子受容性化合物の所定量に、必要により正孔のトラップにならないバインダー樹脂や塗布性改良剤などの添加剤を添加し、適当な溶媒に溶解して塗布溶液を調製し、スピンコート法、ディップコート法やインクジェット法などの方法により陽極２上に塗布し、乾燥して正孔注入層３を形成する。
【０１０５】
正孔注入・輸送能の点から、正孔注入層３中の本発明の高分子化合物と電子受容性化合物との合計の含有量は２０重量％以上、特に５０重量％以上であることが好ましい。
【０１０６】
正孔注入層３の膜厚の上限は、通常1000nm、好ましくは500 nmであり、下限は、通常5 nm、好ましくは10nmである。
【０１０７】
正孔注入層３の上には発光層５が設けられる。発光層５は、電界を与えられた電極間において陰極７からの注入された電子と正孔注入層３から輸送された正孔を効率よく再結合し、かつ、再結合により効率よく発光する材料から形成される。
【０１０８】
このような条件を満たす材料としては、８−ヒドロキシキノリンのアルミニウム錯体などの金属錯体（特開昭５９−１９４３９３号公報）、１０−ヒドロキシベンゾ〔ｈ〕キノリンの金属錯体（特開平６−３２２３６２号公報）、ビススチリルベンゼン誘導体（特開平１−２４５０８７号公報、同２−２２２４８４号公報）、ビススチリルアリーレン誘導体（特開平２−２４７２７８号公報）、（２−ヒドロキシフェニル）ベンゾチアゾールの金属錯体（特開平８−３１５９８３号公報）、シロール誘導体等が挙げられる。これらの発光層材料は、通常は真空蒸着法により正孔注入層３上に積層される。
【０１０９】
素子の発光効率を向上させるとともに発光色を変える目的で、例えば、８−ヒドロキシキノリンのアルミニウム錯体をホスト材料として、クマリン等のレーザ用蛍光色素をドープすること（J. Appl. Phys., 65巻, 3610頁, 1989年）等が行われている。
【０１１０】
素子の駆動寿命を改善する目的においても、前記発光層材料をホスト材料として、蛍光色素をドープすることは有効である。例えば、８−ヒドロキシキノリンのアルミニウム錯体などの金属錯体をホスト材料として、ルブレンに代表されるナフタセン誘導体（特開平４−３３５０８７号公報）、キナクリドン誘導体（特開平５−７０７７３号公報）、ペリレン等の縮合多環芳香族炭化水素環（特開平５−１９８３７７号公報）を、ホスト材料に対して 0.1〜10重量％ドープすることにより、素子の発光特性、特に駆動安定性を大きく向上させることができる。発光層のホスト材料に上記ナフタセン誘導体、キナクリドン誘導体、ペリレン等の蛍光色素をドープする方法としては、共蒸着による方法と蒸着源を予め所定の濃度で混合しておく方法がある。
【０１１１】
高分子系の発光層材料としては、先に挙げたポリ（ｐ−フェニレンビニレン）、ポリ［２−メトキシ−５−（２−エチルヘキシルオキシ）−１，４−フェニレンビニレン］、ポリ（３−アルキルチオフェン）等の高分子材料や、ポリビニルカルバゾール等の高分子に発光材料と電子移動材料を混合した系等が挙げられる。これらの材料は正孔注入層３と同様にスピンコートやディップコート等の方法により正孔注入層３上に塗布して薄膜化される。
【０１１２】
発光層５の膜厚の上限は、通常200 nm、好ましくは100 nmであり、下限は通常10nm、好ましくは30nmである。
【０１１３】
素子の発光特性を向上させるために、図２に示す様に、正孔輸送層４を正孔注入層３と発光層５との間に設けたり、さらには、図３に示す様に電子輸送層６を発光層５と陰極７の間に設けるなどして機能分離型の有機電解発光素子とすることが行われる。
【０１１４】
図２および図３の機能分離型素子において、正孔輸送層４の材料としては、正孔注入層３からの正孔注入効率が高く、かつ、注入された正孔を効率よく輸送することができる材料であることが必要である。そのためには、イオン化ポテンシャルが小さく、しかも正孔移動度が大きく、さらに安定性に優れ、トラップとなる不純物が製造時や使用時に発生しにくいことが要求される。また、発光層５と直接接する層であるために、発光を消光する物質が含まれていないことが望ましい。
【０１１５】
このような正孔輸送材料としては、例えば、４，４’−ビス［Ｎ−（９−ナフチル）−Ｎ−フェニルアミノ］ビフェニルで代表される２個以上の３級アミンを含み２個以上の縮合芳香族炭化水素環が窒素原子に置換した芳香族ジアミン（特開平５−２３４６８１号公報）、４，４’，４”−トリス（１−ナフチルフェニルアミノ）トリフェニルアミン等のスターバースト構造を有する芳香族アミン化合物（J. Lumin., 72-74巻、985頁、1997年）、トリフェニルアミンの四量体から成る芳香族アミン化合物（Chem.Commun., 2175頁、1996年）、２，２’，７，７’−テトラキス−（ジフェニルアミノ）−９，９’−スピロビフルオレン等のスピロ化合物（Synth. Metals, 91巻、209頁、1997年）等が挙げられる。これらの化合物は、単独で用いてもよいし、必要に応じて２種以上を混合して用いてもよい。
【０１１６】
上記の化合物以外に、正孔輸送層４の材料として、ポリビニルカルバゾール、ポリビニルトリフェニルアミン（特開平７−５３９５３号公報）、テトラフェニルベンジジンを含有するポリアリーレンエーテルサルホン（Polym. Adv. Tech., 7巻、33頁、1996年）等の高分子材料が挙げられる。
【０１１７】
正孔輸送層４は、上記の正孔輸送材料を塗布法あるいは真空蒸着法により前記正孔注入層３上に積層することにより形成される。
【０１１８】
塗布法の場合は、正孔輸送材料の１種または２種以上と、必要により正孔のトラップにならないバインダー樹脂や塗布性改良剤などの添加剤とを添加し、適当な溶媒に溶解して塗布溶液を調製し、スピンコート法などの方法により陽極２上に塗布し、乾燥して正孔輸送層４を形成する。この場合、バインダー樹脂としては、ポリカーボネート、ポリアリレート、ポリエステル等を用いることができる。バインダー樹脂は添加量が多いと正孔移動度を低下させるので、少ない方が望ましく、通常、正孔輸送層４中の割合で５０重量％以下が好ましい。
【０１１９】
真空蒸着法の場合には、正孔輸送材料を真空容器内に設置されたルツボに入れ、真空容器内を適当な真空ポンプで10^-4Pa程度にまで排気した後、ルツボを加熱して、正孔輸送材料を蒸発させ、ルツボと向き合って置かれた、正孔注入層３が形成された基板１上に正孔輸送層４を形成させる。
【０１２０】
正孔輸送層４の膜厚の上限は、通常300 nm、好ましくは100 nmであり、下限は通常10nm、好ましくは30nmである。このように薄い膜を一様に形成するためには、一般に真空蒸着法がよく用いられる。
【０１２１】
有機電界発光素子の発光効率をさらに向上させる方法として、図３に示すように発光層４の上にさらに電子輸送層６を積層することもできる。この電子輸送層６に用いられる化合物には、陰極７からの電子注入が容易で、電子の輸送能力がさらに大きいことが要求される。この様な電子輸送材料としては、既に発光層材料として挙げた８−ヒドロキシキノリンのアルミ錯体、オキサジアゾール誘導体（Appl. Phys. Lett., 55巻, 1489頁, 1989年） やそれらをポリメタクリル酸メチル（ＰＭＭＡ）等の樹脂に分散した系、フェナントロリン誘導体（特開平５−３３１４５９号公報）、２−ｔ−ブチル−９，１０−Ｎ，Ｎ’−ジシアノアントラキノンジイミン、ｎ型水素化非晶質炭化シリコン、ｎ型硫化亜鉛、ｎ型セレン化亜鉛等が挙げられる。
【０１２２】
電子輸送層６の膜厚の上限は、通常200 nm、好ましくは100 nmであり、下限は通常5nm、好ましくは10nmである。
【０１２３】
陰極７は、発光層５に電子を注入する役割を果たす。陰極７の形成材料としては、前記陽極２に使用される材料を用いることが可能であるが、効率よく電子注入を行なうには、仕事関数の低い金属が好ましく、スズ、マグネシウム、インジウム、カルシウム、アルミニウム、銀等の適当な金属またはそれらの合金が用いられる。具体例としては、マグネシウム−銀合金、マグネシウム−インジウム合金、アルミニウム−リチウム合金等の低仕事関数合金電極が挙げられる。さらに、陰極７と発光層５または電子輸送層６の界面にＬｉＦ、ＭｇＦ_２、Ｌｉ_２Ｏ等の極薄絶縁膜（0.1〜5nm）を挿入することも、素子の効率を向上させる有効な方法である（Appl. Phys. Lett., 70巻，152頁，1997年；特開平１０−７４５８６号公報；IEEE Trans. Electron. Devices，44巻，1245頁，1997年）。
【０１２４】
陰極７の膜厚は通常、陽極２と同様である。低仕事関数金属から成る陰極を保護する目的で、この上にさらに、仕事関数が高く大気に対して安定な金属層を積層することは素子の安定性を増す。この目的のために、アルミニウム、銀、銅、ニッケル、クロム、金、白金等の金属が使われる。
【０１２５】
図１〜３は、本発明で採用される素子構造の一例であって、本発明は何ら図示のものに限定されるものではない。例えば、図１とは逆の構造、即ち、基板上に陰極７、発光層５、正孔注入層３、陽極２の順に積層することも可能であり、既述したように少なくとも一方が透明性の高い２枚の基板の間に本発明の有機電界発光素子を設けることも可能である。同様に、図２および図３に示した前記各層構成とは逆の構造に積層することも可能である。
【０１２６】
更に、本発明の有機電界発光素子の性能を損なわない限り、図１、図２および図３に示した各層間に任意の層を有していてもよい。
【０１２７】
このような本発明の有機電界発光素子は、単一の素子、アレイ状に配置された構造からなる素子、陽極と陰極がＸ−Ｙマトリックス状に配置された構造のいずれにも適用することができる。
【０１２８】
【実施例】
次に、本発明を合成例、実験例、実施例および比較例によって更に具体的に説明するが、本発明はその要旨を超えない限り、以下の実施例の記載に限定されるものではない。
【０１２９】
まず、一般式（Ｉ），（II）で表される繰り返し単位を有する高分子化合物の原料となる、１，４−フェニレンジアミン誘導体の合成例を示す。
【０１３０】
合成例１
（１−１）Ｎ，Ｎ'−ジフェニル−Ｎ，Ｎ'−ビス（４−メトキシフェニル）−１，４−フェニレンジアミン（ＢＭＰＰ）の合成
【０１３１】
【化２７】

【０１３２】
Ｎ，Ｎ'−ジフェニル−１，４−フェニレンジアミン（７７．０ミリモル）と４−ヨードアニソール（２３１ミリモル）とをテトラグライム１５０ミリリットルに溶かし、銅粉末（１５４ミリモル）および炭酸カリウム（１１２ミリモル）の存在下、窒素雰囲気中２００℃で８時間反応を行った。その結果、式（Ｖ）で示されるＢＭＰＰ（３４．８ｇ、収率９６％）を得た。
【０１３３】
（１−２）Ｎ，Ｎ'−ジフェニル−Ｎ，Ｎ'−（４−ヒドロキシフェニル）−１，４−フェニレンジアミン（ＢＨＰＰ）の合成
【０１３４】
【化２８】

【０１３５】
ＢＭＰＰ（５０．０ミリモル）を３６０ミリリットルの塩化メチレンに溶かし、窒素雰囲気下、ドライアイス−エタノールバスで系内を−６５℃以下に冷やし、これに三臭化ほう素（１００ミリモル）の塩化メチレン溶液（１００ミリリットル）を滴下した。滴下終了後、冷媒バスを外し２時間撹拌した後、酢酸エチルで抽出し、シリカゲルカラムクロマトフラフィーによって精製した。その結果、式（VI）で示されるＢＨＰＰ（１６．２ｇ、収率７３％）を得た。
【０１３６】
以下に、ＢＨＰＰの^１Ｈ−ＮＭＲ（ＤＭＳＯ−ｄ_６）データを示す。
９．３６１（２Ｈ，Ｓ）
７．１８９（４Ｈ，ｄｄ，Ｊ＝６．７，６．６）
６．９３６（４Ｈ，ｄｄ，Ｊ＝５．７，１．７）
６．８７５（４Ｈ，Ｓ）
６．８６５−６．８３７（６Ｈ，ｍ）
６．７５１（４Ｈ，ｄｄ，Ｊ＝５．７，１．７）
【０１３７】
合成例２
本発明の１，４−フェニレンジアミン誘導体：（２−１）Ｎ−フェニル−Ｎ，Ｎ'，Ｎ'−トリス（４−メトキシフェニル）−１，４−フェニレンジアミン（ＴＭＰＰ）の合成
【０１３８】
【化２９】

【０１３９】
Ｎ−フェニル−１，４−フェニレンジアミン（１０．０ミリモル）と４−ヨードアニソール（４５．０ミリモル）とをテトラグライム２０ミリリットルに溶かし、銅粉末（３０．０ミリモル）および炭酸カリウム（２２．５ミリモル）の存在下、窒素雰囲気中２００℃で７時間反応を行い、翌日、銅粉末（１５．０ミリモル）および炭酸カリウム（１５．０ミリモル）を反応系中に加え、窒素雰囲気中２００℃で６時間反応を行った後、トルエンで抽出し、シリカゲルカラムクロマトグラフィーによって精製した。その結果、式（VII）で示されるＴＭＰＰ（２．２ｇ、収率４４％）を得た。
【０１４０】
（２−２）Ｎ−フェニル−Ｎ，Ｎ'，Ｎ'−トリス（４−ヒドロキシフェニル）−１，４−フェニレンジアミン（ＴＨＰＰ）の合成
【０１４１】
【化３０】

【０１４２】
ＴＭＰＰ（４．３ミリモル）を３５ミリリットルの塩化メチレンに溶かし、窒素雰囲気下、ドライアイス−エタノールバスで系内を−６５℃以下に冷やし、これに三臭化ほう素（１４ミリモル）の塩化メチレン溶液（１４ミリリットル）を滴下した。滴下終了後、冷媒バスを外し２時間撹拌した後、酢酸エチルで抽出し、シリカゲルカラムクロマトフラフィーによって精製した。その結果、式（VIII）で示されるＴＨＰＰ（１．１ｇ、収率５６％）を得た。
【０１４３】
以下に、ＴＨＰＰの^１Ｈ−ＮＭＲ（ＤＭＳＯ−ｄ_６）データを示す。
９．３１４（１Ｈ，Ｓ）
９．２３９（２Ｈ，Ｓ）
７．１４９（２Ｈ，ｄｄ，Ｊ＝６．６，６．４）
６．９２７−６．６６２（１９Ｈ，ｍ）
【０１４４】
次に高分子化合物の合成例を示す。
【０１４５】
合成例３
１，４−フェニレンジアミン含有高分子化合物（ＰＰＰＥＫ）の合成
【０１４６】
【化３１】

【０１４７】
ＢＨＰＰ（２０．０ミリモル）と４，４'−ジフルオロベンゾフェノン（２０．０ミリモル）とを２００ミリリットルの１−メチル２−ピロリジノン（ＮＭＰ）に溶かし、炭酸カリウム（１２０ミリモル）の存在下、窒素雰囲気中１４５℃で２０時間、縮合反応させた。放冷後、酢酸１０ミリリットルを反応系に加え、メタノール中に放出し、得られたポリマーを水洗いし、無機塩を除いた。６０℃で減圧乾燥させた後、ポリマーを３００ミリリットルのクロロホルムに溶かし、メタノールに放出し再沈殿させた。最後に、４００ミリリットルのアセトンで懸洗することにより、低分子量成分を除き、繰り返し単位（IX）からなるホモポリマーＰＰＰＥＫ（収量１１．８ｇ、収率９５％）を得た。
【０１４８】
このポリマーのＴｇは１８３℃、窒素雰囲気下の熱分解温度は５５０℃以上であり、重量平均分子量（Ｍｗ）は４６，７００、数平均分子量（Ｍｎ）７，５２０であった。なお、分子量はクロロホルム中でＧＰＣ測定により、ポリスチレンを標準試料として求めた。
【０１４９】
合成例４
本発明の高分子化合物：分岐型１，４−フェニレンジアミン含有高分子化合物（ＰＰＰＥＫ−ｂ３）の合成
【０１５０】
【化３２】

【０１５１】
ＢＨＰＰ（４．７８ミリモル）とＴＨＰＰ（０．１５ミリモル）と４，４'−ジフルオロベンゾフェノン（５．００ミリモル）とを３９ミリリットルのＮＭＰに溶かし、炭酸カリウム（２３．１ミリモル）の存在下、窒素雰囲気中１４５℃で２０時間、縮合反応させた。放冷後、酢酸２ミリリットルを反応系に加え、メタノール中に放出し、得られたポリマーを水洗いし、無機塩を除いた。６０℃で減圧乾燥させた後、ポリマーを１００ミリリットルのクロロホルムに溶かし、メタノールに放出し再沈殿させた。最後に、アセトンでソックスレー抽出することにより、低分子量成分を除き、繰り返し単位（IX）で示されるＰＰＰＥＫ主鎖に対し、繰り返し単位（X）で表される分岐ユニットを理論上３モル％含有するＰＰＰＥＫ−ｂ３（収量１．７８ｇ、収率約７４％）を得た。
【０１５２】
このポリマーのＴｇは１９０℃、窒素雰囲気下の熱分解温度は５５０℃以上であり、重量平均分子量（Ｍｗ）は２９，６００、数平均分子量（Ｍｎ）５，７００であった。なお、分子量はクロロホルム中でＧＰＣ測定により、ポリスチレンを標準試料として求めた。
【０１５３】
次に、合成例３，４で得られた１，４−フェニレンジアミン含有高分子化合物の粘度を測定する実験例を示す。
【０１５４】
実験例１
１，４−フェニレンジアミン含有高分子化合物（ＰＰＰＥＫ）および分岐型１，４−フェニレンジアミン含有高分子化合物（ＰＰＰＥＫ−ｂ３）について各々高分子化合物濃度を変えてシクロヘキサノン溶液を調製してその粘度を（株）東京計器製回転粘度計により測定し、高分子化合物濃度と粘度との関係を図５に示した。
【０１５５】
図５に示す如く、ＰＰＰＥＫとＰＰＰＥＫ−ｂ３との間には、その溶液の粘度変化に大きな違いが見られ、本発明の高分子化合物であるＰＰＰＥＫ−ｂ３は高粘性であることがわかる。
【０１５６】
以下に、合成された１，４−フェニレンジアミン含有高分子化合物を用いた有機電界発光素子の性能評価を行う実施例を挙げる。
【０１５７】
実施例１
図３に示す構造を有する有機電界発光素子を以下の方法で作製した。
【０１５８】
ガラス基板１上にインジウム・スズ酸化物（ＩＴＯ）透明導電膜を 120nm堆積したもの（ジオマテック社製；電子ビーム成膜品；シート抵抗15Ω／ｓｑ）を通常のフォトリソグラフィ技術と塩酸エッチングを用いて2mm幅のストライプにパターニングして陽極２を形成した。パターン形成したＩＴＯ基板を、アセトンによる超音波洗浄、純水による水洗、イソプロピルアルコールによる超音波洗浄の順で洗浄後、窒素ブローで乾燥させ、最後に紫外線／オゾン洗浄を行った。
【０１５９】
このＩＴＯガラス基板上に、分岐型１，４−フェニレンジアミン含有高分子化合物（ＰＰＰＥＫ−ｂ３）とＰＰＢの混合物を下記の条件でスピンコートした。
［スピンコート条件］
溶媒 ：シクロヘキサノン
ＰＰＰＥＫ−ｂ３ ：5.0 mg／ml
ＰＰＢ ：0.5 mg／ml
スピナ回転数 ：1500 rpm
スピナ回転時間 ：30秒
乾燥条件 ：120℃で2時間
【０１６０】
上記のスピンコートにより20nmの膜厚の均一な薄膜形状を有する正孔注入層３を形成した。
【０１６１】
次に、上記正孔注入層３を塗布成膜した基板を真空蒸着装置内に設置した。この装置の粗排気を油回転ポンプにより行った後、装置内の真空度が2×10^-6Torr（約2.7×10^-4Pa）以下になるまで液体窒素トラップを備えた油拡散ポンプを用いて排気した。この装置内に配置されたセラミックるつぼに入れた以下に示す芳香族ジアミン化合物：４，４’−ビス［Ｎ−（９−フェナンチル）−Ｎ−フェニルアミノ］ビフェニルを加熱して蒸着を行った。蒸着時の真空度は1.3×10^-6Torr（約1.7×10^-4Pa）、蒸着速度は0.3nm/秒で、膜厚20nmの膜を正孔注入層３の上に積層して正孔輸送層４を完成させた。
【０１６２】
【化３３】

【０１６３】
引続き、発光層５の材料として、以下の構造式に示すアルミニウムの８−ヒドロキシキノリン錯体：Al(C₉H₆NO)₃、とルブレンとを同時に蒸着した。
【０１６４】
【化３４】

【０１６５】
アルミニウムの８−ヒドロキシキノリン錯体に対するルブレンの割合は2.5vol.%になるようにした。この時のアルミニウムの８−ヒドロキシキノリン錯体のるつぼ温度は275〜285℃の範囲で制御し、蒸着時の真空度は1.2×10^-6Torr（約1.6×10^-4Pa）、蒸着速度は0.4nm/秒であった。またルブレンのるつぼ温度は240〜250℃の範囲で制御し、蒸着速度は0.01nm/秒であった。このように蒸着された発光層５の膜厚は30nmであった。
【０１６６】
続いて、電子輸送層６としてアルミニウムの８−ヒドロキシキノリン錯体：Al(C₉H₆NO)₃を正孔輸送層４と同様にして蒸着を行った。この時のアルミニウムの８−ヒドロキシキノリン錯体のるつぼ温度は275〜285℃の範囲で制御し、蒸着時の真空度は1.1×10^-6Torr（約1.5×10^-4Pa）、蒸着速度は0.4nm/秒で、蒸着された電子輸送層６の膜厚は45nmであった。
【０１６７】
なお、上記の正孔輸送層４および発光層５、電子輸送層６を真空蒸着する時の基板温度は室温に保持した。
【０１６８】
ここで、電子輸送層６までの蒸着を行った素子を一度前記真空蒸着装置内より大気中に取り出して、陰極蒸着用のマスクとして 2mm幅のストライプ状シャドーマスクを、陽極２のＩＴＯストライプと直交するように素子に密着させた後、別の真空蒸着装置内に設置して、各有機層形成時と同様にして装置内の真空度が2×10^-6Torr（約2.7×10^-4Pa）以下になるまで排気した。
【０１６９】
その後、陰極７として、先ず、フッ化リチウム（LiF）をモリブデンボートを用いて、蒸着速度0.02nm／秒、真空度7.0×10^-6Torr（約9.3×10^-4Pa）で、0.5nmの膜厚となるように電子輸送層６の上に成膜した。次に、アルミニウムを同様にモリブデンボートにより加熱して、蒸着速度0.5nm/秒、真空度1×10^-5Torr（約1.3×10^-3Pa）で、膜厚80nmのアルミニウム層を形成して、陰極７を完成させた。以上の２層型陰極７の蒸着時の基板温度は室温に保持した。
【０１７０】
以上の様にして、2mm×2mmのサイズの発光面積部分を有する有機電界発光素子が得られた。この素子の発光特性を表１に示す。表１において、発光輝度は250mA／cm²の電流密度での値、発光効率は100cd／m²での値、輝度／電流は輝度−電流密度特性の傾きを、電圧は100cd／m²での値を各々示す。
【０１７１】
表１より、駆動電圧の低い、高輝度かつ高発光効率で発光する素子が得られたことが明らかである。
【０１７２】
【表１】

【０１７３】
以上の結果から明らかなように、塗布プロセスに有利な、本発明の高分子化合物と電子受容性化合物を含有する正孔注入層を形成することにより、低電圧で駆動可能かつ耐熱性の向上した素子を得ることができる。
【０１７４】
【発明の効果】
以上詳述した通り、本発明の新規高分子化合物、好ましくは本発明の新規１，４−フェニレンジアミン誘導体より合成される高分子化合物を用いることにより、低電圧、高発光効率で駆動させることができ、かつ良好な耐熱性を有し、長期間にわたって安定な発光特性を維持することができる有機電界発光素子であって、陽極の表面粗さに起因する素子作製時の短絡欠陥を防止した有機電界発光素子が提供される。
【０１７５】
従って、本発明による有機電界発光素子は、フラットパネル・ディスプレイ（例えばＯＡコンピュータ用や壁掛けテレビ）や面発光体としての特徴を生かした光源（例えば、複写機の光源、液晶ディスプレイや計器類のバックライト光源）、表示板、標識灯への応用が考えられ、特に、高耐熱性が要求される車載用表示素子としては、その技術的価値は大きいものである。
【図面の簡単な説明】
【図１】本発明の有機電界発光素子の実施の形態の一例を示す模式的な断面図である。
【図２】本発明の有機電界発光素子の実施の形態の他の例を示す模式的な断面図である。
【図３】本発明の有機電界発光素子の実施の形態の別の例を示す模式的な断面図である。
【図４】本発明の高分子化合物のイオン化ポテンシャルと電子受容性化合物の電子親和力との関係を示したエネルギー準位図である。
【図５】合成例３，４で製造された１，４−フェニレンジアミン含有高分子化合物を含むシクロヘキサノン溶液の粘度変化を示すグラフである。
【符号の説明】
１ 基板
２ 陽極
３ 正孔注入層
４ 正孔輸送層
５ 発光層
６ 電子輸送層
７ 陰極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a novel polymer compound, a novel 1,4-phenylenediamine derivative as a combined intermediate of the polymer compound, a charge transport material, an organic electroluminescent element material and an organic electroluminescence using the polymer compound. The present invention relates to a thin film device that emits light by applying an electric field to a light emitting layer made of an element, that is, an organic compound.
[0002]
[Prior art]
Conventionally, as a thin film type electroluminescent (EL) element, there are ZnS, CaS, SrS, etc. which are inorganic material II-VI compound semiconductors, Mn which is an emission center, rare earth elements (Eu, Ce, Tb, Sm, etc.) ) Is generally used, but an EL element made from the above inorganic material is
1) AC drive is required (50-1000Hz),
2) High drive voltage (~ 200V),
3) Full color is difficult,
4) The cost of the peripheral drive circuit is high.
Has the problem.
[0003]
However, in recent years, EL devices using organic thin films have been developed to improve the above problems. In particular, in order to improve luminous efficiency, the type of electrode is optimized for the purpose of improving the efficiency of carrier injection from the electrode, and a hole transporting layer made of aromatic diamine and a light emitting layer made of 8-hydroxyquinoline aluminum complex, As a result of the development of an organic electroluminescent device provided with non-patent document 1, the luminous efficiency is greatly improved as compared with a conventional EL device using a single crystal such as anthracene, which is close to practical characteristics.
[0004]
In addition to the electroluminescent device using the low molecular weight material as described above, as a material of the light emitting layer, poly (p-phenylene vinylene), poly [2-methoxy-5- (2-ethylhexyloxy) -1,4 -Phenylene vinylene], poly (3-alkylthiophene), and other electroluminescent devices using polymer materials such as polyfluorene, and low molecular light emitting materials and electron transfer materials mixed and dispersed in polymers such as polyvinylcarbazole Devices are also being developed.
[0005]
By the way, the biggest problem of the organic electroluminescent element is the lifetime during driving. Examples of the instability during driving include a decrease in light emission luminance, a voltage increase during constant current driving, and the generation of a non-light emitting portion (dark spot). Although there are several causes of these instabilities, the deterioration of the thin film shape of the organic layer is dominant. It is considered that the deterioration of the thin film shape is caused by crystallization (or aggregation) of the organic amorphous film due to heat generated when the element is driven. In particular, contact between the anode and the hole transport layer is important for increasing the drive voltage.
[0006]
Therefore, in order to improve the contact between the anode and the hole transport layer, it has been studied to provide a hole injection layer between the two layers to lower the drive voltage. The conditions required for the material used for the hole injection layer include that the contact with the anode is good and a uniform thin film can be formed, and that it is thermally stable, that is, the melting point and the glass transition temperature (Tg) are high, preferably It must have a melting point of 300 ° C or higher and a glass transition temperature of 120 ° C or higher. Furthermore, it is required to have an appropriate ionization potential that facilitates hole injection from the anode and allows the injected holes to be efficiently transferred to the hole transport layer. In addition, a high hole mobility is required in a series of hole injection and transport processes. Various materials for the hole injection layer have been studied. For example, porphyrin derivatives, phthalocyanine compounds (Patent Document 1), starburst aromatic triamines (Patent Document 2), sputtered carbon films, and vanadium oxides. Metal oxides such as ruthenium oxide and molybdenum oxide have been reported.
[0007]
However, in the method of inserting a hole injection layer between the anode and the hole transport layer, when a porphyrin derivative or a phthalocyanine compound is used as the hole injection layer, the spectrum changes due to light absorption by these films themselves. There is a problem that it is colored in appearance and is not transparent.
[0008]
Although the starburst type aromatic triamine has an advantage of having an appropriate ionization potential and good transparency, it has a problem in heat resistance because of its low glass transition point and melting point.
[0009]
Many hole injection layers containing various conjugated and non-conjugated polymer compounds have also been proposed. In general, indium tin oxide (ITO) used as an anode for organic electroluminescent devices often has protrusions locally in addition to having a surface roughness (Ra) of about 10 nm. Although there was a problem of causing short-circuit defects, an effect of reducing the defects can be obtained by applying a solution containing a polymer compound on the anode to provide a hole injection layer.
[0010]
As such a hole injection layer material, for example, use of a conjugated polymer such as polythienylene vinylene, polythiophene, or polyaniline has been proposed. However, these have a problem in solubility in a solvent, and thus have a problem in the manufacturing process.
[0011]
In addition, it has been proposed to use a non-conjugated polymer not mixed with an electron-accepting compound as a hole transport layer (Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6). Such a device is 20 cd / m at 6 V as described in FIG.²The driving voltage is high, and the luminous efficiency at that time is as low as 1 cd / A.
[0012]
Furthermore, it is disclosed that the device can be driven at a low voltage by mixing an electron accepting compound with a non-conjugated hole transporting polymer and using it as a hole injection layer (Patent Document 7). However, the polymer disclosed in Patent Document 7 has a low glass transition temperature Tg and has a difficulty in heat resistance.
[0013]
Most of the non-conjugated polymers disclosed in the above-mentioned documents contain two diarylamino structures linked by a biphenylene group, and the hole transport property of the polymer is usually the biphenylene-diarylamino structure. Due to part.
[0014]
However, the monomer component of the structure is harmful to the human body, and since the structure has a large reorientation energy in charge transfer, there is a large energy barrier for hole injection / transport. It is considered that the organic electroluminescence device having a hole injecting layer using sapphire has an insufficient driving life.
[0015]
As the hole transporting site, the partial structure derived from 1,4-phenylenediamine is considered to have a small reorientation energy and a large hole mobility, but this 1,4-phenylenediamine site and benzophenone site are An example in which the non-conjugated polymer is used as a hole transport layer is disclosed in Patent Document 4. In the polymer described in this document, a lower alkyl group is bonded to a 1,4-phenylenediamine moiety, and the alkyl group undergoes a radical reaction with a benzophenone moiety by light irradiation to be crosslinked and insolubilized. It is characterized by.
[0016]
By the way, in order to lower the driving voltage of an organic electroluminescent device, a hole transporting polymer is often used together with an electron accepting compound in the hole injection layer of the device. However, since an absorption band accompanying charge transfer from the polymer to the electron-accepting compound exists in a low energy region, in the case of the polymer described in Patent Document 4, photocrosslinking does not occur in the presence of the electron-accepting compound, and the document The effect described in is not achieved.
[0017]
The polymer before photocrosslinking in Patent Document 4 has a low ionization potential because the electron-donating alkyl group is directly bonded to the 1,4-phenylenediamine moiety, and the polymer and the electron-accepting compound are mixed. When used as a hole injection layer, it seems that charge transfer to the hole transport layer is not performed efficiently. Further, the polymer may have insufficient heat resistance due to the alkyl group possessed by the phenylenediamine moiety.
[0018]
As will be described later, in the case of forming a polymer-containing layer in an organic electroluminescent element, it is preferable to use a printing method in terms of productivity. Specific examples include offset printing, flexographic printing, screen printing, and ink jet printing. When a layer is formed with high accuracy by these printing methods, a certain degree of viscosity is required for the polymer-containing composition to be a coating solution.
[0019]
[Patent Document 1]
JP 63-295695 A
[Patent Document 2]
Japanese Patent Laid-Open No. 4-308688
[Patent Document 3]
JP-A-9-188756
[Patent Document 4]
JP-A-9-255774
[Patent Document 5]
Japanese Patent Laid-Open No. 11-135262
[Patent Document 6]
WO97 / 33193 Publication
[Patent Document 7]
Japanese Patent Laid-Open No. 11-283750
[Non-Patent Document 1]
Appl. Phys. Lett., 51, 913, 1987
[0020]
[Problems to be solved by the invention]
The high voltage at the time of driving the organic electroluminescent element and the low stability including heat resistance are serious problems as light sources for facsimiles, copiers, liquid crystal display backlights, etc. It is not desirable as a display element such as a panel display.
[0021]
The present invention solves the above-mentioned conventional problems, can be driven with low voltage and high luminous efficiency, has good heat resistance, and can maintain stable luminous characteristics over a long period of time. An organic electroluminescent element which is a light emitting element and prevents short-circuit defects at the time of element production due to the surface roughness of the anode, and a novel polymer compound suitable as a hole injection layer material of the organic electroluminescent element, An object is to provide a novel 1,4-phenylenediamine derivative as a synthetic intermediate of the polymer compound, a charge transport material containing the polymer compound, and an organic electroluminescent element material.
[0022]
[Means for Solving the Problems]
  The polymer compound of the present invention contains a repeating unit represented by the following general formula (II).The weight average molecular weight is 1,000 to 1,000,000.Preferably, the polymer compound of the present invention includes a repeating unit represented by the following general formula (I) and the following general formula (II).
[0023]
[Chemical 9A]

(In the formula, ring A1 and ring A2 are each independently a benzene ring or a benzene ring condensed with an arbitrary ring, and this benzene ring or condensed ring is an alkyl group which may have a substituent, An alkenyl group which may have a substituent, an alkynyl group which may have a substituent, an aralkyl group which may have a substituent, an acyl group which may have a substituent, a substituent May be substituted with one or two or more substituents selected from the group consisting of an aromatic hydrocarbon ring group which may have a substituent and an aromatic heterocyclic group which may have a substituent. Good.
  Ar¹Or Ar⁸Each independently represents an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a substituent. A good aralkyl group, an acyl group which may have a substituent, an amino group which may have a substituent, an alkoxycarbonyl group which may have a substituent, and a substituent. An aromatic ring which may be substituted with one or two or more substituents selected from the group consisting of an aromatic hydrocarbon ring group and an aromatic heterocyclic group which may have a substituent.
  X, Y¹And Y²Each independently represents a divalent linking group selected from a partial structure represented by the following structural formula. )
[Chemical 9B]

(Wherein Ar¹¹Or Ar ¹⁷ Each independently represents an optionally substituted aromatic ring.To express. )
[0024]
The charge transport material of the present invention contains such a polymer compound of the present invention.
[0025]
The organic electroluminescent element material of the present invention contains such a polymer compound of the present invention.
[0026]
The organic electroluminescent element of the present invention is an organic electroluminescent element having an anode, a cathode, and a light emitting layer existing between the two electrodes on a substrate, and has such a layer containing the polymer compound of the present invention. And
[0027]
That is, the present inventors have intensively studied to solve the conventional problems and provide an organic electroluminescence device capable of maintaining stable light emission characteristics at a high temperature. As a result, the light emission sandwiched between the anode and the cathode on the substrate. In the organic electroluminescent device having a layer, the above-described problem can be solved by providing a layer made of a polymer compound containing an electron-accepting compound and having a high Tg between the anode and the light-emitting layer. The high molecular compound having the repeating unit represented by the above general formula (II), which can be easily found, can easily achieve a glass transition temperature Tg ≧ 120 ° C., and has such a high Tg. It was found that the light emitting characteristics and heat resistance of the device can be improved at the same time by mixing and using an electron-accepting compound, and the present invention has been completed.
[0028]
The polymer compound of the present invention has an electron donating property. By mixing the polymer compound with an electron accepting compound, charge transfer occurs, and as a result, holes that are free carriers are generated. The degree becomes higher. By providing such a layer, the electrical connection between the light emitting layer and the anode is improved, the driving voltage is lowered, and the stability during continuous driving is also improved.
[0029]
In addition, by forming a layer mainly composed of such a polymer compound on the anode by a coating process, the surface roughness of the anode is relaxed, and a good surface smoothing effect can be obtained. The effect that the short circuit defect at the time of manufacture is prevented is also show | played.
[0030]
Further, since this polymer compound has a cross-link structure, it has a higher Tg than that of a linear polymer compound. That is, the polymer compound of the present invention has a crosslink structure, and preferably has a Tg of 150 ° C. or higher. Moreover, when forming the layer containing this high molecular compound with a printing method, the viscosity of a coating liquid (composition for printing) is adjusted to an appropriate range by adjusting the ratio of the crosslink in a compound. This is preferable because the film thickness can be precisely controlled.
[0031]
Note that the layer containing the polymer compound and the electron-accepting compound according to the present invention is a layer exhibiting hole transporting properties, and may be anywhere between the anode and the light-emitting layer. Although it is not limited to what is directly provided on the anode as shown in -3, in order to make full use of the advantages of this layer, such as good electrical bonding with the anode (inorganic material) and high heat resistance, the anode and Most advantageously, it is formed as a hole injection layer at the contact position.
[0032]
In the organic electroluminescence device of the present invention, the value obtained by subtracting the electron affinity of the electron-accepting compound from the ionization potential of the polymer compound is preferably 0.7 eV or less, and the electron-accepting in the layer containing these The content of the functional compound is preferably in the range of 0.1 to 50% by weight with respect to the polymer compound.
[0033]
In the organic electroluminescent element of the present invention, the electron accepting compound is preferably at least one compound selected from the following compound group.
[0034]
[Chemical Formula 10]

[0035]
The 1,4-phenylenediamine derivative of the present invention is a monomer useful as a synthetic intermediate for the polymer compound of the present invention, and is represented by the following general formula (IV ′).
[0036]
Embedded image

(Wherein R⁶, R⁷, R⁹, R¹⁰Each independently has a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a substituent. An aralkyl group which may have a substituent, an acyl group which may have a substituent, an amino group which may have a substituent, an alkoxycarbonyl group which may have a substituent, and a substituent. An aromatic hydrocarbon ring group which may be substituted, or an aromatic heterocyclic group which may have a substituent,
R⁸Is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, an aralkyl group which may have a substituent, An acyl group that may have a substituent, an aromatic hydrocarbon ring group that may have a substituent, or an aromatic heterocyclic group that may have a substituent. )
[0037]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
First, the polymer compound of the present invention will be described.
The polymer compound of the present invention has a repeating unit represented by the general formula (II), and preferably has a repeating unit represented by the general formulas (I) and (II). .
[0038]
Ring A1 of general formula (I) and ring A2 of general formula (II) are each independently a benzene ring (phenylene group) or a benzene ring condensed with an arbitrary ring, and rings A1 and A2 are condensed rings. In some cases, examples of the condensed ring include a 2-condensed ring such as the following naphthalene ring and a 3-condensed ring such as an anthracene ring, but are not limited thereto.
[0039]
Embedded image

[0040]
The benzene ring of rings A1 and A2 or the condensed benzene ring portion of ring A1 and A2 and / or the ring condensed to the benzene ring may have a substituent.
[0041]
The substituents that the rings A1 and A2 may have include an alkyl group that may have a substituent, an alkenyl group that may have a substituent, an alkynyl group that may have a substituent, and a substituent. An aralkyl group which may have a group, an acyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, and an aromatic which may have a substituent 1 or 2 or more types selected from the group consisting of group heterocyclic groups, more specifically, alkyl groups having 1 to 6 carbon atoms, such as a methyl group and an ethyl group, which may have a substituent. An optionally substituted alkenyl group having 1 to 6 carbon atoms such as a vinyl group; an optionally substituted alkynyl group having 1 to 6 carbon atoms such as an ethynyl group; An aralkyl group such as a benzyl group which may have; an acetyl group which may have a substituent; An acyl group having 1 to 6 carbon atoms such as a group; an aromatic hydrocarbon ring group such as a phenyl group or a naphthyl group which may have a substituent; a thienyl group which may have a substituent; An aromatic heterocyclic group.
[0042]
Examples of the substituent that these substituents may have include one or more of the following substituent group Z.
[Substituent group Z]
An alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; an alkenyl group having 1 to 6 carbon atoms such as a vinyl group; an alkynyl group having 1 to 6 carbon atoms such as an ethynyl group; a methoxycarbonyl group and an ethoxycarbonyl group An alkoxycarbonyl group having 2 to 7 carbon atoms; a dialkylamino group having 1 to 10 carbon atoms such as a dimethylamino group and a diethylamino group; a diarylamino group such as a diphenylamino group, a ditolylamino group and a carbazolyl group; a phenylmethylamino group and the like Arylalkylamino group; acyl group having 1 to 6 carbon atoms such as acetyl group; halogen atom such as fluorine atom; haloalkyl group such as trifluoromethyl group; aryloxy group such as phenoxy group and benzyloxy group; cyano group; Group, aromatic hydrocarbon ring group such as naphthyl group
[0043]
The substituents that the rings A1 and A2 have are more preferably groups that do not excessively reduce the ionization potential of the polymer compound that is formed. Is an alkoxycarbonyl group having 2 to 7 carbon atoms such as a methoxycarbonyl group or an ethoxycarbonyl group; an acyl group having 1 to 6 carbon atoms such as an acetyl group; a halogen atom such as a fluorine atom; or a haloalkyl group such as a trifluoromethyl group. Particularly preferably, the hydrogen atom, that is, the rings A1 and A2 are preferably unsubstituted.
[0044]
Ar¹Or Ar⁸Each independently represents an optionally substituted aromatic ring, which is preferably a 5- or 6-membered monocyclic ring or a 2-3 condensed ring, an aromatic hydrocarbon ring or an aromatic ring. Group heterocycle, specifically, benzene ring, naphthalene ring, phenanthrene ring, anthracene ring, pyridine ring, quinoline ring, thiophene ring, benzothiophene ring, furan ring, pyrrole ring, indole ring, benzofuran ring, carbazole ring It is done.
[0045]
This Ar¹Or Ar⁸Examples of the substituent that the aromatic hydrocarbon ring may have include an alkyl group which may have a substituent, an alkenyl group which may have a substituent, and an alkynyl group which may have a substituent. , An aralkyl group which may have a substituent, an acyl group which may have a substituent, an amino group which may have a substituent, an alkoxycarbonyl group which may have a substituent, One or more selected from the group consisting of an aromatic hydrocarbon ring group which may have a substituent and an aromatic heterocyclic group which may have a substituent, more specifically Is an alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group which may have a substituent; an alkenyl group having 1 to 6 carbon atoms such as a vinyl group which may have a substituent An alkynyl having 1 to 6 carbon atoms such as an ethynyl group which may have a substituent An aralkyl group such as a benzyl group which may have a substituent; an acyl group having 1 to 6 carbon atoms such as an acetyl group which may have a substituent; an optionally substituted group; Amino group, for example, a dialkylamino group having 1 to 10 carbon atoms such as dimethylamino group and diethylamino group; diarylamino group such as diphenylamino group, ditolylamino group and carbazolyl group; arylalkylamino group such as phenylmethylamino group; substituent A methoxycarbonyl group which may have a C 2-7 alkoxycarbonyl group such as an ethoxycarbonyl group; an aromatic hydrocarbon ring group such as a phenyl group or a naphthyl group which may have a substituent; An aromatic heterocyclic group such as a thienyl group, which may have a substituent.
[0046]
Examples of the substituent that these substituents may have include one or more of the aforementioned substituent group Z.
[0047]
Ar¹~ Ar⁸More preferably, the substituent that is present is a group that does not excessively lower the ionization potential of the polymer compound to be formed, and the substituent that does not have a problem of such a decrease in ionization potential is a hydrogen atom, An optionally substituted acyl group having 1 to 6 carbon atoms such as an acetyl group, and an optionally substituted alkoxy group having 2 to 7 carbon atoms such as a methoxycarbonyl group and an ethoxycarbonyl group. Group, particularly preferably a hydrogen atom, ie Ar¹~ Ar⁸Is preferably unsubstituted.
[0048]
Ar contained in one repeating unit¹~ Ar⁴Or Ar⁵~ Ar⁸May be the same or different, but are preferably different from the amorphous aspect of the polymer compound, and are preferably the same from the viewpoint of productivity due to easy synthesis.
[0049]
  X, Y¹And Y²Are independent of each otherDownAnd a divalent linking group selected from the partial structure represented by the structural formula.
[0050]
Embedded image

[0051]
In the above formula, Ar¹¹Or Ar¹⁸Are each independently an optionally substituted aromatic ring, preferably an optionally substituted 5- or 6-membered ring alone or 2-3 condensed ring aromatic hydrocarbon Ring or aromatic heterocycle, specifically, benzene ring, naphthalene ring, phenanthrene ring, anthracene ring, pyridine ring, quinoline ring, thiophene ring, benzothiophene ring, furan ring, pyrrole ring, indole ring, benzofuran ring And a carbazole ring.
[0052]
Examples of the substituent that such an aromatic ring may have are as follows:²¹, R²²Are exemplified.
[0053]
R²¹And R²²Each independently has a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a substituent. An aralkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryloxy group which may have a substituent, an amino group which may have a substituent, and a substituent. Represents an aromatic hydrocarbon ring group which may be substituted, or an aromatic heterocyclic group which may have a substituent, and more specifically, has 1 to 6 carbon atoms such as a hydrogen atom, a methyl group or an ethyl group. An alkyl group; an optionally substituted alkenyl group having 1 to 6 carbon atoms such as a vinyl group; an optionally substituted alkynyl group having 1 to 6 carbon atoms such as an ethynyl group; An aralkyl group such as a benzyl group which may have a group; A C1-C6 alkoxy group such as a methoxy group or an ethoxy group; an aryloxy group such as a phenoxy group or a benzyloxy group which may have a substituent; an amino which may have a substituent A dialkylamino group having 1 to 10 carbon atoms such as a dimethylamino group and a diethylamino group; a diarylamino group such as a diphenylamino group, a ditolylamino group and a carbazolyl group; an arylalkylamino group such as a phenylmethylamino group; An aromatic hydrocarbon ring group such as a phenyl group and a naphthyl group which may have; an aromatic heterocyclic group such as a thienyl group which may have a substituent.
[0054]
Examples of the substituent that these substituents may have include one or more of the aforementioned substituent group Z.
[0055]
Ar¹¹~ Ar¹⁸A substituent of R²¹, R²²Preferred as these are a hydrogen atom (that is, unsubstituted), a methyl group, an ethyl group, and a methoxy group.
[0056]
X, Y¹, Y²Is preferably
Embedded image

And in particular,
Embedded image

It is preferable that R¹¹~ R¹⁷Is Ar¹¹~ Ar¹⁸Are the same as those described above as the substituent that may be present, and the same applies to preferable groups.
[0057]
The repeating unit represented by the general formula (I) is preferably represented by the following general formula (I ′), and the repeating unit represented by the general formula (II) is represented by the following general formula (II) It is preferably represented by ').
[0058]
Embedded image

[0059]
Embedded image

[0060]
Ring B1, ring B2, ring B4 and ring B5 in general formula (I ′) and ring B6, ring B7, ring B9 and ring B10 in general formula (II ′) are each independently substituted. A benzene ring which may be substituted or a naphthalene ring which may have a substituent, preferably a benzene ring. The substituent that this benzene ring or naphthalene ring may have is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, An aralkyl group which may have a substituent, an acyl group which may have a substituent, an amino group which may have a substituent, an alkoxycarbonyl group which may have a substituent, a substitution One or two or more selected from the group consisting of an aromatic hydrocarbon ring group which may have a group and an aromatic heterocyclic group which may have a substituent, more specifically An alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group which may have a substituent; an alkenyl group having 1 to 6 carbon atoms such as a vinyl group which may have a substituent; Alkyl having 1 to 6 carbon atoms such as ethynyl group which may have a substituent. An aralkyl group such as a benzyl group which may have a substituent; an acyl group having 1 to 6 carbon atoms such as an acetyl group which may have a substituent; An amino group, for example, a dialkylamino group having 1 to 10 carbon atoms such as a dimethylamino group and a diethylamino group; a diarylamino group such as a diphenylamino group, a ditolylamino group and a carbazolyl group; an arylalkylamino group such as a phenylmethylamino group; A methoxycarbonyl group which may have a substituent; an alkoxycarbonyl group having 2 to 7 carbon atoms such as a methoxycarbonyl group; an aromatic hydrocarbon such as a phenyl group or naphthyl group which may have a substituent; Ring group; an aromatic heterocyclic group such as a thienyl group which may have a substituent.
[0061]
Examples of the substituent that these substituents may have include one or more of the aforementioned substituent group Z.
[0062]
More preferably, the substituents of the rings B1, B2, B4, B5, B6, B7, B9, and B10 are groups that do not excessively reduce the ionization potential of the polymer compound to be formed. As a substituent that does not cause a problem of low ionization potential, it may have a hydrogen atom, a substituent, an acyl group having 2 to 7 carbon atoms such as an acetyl group, or a methoxy group. Examples thereof include C2-C7 alkoxycarbonyl groups such as a carbonyl group and an ethoxycarbonyl group, but hydrogen atoms, that is, rings B1, B2, B4, B5, B6, B7, B9, and B10 are preferably unsubstituted. Preferably there is.
[0063]
Rings B1, B2, B4 and B5 or rings B6, B7, B9 and B10 contained in one repeating unit may be the same or different, but the amorphous nature of the polymer compound From these points, it is preferable that they are different from each other.
[0064]
Ring B3 in the general formula (I ′) and ring B8 in the general formula (II ′) are optionally substituted benzene rings.
[0065]
Examples of the substituent that the rings B3 and B8 may have include an alkyl group that may have a substituent, an alkenyl group that may have a substituent, an alkynyl group that may have a substituent, and a substituent. An aralkyl group which may have a group, an acyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, and an aromatic which may have a substituent 1 or 2 or more types selected from the group consisting of group heterocyclic groups, more specifically, alkyl groups having 1 to 6 carbon atoms, such as a methyl group and an ethyl group, which may have a substituent. An optionally substituted alkenyl group having 1 to 6 carbon atoms such as a vinyl group; an optionally substituted alkynyl group having 1 to 6 carbon atoms such as an ethynyl group; An aralkyl group such as a benzyl group, which may have a substituent; An acyl group having 1 to 6 carbon atoms such as a ru group; an aromatic hydrocarbon ring group such as a phenyl group or a naphthyl group which may have a substituent; a thienyl group which may have a substituent; An aromatic heterocyclic group.
[0066]
Examples of the substituent that these substituents may have include one or more of the aforementioned substituent group Z.
[0067]
The substituents that the rings B3 and B8 have are more preferably groups that do not excessively lower the ionization potential of the polymer compound that is formed. Includes a hydrogen atom, an optionally substituted acyl group having 1 to 6 carbon atoms such as an acetyl group, and particularly preferably a hydrogen atom, that is, rings B3 and B8 are unsubstituted. preferable.
[0068]
Such a polymer compound of the present invention is preferably a monomer represented by the following general formula (IV), more preferably a monomer represented by the following general formula (III) and the following general formula (IV) Synthesized. It is particularly preferably synthesized from the 1,4-phenylenediamine derivative of the present invention represented by the following general formula (IV ′), and particularly preferably represented by the following general formula (III ′) and the following general formula (IV ′). 1,4-phenylenediamine derivative.
[0069]
Embedded image

(In the above formula, ring B1 to ring B10 have the same meanings as in general formula (I ′) and general formula (II ′)).
[0070]
Embedded image

[0071]
Embedded image

[0072]
R in the above formula¹, R², R⁴, R⁵, R⁶, R⁷, R⁹, R¹⁰Each independently represents an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a substituent. A good aralkyl group, an acyl group which may have a substituent, an amino group which may have a substituent, an alkoxycarbonyl group which may have a substituent, and a substituent. An aromatic hydrocarbon ring group or an aromatic heterocyclic group which may have a substituent, more specifically, a carbon number such as a methyl group or an ethyl group which may have a substituent. An alkyl group having 1 to 6 carbon atoms; an optionally substituted alkenyl group having 1 to 6 carbon atoms such as a vinyl group; an optionally substituted substituent having 1 to 6 carbon atoms such as an ethynyl group; An alkynyl group; an aralkyl group such as a benzyl group which may have a substituent; An acyl group having 1 to 6 carbon atoms such as an acetyl group; an amino group optionally having a substituent such as a dialkylamino group having 1 to 10 carbon atoms such as a dimethylamino group and a diethylamino group; Diarylamino groups such as amino group, ditolylamino group and carbazolyl group; arylalkylamino groups such as phenylmethylamino group; methoxycarbonyl group which may have a substituent; C2-C7 such as ethoxycarbonyl group An alkoxycarbonyl group; an aromatic hydrocarbon ring group such as a phenyl group or a naphthyl group which may have a substituent; and an aromatic heterocyclic group such as a thienyl group which may have a substituent.
[0073]
R³, R⁸Is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, an aralkyl group which may have a substituent, An acyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, or an aromatic heterocyclic group which may have a substituent, more specifically, Is an alkyl group having 1 to 6 carbon atoms such as a methyl group or an ethyl group which may have a substituent; an alkenyl group having 1 to 6 carbon atoms such as a vinyl group which may have a substituent An optionally substituted alkynyl group having 1 to 6 carbon atoms such as an ethynyl group; an optionally substituted aralkyl group such as a benzyl group; an optionally substituted group; An acyl group having 1 to 6 carbon atoms such as an acetyl group; a phenyl group which may have a substituent; Aromatic hydrocarbon ring groups such as methyl group, which may have a substituent, an aromatic heterocyclic group such as thienyl group.
[0074]
Examples of the substituent that these substituents may have include one or more of the aforementioned substituent group Z.
[0075]
R¹Or R⁵, R⁶Or R¹⁰Is preferably a hydrogen atom (that is, unsubstituted), or an acyl group having 1 to 6 carbon atoms such as an acetyl group, which may have a substituent, and does not have the problem of lowering the ionization potential described above. And particularly preferably a hydrogen atom (that is, unsubstituted).
[0076]
Although the preferable specific example of the repeating unit of the high molecular compound of this invention is shown below, this invention is not limited to these at all.
[0077]
As the repeating unit represented by the general formula (II ′), the following are preferable.
Embedded image

[0078]
As the repeating unit represented by the general formula (I ′), the following are preferable.
Embedded image

[0079]
Embedded image

[0080]
The polymer compound of the present invention is
(1) A polymer compound composed of one or more repeating units represented by general formula (II)
and
(2) A polymer compound comprising one or more repeating units represented by the general formula (I) and one or more repeating units represented by the general formula (II),
And a copolymer corresponding to the above (2). Specifically, a polymer compound containing the repeating unit of the general formula (II) at a ratio of 0.1 to 10 mol% with respect to the repeating unit of the general formula (I) is particularly preferable for the production of the organic electroluminescence device.
[0081]
The polymer compound of the present invention containing the repeating unit represented by the general formula (II), that is, the polymer compound of the present invention containing a cross-link structure is a coating solution containing high Tg and the polymer compound as described above. This is also preferable in terms of viscosity.
[0082]
Furthermore, the polymer compound of the present invention may contain repeating units derived from other various monomers as long as the performance is not impaired. As a repeating unit derived from another monomer, for example, in the repeating unit represented by the general formula (I),
Embedded image

Instead of
Embedded image

As the compound useful for the production of an organic electroluminescent device, the content of the repeating unit represented by the general formulas (I) and (II) is usually 20 mol% per molecule. Above, preferably 50 mol% or more, more preferably 80 mol% or more.
[0083]
In the above formula, R^a, R^b, R^cEach independently has an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, and a substituent. An aralkyl group which may have a substituent, an acyl group which may have a substituent, an amino group which may have a substituent, an alkoxycarbonyl group which may have a substituent, and a substituent which may have A good aromatic hydrocarbon ring group, or an aromatic heterocyclic group which may have a substituent, more specifically, a carbon such as a methyl group or an ethyl group which may have a substituent. An alkyl group having 1 to 6 carbon atoms; an optionally substituted alkenyl group having 1 to 6 carbon atoms such as a vinyl group; an optionally substituted carbon group having 1 to 6 carbon atoms such as an ethynyl group; An alkynyl group, which may have a substituent, an aralkyl group such as a benzyl group; An optionally substituted acyl group having 1 to 6 carbon atoms such as an acetyl group; an amino group optionally having a substituent, for example, a dialkylamino group having 1 to 10 carbon atoms such as a dimethylamino group and a diethylamino group; Diarylamino groups such as diphenylamino group, ditolylamino group and carbazolyl group; arylalkylamino groups such as phenylmethylamino group; methoxycarbonyl group which may have a substituent; 2 to 7 carbon atoms such as ethoxycarbonyl group An alkoxycarbonyl group which may have a substituent, an aromatic hydrocarbon ring group such as a phenyl group or a naphthyl group; an aromatic heterocyclic group such as a thienyl group which may have a substituent .
[0084]
Examples of the substituent that these substituents may have include one or more of the aforementioned substituent group Z.
[0085]
Among these polymer compounds, those having a weight average molecular weight of 1,000 to 1,000,000 are particularly useful for the production of organic electroluminescent devices. Further, when the layer containing the polymer compound is formed by a coating method, although there are differences depending on the degree of crosslinking, those having a weight average molecular weight of about 10,000 to 200,000 are usually preferred from the viewpoint of solubility.
[0086]
The polymer compound of the present invention, for example, first synthesizes a 1,4-phenylenediamine derivative having a hydroxyphenyl group, and an aromatic compound such as 4,4′-difluorobenzophenone or bis (4-fluorophenyl) sulfone. It is obtained by reacting with fluoride.
[0087]
Since the polymer compound of the present invention has high charge transport properties, it can be suitably used as an electrophotographic photosensitive member, an organic electroluminescent device, a photoelectric conversion device, an organic solar cell, an organic rectifying device and the like as a charge transport material. In particular, since it has excellent hole transportability, it is suitable as a hole transport material.
[0088]
In addition, by using the polymer compound of the present invention, an organic electroluminescent element that is excellent in heat resistance and stably driven (emits light) for a long period of time can be obtained, and therefore, it is suitable as an organic electroluminescent element material.
[0089]
Next, embodiments of the organic electroluminescent element of the present invention will be described in detail with reference to the drawings.
[0090]
1 to 3 are schematic cross-sectional views showing an embodiment of the organic electroluminescence device of the present invention, wherein 1 is a substrate, 2 is an anode, 3 is a hole injection layer, 4 is a hole transport layer, The light emitting layer, 6 represents an electron transport layer, and 7 represents a cathode.
[0091]
The substrate 1 serves as a support for the organic electroluminescent element, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, a glass plate or a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. If the gas barrier property of the substrate is too low, the organic electroluminescent element may be deteriorated by the outside air passing through the substrate, which is not preferable. For this reason, a dense silicon oxide film or the like may be provided on one side or both sides of the synthetic resin substrate to ensure gas barrier properties.
[0092]
An anode 2 is provided on the substrate 1, and the anode 2 plays a role of hole injection into the hole injection layer 3. The anode 2 is usually composed of a metal such as aluminum, gold, silver, nickel, palladium, or platinum, a metal oxide such as an oxide of indium and / or tin, a metal halide such as copper iodide, or carbon black. Is done. In general, the anode 2 is often formed by sputtering, vacuum deposition, or the like. Also, the anode 2 is formed by dispersing fine particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, etc. in an appropriate binder resin solution and applying the solution onto the substrate 1. You can also. The anode 2 can also be formed by stacking different materials. The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 1000 nm or less, preferably The lower limit is about 10 nm, preferably about 20 nm. If it may be opaque, the anode 2 may be the same as the substrate 1. Furthermore, it is also possible to laminate different conductive materials on the anode 2 described above.
[0093]
In the present invention, the hole injection layer 3 is provided on the anode 2 in the element structure of FIG. Conditions required for the material used for the hole injection layer 3 include a material having high hole injection efficiency from the anode 2 and capable of efficiently transporting the injected holes. It is done. For this purpose, the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is high, and trapping impurities are unlikely to be generated during manufacturing or use. Required. In addition to the above general requirements, when considering applications for in-vehicle displays, the device is required to have a heat resistance of 120 ° C. or higher.
[0094]
In the organic electroluminescent element of the present invention, the hole injection layer 3 is preferably a repeating unit represented by the general formula (II) or a repeating unit represented by the general formulas (I) and (II). It contains the polymer compound of the present invention having an electron-accepting compound.
[0095]
In the present invention, the light emitting characteristics and heat resistance of the device can be improved at the same time by using a mixture of the polymer compound of the present invention having a Tg of 120 ° C. or more and an electron accepting compound. That is, by mixing an electron-accepting compound with the electron-donating polymer compound, charge transfer occurs, and as a result, holes that are free carriers are generated, and the electrical conductivity of the hole-injecting layer is increased. For this reason, the electrical junction between the light emitting layer 5 and the anode 2 is improved by providing the hole injection layer 3 according to the present invention, and the driving voltage is lowered and the stability during continuous driving is also improved. Further, by using a polymer compound having a Tg of 120 ° C. or higher as the base material of the hole injection layer 3, the heat resistance of the device is greatly improved.
[0096]
In addition, by forming such a hole injection layer 3 mainly composed of the polymer compound of the present invention on the anode 2 by the coating process, the surface roughness of the anode 2 described above is relaxed and good. The effect of smoothing the surface is obtained, and the effect of preventing short-circuit defects during device fabrication is also achieved.
[0097]
The electron-accepting compound used for the hole injection layer 3 in combination with the polymer compound of the present invention may be any compound that causes charge transfer with the polymer compound. As a result, two physical properties of the ionization potential of the polymer compound of the present invention used for the hole injection layer 3: IP (polymer compound of the present invention) and electron affinity of the electron acceptor compound (acceptor): EA (acceptor). value,
IP (polymer compound of the present invention) -EA (acceptor) ≦ 0.7 eV,
It was found that this is particularly effective for the purpose of the present invention.
[0098]
This will be described with reference to the energy level diagram of FIG. In general, the ionization potential and the electron affinity are determined based on the vacuum level. The ionization potential is defined by the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of the material to the vacuum level, and the electron affinity is the LUMO (lowest empty molecule) of the electron at the vacuum level. Defined by the energy that falls to the orbital level and stabilizes.
[0099]
The difference in ion affinity between the HOMO level of the polymer compound of the present invention shown in FIG. 4 and the LUMO level of the electron-accepting compound is preferably 0.7 eV or less. The ionization potential can be directly measured by photoelectron spectroscopy or can be obtained by correcting the electrochemically measured oxidation potential with respect to the reference electrode. In the case of the latter method, for example, when a saturated sweet potato electrode (SCE) is used as a reference electrode,
Ionization potential = oxidation potential (vs.SCE) + 4.3 eV
(“Molecular Semiconductors”, Springer-Verlag, 1985, page 98). The electron affinity can be obtained by subtracting the optical band gap from the above-mentioned ionization potential, or similarly obtained by the above formula from the electrochemical reduction potential.
[0100]
The relational expression between the ionization potential and the electron affinity uses an oxidation potential and a reduction potential,
(Oxidation potential of the polymer compound of the present invention) − (reduction potential of the acceptor) ≦ 0.7V.
[0101]
The content of the electron accepting compound in the hole injection layer 3 is preferably in the range of 0.1 to 50% by weight with respect to the polymer compound of the present invention. More preferably, a concentration range of 1 to 30% by weight is desirable for practical properties.
[0102]
The electron-accepting compound is not particularly limited as long as it satisfies the above relationship, but preferred examples are shown below with abbreviated names.
[0103]
Embedded image

[0104]
The hole injection layer 3 containing the polymer compound of the present invention and the electron accepting compound is formed on the anode 2 by a coating method. That is, a predetermined amount of the polymer compound and the electron-accepting compound of the present invention having the repeating unit represented by the general formula (II) or the repeating unit represented by the general formulas (I) and (II). If necessary, add additives such as binder resin and coating property improver that do not trap holes, dissolve in an appropriate solvent to prepare coating solution, spin coating method, dip coating method, ink jet method, etc. Is applied onto the anode 2 and dried to form the hole injection layer 3.
[0105]
From the viewpoint of hole injection / transport capability, the total content of the polymer compound of the present invention and the electron-accepting compound in the hole injection layer 3 is preferably 20% by weight or more, particularly preferably 50% by weight or more. .
[0106]
The upper limit of the thickness of the hole injection layer 3 is usually 1000 nm, preferably 500 nm, and the lower limit is usually 5 nm, preferably 10 nm.
[0107]
A light emitting layer 5 is provided on the hole injection layer 3. The light-emitting layer 5 is a material that efficiently recombines electrons injected from the cathode 7 and holes transported from the hole injection layer 3 between electrodes to which an electric field is applied, and efficiently emits light by recombination. Formed from.
[0108]
Materials satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (JP 59-194393), metal complexes of 10-hydroxybenzo [h] quinoline (JP 6-322362 A). Gazette), bisstyrylbenzene derivatives (JP-A-1-245087, JP-A-2-222484), bisstyrylarylene derivatives (JP-A-2-247278), metal complexes of (2-hydroxyphenyl) benzothiazole ( JP-A-8-315983), silole derivatives and the like. These light emitting layer materials are usually laminated on the hole injection layer 3 by a vacuum deposition method.
[0109]
For the purpose of improving the luminous efficiency of the device and changing the emission color, for example, doping a fluorescent dye for lasers such as coumarin with an aluminum complex of 8-hydroxyquinoline as a host material (J. Appl. Phys., Volume 65) , 3610, 1989).
[0110]
In order to improve the driving life of the device, it is effective to dope a fluorescent dye using the light emitting layer material as a host material. For example, using a metal complex such as an aluminum complex of 8-hydroxyquinoline as a host material, a naphthacene derivative represented by rubrene (Japanese Patent Laid-Open No. 4-335087), a quinacridone derivative (Japanese Patent Laid-Open No. 5-70773), perylene, etc. By doping a condensed polycyclic aromatic hydrocarbon ring (Japanese Patent Laid-Open No. 5-198377) with 0.1 to 10% by weight with respect to the host material, the light emission characteristics of the device, particularly the driving stability, can be greatly improved. . As a method of doping the host material of the light emitting layer with a fluorescent dye such as the naphthacene derivative, quinacridone derivative, or perylene, there are a method by co-evaporation and a method in which a deposition source is mixed in advance at a predetermined concentration.
[0111]
Examples of the polymer light emitting layer material include poly (p-phenylene vinylene), poly [2-methoxy-5- (2-ethylhexyloxy) -1,4-phenylene vinylene], poly (3-alkyl) mentioned above. Examples thereof include a polymer material such as thiophene) and a system in which a light emitting material and an electron transfer material are mixed with a polymer such as polyvinyl carbazole. These materials are coated on the hole injection layer 3 by a method such as spin coating or dip coating in the same manner as the hole injection layer 3 to form a thin film.
[0112]
The upper limit of the thickness of the light emitting layer 5 is usually 200 nm, preferably 100 nm, and the lower limit is usually 10 nm, preferably 30 nm.
[0113]
In order to improve the light emitting characteristics of the device, a hole transport layer 4 is provided between the hole injection layer 3 and the light emitting layer 5 as shown in FIG. 2, and further, as shown in FIG. The layer 6 is provided between the light emitting layer 5 and the cathode 7 to form a function-separated organic electroluminescent device.
[0114]
2 and 3, the material for the hole transport layer 4 has high hole injection efficiency from the hole injection layer 3 and can efficiently transport the injected holes. It must be a material that can be made. For this purpose, it is required that the ionization potential is low, the hole mobility is high, the stability is high, and impurities that become traps are not easily generated during production or use. In addition, since the layer is in direct contact with the light emitting layer 5, it is desirable that no substance that quenches light emission is contained.
[0115]
Examples of such a hole transport material include two or more tertiary amines represented by 4,4′-bis [N- (9-naphthyl) -N-phenylamino] biphenyl, and two or more A starburst structure such as an aromatic diamine in which a condensed aromatic hydrocarbon ring is substituted with a nitrogen atom (Japanese Patent Laid-Open No. 5-234681), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) triphenylamine, etc. Aromatic amine compound (J. Lumin., 72-74, 985, 1997), aromatic amine compound composed of tetraphenylamine tetramer (Chem. Commun., 2175, 1996), 2 , 2 ', 7,7'-tetrakis- (diphenylamino) -9,9'-spirobifluorene (Synth. Metals, 91, 209, 1997) and the like. Can be used alone or as needed. It may be used as a mixture of two or more Te.
[0116]
In addition to the above-mentioned compounds, polyarylene ether sulfone (Polym. Adv. Tech.) Containing polyvinylcarbazole, polyvinyltriphenylamine (Japanese Patent Laid-Open No. 7-53953), and tetraphenylbenzidine as materials for the hole transport layer 4. , Vol. 7, p. 33, 1996).
[0117]
The hole transport layer 4 is formed by laminating the above hole transport material on the hole injection layer 3 by a coating method or a vacuum deposition method.
[0118]
In the case of the coating method, one or more of the hole transport materials and, if necessary, additives such as a binder resin and a coating property improving agent that do not trap holes are added and dissolved in a suitable solvent. A coating solution is prepared, applied onto the anode 2 by a method such as spin coating, and dried to form the hole transport layer 4. In this case, polycarbonate, polyarylate, polyester or the like can be used as the binder resin. When the amount of the binder resin added is large, the hole mobility is lowered. Therefore, it is desirable that the binder resin is small.
[0119]
In the case of the vacuum deposition method, the hole transport material is put in a crucible installed in a vacuum vessel, and the inside of the vacuum vessel is filled with an appropriate vacuum pump.^-FourAfter evacuating to about Pa, 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 hole injection layer 3 is formed, facing the crucible. Let
[0120]
The upper limit of the thickness of the hole transport layer 4 is usually 300 nm, preferably 100 nm, and the lower limit is usually 10 nm, preferably 30 nm. In order to uniformly form such a thin film, a vacuum deposition method is often used in general.
[0121]
As a method for further improving the light emission efficiency of the organic electroluminescence device, an electron transport layer 6 may be further laminated on the light emitting layer 4 as shown in FIG. The compound used for the electron transport layer 6 is required to be easy to inject electrons from the cathode 7 and to have a larger electron transport capability. Examples of such electron transport materials include 8-hydroxyquinoline aluminum complexes and oxadiazole derivatives (Appl. Phys. Lett., 55, 1489, 1989), which have already been mentioned as light emitting layer materials, and polymethacrylic acid. A system dispersed in a resin such as methyl acid (PMMA), a phenanthroline derivative (Japanese Patent Laid-Open No. 5-331459), 2-t-butyl-9,10-N, N′-dicyanoanthraquinonediimine, n-type hydrogenation Examples thereof include crystalline silicon carbide, n-type zinc sulfide, and n-type zinc selenide.
[0122]
The upper limit of the thickness of the electron transport layer 6 is usually 200 nm, preferably 100 nm, and the lower limit is usually 5 nm, preferably 10 nm.
[0123]
The cathode 7 serves to inject electrons into the light emitting layer 5. As a material for forming the cathode 7, the material used for the anode 2 can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable, and tin, magnesium, indium, calcium, A suitable metal such as aluminum or silver or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy. Further, LiF, MgF at the interface between the cathode 7 and the light emitting layer 5 or the electron transport layer 6₂, Li₂Inserting an ultra-thin insulating film (0.1-5 nm) such as O is also an effective method for improving the efficiency of the device (Appl. Phys. Lett., 70, 152, 1997; No. 74586; IEEE Trans. Electron. Devices, 44, 1245, 1997).
[0124]
The film thickness of the cathode 7 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of a low work function metal, further laminating a metal layer having a high work function and stable to the atmosphere on the cathode increases the stability of the device. For this purpose, metals such as aluminum, silver, copper, nickel, chromium, gold, platinum are used.
[0125]
1-3 are examples of the element structure employed in the present invention, and the present invention is not limited to the illustrated one. For example, a structure opposite to that shown in FIG. 1, that is, a cathode 7, a light emitting layer 5, a hole injection layer 3, and an anode 2 can be laminated in this order on a substrate, and at least one of them is transparent as described above. It is also possible to provide the organic electroluminescence device of the present invention between two high-height substrates. Similarly, it is also possible to laminate in a structure opposite to that of each of the layers shown in FIGS.
[0126]
Furthermore, as long as the performance of the organic electroluminescent device of the present invention is not impaired, an arbitrary layer may be provided between the layers shown in FIGS. 1, 2, and 3.
[0127]
Such an 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. it can.
[0128]
【Example】
Next, the present invention will be described more specifically with reference to synthesis examples, experimental examples, examples and comparative examples. However, the present invention is not limited to the description of the following examples unless it exceeds the gist.
[0129]
First, a synthesis example of a 1,4-phenylenediamine derivative that is a raw material of a polymer compound having a repeating unit represented by the general formulas (I) and (II) is shown.
[0130]
Synthesis example 1
(1-1) Synthesis of N, N′-diphenyl-N, N′-bis (4-methoxyphenyl) -1,4-phenylenediamine (BMPP)
[0131]
Embedded image

[0132]
N, N′-diphenyl-1,4-phenylenediamine (77.0 mmol) and 4-iodoanisole (231 mmol) are dissolved in 150 ml of tetraglyme, and copper powder (154 mmol) and potassium carbonate (112 mmol) are dissolved. The reaction was carried out in a nitrogen atmosphere at 200 ° C. for 8 hours. As a result, BMPP (34.8 g, yield 96%) represented by the formula (V) was obtained.
[0133]
(1-2) Synthesis of N, N′-diphenyl-N, N ′-(4-hydroxyphenyl) -1,4-phenylenediamine (BHPP)
[0134]
Embedded image

[0135]
BMPP (50.0 mmol) was dissolved in 360 ml of methylene chloride, and the inside of the system was cooled to −65 ° C. or less with a dry ice-ethanol bath in a nitrogen atmosphere, and boron tribromide (100 mmol) in methylene chloride was added thereto. Solution (100 milliliters) was added dropwise. After completion of the dropping, the refrigerant bath was removed and the mixture was stirred for 2 hours, extracted with ethyl acetate, and purified by silica gel column chromatography. As a result, BHPP (16.2 g, yield 73%) represented by the formula (VI) was obtained.
[0136]
Below, BHPP¹H-NMR (DMSO-d₆) Show data.
9.361 (2H, S)
7.189 (4H, dd, J = 6.7, 6.6)
6.936 (4H, dd, J = 5.7, 1.7)
6.875 (4H, S)
6.865-6.837 (6H, m)
6.751 (4H, dd, J = 5.7, 1.7)
[0137]
Synthesis example 2
1,4-phenylenediamine derivative of the present invention: (2-1) Synthesis of N-phenyl-N, N ′, N′-tris (4-methoxyphenyl) -1,4-phenylenediamine (TMPP)
[0138]
Embedded image

[0139]
N-phenyl-1,4-phenylenediamine (10.0 mmol) and 4-iodoanisole (45.0 mmol) are dissolved in 20 ml of tetraglyme, and copper powder (30.0 mmol) and potassium carbonate (22. In the presence of 5 mmol), the reaction was carried out at 200 ° C. for 7 hours in a nitrogen atmosphere, and the following day, copper powder (15.0 mmol) and potassium carbonate (15.0 mmol) were added to the reaction system, The mixture was reacted for 6 hours, extracted with toluene, and purified by silica gel column chromatography. As a result, TMPP represented by the formula (VII) (2.2 g, yield 44%) was obtained.
[0140]
(2-2) Synthesis of N-phenyl-N, N ′, N′-tris (4-hydroxyphenyl) -1,4-phenylenediamine (THPP)
[0141]
Embedded image

[0142]
TMPP (4.3 mmol) was dissolved in 35 ml of methylene chloride, and the inside of the system was cooled to −65 ° C. or lower with a dry ice-ethanol bath in a nitrogen atmosphere, and boron tribromide (14 mmol) in methylene chloride was added thereto. Solution (14 ml) was added dropwise. After completion of the dropping, the refrigerant bath was removed and the mixture was stirred for 2 hours, extracted with ethyl acetate, and purified by silica gel column chromatography. As a result, THPP (1.1 g, yield 56%) represented by the formula (VIII) was obtained.
[0143]
Below, THPP¹H-NMR (DMSO-d₆) Show data.
9.314 (1H, S)
9.239 (2H, S)
7.149 (2H, dd, J = 6.6, 6.4)
6.927-6.662 (19H, m)
[0144]
Next, synthesis examples of polymer compounds are shown.
[0145]
Synthesis example 3
Synthesis of 1,4-phenylenediamine-containing polymer (PPPEK)
[0146]
Embedded image

[0147]
BHPP (20.0 mmol) and 4,4′-difluorobenzophenone (20.0 mmol) were dissolved in 200 ml of 1-methyl 2-pyrrolidinone (NMP) and a nitrogen atmosphere in the presence of potassium carbonate (120 mmol). The condensation reaction was carried out at 145 ° C. for 20 hours. After allowing to cool, 10 ml of acetic acid was added to the reaction system and released into methanol, and the resulting polymer was washed with water to remove inorganic salts. After drying at 60 ° C. under reduced pressure, the polymer was dissolved in 300 ml of chloroform and released into methanol for reprecipitation. Finally, the suspension was washed with 400 ml of acetone to obtain a homopolymer PPPEK (yield 11.8 g, yield 95%) composed of repeating units (IX), excluding low molecular weight components.
[0148]
The polymer had a Tg of 183 ° C., a thermal decomposition temperature in a nitrogen atmosphere of 550 ° C. or higher, a weight average molecular weight (Mw) of 46,700, and a number average molecular weight (Mn) of 7,520. The molecular weight was determined by GPC measurement in chloroform using polystyrene as a standard sample.
[0149]
Synthesis example 4
Polymer compound of the present invention: Synthesis of branched 1,4-phenylenediamine-containing polymer compound (PPPEK-b3)
[0150]
Embedded image

[0151]
BHPP (4.78 mmol), THPP (0.15 mmol) and 4,4′-difluorobenzophenone (5.00 mmol) were dissolved in 39 ml of NMP and in the presence of potassium carbonate (23.1 mmol). The condensation reaction was carried out at 145 ° C. for 20 hours in a nitrogen atmosphere. After allowing to cool, 2 ml of acetic acid was added to the reaction system and released into methanol, and the resulting polymer was washed with water to remove inorganic salts. After drying at 60 ° C. under reduced pressure, the polymer was dissolved in 100 ml of chloroform and released into methanol for reprecipitation. Finally, by soxhlet extraction with acetone, the low molecular weight component is excluded, and the branched unit represented by the repeating unit (X) is theoretically contained at 3 mol% with respect to the PPPEK main chain represented by the repeating unit (IX). PPPEK-b3 (yield 1.78 g, yield 74%) was obtained.
[0152]
The polymer had a Tg of 190 ° C., a thermal decomposition temperature in a nitrogen atmosphere of 550 ° C. or higher, a weight average molecular weight (Mw) of 29,600, and a number average molecular weight (Mn) of 5,700. The molecular weight was determined by GPC measurement in chloroform using polystyrene as a standard sample.
[0153]
Next, experimental examples for measuring the viscosity of the 1,4-phenylenediamine-containing polymer compound obtained in Synthesis Examples 3 and 4 are shown.
[0154]
Experimental example 1
For the 1,4-phenylenediamine-containing polymer compound (PPPEK) and the branched 1,4-phenylenediamine-containing polymer compound (PPPEK-b3), the cyclohexanone solution was prepared by changing the polymer compound concentration, and the viscosity was FIG. 5 shows the relationship between the polymer compound concentration and the viscosity, as measured with a rotational viscometer manufactured by Tokyo Keiki Co., Ltd.
[0155]
As shown in FIG. 5, there is a large difference in the viscosity change of the solution between PPPEK and PPPEK-b3, and it can be seen that PPPEK-b3, which is the polymer compound of the present invention, is highly viscous.
[0156]
Below, the Example which performs the performance evaluation of the organic electroluminescent element using the synthesize | combined 1, 4- phenylenediamine containing polymer compound is given.
[0157]
Example 1
An organic electroluminescent element having the structure shown in FIG. 3 was produced by the following method.
[0158]
An indium tin oxide (ITO) transparent conductive film deposited on a glass substrate 1 with a thickness of 120 nm (manufactured by Geomat Corp .; electron beam film-formed product; sheet resistance 15 Ω / sq) is obtained using ordinary photolithography technology and hydrochloric acid etching. The anode 2 was formed by patterning into a stripe having a width of 2 mm. The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with acetone, water with pure water, and ultrasonic cleaning with isopropyl alcohol, then dried with nitrogen blow, and finally UV / ozone cleaning was performed.
[0159]
A mixture of a branched 1,4-phenylenediamine-containing polymer compound (PPPEK-b3) and PPB was spin-coated on the ITO glass substrate under the following conditions.
[Spin coating conditions]
Solvent: Cyclohexanone
PPPEK-b3: 5.0 mg / ml
PPB: 0.5 mg / ml
Spinner speed: 1500 rpm
Spinner rotation time: 30 seconds
Drying conditions: 2 hours at 120 ° C
[0160]
The hole injection layer 3 having a uniform thin film shape with a thickness of 20 nm was formed by the above spin coating.
[0161]
Next, the substrate on which the hole injection layer 3 was applied and formed was placed in a vacuum evaporation apparatus. After rough evacuation of this equipment with an oil rotary pump, the degree of vacuum in the equipment is 2 × 10^-6Torr (about 2.7 x 10^-FourPa) until evacuated using an oil diffusion pump equipped with a liquid nitrogen trap. The following aromatic diamine compound: 4,4'-bis [N- (9-phenanthyl) -N-phenylamino] biphenyl placed in a ceramic crucible placed in this apparatus was heated for vapor deposition. Vacuum degree during deposition is 1.3 × 10^-6Torr (approximately 1.7 × 10^-FourPa), the vapor deposition rate was 0.3 nm / second, and a 20 nm thick film was laminated on the hole injection layer 3 to complete the hole transport layer 4.
[0162]
Embedded image

[0163]
Subsequently, as a material of the light emitting layer 5, an 8-hydroxyquinoline complex of aluminum represented by the following structural formula: Al (C₉H₆NO)_Three, And rubrene were deposited at the same time.
[0164]
Embedded image

[0165]
The ratio of rubrene to the 8-hydroxyquinoline complex of aluminum was adjusted to 2.5 vol.%. At this time, the crucible temperature of the aluminum 8-hydroxyquinoline complex is controlled in the range of 275 to 285 ° C., and the degree of vacuum during the deposition is 1.2 × 10 6.^-6Torr (approximately 1.6 × 10^-FourPa), the deposition rate was 0.4 nm / sec. Moreover, the crucible temperature of rubrene was controlled in the range of 240-250 degreeC, and the vapor deposition rate was 0.01 nm / sec. The film thickness of the light-emitting layer 5 thus deposited was 30 nm.
[0166]
Subsequently, as the electron transport layer 6, an 8-hydroxyquinoline complex of aluminum: Al (C₉H₆NO)_ThreeWas deposited in the same manner as the hole transport layer 4. At this time, the crucible temperature of the aluminum 8-hydroxyquinoline complex is controlled in the range of 275 to 285 ° C., and the degree of vacuum during the deposition is 1.1 × 10 6.^-6Torr (about 1.5 × 10^-FourPa), the deposition rate was 0.4 nm / second, and the thickness of the deposited electron transport layer 6 was 45 nm.
[0167]
In addition, the substrate temperature at the time of vacuum-depositing said positive hole transport layer 4, the light emitting layer 5, and the electron carrying layer 6 was hold | maintained at room temperature.
[0168]
Here, the element on which the electron transport layer 6 has been deposited is once taken out from the vacuum deposition apparatus into the atmosphere, and a 2 mm wide striped shadow mask is orthogonal to the ITO stripe of the anode 2 as a mask for cathode deposition. After being in close contact with the element, it is installed in another vacuum vapor deposition apparatus, and the degree of vacuum in the apparatus is 2 × 10 10 as in the case of forming each organic layer.^-6Torr (about 2.7 x 10^-FourPa) exhausted until below.
[0169]
Thereafter, as the cathode 7, first, lithium fluoride (LiF) was vapor deposited at a rate of 0.02 nm / second using a molybdenum boat, and the degree of vacuum was 7.0 × 10.^-6Torr (approximately 9.3 × 10^-FourPa), a film was formed on the electron transport layer 6 to a thickness of 0.5 nm. Next, aluminum was similarly heated by a molybdenum boat, the deposition rate was 0.5 nm / second, and the degree of vacuum was 1 × 10.^-FiveTorr (about 1.3 × 10^-3Pa), an aluminum layer having a thickness of 80 nm was formed, and the cathode 7 was completed. The substrate temperature at the time of vapor deposition of the above two-layered cathode 7 was kept at room temperature.
[0170]
As described above, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained. The light emission characteristics of this device are shown in Table 1. In Table 1, the luminance is 250mA / cm²The current density value and luminous efficiency are 100cd / m²Value, brightness / current is the slope of brightness-current density characteristics, voltage is 100cd / m²The values at are shown respectively.
[0171]
From Table 1, it is clear that an element that emits light with high luminance and high luminous efficiency with a low driving voltage was obtained.
[0172]
[Table 1]

[0173]
As is clear from the above results, by forming a hole injection layer containing the polymer compound of the present invention and an electron-accepting compound, which is advantageous for the coating process, it can be driven at a low voltage and has improved heat resistance. An element can be obtained.
[0174]
【The invention's effect】
As described above in detail, by using the novel polymer compound of the present invention, preferably a polymer compound synthesized from the novel 1,4-phenylenediamine derivative of the present invention, it can be driven with low voltage and high luminous efficiency. Organic electroluminescent device that has good heat resistance and can maintain stable light emission characteristics over a long period of time, and that prevents short circuit defects during device fabrication due to the surface roughness of the anode An electroluminescent device is provided.
[0175]
Accordingly, the organic electroluminescent device according to the present invention is a light source (for example, a light source of a copying machine, a liquid crystal display, or a back of an instrument) utilizing characteristics of a flat panel display (for example, for OA computers or wall-mounted televisions) or a surface light emitter. It can be applied to a light source), a display panel, and a marker lamp, and the technical value is particularly great as an in-vehicle display element that requires high heat resistance.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an example of an embodiment of an organic electroluminescent element of the present invention.
FIG. 2 is a schematic cross-sectional view showing another example of the embodiment of the organic electroluminescent element of the present invention.
FIG. 3 is a schematic cross-sectional view showing another example of the embodiment of the organic electroluminescent element of the present invention.
FIG. 4 is an energy level diagram showing the relationship between the ionization potential of the polymer compound of the present invention and the electron affinity of the electron-accepting compound.
FIG. 5 is a graph showing a change in viscosity of a cyclohexanone solution containing a 1,4-phenylenediamine-containing polymer compound produced in Synthesis Examples 3 and 4.
[Explanation of symbols]
1 Substrate
2 Anode
3 Hole injection layer
4 hole transport layer
5 Light emitting layer
6 Electron transport layer
7 Cathode

Claims (13)

A polymer compound comprising a repeating unit represented by the following general formula (II) and having a weight average molecular weight of 1,000 to 1,000,000.

(In the formula, ring A2 is a benzene ring or a benzene ring condensed with an arbitrary ring, and this benzene ring or condensed ring has an alkyl group which may have a substituent and a substituent. An alkynyl group which may have a substituent, an alkynyl group which may have a substituent, an aralkyl group which may have a substituent, an acyl group which may have a substituent, and a substituent which may have It may be substituted with one or more substituents selected from the group consisting of an aromatic hydrocarbon ring group and an optionally substituted aromatic heterocyclic group.
Ar ⁵ to Ar ⁸ are each independently an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a substituent. An aralkyl group which may have, an acyl group which may have a substituent, an amino group which may have a substituent, an alkoxycarbonyl group which may have a substituent, and a substituent. Aromatic group optionally substituted with one or more substituents selected from the group consisting of an aromatic hydrocarbon ring group which may be substituted and an aromatic heterocyclic group which may have a substituent Represents a family ring.
Y ¹ and Y ² each independently represent a divalent linking group selected from a partial structure represented by the following structural formula. )

(In the formula, Ar ¹¹ to Ar ¹⁷ each independently represents an aromatic ring which may have a substituent.) The polymer compound according to claim 1, comprising a repeating unit represented by the following general formula (I) and the following general formula (II).

(In the formula, ring A1 and ring A2 are each independently a benzene ring or a benzene ring condensed with an arbitrary ring, and this benzene ring or condensed ring is an alkyl group which may have a substituent, An alkenyl group which may have a substituent, an alkynyl group which may have a substituent, an aralkyl group which may have a substituent, an acyl group which may have a substituent, a substituent May be substituted with one or two or more substituents selected from the group consisting of an aromatic hydrocarbon ring group which may have a substituent and an aromatic heterocyclic group which may have a substituent. Good.
Ar ¹ to Ar ⁸ are each independently an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or a substituent. An aralkyl group which may have, an acyl group which may have a substituent, an amino group which may have a substituent, an alkoxycarbonyl group which may have a substituent, and a substituent. Aromatic group optionally substituted with one or more substituents selected from the group consisting of an aromatic hydrocarbon ring group which may be substituted and an aromatic heterocyclic group which may have a substituent Represents a family ring.
X, Y ¹ and Y ² each independently represents a divalent linking group selected from a partial structure represented by the following structural formula. )

(In the formula, Ar ¹¹ to Ar ¹⁷ each independently represents an aromatic ring which may have a substituent.) 3. The polymer compound according to claim 2, wherein the repeating unit represented by the general formula (I) is represented by the following general formula (I ′).

(In the formula, ring B1, ring B2, ring B4 and ring B5 each independently represent a benzene ring or a naphthalene ring, and this benzene ring or naphthalene ring is an alkyl group which may have a substituent, An alkenyl group which may have a group, an alkynyl group which may have a substituent, an aralkyl group which may have a substituent, an acyl group which may have a substituent, and a substituent. An optionally substituted amino group, an optionally substituted alkoxycarbonyl group, an optionally substituted aromatic hydrocarbon ring group, and an optionally substituted aromatic group It may be substituted with one or more substituents selected from the group consisting of heterocyclic groups.
Ring B3 is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, and an aralkyl which may have a substituent. Selected from the group consisting of a group, an acyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, and an aromatic heterocyclic group which may have a substituent. Represents a benzene ring which may be substituted with one or more substituents.
X has the same meaning as in formula (I). ) The polymer compound according to any one of claims 1 to 3, wherein the repeating unit represented by the general formula (II) is represented by the following general formula (II ').

(In the formula, ring B6, ring B7, ring B9 and ring B10 are each independently a benzene ring or naphthalene ring, and this benzene ring or naphthalene ring is an alkyl group which may have a substituent, An alkenyl group which may have a group, an alkynyl group which may have a substituent, an aralkyl group which may have a substituent, an acyl group which may have a substituent, and a substituent. An optionally substituted amino group, an optionally substituted alkoxycarbonyl group, an optionally substituted aromatic hydrocarbon ring group, and an optionally substituted aromatic group It may be substituted with one or more substituents selected from the group consisting of heterocyclic groups.
Ring B8 is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, and an aralkyl which may have a substituent. Selected from the group consisting of a group, an acyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, and an aromatic heterocyclic group which may have a substituent. Represents a benzene ring which may be substituted with one or more substituents.
Y ¹ and Y ² have the same meaning as in formula (II). ) 5. The composition according to claim 2, which is synthesized using a monomer represented by the following general formula (III) and the following general formula (IV) and an aromatic difluoride. High molecular compound.

(In formula (III), ring B1, ring B2, ring B4 and ring B5 each independently represent a benzene ring or a naphthalene ring, and this benzene ring or naphthalene ring is an alkyl which may have a substituent. A group, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, an aralkyl group which may have a substituent, an acyl group which may have a substituent, An amino group which may have a substituent, an alkoxycarbonyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, and a substituent It may be substituted with one or more substituents selected from the group consisting of good aromatic heterocyclic groups.
Ring B3 is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, and an aralkyl which may have a substituent. Selected from the group consisting of a group, an acyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, and an aromatic heterocyclic group which may have a substituent. Represents a benzene ring which may be substituted with one or more substituents.
In formula (IV), ring B6, ring B7, ring B9 and ring B10 are each independently a benzene ring or naphthalene ring, and this benzene ring or naphthalene ring is an alkyl group which may have a substituent. , An alkenyl group which may have a substituent, an alkynyl group which may have a substituent, an aralkyl group which may have a substituent, an acyl group which may have a substituent, a substituent An amino group which may have a group, an alkoxycarbonyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, and a substituent. It may be substituted with one or more substituents selected from the group consisting of aromatic heterocyclic groups.
Ring B8 is an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, and an aralkyl which may have a substituent. Selected from the group consisting of a group, an acyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, and an aromatic heterocyclic group which may have a substituent. Represents a benzene ring which may be substituted with one or more substituents. ) 1,4-phenylenediamine derivative represented by the following general formula (IV ′).

(In the formula, R ⁶ , R ⁷ , R ⁹ and R ¹⁰ are each independently a hydrogen atom, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, or a substituent. An alkynyl group which may have a substituent, an aralkyl group which may have a substituent, an acyl group which may have a substituent, an amino group which may have a substituent, and a substituent. Represents an optionally substituted alkoxycarbonyl group, an optionally substituted aromatic hydrocarbon ring group, or an optionally substituted aromatic heterocyclic group,
R ⁸ represents an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an alkynyl group which may have a substituent, or an aralkyl which may have a substituent. A group, an acyl group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. )   A charge transport material comprising the polymer compound according to any one of claims 1 to 5.   Organic electroluminescent element material containing the high molecular compound of any one of Claim 1 thru | or 5.   6. An organic electroluminescence device having an anode, a cathode, and a light emitting layer existing between the two electrodes on a substrate, comprising a layer containing the polymer compound according to any one of claims 1 to 5. Organic electroluminescent device.   10. The organic electroluminescent device according to claim 9, wherein a layer containing the polymer compound and the electron accepting compound is provided between the light emitting layer and the anode.   11. The organic electroluminescent device according to claim 10, wherein a value obtained by subtracting the electron affinity of the electron accepting compound from the ionization potential of the polymer compound is 0.7 eV or less.   The content of the electron-accepting compound in the layer containing the polymer compound and the electron-accepting compound according to claim 10 or 11 is in a range of 0.1 to 50% by weight with respect to the polymer compound. An organic electroluminescent element characterized by being. The organic electroluminescent element according to claim 10, wherein the electron-accepting compound is at least one selected from the following compound group.

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