JP2004087372A - Organic electroluminescent device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL device which has enough luminance and is excellent in stability and durability capable of making the area of the device larger, and easy to produce the device. <P>SOLUTION: The EL device comprises one or a plurality of organic compound layers sandwiched between a pair of electrodes consisting of an anode and a cathode, at least one of which is transparent or semi-transparent, where at least one of the organic compound layers includes one or more kinds of charge transport polyurethane made up of repeating units, and the repeating unit includes at least a kind of a structure selected from the structures shown by the following formulas (I-1) and (I-2) as a portion structure. <P>COPYRIGHT: (C)2004,JPO

Description

【００１３】
一般式（Ｉ−１）及び（Ｉ−２）中、Ａｒは、一般式（ＩＩ−１）で表される置換基または（ＩＩ−２）で表される置換基を表し、Ｘは置換または未置換の２価の芳香族基を表し、ｋは０または１を表す。
【００１４】
【化５】

【００１５】
一般式（ＩＩ−１）及び（ＩＩ−２）中、Ａｒ_１、Ａｒ_２及びＡｒ_３は、置換もしくは未置換のベンゼン環、または置換もしくは未置換の芳香環数２〜１０の多核芳香族炭化水素、または置換もしくは未置換の芳香環数２〜１０の縮合芳香族炭化水素、または置換もしくは未置換の芳香族複素環、または少なくとも１種の芳香族複素環を含む置換もしくは未置換の芳香族基を表し、Ｒ_１、Ｒ_２、Ｒ_３及びＲ_４は、水素原子、アルキル基、アルコキシ基、シアノ基、ハロゲン原子、置換アミノ基、置換もしくは未置換のアリール基、または置換もしくは未置換のアラルキル基を表し、それぞれ独立であっても、少なくとも２種以上が同一であってもよい。ｎは０〜１０の整数を表す。
【００１６】
＜２＞　前記有機化合物層が少なくともキャリア輸送能を持つ発光層及び電子輸送層から構成され、前記発光層が、前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し単位よりなる電荷輸送性ポリウレタンを、少なくとも１種含有してなることを特徴とする＜１＞に記載の有機電界発光素子である。
【００１７】
＜３＞　前記有機化合物層が少なくともホール輸送層、発光層及び電子輸送層から構成され、前記発光層が、前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し単位よりなる電荷輸送性ポリウレタンを、少なくとも１種含有してなることを特徴とする＜１＞に記載の有機電界発光素子である。
【００１８】
＜４＞　前記有機化合物層が少なくともキャリア輸送能を持つ発光層から構成され、前記発光層が、前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し単位よりなる電荷輸送性ポリウレタンを、少なくとも１種含有してなることを特徴とする＜１＞に記載の有機電界発光素子である。
【００１９】
＜５＞　前記有機化合物層が少なくともホール輸送層及びキャリア輸送能を持つ発光層から構成され、前記発光層が、前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し単位よりなる電荷輸送性ポリウレタンを、少なくとも１種含有してなることを特徴とする＜１＞に記載の有機電界発光素子である。
【００２０】
＜６＞　前記発光層が、電荷輸送性材料を含むことを特徴とする＜２＞〜＜５＞のいずれかに記載の有機電界発光素子である。
【００２１】
＜７＞　前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し単位よりなる電荷輸送性ポリウレタンが、下記一般式（ＩＩＩ−１）または（ＩＩＩ−２）で示されるポリウレタンであることを特徴とする＜１＞〜＜６＞のいずれかに記載の有機電界発光素子である。
【００２２】
【化６】

【００２３】
一般式（ＩＩＩ−１）及び（ＩＩＩ−２）中、Ａは上記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を表し、Ｒは水素原子、アルキル基、置換もしくは未置換のアリール基、または置換もしくは未置換のアラルキル基を表し、Ｔは炭素数１〜６の２価の直鎖状炭化水素基、または炭素数２〜１０の２価の分枝鎖状炭化水素基を表し、Ｙはジイソシアネート残基を表し、Ｚは２価アルコール残基を表し、ｍは０または１を表し、ｐは５〜５０００の整数を表す。
【００２４】
なお、本発明の有機ＥＬ素子において、有機化合物層は、機能分離型のもの、例えば、少なくともホール輸送層及び発光層から構成され、該ホール輸送層が前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し単位よりなるホール輸送性ポリウレタンを含有してなるものや、キャリア輸送能と発光能とを兼ね備えたもの、すなわち、有機化合物層が発光層のみから構成されてなり、該発光層が、前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し単位よりなる電荷輸送性ポリウレタンを含有してなるもののいずれであってもよい。
また、本発明の有機ＥＬ素子において、有機化合物層が発光層のみから構成される場合、該発光層は、電荷輸送性材料（電荷輸送性ポリウレタン以外のホール輸送材料、電子輸送材料）を含んでいてもよい。
【００２５】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明の有機ＥＬ素子は、少なくとも一方が透明または半透明である陽極及び陰極よりなる一対の電極間に挾持された、一つまたは複数の有機化合物層より構成され、該有機化合物層の少なくとも一層が、下記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し単位よりなる電荷輸送性ポリウレタン（以下、単に「電荷輸送性ポリウレタン」という場合がある）を１種以上含有することを特徴とする。本発明の有機ＥＬ素子は、前記電荷輸送性ポリウレタンを含有してなる層を有することで、十分な輝度を有し、安定性及び耐久性に優れる。さらに、前記電荷輸送性ポリウレタンを用いることで、有機ＥＬ素子の大面積化が可能であり、容易に製造することができる。
【００２６】
【化７】

【００２７】
一般式（Ｉ−１）及び（Ｉ−２）中、Ａｒは、一般式（ＩＩ−１）で表される置換基または（ＩＩ−２）で表される置換基を表し、Ｘは置換または未置換の２価の芳香族基を表し、ｋは０または１を表す。
【００２８】
【化８】

【００２９】
一般式（ＩＩ−１）及び（ＩＩ−２）中、Ａｒ_１、Ａｒ_２及びＡｒ_３は、置換もしくは未置換のベンゼン環、または置換もしくは未置換の芳香環数２〜１０の多核芳香族炭化水素、または置換もしくは未置換の芳香環数２〜１０の縮合芳香族炭化水素、または置換もしくは未置換の芳香族複素環、または少なくとも１種の芳香族複素環を含む置換もしくは未置換の芳香族基を表し、Ｒ_１、Ｒ_２、Ｒ_３及びＲ_４は、水素原子、アルキル基、アルコキシ基、シアノ基、ハロゲン原子、置換アミノ基、置換もしくは未置換のアリール基、または置換もしくは未置換のアラルキル基を表し、それぞれ独立であっても、少なくとも２種以上が同一であってもよい。ｎは０〜１０の整数を表す。
【００３０】
前記多核芳香族炭化水素とは、炭素と水素とから構成される芳香環が２個以上存在し、環同士が炭素−炭素単結合によって結合している炭化水素を表す。具体的には、ビフェニル、ターフェニル等が挙げられる。また、前記縮合芳香族炭化水素とは、炭素と水素とから構成される芳香環が２個以上存在し、環同士が１対の炭素原子を共有している炭化水素を表す。具体的には、ナフタレン、アントラセン、フェナントレン、フルオレン等が挙げられる。また、前記芳香族複素環とは、炭素と水素以外の元素を含む芳香環を表す。具体的には、ピロール環、フラン環、チオフェン環、イミダゾール環、オキサゾール環、カルバゾール環、チアゾール環、ピラゾール環、ピリジン環、キノリン環、等が挙げられる。さらに、前記芳香族複素環を含む芳香族基とは、その構造中に少なくとも１種の芳香族複素環が置換、縮合あるいは連結された形で含む置換基を表す。
【００３１】
なお、上記芳香族複素環を含む芳香族基は、すべてが共役系で構成されたもの、あるいは一部が非共役系で構成されたもののいずれでもよいが、電荷輸送性や発光効率の点で、すべてが共役系で構成されたものが好ましい。
【００３２】
また、前記ベンゼン環、多核芳香族炭化水素、縮合芳香族炭化水素、芳香族複素環、または少なくとも１種の芳香族複素環を含む芳香族基の置換基としては、水素原子、アルキル基、アルコキシ基、アラルキル基、置換アミノ基、シアノ基、ハロゲン原子等が挙げられ、これらの中では、水素原子、アルキル基、アルコキシ基、アラルキル基、置換アミノ基、シアノ基、ハロゲン原子が好ましい。
【００３３】
上記アルキル基としては、炭素数が１〜１０の範囲のものが好ましく、炭素数が１〜３の範囲のものがより好ましい。具体的には、例えば、メチル基、エチル基、プロピル基、イソプロピル基等が挙げられる。
【００３４】
前記アルコキシル基としては、炭素数が１〜１０の範囲のものが好ましく、炭素数が１〜３の範囲のものがより好ましい。具体的には例えば、メトキシ基、エトキシ基、プロポキシ基、イソプロポキシ基等が挙げられる。
【００３５】
前記アリール基としては、炭素数が６〜２０の範囲のものが好ましく、炭素数が６〜７の範囲のものがより好ましい。具体的には例えば、フェニル基、トルイル基等が挙げられる。
【００３６】
また前記アラルキル基としては、炭素数が７〜２０の範囲のものが好ましく、炭素数が７〜８の範囲のものがより好ましい。具体的には、例えば、ベンジル基、フェネチル基等が挙げられる。
置換アミノ基の置換基としては、アルキル基、アリール基、アラルキル基等が挙げられ、具体例は前述の通りである。
【００３７】
前記一般式（Ｉ−１）及び（Ｉ−２）中、Ｘは、置換または未置換の２価の芳香族基を表し、具体的には、下記式（１）〜（１３）から選択された基が挙げられる。
【００３８】
【化９】

【００３９】
式（１）〜（１３）中、Ｒ_５は、水素原子、炭素数１〜４のアルキル基、置換もしくは未置換のフェニル基、または置換もしくは未置換のアラルキル基を表し、Ｒ_６〜Ｒ_１７は、それぞれ水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシル基、置換もしくは未置換のフェニル基、置換もしくは未置換のアラルキル基、またはハロゲン原子を表し、ａは０または１を表す。
また、Ｖは下記式（１４）〜（２９）から選択された基を表す。
【００４０】
【化１０】

【００４１】
式（１３）〜（２９）中、ｂは１〜１０の整数を表し、ｃは１〜３の整数を表す。
【００４２】
これらの中でも、前記Ｘが下記構造式（Ａ）または（Ｂ）で示されるビフェニレン構造を有する場合、「Ｔｈｅ　Ｓｉｘｔｈ　Ｉｎｔｅｒｎａｔｉｏｎａｌ　Ｃｏｎｇｒｅｓｓ　ｏｎ　Ａｄｖａｎｃｅｓ　ｉｎ　Ｎｏｎ−ｉｍｐａｃｔ　Ｐｒｉｎｔｉｎｇ　Ｔｅｃｈｎｏｌｏｇｉｅｓ，３０６，（１９９０）　」にも報告されているように、モビリティーが高いポリマーが得られることから、特に好ましい。
【００４３】
【化１１】

【００４４】
なお、一般式（Ｉ−１）及び（Ｉ−２）中、ｋは０または１を表す。
以下、一般式（Ｉ−１）及び（Ｉ−２）で示される構造の具体例を表１〜表１１に示すが、本発明は、これら具体例に限定されるわけではない。なお、表１〜表６における構造番号１〜５３は、一般式（Ｉ−１）で示される構造の具体例を示し、表７〜表１１における構造番号５４〜９６は、一般式（Ｉ−２）で示される構造の具体例を示す。
【００４５】
【表１】

【００４６】
【表２】

【００４７】
【表３】

【００４８】
【表４】

【００４９】
【表５】

【００５０】
【表６】

【００５１】
【表７】

【００５２】
【表８】

【００５３】
【表９】

【００５４】
【表１０】

【００５５】
【表１１】

【００５６】
【００５７】
一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し単位よりなる電荷輸送性ポリウレタンとしては、下記一般式（ＩＩＩ−１）または（ＩＩＩ−２）で示されるものが好適に使用される。
【００５８】
【化１２】

【００５９】
一般式（ＩＩＩ−１）または（ＩＩＩ−２）中、Ａは前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を表し、一つのポリマー中に２種類以上の構造Ａが含まれてもよい。
【００６０】
一般式（ＩＩＩ−１）または（ＩＩＩ−２）式中、Ｒは水素原子、アルキル基、置換もしくは未置換のアリール基、または置換もしくは未置換のアラルキル基を表す。アルキル基としては、炭素数が１〜１０の範囲のものが好ましく、炭素数１〜３の範囲のものがより好ましい。具体的には、例えば、メチル基、エチル基、プロピル基、イソプロピル基等が挙げられる。
【００６１】
上記アリール基としては、炭素数が６〜２０の範囲のものが好ましく、炭素数６〜７の範囲のものがより好ましい。具体的には、例えば、フェニル基、トルイル基等が挙げられる。
【００６２】
前記アラルキル基としては、炭素数が７〜２０の範囲のものが好ましく、炭素数が７〜８の範囲のものがより好ましい。具体的には、例えば、ベンジル基、フェネチル基等が挙げられる。また、置換アリール基、置換アラルキル基の置換基としては、水素原子、アルキル基、アルコキシ基、置換アミノ基、ハロゲン原子等が挙げられる。
【００６３】
前記一般式（ＩＩＩ−１）または（ＩＩＩ−２）中、Ｔは、炭素数１〜６の２価の直鎖状炭化水素基、または炭素数２〜１０の２価の分枝鎖状炭化水素基を示し、好ましくは炭素数が２〜６の２価の直鎖状炭化水素基、及び炭素数３〜７の２価の分枝鎖状炭化水素基より選択される。具体的な構造を以下に示す。
【００６４】
【化１３】

【００６５】
また、前記一般式（ＩＩＩ−１）または（ＩＩＩ−２）中、Ｙは２価のアルコール残基を表し、Ｚは２価のカルボン酸残基を表す。Ｙ及びＺとしては、具体的には下記式（３０）〜（３６）から選択された基が挙げられる。
【００６６】
【化１４】

【００６７】
式（３０）〜（３６）中、Ｒ_１８及びＲ_１９は、それぞれ水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシル基、置換もしくは未置換のフェニル基、置換もしくは未置換のアラルキル基、またはハロゲン原子を表し、ｄ及びｅは、それぞれ１〜１０の整数を、ｆ及びｇは、それぞれ０、１または２の整数を、ｈ及びｉはそれぞれ０または１を表す。また、Ｖは前記式（１４）〜（２９）中におけるＶと同様である。
【００６８】
さらに、前記一般式（ＩＩＩ−１）または（ＩＩＩ−２）中、ｍは０または１を表し、ｐは５〜５０００の整数を表す。なお、ｐは１０〜１０００の範囲であることが好ましい。
【００６９】
以下、表１２及び１３に、一般式（ＩＩＩ−１）及び（ＩＩＩ−２）で示される電荷輸送性ポリウレタンの具体例を示すが、本発明は、これら具体例に限定されるわけではない。なお、表１２及び１３において、Ａの欄の番号は、前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造の具体例である表１〜表１１で示した構造番号に対応している。また、Ｚの欄が「−」であるものは、一般式（ＩＩＩ−１）で示される電荷輸送性ポリウレタンの具体例を示し、Ｙの欄が「−」であるものは、一般式（ＩＩＩ−２）で示される電荷輸送性ポリウレタンの具体例を示す。以下、各番号を付した具体例、例えば、１５の番号を付した具体例は例示化合物（１５）という。
【００７０】
【表１２】

【００７１】
【表１３】

【００７２】
前記電荷輸送性ポリウレタンの質量平均分子量Ｍｗは、１０，０００〜３００，０００の範囲にあることが好ましく、２０，０００〜１００，０００の範囲にあることがより好ましい。
【００７３】
前記電荷輸送性ポリウレタンは、下記構造式（ＩＶ−１）〜（ＩＶ−４）で示される電荷輸送性モノマーを、例えば、第４版実験化学講座第２８巻（丸善、１９９２）、新高分子実験学第２巻（共立出版、１９９５）、等に記載された公知の方法で重合させることによって合成することができる。なお、構造式（ＩＶ−１）〜（ＩＶ−４）中、Ａ、Ｔ、ｍは、各々前記一般式（ＩＩＩ−１）または（ＩＩＩ−２）におけるＡ、Ｔ、ｍと同様である。
【００７４】
【化１５】

【００７５】
具体的には、例えば、一般式（ＩＶ−１）及び（ＩＶ−２）で示される電荷輸送性モノマーの場合、電荷輸送性ポリウレタンは、次のようにして合成することができる。
電荷輸送性モノマーが一般式（ＩＶ−１）で示される２価アルコールの場合には、ＯＮＣ−Ｙ−ＮＣＯで示されるジイソシアネート類と当量混合し、また電荷輸送性モノマーが一般式（ＩＶ−２）で示されるジイソシアネート類の場合には、ＨＯ−Ｙ−ＯＨで示される２価アルコール類と当量混合し、重付加する。触媒としては、ジラウリル酸ジブチルスズ（ＩＩ）、二酢酸ジブチルスズ（ＩＩ）、ナフテン酸鉛等の有機金属化合物といった通常の重付加によるポリウレタン合成反応に用いるものが使用できる。また、芳香族系のジイソシアネートを電荷輸送性ポリウレタンの合成に用いる場合には、トリエチレンジアミン等の第三アミンを触媒として用いることができる。これら有機金属化合物と第三アミンとは触媒として混合して用いてもよい。
【００７６】
用いられる触媒の量は、電荷輸送性モノマー１質量部に対して、１／１０，０００〜１／１０質量部の範囲であることが好ましく、１／１，０００〜１／５０質量部の範囲であることがより好ましい。
【００７７】
溶剤としては、電荷輸送性モノマーとジイソシアネート、もしくは２価アルコール類とを溶解するものであれば、任意の溶剤を用いることができるが、反応性の点から極性の低い溶媒やアルコールとの水素結合を生じない溶媒を用いることが好ましく、トルエン、クロロベンゼン、ジクロロベンゼン、１−クロロナフタレン等が有効である。用いられる溶剤の量は、電荷輸送性モノマー１質量部に対して、１〜１００質量部の範囲であることが好ましく、２〜５０質量部の範囲であることがより好ましい。なお、反応温度は任意に設定できる。
【００７８】
反応終了後は、反応溶液をそのまま、メタノール、エタノール等のアルコール類や、アセトン等のポリマーが溶解しにくい貧溶剤中に滴下し、電荷輸送性ポリウレタンを析出させて分離した後、水や有機溶剤で十分洗浄し、乾燥させる。さらに、必要であれば適当な有機溶剤に溶解させ、貧溶剤中に滴下し、電荷輸送性ポリウレタンを析出させる再沈殿処理を繰り返してもよい。再沈殿処理の際には、メカニカルスターラー等で、貧溶剤を効率よく撹拌しながら行うことが好ましい。
【００７９】
上記再沈殿処理の際に電荷輸送性ポリウレタンを溶解させる溶剤量は、電荷輸送性ポリウレタン１質量部に対して、１〜１００質量部の範囲であることが好ましく、２〜５０質量部の範囲であることがより好ましい。また、前記貧溶剤の量は電荷輸送性ポリウレタン１質量部に対して、１〜１，０００質量部の範囲であることが好ましく、１０〜５００質量部の範囲であることがより好ましい。
【００８０】
前記一般式（ＩＶ−３）及び（ＩＶ−４）で示される電荷輸送性モノマーの場合、電荷輸送性ポリウレタンは、次のようにして合成することができる。電荷輸送性モノマーが一般式（ＩＶ−３）で示されるビスクロロホルメートの場合には、_２ＨＮ−Ｙ−ＮＨ_２で示されるジアミン類と当量混合し、また電荷輸送性モノマーが一般式（ＩＶ−４）で示されるジアミン類の場合には、ＣｌＯＣＯ−Ｙ−ＯＣＯＣｌで示されるビスクロロホルメート類と当量混合し、重縮合する。
【００８１】
溶剤としては、塩化メチレン、ジクロロエタン、トリクロロエタン、テトラヒドロフラン（ＴＨＦ）、トルエン、クロロベンゼン、１−クロロナフタレン等が有効であり、溶剤量としては電荷輸送性モノマー１質量部に対して、１〜１００質量部の範囲であることが好ましく、２〜５０質量部の範囲であることがより好ましい。反応温度は任意に設定できる。重合後は、前述のように再沈殿処理により精製する。
【００８２】
また、前記_２ＨＮ−Ｙ−ＮＨ_２で示されるジアミン類の塩基性度の高い場合には、界面重合法も用いることができる。すなわち、ジアミン類を水に加え、当量の酸を加えて溶解させた後、激しく撹拌しながらジアミン類と前記一般式（ＩＶ−３）で示される当量の電荷輸送性モノマー溶液とを加えることによって重合することができる。この際、水の量はジアミン類１質量部に対して、１〜１，０００質量部の範囲であることが好ましく、１０〜５００質量部の範囲であることがより好ましい。
【００８３】
電荷輸送性モノマーを溶解させる溶剤としては、塩化メチレン、ジクロロエタン、トリクロロエタン、トルエン、クロロベンゼン、１−クロロナフタレン等が有効である。反応温度は任意に設定でき、反応を促進するために、アンモニウム塩、スルホニウム塩等の相間移動触媒を用いることが効果的である。用いられる相間移動触媒の量は、電荷輸送性モノマー１質量部に対して、０．１〜１０質量部の範囲であることが好ましく、０．２〜５質量部の範囲であることがより好ましい。
【００８４】
次に、本発明の有機ＥＬ素子の層構成について詳記する。
本発明の有機ＥＬ素子は、少なくとも一方が透明または半透明である一対の電極と、それら電極間に挾持された発光層を含む一つまたは複数の有機化合物層より構成され、該有機化合物層の少なくとも１層に前記電荷輸送性ポリウレタンを含有してなる。
【００８５】
本発明の有機ＥＬ素子においては、有機化合物層が１つの場合は、該有機化合物層はキャリア輸送能を持つ発光層であり、該発光層が前記電荷輸送性ポリウレタンを含有してなる。また、有機化合物層が複数の場合（機能分離型の場合）は、それらの少なくとも一つは発光層（この発光層はキャリア輸送能を有していてもよいし、有していなくてもよい）であり、他の有機化合物層は、キャリア輸送層、すなわち、ホール輸送層、電子輸送層、または、ホール輸送層及び電子輸送層として構成され、これらの少なくとも一層が、前記電荷輸送性ポリウレタンを含有してなる。
【００８６】
具体的には、例えば、少なくとも発光層及び電子輸送層から構成される有機ＥＬ素子、少なくともホール輸送層、発光層及び電子輸送層から構成される有機ＥＬ素子、あるいは、少なくともホール輸送層及び発光層から構成される有機ＥＬ素子において、これらの少なくとも一層（発光層、ホール輸送層、電子輸送層）が前記電荷輸送性ポリウレタンを含有してなるもの等が挙げられる。
【００８７】
また、本発明の有機ＥＬ素子においては、発光層が、電荷輸送性材料（前記電荷輸送性ポリウレタン以外のホール輸送性材料、電子輸送性材料）を含有していることが好ましい。詳しくは、後述する。
【００８８】
以下、図面を参照しつつ、より詳細に説明するが、本発明はこれらに限定されるわけではない。
図１〜図４は、本発明の有機ＥＬ素子の層構成を説明するための模式的断面図であって、図１、図２、図４は、有機化合物層が複数の場合の一例であり、図３は、有機化合物層が１つの場合の例を示す。なお、図１〜図４において、同様の機能を有するものは同じ符号を付して説明する。
【００８９】
図１に示す有機ＥＬ素子は、透明絶縁体基板１表面に、透明電極２、キャリア輸送能を持つ発光層６、電子輸送層５及び背面電極７を順次積層してなる。図２に示す有機ＥＬ素子は、透明絶縁体基板１表面に、透明電極２、ホール輸送層３、発光層４、電子輸送層５及び背面電極７を順次積層してなる。図３に示す有機ＥＬ素子は、透明絶縁体基板１表面に、透明電極２、キャリア輸送能を持つ発光層６及び背面電極７を順次積層してなる。図４に示す有機ＥＬ素子は、透明絶縁体基板１表面に、透明電極２、ホール輸送層３、キャリア輸送能を持つ発光層６及び背面電極７を順次積層してなる。以下、各々を詳しく説明する。
【００９０】
なお、図１、図２及び図４に示す有機ＥＬ素子は、発光材料（発光層）が、明確なキャリア輸送性を示さないものを用いる場合に、有機ＥＬ素子の耐久性向上あるいは発光効率の向上を図る目的で、発光層４あるいはキャリア輸送能を持つ発光層６と透明電極２との間にホール輸送層を設けたり、発光層４あるいはキャリア輸送能を持つ発光層６と背面電極７との間に電子輸送層を設けたりした層構成のものである。
【００９１】
本発明における前記電荷輸送性ポリウレタンを含有してなる有機化合物層は、図１に示される有機ＥＬ素子の層構成の場合には、例えば、電子輸送層５、キャリア輸送能を持つ発光層６としていずれも用いることができるが、キャリア輸送能を持つ発光層６として用いることが好ましい。また、図２に示される有機ＥＬ素子の層構成の場合には、前記電荷輸送性ポリウレタンを含有してなる有機化合物層を発光層４として用いることが好ましい。また、図３に示される有機ＥＬ素子の層構成の場合には、前記電荷輸送性ポリウレタンを含有してなる有機化合物層をキャリア輸送能を持つ発光層６として用いることが好ましい。さらに、図４に示される有機ＥＬ素子の層構成の場合には、前記電荷輸送性ポリウレタンを含有してなる有機化合物層を、例えば、ホール輸送層３、キャリア輸送能を持つ発光層６としていずれも用いることができるが、キャリア輸送能を持つ発光層６として用いることが好ましい。
【００９２】
なお、本発明における前記電荷輸送性ポリウレタンを含有してなる有機化合物層は良好なホール輸送能を有し、例えば前記のように図４で表される発光素子のホール輸送層３にも用いることができる。この場合、キャリア輸送能を持つ発光層６には電子輸送性の発光層が設けられ、代表的な例としては下図（Ｖ−１〜９）に示される化合物を挙げることができる。
【００９３】
【化１６】

【００９４】
図１〜図４に示される有機ＥＬ素子の層構成の場合、発光層４もしくはキャリア輸送能を持つ発光層６は、目的に応じて機能（ホール輸送能、あるいは電子輸送能）が付与された前記電荷輸送性ポリウレタンを含有する有機化合物層であることが好ましい。この場合の有機化合物層は、基本的には前記電荷輸送性ポリウレタン単独で形成されるが、有機ＥＬ素子に注入されるホールと電子とのバランスを調節するために、前記電荷輸送性ポリウレタン以外の電子輸送材料を層全体の質量に対して１０〜５０質量％の範囲で分散させてもよい。このような電子輸送材料としては、前記電荷輸送性ポリウレタンと強い電子相互作用を示さない有機化合物を用いることが好ましく、より好ましくは下記例示化合物（ＶＩ）が用いられるが、これに限定されるものではない。
【００９５】
同様にホール移動度を調節するために、電荷輸送性ポリウレタン以外のホール輸送材料、好ましくはテトラフェニレンジアミン誘導体を層全体の質量に対して１０〜５０質量％の範囲で同時に分散させて用いてもよい。
【００９６】
また、発光層４もしくはキャリア輸送能を持つ発光層６には、有機ＥＬ素子の耐久性向上あるいは発光効率の向上を目的として、前記電荷輸送性ポリウレタンと異なる色素化合物をドーピングしてもよい。ドーピングは溶液または分散液中に所定の色素を混合することで行う。発光層中における色素化合物のドーピングの割合としては、層全体の質量の０．００１〜４０質量％の範囲であることが好ましく、０．０１〜１０質量％の範囲であることがより好ましい。
【００９７】
このようなドーピングに用いられる色素化合物としては、発光材料との相溶性がよく、かつ発光層の良好な薄膜形成を妨げない有機化合物が用いられ、ＤＣＭ誘導体、キナクリドン誘導体、ルブレン誘導体、ポルフィリン系化合物等が好適に用いられる。具体例として、下記の化合物（ＶＩＩ−１）〜（ＶＩＩ−４）が用いられるが、これらに限定されたものではない。
【００９８】
【化１７】

【００９９】
【化１８】

【０１００】
図１〜図４に示される層構成の有機ＥＬ素子の場合、透明絶縁体基板１は、発光を取り出すため透明なものが好ましく、ガラス、プラスチックフィルム等が用いられる。また、透明電極２は、透明絶縁体基板１と同様に発光を取り出すため透明であって、かつホールの注入を効率よく行うために仕事関数の大きなものが好ましく、酸化スズインジウム（ＩＴＯ）、酸化スズ（ＮＥＳＡ）、酸化インジウム、酸化亜鉛等の酸化膜、及び蒸着あるいはスパッタされた金、白金、パラジウム等が好ましく用いられる。
【０１０１】
図１及び図２に示される層構成の有機ＥＬ素子の場合、電子輸送層５には、電子輸送能を示す化合物が電荷輸送性材料として用いられる。このような電子輸送層に用いられる電子輸送性材料としては、有機低分子の場合、真空蒸着法により良好な薄膜形成が可能な有機化合物が好ましく用いられ、具体的にはオキサジアゾール誘導体、ニトロ置換フルオレノン誘導体、ジフェノキノン誘導体、チオピランジオキシド誘導体、フルオレニリデンメタン誘導体等を挙げることができる。また、高分子の場合、それ自身を含む溶液または分散液を塗布・乾燥することにより良好な薄膜形成が可能であることが条件である。電子輸送性材料としては、具体的に下記の化合物（ＶＩＩＩ−１）〜（ＶＩＩＩ−３）が好ましく用いられるが、これらに限定されるものではない。また、他の汎用の樹脂等と混合して用いてもよい。
【０１０２】
【化１９】

【０１０３】
図２及び図４に示される層構成の有機ＥＬ素子の場合、ホール輸送層３には、ホール輸送能を示す化合物が電荷輸送性材料として用いられる。ホール輸送性材料が有機低分子の場合には、真空蒸着法、もしくは低分子と結着樹脂を含む溶液または分散液を塗布・乾燥することにより良好な薄膜形成が可能であることが材料選択の条件とされる。また、高分子の場合には、それ自身を含む溶液または分散液を塗布・乾燥することにより良好な薄膜形成が可能であることが材料選択の条件である。
【０１０４】
ホール輸送性材料としては、テトラフェニレンジアミン誘導体、トリフェニルアミン誘導体、カルバゾール誘導、スチルベン誘導体、アリールヒドラゾン誘導体、ポルフィリン系化合物等が好ましく用いられるが、特に好適な具体例として下記例示化合物（ＩＸ−１）〜（ＩＸ−８）を挙げることができるが、これらの中では、電荷輸送性ポリウレタンとの相溶性がよいことから、テトラフェニレンジアミン誘導体が好ましく用いられる。また、上記化合物を他の汎用の樹脂等と混合して用いてもよい。
【０１０５】
【化２０】

【０１０６】
図１〜図４に示される層構成の有機ＥＬ素子の場合、背面電極７には、真空蒸着可能で、かつ電子注入を効率よく行うために仕事関数の小さな金属が使用されるが、特にマグネシウム、アルミニウム、銀、インジウム及びこれらの合金が好ましく用いられる。また、背面電極７の表面には、さらに素子の水分や酸素による劣化を防ぐために保護層を設けてもよい。具体的な保護層の材料としては、Ｉｎ、Ｓｎ、Ｐｂ、Ａｕ、Ｃｕ、Ａｇ、Ａｌ等の金属、ＭｇＯ、ＳｉＯ_２、ＴｉＯ_２等の金属酸化物、ポリエチレン樹脂、ポリウレア樹脂、ポリイミド樹脂等の樹脂等が挙げられる。保護層の形成には、真空蒸着法、スパッタリング法、プラズマ重合法、ＣＶＤ法、コーティング法が適用できる。
【０１０７】
これら図１〜図４に示される有機ＥＬ素子の各層形成は以下のように行われる。まず、透明電極２の表面に各有機ＥＬ素子の層構成に応じて、ホール輸送層３あるいはキャリア輸送能を持つ発光層６を形成する。ホール輸送層３及びキャリア輸送能を持つ発光層６は、上記各材料を真空蒸着法、もしくは有機溶媒中に溶解あるいは分散し、得られた塗布液を用いて前記透明電極２表面に製膜するスピンコーティング法、ディップ法等により形成される。
【０１０８】
次に、各有機ＥＬ素子の層構成に応じて、ホール輸送層３、発光層４、電子輸送層５あるいはキャリア輸送能を持つ発光層６は、上記各材料を、真空蒸着法、もしくは有機溶媒中に溶解或いは分散し、得られた塗布液を用いて前記透明電極２表面に製膜するスピンコーティング法、ディップ法等を用いることによって形成される。
【０１０９】
形成されるホール輸送層３、発光層４及び電子輸送層５の膜厚は、各々０．１μｍ以下であることが好ましく、特に０．０３〜０．０８μｍの範囲であることが好ましい。また、キャリア輸送能を持つ発光層６の膜厚は、０．０３〜０．２μｍの範囲であることが好ましく、０．０３〜０．１μｍの範囲であることがより好ましい。
【０１１０】
上記各材料（前記電荷輸送性ポリウレタン、発光材料等）の分散状態は分子分散状態でも微粒子分散状態でも構わない。塗布液を用いた製膜法の場合、分子分散状態とするためには、分散溶媒は上記各材料の共通溶媒を用いる必要があり、微粒子分散状態とするためには、分散溶媒は上記各材料の分散性及び溶解性を考慮して選択する必要がある。微粒子状に分散するためには、ボールミル、サンドミル、ペイントシェイカー、アトライター、ボールミル、ホモジェナイザー、超音波法等が利用できる。
【０１１１】
そして、最後に、電子輸送層５あるいはキャリア輸送能を持つ発光層６の表面に、背面電極７を真空蒸着法により形成することにより素子が完成される。
【０１１２】
本発明の有機ＥＬ素子は、一対の電極間に、例えば、４〜２０Ｖで、電流密度１〜２００ｍＡ／ｃｍ^２の直流電圧を印加することによって、５００ｃｄ／ｍ^２程度以上に十分発光させることができる。
【０１１３】
【実施例】
以下、実施例によって本発明を説明するが、本発明はこれらの実施例に制限されるものではない。
まず、各実施例に用いた電荷輸送性ポリウレタンは、例えば以下のようにして得た。
【０１１４】
−合成例１〔例示化合物（３）〕−
下記化合物（Ｘ−１）２．０ｇとクロロベンゼン３０ｍｌとを、容量５０ｍｌのフラスコに入れて攪拌し溶解させ、該フラスコ中に、ヘキサメチレンジイソシアネート０．５４ｇをクロロベンゼン１０ｍｌに溶解した溶液を３０分かけて滴下した後、窒素気流下、１５０℃で２時間加熱攪拌した。反応終了後、室温まで冷却し、反応溶液を撹拌されたメタノール３００ｍｌ中に滴下してポリマーを析出させた。得られたポリマーを濾過し、十分にメタノールで洗浄し乾燥させた後、テトラヒドロフラン（ＴＨＦ）３０ｍｌに溶解し、この溶液をメタノール３００ｍｌ中に滴下する再沈殿を３回繰り返すことによって、１．８ｇの電荷輸送性ポリウレタンを得た。分子量はＧＰＣにて測定したところ、Ｍｗ＝４．７１×１０^４（スチレン換算）であり、モノマーの分子量から求めたｐの値は約９０であった。
【０１１５】
【化２１】

【０１１６】
−合成例２〔例示化合物（２８）〕−
下記化合物（Ｘ−２）２．０ｇとクロロベンゼン３０ｍｌとを、容量５０ｍｌのフラスコに入れて攪拌し溶解させ、該フラスコ中に、ヘキサメチレンジイソシアネート０．５２ｇをクロロベンゼン１０ｍｌに溶解した溶液を３０分かけて滴下した後、窒素気流下、１５０℃で２時間加熱攪拌した。反応終了後、室温まで冷却し、反応溶液を撹拌されたメタノール３００ｍｌ中に滴下してポリマーを析出させた。得られたポリマーを濾過し、十分にメタノールで洗浄し乾燥させた後、テトラヒドロフラン（ＴＨＦ）３０ｍｌに溶解し、この溶液をメタノール３００ｍｌ中に滴下する再沈殿を３回繰り返すことによって、２．１ｇの電荷輸送性ポリウレタンを得た。分子量はＧＰＣにて測定したところ、Ｍｗ＝７．７９×１０^４（スチレン換算）であり、モノマーの分子量から求めたｐの値は約６０であった。
【０１１７】
【化２２】

【０１１８】
−合成例３〔例示化合物（２４）〕−
化合物（Ｘ−３）２．０ｇとクロロベンゼン３０ｍｌとを、容量５０ｍｌのフラスコに入れて攪拌し溶解させ、該フラスコ中に、ヘキサメチレンジイソシアネート０．５２ｇをクロロベンゼン１０ｍｌに溶解した溶液を３０分かけて滴下した後、窒素気流下、１５０℃で３時間加熱攪拌した。反応終了後、室温まで冷却し、反応溶液を撹拌されたメタノール３００ｍｌ中に滴下してポリマーを析出させた。得られたポリマーを濾過し、十分にメタノールで洗浄した後乾燥させた後、テトラヒドロフラン（ＴＨＦ）３０ｍｌに溶解し、この溶液をメタノール３００ｍｌに滴下する再沈殿を３回繰り返すことによって、１．９ｇの電荷輸送性ポリウレタンを得た。分子量はＧＰＣにて測定したところ、Ｍｗ＝１．０５×１０^５（スチレン換算）であり、モノマーの分子量から求めたｐの値は約６０であった。
【０１１９】
【化２３】

【０１２０】
（実施例１）
電荷輸送性ポリウレタン〔例示化合物（３）〕（Ｍｗ＝４．８５×１０^４）の５質量％ジクロロエタン溶液を調製し、０．１μｍのポリテトラフルオロエチレン（ＲＴＦＥ）フィルターで濾過した。２−プロパノール（電子工業用、関東化学社製）中で超音波洗浄乾燥後、２ｍｍ幅の短冊型ＩＴＯ電極をエッチングにより形成したガラス基板表面に、前記溶液をディップ法により塗布し、膜厚約０．１μｍのホール輸送能を持つ発光層を形成した。十分乾燥させたこの発光層の表面に、電子輸送材料として昇華精製した前記例示化合物（Ｖ−１）をタングステンボートに入れ、真空蒸着法により蒸着して膜厚０．０５μｍの電子輸送層を形成した。この時の真空度は１．３３×１０^−３Ｐａ、ボート温度は３００℃であった。続いて上記電荷輸送層の表面にＭｇ−Ａｇ合金を共蒸着により蒸着して、２ｍｍ幅、０．１５μｍ厚の背面電極をＩＴＯ電極と交差するように形成した。作製された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
【０１２１】
以上のように作製した有機ＥＬ素子を、真空中（１．３３×１０^−１Ｐａ）でＩＴＯ電極側をプラス、Ｍｇ−Ａｇ背面電極をマイナスとして０Ｖから１Ｖ毎に２０Ｖまでの直流電圧を印加し、発光について測定を行い、このときの最高輝度、及び発光色を評価した。それらの結果を表１４に示す。また、乾燥窒素中で有機ＥＬ素子の発光寿命の測定を行った。発光寿命の評価は、初期輝度が５０ｃｄ／ｍ^２となるように電流値を設定し、定電流駆動により輝度が初期値から半減するまでの時間を素子寿命（ｈｏｕｒ）とした。この時の駆動電流密度を素子寿命と共に表１４に示す。
【０１２２】
（実施例２）
実施例１と同様に洗浄乾燥後、２ｍｍ幅の短冊型ＩＴＯ電極をエッチングにより形成したガラス基板表面に、ホール輸送材料として昇華精製した前記例示化合物（ＩＸ−２）をタングステンボートに入れ、真空蒸着法により蒸着して膜厚０．０５μｍのホール輸送層を形成した。この時の真空度は１．３３×１０^−３Ｐａ、ボート温度は３００℃であった。続いて、実施例１で用いた濾過済みの電荷輸送性ポリウレタン〔例示化合物（３）〕（Ｍｗ＝４．８５×１０^４）の５質量％ジクロロエタン溶液を用いて、ディップ法により塗布し、前記ホール輸送層の表面に膜厚約０．１μｍの発光層を形成した。十分乾燥させたこの発光層の表面に、最後にＭｇ−Ａｇ合金を共蒸着により蒸着して、２ｍｍ幅、０．１５μｍ厚の背面電極をＩＴＯ電極と交差するように形成した。作製された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１２３】
（実施例３）
実施例１で用いた電荷輸送性ポリウレタン〔例示化合物（３）〕（Ｍｗ＝４．８５×１０^４）２質量部と、電子輸送材料として前記化合物例示（ＶＩＩＩ−１）１質量部とを混合し、１０質量％のジクロロエタン溶液を調製し、０．１μｍのＰＴＦＥフィルターで濾過した。この溶液を用いて、洗浄乾燥後、２ｍｍ幅の短冊型ＩＴＯ電極をエッチングにより形成したガラス基板表面に、ディップ法により塗布して膜厚０．１５μｍのキャリア輸送能を持つ発光層を形成した。十分乾燥させたこの発光層の表面に、Ｍｇ−Ａｇ合金を共蒸着により蒸着して、２ｍｍ幅、０．１５μｍ厚の背面電極をＩＴＯ電極と交差するように形成した。作製された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１２４】
（実施例４）
電荷輸送性ポリウレタンとして例示化合物（２８）（Ｍｗ＝７．７９×１０^４）を用いた以外は、実施例１と同様にして有機ＥＬ素子を作製した。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１２５】
（実施例５）
電荷輸送性ポリウレタンとして例示化合物（２８）（Ｍｗ＝７．７９×１０^４）を用いた以外は、実施例２と同様にして有機ＥＬ素子を作製した。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１２６】
（実施例６）
電荷輸送性ポリウレタンとして例示化合物（２８）（Ｍｗ＝７．７９×１０^４）を用いた以外は、実施例３と同様にして有機ＥＬ素子を作製した。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１２７】
（実施例７）
実施例４で用いた電荷輸送性ポリウレタン〔例示化合物（２８）〕（Ｍｗ＝７．７９×１０^４）１質量部と、発光材料として前記例示化合物（Ｖ−１）１質量部とを混合し、１０質量％のジクロロエタン溶液を調製し、０．１μｍのＰＴＦＥフィルターで濾過した。この溶液を用いて、洗浄乾燥後、２ｍｍ幅の短冊型ＩＴＯ電極をエッチングにより形成したガラス基板表面に、ディップ法により塗布して膜厚０．１５μｍのキャリア輸送能を持つ発光層を形成した。十分乾燥させたこの発光層の表面に、あらかじめ調製し、０．１μｍのポリテトラフルオロエチレン（ＰＴＦＥ）フィルターで濾過した電荷輸送性ポリウレタン［例示化合物（２４）］（Ｍｗ＝１．０５×１０^５）の５質量％ジクロロエタン溶液を用いてスピンコート法により塗布し、厚さ０．１μｍの電子輸送層を形成した。この電子輸送層の表面に、最後にＭｇ−Ａｇ合金を共蒸着により蒸着して、２ｍｍ幅、０．１５μｍ厚の背面電極をＩＴＯ電極と交差するように形成した。作製された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１２８】
（実施例８）
実施例１と同様に洗浄乾燥後、２ｍｍ幅の短冊型ＩＴＯ電極をエッチングにより形成したガラス基板表面に、実施例４で用いた電荷輸送性ポリウレタン［例示化合物（２８）］（Ｍｗ＝７．７９×１０^４）溶液を用い、ディップ法により厚さ０．１μｍのホール輸送層を形成した。さらに、その表面に、前記例示化合物（Ｖ−１）を用い、真空蒸着法により厚さ０．０６５μｍの発光層を形成した。十分乾燥させた後、あらかじめ調製し、０．１μｍのポリテトラフルオロエチレン（ＰＴＦＥ）フィルターで濾過した電荷輸送性ポリウレタン［例示化合物（２４）］（Ｍｗ＝１．０５×１０^５）の５質量％ジクロロエタン溶液を用いて、前記発光層表面にスピンコート法により塗布し、厚さ０．１μｍの電子輸送層を形成した。この電子輸送層の表面に、最後にＭｇ−Ａｇ合金を共蒸着により蒸着して、２ｍｍ幅、０．１５μｍ厚の背面電極をＩＴＯ電極と交差するように形成した。作製された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１２９】
（実施例９）
ホール輸送材料として、電荷輸送性ポリウレタン〔例示化合物（２８）〕（Ｍｗ＝７．７９×１０^４）を１質量部、発光材料として前記例示化合物（ＶＩＩ−１）を１質量部、電子輸送材料として電荷輸送性ポリウレタン［例示化合物（２４）］（Ｍｗ＝１．０５×１０^５）を１質量部用いた以外は、実施例３と同様にして有機ＥＬ素子を作製した。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１３０】
（比較例１）
実施例１と同様に、洗浄乾燥後、２ｍｍ幅の短冊型ＩＴＯ電極をエッチングにより形成したガラス基板表面に、前記例示化合物（ＩＸ−１）で示されるホール輸送材料より構成される厚さ０．０５０μｍのホール輸送層、前記例示化合物（Ｖ−１）で示される発光材料より構成される厚さ０．０６５μｍの発光層を順次真空蒸着法により形成した。さらにその発光層の表面に、最後にＭｇ−Ａｇ合金を共蒸着により蒸着して、２ｍｍ幅、０．１５μｍ厚の背面電極をＩＴＯ電極と交差するように形成した。作製された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１３１】
（比較例２）
実施例１と同様に、洗浄乾燥後、２ｍｍ幅の短冊型ＩＴＯ電極をエッチングにより形成したガラス基板表面に、前記例示化合物（ＶＩＩ−１）で示される発光材料より構成される厚さ０．０６５μｍの発光層、前記例示化合物（ＶＩＩＩ−１）で示される電子輸送材料より構成される厚さ０．０５０μｍの電子輸送層を順次真空蒸着法により形成した。さらにその電子輸送層の表面に、最後にＭｇ−Ａｇ合金を共蒸着により蒸着して、２ｍｍ幅、０．１５μｍ厚の背面電極をＩＴＯ電極と交差するように形成した。作製された有機ＥＬ素子の有効面積は０．０４ｃｍ^２　であった。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１３２】
（比較例３）
ホール輸送材料として前記例示化合物（ＩＸ−１）を１質量部と、発光材料として前記例示化合物（Ｖ−１）を１質量部と、結着樹脂としてポリメチルメタクリレート（ＰＭＭＡ）を１質量部と、を混合し、１０質量％のジクロロエタン溶液を調製し、０．１μｍのＰＴＦＥフィルターで濾過した。この溶液を用いて、２ｍｍ幅の短冊型ＩＴＯ電極をエッチングにより形成したガラス基板表面に、ディップ法により塗布して、膜厚０．１５μｍのホール輸送層を形成した。十分乾燥させたホール輸送層の表面に、Ｍｇ−Ａｇ合金を共蒸着により蒸着して、２ｍｍ幅、０．１５μｍ厚の背面電極をＩＴＯ電極と交差するように形成した。作製された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１３３】
（比較例４）
ホール輸送性材料として前記例示化合物（ＩＸ−６）を２質量部と、発光材料として前記例示化合物（ＶＩＩ−１）を０．１質量部と、電子輸送材料として前記化合物（ＶＩＩＩ−１）を１質量部とを混合し、１０質量％のジクロロエタン溶液を調製し、０．１μｍのＰＴＦＥフィルターで濾過した。この溶液を用いて、２ｍｍ幅の短冊型ＩＴＯ電極をエッチングにより形成したガラス基板表面に、ディップ法により塗布して、膜厚０．１５μｍのホール輸送層を形成した。十分乾燥させた後、ホール輸送層の表面にＭｇ−Ａｇ合金を共蒸着により蒸着して、２ｍｍ幅、０．１５μｍ厚の背面電極をＩＴＯ電極と交差するように形成した。作製された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
上記有機ＥＬについて、実施例１と同様の評価を行った。結果を表１４に示す。
【０１３４】
【表１４】

【０１３５】
上記実施例に示すように、本発明の有機ＥＬ素子は、駆動電流密度が低いにもかかわらず高い最高輝度を示し、特に実施例４においては、７００ｃｄ／ｍ^２以上の最高輝度が得られた。これに対し、比較例の有機ＥＬ素子では、十分な素子寿命が得られなかった。
【０１３６】
【発明の効果】
前記一般式（Ｉ−１）及び（Ｉ−２）で示される構造から選択された少なくとも１種を部分構造として含む繰り返し構造単位からなる電荷輸送性ポリウレタンは、有機ＥＬ素子に好適なイオン化ポテンシャルや電荷移動度及び発光特性を持ち、また、スピンコーティング法、ディップ法等を用いて良好な薄膜を形成することが可能であるので、これを用いて形成された本発明の有機ＥＬ素子は、十分に高い輝度を示し、また、膜厚を比較的厚く設定できるため、ピンホール等の不良も少なく、大面積化も容易であり、しかも優れた耐久性を有する。
【図面の簡単な説明】
【図１】本発明の積層型有機ＥＬ素子の一例を示す模式的断面図である。
【図２】本発明の積層型有機ＥＬ素子の他の一例を示す模式的断面図である。
【図３】本発明の有機ＥＬ素子の他の一例を示す模式的断面図である。
【図４】本発明の積層型有機ＥＬ素子の他の一例を示す模式的断面図である。
【符号の説明】
１　透明絶縁体基板
２　透明電極
３　ホール輸送層
４　発光層
５　電子輸送層
６　キャリア輸送能を持つ発光層
７　背面電極[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an organic electroluminescent device (hereinafter, referred to as “organic EL device”), and more particularly, to an organic EL device using a specific charge transporting polymer.
[0002]
[Prior art]
2. Description of the Related Art An electroluminescent element (hereinafter, referred to as an “EL element”) is a self-luminous all-solid-state element, has high visibility and is resistant to impact, and is widely expected to be applied. At present, the EL devices using inorganic phosphors are mainly used. However, since an AC voltage of 200 V or more is required for driving, there are problems such as high manufacturing cost and insufficient luminance. are doing.
[0003]
On the other hand, research on EL devices using organic compounds started with the use of single crystals such as anthracene. However, in the case of single crystals, the film thickness was as large as about 1 mm, and a driving voltage of 100 V or more was required. For this reason, thinning by vapor deposition has been attempted (Thin Solid Films, Vol. 94, 171 (1982)), but the thin film obtained by this method still has a high driving voltage of 30 V, and has a low Sufficient luminance could not be obtained due to the low density of electron and hole carriers and the low probability of photon generation due to carrier recombination.
[0004]
However, in recent years, in a function separation type EL device in which thin films of a hole transporting organic low molecular compound and a fluorescent organic low molecular compound having an electron transporting ability are sequentially laminated by a vacuum deposition method, a low driving voltage of about 10 V is used. 1000 cd / m ² A device capable of obtaining the above high luminance has been reported (Appl. Phys. Lett., Vol. 51, 913 (1987)), and since then, research and development of a stacked EL device have been actively conducted. In these stacked EL devices, a hole and an electron are emitted from a fluorescent light emitting layer made of a fluorescent organic compound while maintaining a carrier balance of holes and electrons from an electrode through a charge transporting layer made of a charge transporting organic compound. The holes and electrons that are injected into the light emitting layer and confined in the light emitting layer are recombined with each other, thereby realizing high-luminance light emission.
[0005]
However, in this type of EL element, a thin film having a thickness of 0.1 μm or less is formed in a plurality of vapor deposition steps, so that a pinhole is liable to occur, and in order to obtain sufficient performance, under a strictly controlled condition. It is necessary to control the film thickness. Therefore, there is a problem that productivity is low and it is difficult to increase the area. In addition, this EL element has several mA / cm ² , It generates a large amount of Joule heat. For this reason, the phenomenon that the charge-transporting low-molecular compound or fluorescent organic low-molecular compound formed in an amorphous glass state by vapor deposition gradually crystallizes and finally melts, causing a reduction in luminance and dielectric breakdown. There are many problems, and as a result, there is a problem that the life of the element is shortened.
[0006]
In order to solve the above-mentioned problem relating to the thermal stability of the EL element, it is possible to use a starburst amine which can obtain a stable amorphous glass state as a hole transporting material (for the 40th Applied Physics Association Conference Proceedings 30a). -SZK-14 (1993), etc.), and EL devices using a polymer in which triphenylamine is introduced into the side chain of polyphosphazene (Preliminary proceedings of the 42nd Polymer Symposium, 20J21 (1993)). .
[0007]
However, these materials alone have an energy barrier due to the ionization potential of the hole transporting material, so that the hole injecting property from the anode or the hole injecting property into the light emitting layer cannot be satisfied. In addition, in the case of the former starburst amine, purification is difficult due to low solubility, and it is difficult to increase the purity.In the case of the latter polymer, a high current density cannot be obtained and sufficient There are also problems such as lack of brightness.
[0008]
On the other hand, with the aim of solving the problems of productivity and large area in stacked organic EL devices, research and development of single-layered EL devices have been promoted, and conductive polymers such as poly (p-phenylenevinylene) have been developed. Element (Nature, Vol. 357, 477 (1992), etc.), or a device in which an electron transporting material and a fluorescent dye are mixed in a hole transporting polyvinyl carbazole (Preliminary Proceedings of the 38th Annual Conference of the Related Lectures on Applied Physics, 31p) -G-12 (1991)), but the luminance, luminous efficiency and the like are still lower than those of the stacked EL device using an organic low-molecular compound. Further, in the fabrication method, it is reported that a wet coating method is desirable from the viewpoint of simplification of manufacturing, workability, large area, cost, and the like, and that an element can be obtained by a casting method (50th report). Proceedings of the Japan Society of Applied Physics, 29p-ZP-5 (1989), 51st Proceedings of the Japan Society of Applied Physics, 28a-PB-7 (1990)). However, the charge transporting material has poor solubility and compatibility with solvents and resins, and thus is easily crystallized, and thus has a problem in production or characteristics.
[0009]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-mentioned problems of the conventional technology. That is, an object of the present invention is to provide an organic EL element which has sufficient luminance, is excellent in stability and durability, can have a large area, and is easy to manufacture.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors have conducted intensive studies on the charge transporting material, and as a result, at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure. Since the charge transporting polyurethane containing not only has a charge injection property, a charge mobility, and a thin film forming property suitable as an organic EL element, but also has an extremely good light emitting property in a solid state, it can be used as a light emitting material. Also, they have found that they function as elements having excellent luminance and luminous efficiency, and have completed the present invention.
[0011]
That is, the present invention
<1> An electroluminescent device comprising one or a plurality of organic compound layers sandwiched between a pair of electrodes comprising an anode and a cathode, at least one of which is transparent or translucent, wherein at least one of the organic compound layers is Contains at least one kind of charge transporting polyurethane composed of a repeating unit containing at least one kind selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure. Organic electroluminescent device.
[0012]
Embedded image

[0013]
In the general formulas (I-1) and (I-2), Ar represents a substituent represented by the general formula (II-1) or a substituent represented by (II-2); Represents an unsubstituted divalent aromatic group, and k represents 0 or 1.
[0014]
Embedded image

[0015]
In the general formulas (II-1) and (II-2), Ar ₁ , Ar ₂ And Ar ₃ Is a substituted or unsubstituted benzene ring, or a substituted or unsubstituted polynuclear aromatic hydrocarbon having 2 to 10 aromatic rings, or a substituted or unsubstituted fused aromatic hydrocarbon having 2 to 10 aromatic rings, or substituted Or an unsubstituted aromatic heterocyclic ring or a substituted or unsubstituted aromatic group containing at least one aromatic heterocyclic ring; ₁ , R ₂ , R ₃ And R ₄ Represents a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, a halogen atom, a substituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group. The above may be the same. n represents an integer of 0 to 10.
[0016]
<2> The organic compound layer includes at least a light emitting layer having a carrier transporting ability and an electron transporting layer, and the light emitting layer is selected from the structures represented by the general formulas (I-1) and (I-2). <1> The organic electroluminescent device according to <1>, further comprising at least one kind of charge transporting polyurethane composed of a repeating unit containing at least one kind as a partial structure.
[0017]
<3> The organic compound layer includes at least a hole transport layer, a light emitting layer, and an electron transport layer, and the light emitting layer is selected from the structures represented by the general formulas (I-1) and (I-2). <1> The organic electroluminescent device according to <1>, comprising at least one kind of a charge transporting polyurethane composed of a repeating unit containing at least one kind as a partial structure.
[0018]
<4> The organic compound layer includes at least a light emitting layer having a carrier transporting ability, and the light emitting layer is at least one selected from the structures represented by the general formulas (I-1) and (I-2). <1> The organic electroluminescent device according to <1>, wherein the organic electroluminescent device includes at least one kind of a charge transporting polyurethane composed of a repeating unit containing, as a partial structure.
[0019]
<5> The organic compound layer includes at least a hole transport layer and a light emitting layer having a carrier transporting ability, and the light emitting layer is selected from the structures represented by the general formulas (I-1) and (I-2). <1> The organic electroluminescent device according to <1>, further comprising at least one kind of charge transporting polyurethane composed of a repeating unit containing at least one kind as a partial structure.
[0020]
<6> The organic electroluminescent device according to any one of <2> to <5>, wherein the light emitting layer contains a charge transporting material.
[0021]
<7> A charge-transporting polyurethane comprising a repeating unit containing at least one selected from the structures represented by formulas (I-1) and (I-2) as a partial structure is represented by the following formula (III-1) The organic electroluminescent device according to any one of <1> to <6>, which is a polyurethane represented by (III) or (III-2).
[0022]
Embedded image

[0023]
In the general formulas (III-1) and (III-2), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), R represents a hydrogen atom, Represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, and T represents a divalent linear hydrocarbon group having 1 to 6 carbon atoms, or a divalent linear hydrocarbon group having 2 to 10 carbon atoms. Y represents a diisocyanate residue, Z represents a dihydric alcohol residue, m represents 0 or 1, and p represents an integer of 5 to 5,000.
[0024]
In the organic EL device of the present invention, the organic compound layer is of a function-separated type, for example, at least comprises a hole transport layer and a light emitting layer, and the hole transport layer is composed of the general formulas (I-1) and (I). -2) those containing a hole-transporting polyurethane composed of a repeating unit containing at least one selected from the structures represented by -2 as a partial structure, or those having both carrier-transporting ability and light-emitting ability, that is, organic The compound layer is composed of only a light-emitting layer, and the light-emitting layer is formed of a repeating unit containing, as a partial structure, at least one selected from the structures represented by formulas (I-1) and (I-2). Any of those containing the following charge transporting polyurethane may be used.
In the organic EL device of the present invention, when the organic compound layer is composed of only the light emitting layer, the light emitting layer contains a charge transporting material (a hole transporting material other than the charge transporting polyurethane, an electron transporting material). It may be.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The organic EL device of the present invention comprises one or a plurality of organic compound layers sandwiched between a pair of electrodes consisting of an anode and a cathode, at least one of which is transparent or translucent. Is a charge-transporting polyurethane composed of a repeating unit containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure (hereinafter, simply referred to as "charge-transporting polyurethane") In some cases). The organic EL device of the present invention has sufficient luminance and excellent stability and durability by having the layer containing the charge transporting polyurethane. Further, by using the charge transporting polyurethane, the area of the organic EL element can be increased, and the organic EL element can be easily manufactured.
[0026]
Embedded image

[0027]
In the general formulas (I-1) and (I-2), Ar represents a substituent represented by the general formula (II-1) or a substituent represented by (II-2); Represents an unsubstituted divalent aromatic group, and k represents 0 or 1.
[0028]
Embedded image

[0029]
In the general formulas (II-1) and (II-2), Ar ₁ , Ar ₂ And Ar ₃ Is a substituted or unsubstituted benzene ring, or a substituted or unsubstituted polynuclear aromatic hydrocarbon having 2 to 10 aromatic rings, or a substituted or unsubstituted fused aromatic hydrocarbon having 2 to 10 aromatic rings, or substituted Or an unsubstituted aromatic heterocyclic ring or a substituted or unsubstituted aromatic group containing at least one aromatic heterocyclic ring; ₁ , R ₂ , R ₃ And R ₄ Represents a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, a halogen atom, a substituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group. The above may be the same. n represents an integer of 0 to 10.
[0030]
The polynuclear aromatic hydrocarbon refers to a hydrocarbon in which two or more aromatic rings composed of carbon and hydrogen are present, and the rings are bonded by a single carbon-carbon bond. Specific examples include biphenyl and terphenyl. The term "condensed aromatic hydrocarbon" refers to a hydrocarbon in which two or more aromatic rings composed of carbon and hydrogen are present, and the rings share a pair of carbon atoms. Specific examples include naphthalene, anthracene, phenanthrene, and fluorene. Further, the aromatic heterocyclic ring represents an aromatic ring containing an element other than carbon and hydrogen. Specific examples include a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, an oxazole ring, a carbazole ring, a thiazole ring, a pyrazole ring, a pyridine ring, and a quinoline ring. Further, the aromatic group containing an aromatic heterocyclic ring refers to a substituent containing at least one kind of aromatic heterocyclic ring in its structure, which is substituted, condensed or linked.
[0031]
Note that the aromatic group containing an aromatic heterocyclic ring may be either entirely composed of a conjugated system or partially composed of a non-conjugated system, but is not limited in terms of charge transportability and luminous efficiency. , Which are all composed of conjugated systems are preferred.
[0032]
Further, as the substituent of the benzene ring, polynuclear aromatic hydrocarbon, condensed aromatic hydrocarbon, aromatic heterocyclic ring, or aromatic group containing at least one kind of aromatic heterocyclic ring, a hydrogen atom, an alkyl group, an alkoxy group, Examples thereof include a group, an aralkyl group, a substituted amino group, a cyano group, and a halogen atom. Of these, a hydrogen atom, an alkyl group, an alkoxy group, an aralkyl group, a substituted amino group, a cyano group, and a halogen atom are preferable.
[0033]
The alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 3 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group.
[0034]
The alkoxyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 3 carbon atoms. Specific examples include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group.
[0035]
The aryl group preferably has 6 to 20 carbon atoms, and more preferably has 6 to 7 carbon atoms. Specific examples include a phenyl group and a toluyl group.
[0036]
The aralkyl group preferably has 7 to 20 carbon atoms, and more preferably 7 to 8 carbon atoms. Specific examples include a benzyl group and a phenethyl group.
Examples of the substituent of the substituted amino group include an alkyl group, an aryl group, and an aralkyl group, and specific examples are as described above.
[0037]
In the general formulas (I-1) and (I-2), X represents a substituted or unsubstituted divalent aromatic group, and is specifically selected from the following formulas (1) to (13). Group.
[0038]
Embedded image

[0039]
In the formulas (1) to (13), R ₅ Represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a substituted or unsubstituted phenyl group, or a substituted or unsubstituted aralkyl group; ₆ ~ R ₁₇ Represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, or a halogen atom, and a represents 0 or Represents 1.
V represents a group selected from the following formulas (14) to (29).
[0040]
Embedded image

[0041]
In the formulas (13) to (29), b represents an integer of 1 to 10, and c represents an integer of 1 to 3.
[0042]
Among them, when X has a biphenylene structure represented by the following structural formula (A) or (B), it is also reported in "The Sixth International Congress on Advances in Non-impact Printing Technologies, 306, (1990)". As described above, a polymer having high mobility can be obtained, and is particularly preferable.
[0043]
Embedded image

[0044]
In the general formulas (I-1) and (I-2), k represents 0 or 1.
Hereinafter, specific examples of the structures represented by formulas (I-1) and (I-2) are shown in Tables 1 to 11, but the present invention is not limited to these specific examples. The structure numbers 1 to 53 in Tables 1 to 6 show specific examples of the structure represented by the general formula (I-1), and the structure numbers 54 to 96 in Tables 7 to 11 correspond to the general formula (I- A specific example of the structure shown in 2) will be shown.
[0045]
[Table 1]

[0046]
[Table 2]

[0047]
[Table 3]

[0048]
[Table 4]

[0049]
[Table 5]

[0050]
[Table 6]

[0051]
[Table 7]

[0052]
[Table 8]

[0053]
[Table 9]

[0054]
[Table 10]

[0055]
[Table 11]

[0056]
[0057]
As the charge transporting polyurethane comprising a repeating unit containing at least one selected from the structures represented by the general formulas (I-1) and (I-2) as a partial structure, the following general formula (III-1) or ( Those shown in III-2) are preferably used.
[0058]
Embedded image

[0059]
In the general formula (III-1) or (III-2), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and in one polymer Two or more types of structures A may be included.
[0060]
In the formula (III-1) or (III-2), R represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group. The alkyl group preferably has 1 to 10 carbon atoms, and more preferably 1 to 3 carbon atoms. Specific examples include a methyl group, an ethyl group, a propyl group, and an isopropyl group.
[0061]
The aryl group preferably has 6 to 20 carbon atoms, and more preferably has 6 to 7 carbon atoms. Specific examples include a phenyl group and a toluyl group.
[0062]
The aralkyl group preferably has 7 to 20 carbon atoms, and more preferably 7 to 8 carbon atoms. Specific examples include a benzyl group and a phenethyl group. Examples of the substituent of the substituted aryl group and the substituted aralkyl group include a hydrogen atom, an alkyl group, an alkoxy group, a substituted amino group, and a halogen atom.
[0063]
In the general formula (III-1) or (III-2), T represents a divalent linear hydrocarbon group having 1 to 6 carbon atoms, or a divalent branched hydrocarbon group having 2 to 10 carbon atoms. It represents a hydrogen group, and is preferably selected from a divalent linear hydrocarbon group having 2 to 6 carbon atoms and a divalent branched hydrocarbon group having 3 to 7 carbon atoms. The specific structure is shown below.
[0064]
Embedded image

[0065]
In the general formula (III-1) or (III-2), Y represents a divalent alcohol residue, and Z represents a divalent carboxylic acid residue. Specific examples of Y and Z include groups selected from the following formulas (30) to (36).
[0066]
Embedded image

[0067]
In the formulas (30) to (36), R ₁₈ And R ₁₉ Represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxyl group having 1 to 4 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, or a halogen atom, and d and e represent , Each represents an integer of 1 to 10, f and g each represent an integer of 0, 1 or 2, and h and i each represent 0 or 1. V is the same as V in the above formulas (14) to (29).
[0068]
Further, in the general formula (III-1) or (III-2), m represents 0 or 1, and p represents an integer of 5 to 5000. In addition, it is preferable that p is in the range of 10-1000.
[0069]
Hereinafter, Tables 12 and 13 show specific examples of the charge-transporting polyurethane represented by the general formulas (III-1) and (III-2), but the present invention is not limited to these specific examples. In Tables 12 and 13, the numbers in column A correspond to the structure numbers shown in Tables 1 to 11, which are specific examples of the structures represented by the general formulas (I-1) and (I-2). are doing. Further, those in which the column of Z is "-" indicate specific examples of the charge transporting polyurethane represented by the general formula (III-1), and those in which the column of Y is "-" indicate those of the general formula (III) Specific examples of the charge transporting polyurethane represented by -2) are shown. Hereinafter, specific examples assigned with respective numbers, for example, specific examples assigned with a number of 15 are referred to as Exemplified Compound (15).
[0070]
[Table 12]

[0071]
[Table 13]

[0072]
The weight average molecular weight Mw of the charge transporting polyurethane is preferably in the range of 10,000 to 300,000, and more preferably in the range of 20,000 to 100,000.
[0073]
The charge-transporting polyurethane is prepared by using charge-transporting monomers represented by the following structural formulas (IV-1) to (IV-4), for example, in the fourth edition of Experimental Chemistry Course Vol. 28 (Maruzen, 1992), New Polymer Experiment It can be synthesized by polymerizing by a known method described in Gakkai Vol. 2 (Kyoritsu Shuppan, 1995). In the structural formulas (IV-1) to (IV-4), A, T, and m are the same as A, T, and m in the general formula (III-1) or (III-2), respectively.
[0074]
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[0075]
Specifically, for example, in the case of the charge transporting monomers represented by the general formulas (IV-1) and (IV-2), the charge transporting polyurethane can be synthesized as follows.
When the charge transporting monomer is a dihydric alcohol represented by the general formula (IV-1), the charge transporting monomer is mixed with a diisocyanate represented by ONC-Y-NCO in an equivalent amount, and the charge transporting monomer is represented by the general formula (IV-2) In the case of the diisocyanates represented by the formula (1), they are mixed in equivalent amounts with the dihydric alcohols represented by HO-Y-OH and subjected to polyaddition. As the catalyst, an organic metal compound such as dibutyltin (II) dilaurate, dibutyltin (II) diacetate, lead naphthenate or the like, which is used in a polyurethane synthesis reaction by ordinary polyaddition, can be used. When an aromatic diisocyanate is used for the synthesis of the charge transporting polyurethane, a tertiary amine such as triethylenediamine can be used as a catalyst. These organometallic compounds and tertiary amines may be used as a mixture as a catalyst.
[0076]
The amount of the catalyst used is preferably in the range of 1 / 10,000 to 1/10 parts by mass, and more preferably in the range of 11,000 to 1/50 parts by mass, per 1 part by mass of the charge transporting monomer. Is more preferable.
[0077]
As the solvent, any solvent can be used as long as it dissolves the charge transporting monomer and the diisocyanate or the dihydric alcohol, but a hydrogen bond between the solvent and the alcohol having a low polarity in terms of reactivity can be used. It is preferable to use a solvent that does not cause the above, and toluene, chlorobenzene, dichlorobenzene, 1-chloronaphthalene and the like are effective. The amount of the solvent used is preferably in the range of 1 to 100 parts by mass, more preferably 2 to 50 parts by mass, per 1 part by mass of the charge transporting monomer. The reaction temperature can be set arbitrarily.
[0078]
After completion of the reaction, the reaction solution is dropped as it is into a poor solvent in which alcohols such as methanol and ethanol and a polymer such as acetone are hardly dissolved, and a charge transporting polyurethane is separated by precipitation, and then water or an organic solvent is removed. Wash thoroughly and dry. Further, if necessary, the re-precipitation treatment of dissolving in a suitable organic solvent and dropping it into a poor solvent to precipitate the charge transporting polyurethane may be repeated. In the case of the reprecipitation treatment, it is preferable that the poor solvent is efficiently stirred with a mechanical stirrer or the like.
[0079]
The amount of the solvent for dissolving the charge transporting polyurethane during the reprecipitation treatment is preferably in the range of 1 to 100 parts by mass, and more preferably in the range of 2 to 50 parts by mass with respect to 1 part by mass of the charge transporting polyurethane. More preferably, there is. The amount of the poor solvent is preferably in the range of 1 to 1,000 parts by mass, more preferably 10 to 500 parts by mass, per 1 part by mass of the charge transporting polyurethane.
[0080]
In the case of the charge transporting monomers represented by the formulas (IV-3) and (IV-4), the charge transporting polyurethane can be synthesized as follows. When the charge transporting monomer is a bischloroformate represented by the general formula (IV-3), ₂ HN-Y-NH ₂ In the case where the charge-transporting monomer is a diamine represented by the general formula (IV-4), an equivalent amount is mixed with a bischloroformate represented by ClOCO-Y-OCOCl. And polycondensation.
[0081]
As the solvent, methylene chloride, dichloroethane, trichloroethane, tetrahydrofuran (THF), toluene, chlorobenzene, 1-chloronaphthalene and the like are effective. The amount of the solvent is 1 to 100 parts by mass with respect to 1 part by mass of the charge transporting monomer. And more preferably in the range of 2 to 50 parts by mass. The reaction temperature can be set arbitrarily. After the polymerization, purification is performed by a reprecipitation treatment as described above.
[0082]
Also, ₂ HN-Y-NH ₂ When the basicity of the diamine represented by is high, an interfacial polymerization method can also be used. That is, the diamines are added to water, an equivalent amount of an acid is added and dissolved, and then the diamines and the equivalent amount of the charge transporting monomer solution represented by the general formula (IV-3) are added with vigorous stirring. Can be polymerized. At this time, the amount of water is preferably in the range of 1 to 1,000 parts by mass, more preferably 10 to 500 parts by mass, per 1 part by mass of the diamine.
[0083]
As a solvent for dissolving the charge transporting monomer, methylene chloride, dichloroethane, trichloroethane, toluene, chlorobenzene, 1-chloronaphthalene and the like are effective. The reaction temperature can be arbitrarily set, and it is effective to use a phase transfer catalyst such as an ammonium salt or a sulfonium salt to promote the reaction. The amount of the phase transfer catalyst used is preferably in the range of 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, per 1 part by mass of the charge transporting monomer. .
[0084]
Next, the layer structure of the organic EL device of the present invention will be described in detail.
The organic EL device of the present invention includes a pair of electrodes, at least one of which is transparent or translucent, and one or more organic compound layers including a light emitting layer sandwiched between the electrodes. At least one layer contains the charge transporting polyurethane.
[0085]
In the organic EL device of the present invention, when there is one organic compound layer, the organic compound layer is a light emitting layer having a carrier transporting ability, and the light emitting layer contains the charge transporting polyurethane. When there are a plurality of organic compound layers (function-separated type), at least one of them has a light-emitting layer (this light-emitting layer may or may not have a carrier transporting ability). ), And the other organic compound layer is configured as a carrier transporting layer, that is, a hole transporting layer, an electron transporting layer, or a hole transporting layer and an electron transporting layer, at least one of which is formed of the charge transporting polyurethane. It contains.
[0086]
Specifically, for example, an organic EL device composed of at least a light emitting layer and an electron transport layer, an organic EL device composed of at least a hole transport layer, a light emitting layer and an electron transport layer, or at least a hole transport layer and a light emitting layer And an organic EL device comprising at least one of these (a light emitting layer, a hole transport layer, and an electron transport layer) containing the charge transporting polyurethane.
[0087]
In the organic EL device of the present invention, it is preferable that the light emitting layer contains a charge transporting material (a hole transporting material other than the charge transporting polyurethane and an electron transporting material). Details will be described later.
[0088]
Hereinafter, the present invention will be described in more detail with reference to the drawings, but the present invention is not limited thereto.
FIGS. 1 to 4 are schematic cross-sectional views for explaining the layer structure of the organic EL device of the present invention. FIGS. 1, 2 and 4 show examples in which a plurality of organic compound layers are provided. FIG. 3 shows an example in which there is one organic compound layer. Note that, in FIGS. 1 to 4, components having similar functions are denoted by the same reference numerals and described.
[0089]
The organic EL device shown in FIG. 1 is formed by sequentially laminating a transparent electrode 2, a light emitting layer 6 having a carrier transporting ability, an electron transporting layer 5, and a back electrode 7 on the surface of a transparent insulator substrate 1. The organic EL device shown in FIG. 2 is formed by sequentially laminating a transparent electrode 2, a hole transport layer 3, a light emitting layer 4, an electron transport layer 5, and a back electrode 7 on the surface of a transparent insulator substrate 1. The organic EL device shown in FIG. 3 is formed by sequentially laminating a transparent electrode 2, a light emitting layer 6 having a carrier transporting ability, and a back electrode 7 on the surface of a transparent insulator substrate 1. The organic EL device shown in FIG. 4 is formed by sequentially laminating a transparent electrode 2, a hole transport layer 3, a light emitting layer 6 having a carrier transport ability, and a back electrode 7 on the surface of a transparent insulator substrate 1. Hereinafter, each will be described in detail.
[0090]
In the case where the organic EL element shown in FIGS. 1, 2 and 4 uses a light-emitting material (light-emitting layer) that does not show a clear carrier transporting property, the organic EL element has improved durability or improved luminous efficiency. For the purpose of improvement, a hole transporting layer may be provided between the light emitting layer 4 or the light emitting layer 6 having a carrier transporting ability and the transparent electrode 2, or the light emitting layer 4 or the light emitting layer 6 having a carrier transporting ability may be provided with the back electrode 7. It has a layer configuration in which an electron transporting layer is provided between them.
[0091]
The organic compound layer containing the charge transporting polyurethane in the present invention may be, for example, an electron transporting layer 5 or a light emitting layer 6 having a carrier transporting ability in the case of the organic EL device shown in FIG. Any of them can be used, but it is preferable to use it as the light emitting layer 6 having a carrier transporting ability. In the case of the layer configuration of the organic EL device shown in FIG. 2, it is preferable to use an organic compound layer containing the charge transporting polyurethane as the light emitting layer 4. In the case of the layer structure of the organic EL device shown in FIG. 3, it is preferable to use an organic compound layer containing the charge transporting polyurethane as the light emitting layer 6 having a carrier transporting ability. Further, in the case of the layer structure of the organic EL device shown in FIG. 4, the organic compound layer containing the charge transporting polyurethane may be used as, for example, the hole transporting layer 3 or the light emitting layer 6 having a carrier transporting ability. Can also be used, but is preferably used as the light emitting layer 6 having a carrier transporting ability.
[0092]
The organic compound layer containing the charge-transporting polyurethane in the present invention has a good hole-transporting ability, and may be used for the hole-transporting layer 3 of the light-emitting device shown in FIG. Can be. In this case, the light-emitting layer 6 having a carrier-transporting ability is provided with a light-emitting layer having an electron-transporting property, and typical examples include the compounds shown in the following figures (V-1 to 9).
[0093]
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[0094]
In the case of the layer structure of the organic EL device shown in FIGS. 1 to 4, the light-emitting layer 4 or the light-emitting layer 6 having a carrier transport ability has a function (a hole transport ability or an electron transport ability) according to the purpose. An organic compound layer containing the charge transporting polyurethane is preferable. In this case, the organic compound layer is basically formed of the charge transporting polyurethane alone. However, in order to adjust the balance between holes and electrons injected into the organic EL element, the organic compound layer other than the charge transporting polyurethane is used. The electron transporting material may be dispersed in the range of 10 to 50% by mass based on the total mass of the layer. As such an electron transporting material, it is preferable to use an organic compound that does not show strong electron interaction with the charge transporting polyurethane, and more preferably, the following exemplified compound (VI) is used, but is not limited thereto. is not.
[0095]
Similarly, in order to adjust the hole mobility, a hole transporting material other than the charge transporting polyurethane, preferably a tetraphenylenediamine derivative, may be used by being simultaneously dispersed in the range of 10 to 50% by mass based on the mass of the entire layer. Good.
[0096]
The light emitting layer 4 or the light emitting layer 6 having a carrier transporting ability may be doped with a dye compound different from the charge transporting polyurethane for the purpose of improving the durability or the luminous efficiency of the organic EL device. The doping is performed by mixing a predetermined dye in a solution or a dispersion. The doping ratio of the dye compound in the light emitting layer is preferably in the range of 0.001 to 40% by mass, more preferably in the range of 0.01 to 10% by mass of the total mass of the layer.
[0097]
As the dye compound used for such doping, an organic compound having good compatibility with the light-emitting material and not hindering formation of a good thin film of the light-emitting layer is used. DCM derivatives, quinacridone derivatives, rubrene derivatives, porphyrin-based compounds Etc. are preferably used. As specific examples, the following compounds (VII-1) to (VII-4) are used, but are not limited thereto.
[0098]
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[0099]
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[0100]
In the case of the organic EL device having the layer configuration shown in FIGS. 1 to 4, the transparent insulator substrate 1 is preferably transparent to extract light emission, and glass, a plastic film, or the like is used. The transparent electrode 2 is preferably transparent, like the transparent insulator substrate 1, for extracting light emission, and has a large work function for efficiently injecting holes. Indium tin oxide (ITO), oxide Oxide films such as tin (NESA), indium oxide, and zinc oxide, and gold, platinum, and palladium deposited or sputtered are preferably used.
[0101]
In the case of the organic EL device having the layer configuration shown in FIGS. 1 and 2, a compound having an electron transporting ability is used for the electron transporting layer 5 as a charge transporting material. As the electron transporting material used for such an electron transporting layer, in the case of a low organic molecule, an organic compound capable of forming a good thin film by a vacuum deposition method is preferably used. Specifically, an oxadiazole derivative, a nitro compound Substituted fluorenone derivatives, diphenoquinone derivatives, thiopyran dioxide derivatives, fluorenylidenemethane derivatives and the like can be mentioned. In the case of a polymer, it is a condition that a good thin film can be formed by applying and drying a solution or dispersion containing the polymer itself. As the electron transporting material, specifically, the following compounds (VIII-1) to (VIII-3) are preferably used, but are not limited thereto. Further, it may be used by mixing with other general-purpose resins.
[0102]
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[0103]
In the case of the organic EL device having the layer configuration shown in FIGS. 2 and 4, a compound having a hole transporting ability is used for the hole transporting layer 3 as a charge transporting material. When the hole transporting material is an organic small molecule, it is necessary to select a material that can form a good thin film by vacuum evaporation or by applying and drying a solution or dispersion containing a low molecule and a binder resin. Condition. In the case of a polymer, a condition for selecting a material is that a good thin film can be formed by applying and drying a solution or dispersion containing the polymer itself.
[0104]
As the hole transporting material, a tetraphenylenediamine derivative, a triphenylamine derivative, a carbazole derivative, a stilbene derivative, an arylhydrazone derivative, a porphyrin-based compound, and the like are preferably used. Particularly preferred specific examples include the following compounds (IX-1) ) To (IX-8), and among these, a tetraphenylenediamine derivative is preferably used because of its good compatibility with the charge transporting polyurethane. Further, the above compound may be used as a mixture with another general-purpose resin or the like.
[0105]
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[0106]
In the case of the organic EL device having the layer configuration shown in FIGS. 1 to 4, a metal having a small work function is used for the back electrode 7 so that vacuum deposition is possible and electron injection is performed efficiently. , Aluminum, silver, indium and alloys thereof are preferably used. Further, a protective layer may be further provided on the surface of the back electrode 7 in order to prevent the element from being deteriorated by moisture or oxygen. Specific materials for the protective layer include metals such as In, Sn, Pb, Au, Cu, Ag, and Al, MgO, and SiO. ₂ , TiO ₂ And resin such as polyethylene resin, polyurea resin and polyimide resin. For forming the protective layer, a vacuum evaporation method, a sputtering method, a plasma polymerization method, a CVD method, and a coating method can be applied.
[0107]
Each layer of the organic EL device shown in FIGS. 1 to 4 is formed as follows. First, a hole transport layer 3 or a light emitting layer 6 having a carrier transport ability is formed on the surface of the transparent electrode 2 according to the layer configuration of each organic EL element. The hole transport layer 3 and the light emitting layer 6 having a carrier transport ability are formed on the surface of the transparent electrode 2 using the obtained coating solution by dissolving or dispersing each of the above materials in a vacuum evaporation method or an organic solvent. It is formed by a spin coating method, a dipping method, or the like.
[0108]
Next, depending on the layer configuration of each organic EL element, the hole transporting layer 3, the light emitting layer 4, the electron transporting layer 5, or the light emitting layer 6 having a carrier transporting ability is formed by applying the above materials to each other by a vacuum evaporation method or an organic solvent. It is formed by using a spin coating method, a dip method, or the like in which the transparent electrode 2 is dissolved or dispersed therein and a film is formed on the surface of the transparent electrode 2 using the obtained coating liquid.
[0109]
The thicknesses of the formed hole transport layer 3, light emitting layer 4, and electron transport layer 5 are each preferably 0.1 μm or less, and particularly preferably in the range of 0.03 to 0.08 μm. Further, the thickness of the light emitting layer 6 having a carrier transporting ability is preferably in the range of 0.03 to 0.2 μm, and more preferably in the range of 0.03 to 0.1 μm.
[0110]
The dispersion state of each of the above materials (the charge transporting polyurethane, the light emitting material, and the like) may be a molecular dispersion state or a fine particle dispersion state. In the case of a film-forming method using a coating solution, in order to obtain a molecular dispersion state, it is necessary to use a common solvent of each of the above materials as the dispersion solvent. Must be selected in consideration of the dispersibility and solubility of the polymer. In order to disperse the particles in the form of fine particles, a ball mill, a sand mill, a paint shaker, an attritor, a ball mill, a homogenizer, an ultrasonic method, or the like can be used.
[0111]
Finally, a back electrode 7 is formed on the surface of the electron transport layer 5 or the light emitting layer 6 having a carrier transport ability by a vacuum evaporation method, thereby completing the device.
[0112]
The organic EL device according to the present invention may have a current density of 1 to 200 mA / cm between a pair of electrodes at, for example, 4 to 20 V. ² 500 cd / m2 by applying a DC voltage of ² It is possible to emit light more than enough.
[0113]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples.
First, the charge transporting polyurethane used in each example was obtained, for example, as follows.
[0114]
-Synthesis Example 1 [Exemplified Compound (3)]-
2.0 g of the following compound (X-1) and 30 ml of chlorobenzene are placed in a 50-ml flask and stirred to dissolve. A solution of 0.54 g of hexamethylene diisocyanate in 10 ml of chlorobenzene is placed in the flask for 30 minutes. Then, the mixture was heated and stirred at 150 ° C. for 2 hours under a nitrogen stream. After completion of the reaction, the reaction solution was cooled to room temperature, and the reaction solution was dropped into 300 ml of stirred methanol to precipitate a polymer. The obtained polymer was filtered, sufficiently washed with methanol and dried, then dissolved in 30 ml of tetrahydrofuran (THF), and the solution was added dropwise to 300 ml of methanol. A charge transporting polyurethane was obtained. The molecular weight was measured by GPC, and Mw = 4.71 × 10 ⁴ (In terms of styrene), and the value of p determined from the molecular weight of the monomer was about 90.
[0115]
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[0116]
-Synthesis Example 2 [Exemplified Compound (28)]-
2.0 g of the following compound (X-2) and 30 ml of chlorobenzene were placed in a 50-ml flask and dissolved by stirring, and a solution prepared by dissolving 0.52 g of hexamethylene diisocyanate in 10 ml of chlorobenzene was placed in the flask for 30 minutes. Then, the mixture was heated and stirred at 150 ° C. for 2 hours under a nitrogen stream. After completion of the reaction, the mixture was cooled to room temperature, and the reaction solution was dropped into 300 ml of stirred methanol to precipitate a polymer. The obtained polymer was filtered, sufficiently washed with methanol and dried, then dissolved in 30 ml of tetrahydrofuran (THF), and the solution was dropped into 300 ml of methanol, and reprecipitation was repeated three times to obtain 2.1 g of the polymer. A charge transporting polyurethane was obtained. The molecular weight was measured by GPC, and Mw = 7.79 × 10 ⁴ (In terms of styrene), and the value of p determined from the molecular weight of the monomer was about 60.
[0117]
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[0118]
-Synthesis Example 3 [Exemplified Compound (24)]-
2.0 g of the compound (X-3) and 30 ml of chlorobenzene are placed in a 50-ml flask and dissolved by stirring, and a solution of 0.52 g of hexamethylene diisocyanate in 10 ml of chlorobenzene is dissolved in the flask over 30 minutes. After the dropwise addition, the mixture was heated and stirred at 150 ° C. for 3 hours under a nitrogen stream. After completion of the reaction, the reaction solution was cooled to room temperature, and the reaction solution was dropped into 300 ml of stirred methanol to precipitate a polymer. The obtained polymer was filtered, sufficiently washed with methanol and dried, then dissolved in 30 ml of tetrahydrofuran (THF), and the solution was added dropwise to 300 ml of methanol, and the reprecipitation was repeated three times to obtain 1.9 g of the polymer. A charge transporting polyurethane was obtained. The molecular weight was measured by GPC, and Mw = 1.05 × 10 ⁵ (In terms of styrene), and the value of p determined from the molecular weight of the monomer was about 60.
[0119]
Embedded image

[0120]
(Example 1)
Charge transporting polyurethane [Exemplified Compound (3)] (Mw = 4.85 × 10 ⁴ ) Was prepared and filtered through a 0.1 μm polytetrafluoroethylene (RTFE) filter. After ultrasonic cleaning and drying in 2-propanol (for use in the electronics industry, manufactured by Kanto Chemical Co., Ltd.), the solution was applied by dip method to the surface of a glass substrate on which a rectangular ITO electrode having a width of 2 mm was formed by etching. A light emitting layer having a hole transport ability of 0.1 μm was formed. On the surface of the sufficiently dried light emitting layer, the exemplified compound (V-1) purified by sublimation as an electron transporting material was put into a tungsten boat and deposited by a vacuum evaporation method to form an electron transporting layer having a thickness of 0.05 μm. did. The degree of vacuum at this time is 1.33 × 10 ^-3 Pa, the boat temperature was 300 ° C. Subsequently, a Mg-Ag alloy was deposited on the surface of the charge transport layer by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to cross the ITO electrode. The effective area of the manufactured organic EL device is 0.04 cm. ² Met.
[0121]
The organic EL device manufactured as described above was placed in a vacuum (1.33 × 10 ^-1 At Pa), a DC voltage from 0 V to 20 V was applied from 0 V to 1 V with the ITO electrode side plus and the Mg-Ag back electrode minus, and the emission was measured, and the maximum brightness and emission color at this time were evaluated. Table 14 shows the results. The emission lifetime of the organic EL device was measured in dry nitrogen. The evaluation of the light emission life was such that the initial luminance was 50 cd / m. ² The current value was set so as to be as follows, and the time required for the luminance to be reduced by half from the initial value by constant current driving was defined as the element lifetime (hour). Table 14 shows the drive current density at this time together with the element life.
[0122]
(Example 2)
After washing and drying in the same manner as in Example 1, the above exemplified compound (IX-2) purified by sublimation as a hole transport material was placed in a tungsten boat on the surface of a glass substrate on which a strip-shaped ITO electrode having a width of 2 mm was formed by etching, and vacuum deposited. A hole transport layer having a thickness of 0.05 μm was formed by vapor deposition. The degree of vacuum at this time is 1.33 × 10 ^-3 Pa, the boat temperature was 300 ° C. Subsequently, the filtered charge transporting polyurethane [Exemplified Compound (3)] used in Example 1 (Mw = 4.85 × 10 4) ⁴ Using a 5% by mass dichloroethane solution of the above), the mixture was applied by a dipping method to form a light emitting layer having a thickness of about 0.1 μm on the surface of the hole transport layer. Finally, a Mg-Ag alloy was deposited on the sufficiently dried surface of the light emitting layer by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to cross the ITO electrode. The effective area of the manufactured organic EL device is 0.04 cm. ² Met.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0123]
(Example 3)
Charge transporting polyurethane used in Example 1 [Exemplified Compound (3)] (Mw = 4.85 × 10 ⁴ ) 2 parts by mass and 1 part by mass of the above-mentioned compound (VIII-1) as an electron transporting material were mixed to prepare a 10% by mass dichloroethane solution, which was filtered with a 0.1 µm PTFE filter. Using this solution, after washing and drying, a 2 mm-wide strip-shaped ITO electrode was applied by dip coating on the surface of the glass substrate formed by etching to form a 0.15 μm-thick light-emitting layer having a carrier transporting ability. An Mg-Ag alloy was co-evaporated on the sufficiently dried surface of the light emitting layer to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the manufactured organic EL device is 0.04 cm. ² Met.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0124]
(Example 4)
Exemplary compound (28) (Mw = 7.79 × 10 3) as a charge transporting polyurethane ⁴ An organic EL device was produced in the same manner as in Example 1 except that the above was used.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0125]
(Example 5)
Exemplary compound (28) (Mw = 7.79 × 10 3) as a charge transporting polyurethane ⁴ An organic EL device was produced in the same manner as in Example 2 except that the above was used.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0126]
(Example 6)
Exemplary compound (28) (Mw = 7.79 × 10 3) as a charge transporting polyurethane ⁴ An organic EL device was produced in the same manner as in Example 3 except that the above was used.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0127]
(Example 7)
Charge-transporting polyurethane used in Example 4 [Exemplified Compound (28)] (Mw = 7.99 × 10 ⁴ 1) and 1 part by mass of the exemplified compound (V-1) as a luminescent material was mixed to prepare a 10% by mass dichloroethane solution, which was filtered through a 0.1 μm PTFE filter. Using this solution, after washing and drying, a 2 mm-wide strip-shaped ITO electrode was applied by dip coating on the surface of the glass substrate formed by etching to form a 0.15 μm-thick light-emitting layer having a carrier transporting ability. A charge-transporting polyurethane [exemplified compound (24)] (Mw = 1.05 × 10 5) previously prepared and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter on the surface of the sufficiently dried light emitting layer. ⁵ ) Was applied by a spin coating method using a 5% by mass dichloroethane solution to form an electron transporting layer having a thickness of 0.1 μm. Finally, a Mg-Ag alloy was deposited on the surface of the electron transporting layer by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the manufactured organic EL device is 0.04 cm. ² Met.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0128]
(Example 8)
After washing and drying in the same manner as in Example 1, the charge-transporting polyurethane [exemplified compound (28)] (Mw = 7.79) used in Example 4 was applied to the surface of the glass substrate on which a rectangular ITO electrode having a width of 2 mm was formed by etching. × 10 ⁴ ) Using the solution, a hole transport layer having a thickness of 0.1 μm was formed by a dipping method. Further, a light emitting layer having a thickness of 0.065 μm was formed on the surface by using the exemplified compound (V-1) by a vacuum evaporation method. After sufficiently drying, a charge transporting polyurethane [exemplified compound (24)] (Mw = 1.05 × 10 5) prepared in advance and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter. ⁵ ) Was applied to the surface of the light emitting layer by a spin coating method using a 5% by mass dichloroethane solution to form an electron transporting layer having a thickness of 0.1 μm. Finally, a Mg-Ag alloy was deposited on the surface of the electron transporting layer by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the manufactured organic EL device is 0.04 cm. ² Met.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0129]
(Example 9)
As a hole transporting material, a charge transporting polyurethane [exemplified compound (28)] (Mw = 7.79 × 10 ⁴ ), 1 part by mass of the exemplified compound (VII-1) as a luminescent material, and a charge transporting polyurethane [exemplified compound (24)] as an electron transporting material (Mw = 1.05 × 10 5). ⁵ ) Was used in the same manner as in Example 3 except that 1 part by mass was used to produce an organic EL device.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0130]
(Comparative Example 1)
In the same manner as in Example 1, after washing and drying, a 2 mm-wide strip-shaped ITO electrode was formed on the surface of the glass substrate by etching, and the thickness of the hole transport material represented by Exemplified Compound (IX-1) was reduced to 0.1 mm. A hole transporting layer having a thickness of 050 μm and a light emitting layer having a thickness of 0.065 μm made of the light emitting material represented by the above exemplified compound (V-1) were sequentially formed by vacuum evaporation. Further, a Mg-Ag alloy was finally deposited on the surface of the light emitting layer by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to cross the ITO electrode. The effective area of the manufactured organic EL device is 0.04 cm. ² Met.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0131]
(Comparative Example 2)
After washing and drying, a strip-shaped ITO electrode having a width of 2 mm was formed on the glass substrate by etching in the same manner as in Example 1. And a 0.050 μm-thick electron transporting layer composed of the electron transporting material represented by the above-mentioned exemplary compound (VIII-1) was sequentially formed by a vacuum evaporation method. Further, a Mg-Ag alloy was finally deposited on the surface of the electron transport layer by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the manufactured organic EL device is 0.04 cm. ² Met.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0132]
(Comparative Example 3)
1 part by mass of the exemplified compound (IX-1) as a hole transport material, 1 part by mass of the exemplified compound (V-1) as a light emitting material, and 1 part by mass of polymethyl methacrylate (PMMA) as a binder resin. Were mixed to prepare a 10% by mass dichloroethane solution, which was filtered through a 0.1 μm PTFE filter. Using this solution, a 2 mm-wide strip-shaped ITO electrode was applied by dip coating on the surface of a glass substrate formed by etching to form a hole transport layer having a thickness of 0.15 μm. An Mg-Ag alloy was co-evaporated on the sufficiently dried surface of the hole transport layer to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the manufactured organic EL device is 0.04 cm. ² Met.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0133]
(Comparative Example 4)
2 parts by mass of the exemplified compound (IX-6) as a hole transporting material, 0.1 parts by mass of the exemplified compound (VII-1) as a light emitting material, and the compound (VIII-1) as an electron transporting material. The mixture was mixed with 1 part by mass to prepare a 10% by mass dichloroethane solution, which was filtered with a 0.1 μm PTFE filter. Using this solution, a 2 mm-wide strip-shaped ITO electrode was applied by dip coating on the surface of a glass substrate formed by etching to form a hole transport layer having a thickness of 0.15 μm. After sufficient drying, a Mg-Ag alloy was deposited on the surface of the hole transport layer by co-evaporation to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect the ITO electrode. The effective area of the manufactured organic EL device is 0.04 cm. ² Met.
The same evaluation as in Example 1 was performed for the organic EL. Table 14 shows the results.
[0134]
[Table 14]

[0135]
As shown in the above examples, the organic EL element of the present invention exhibits high maximum luminance despite the low drive current density. Particularly, in Example 4, 700 cd / m ² The above maximum brightness was obtained. On the other hand, in the organic EL element of the comparative example, a sufficient element life was not obtained.
[0136]
【The invention's effect】
The charge transporting polyurethane composed of a repeating structural unit containing at least one selected from the structures represented by the general formulas (I-1) and (I-2) as a partial structure has an ionization potential suitable for an organic EL device, The organic EL device of the present invention, which has charge mobility and light-emitting characteristics and can form a good thin film by using a spin coating method, a dip method, or the like, can be sufficiently formed using the method. Since the brightness is high and the film thickness can be set relatively thick, there are few defects such as pinholes and the like, and it is easy to increase the area and has excellent durability.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing one example of a stacked organic EL device of the present invention.
FIG. 2 is a schematic cross-sectional view showing another example of the stacked organic EL device of the present invention.
FIG. 3 is a schematic sectional view showing another example of the organic EL device of the present invention.
FIG. 4 is a schematic cross-sectional view showing another example of the stacked organic EL device of the present invention.
[Explanation of symbols]
1 Transparent insulator substrate
2 Transparent electrode
3 Hole transport layer
4 Light-emitting layer
5 electron transport layer
6 Emitting layer with carrier transport ability
7 Back electrode

Claims (7)

An electroluminescent device comprising one or a plurality of organic compound layers sandwiched between a pair of electrodes consisting of an anode and a cathode, at least one of which is transparent or translucent, wherein at least one of the organic compound layers is An organic electric field comprising at least one kind of charge transporting polyurethane comprising a repeating unit containing at least one kind selected from the structures represented by formulas (I-1) and (I-2) as a partial structure. Light emitting element.

[In the general formulas (I-1) and (I-2), Ar represents a substituent represented by the general formula (II-1) or a substituent represented by (II-2), and X represents a substituent Alternatively, it represents an unsubstituted divalent aromatic group, and k represents 0 or 1. ]

[In the general formulas (II-1) and (II-2), Ar ₁ , Ar ₂ and Ar ₃ represent a substituted or unsubstituted benzene ring or a substituted or unsubstituted polynuclear aromatic having 2 to 10 aromatic rings. Hydrocarbons, substituted or unsubstituted fused aromatic hydrocarbons having 2 to 10 aromatic rings, or substituted or unsubstituted aromatic heterocycles, or substituted or unsubstituted aromatics containing at least one aromatic heterocycle R ₁ , R ₂ , R ₃ and R ₄ represent a hydrogen atom, an alkyl group, an alkoxy group, a cyano group, a halogen atom, a substituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted group And each may be independent or at least two or more of them may be the same. n represents an integer of 0 to 10. ] The organic compound layer includes at least a light emitting layer having a carrier transporting ability and an electron transporting layer, and the light emitting layer has at least one selected from the structures represented by the general formulas (I-1) and (I-2). 2. The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device comprises at least one kind of charge transporting polyurethane composed of a repeating unit containing a seed as a partial structure. The organic compound layer includes at least a hole transport layer, a light emitting layer, and an electron transport layer, and the light emitting layer is at least one selected from the structures represented by the general formulas (I-1) and (I-2). The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device comprises at least one kind of charge-transporting polyurethane composed of a repeating unit containing as a partial structure. The organic compound layer includes at least a light emitting layer having a carrier transporting ability, and the light emitting layer has a partial structure of at least one selected from the structures represented by the general formulas (I-1) and (I-2). The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device comprises at least one kind of a charge transporting polyurethane composed of a repeating unit containing: The organic compound layer includes at least a hole transporting layer and a light emitting layer having a carrier transporting ability, and the light emitting layer has at least one selected from the structures represented by the general formulas (I-1) and (I-2). 2. The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device comprises at least one kind of charge transporting polyurethane composed of a repeating unit containing a seed as a partial structure. The organic electroluminescent device according to claim 2, wherein the light emitting layer contains a charge transporting material. The charge transporting polyurethane comprising a repeating unit containing at least one selected from the structures represented by the general formulas (I-1) and (I-2) as a partial structure is represented by the following general formula (III-1) or ( The organic electroluminescent device according to any one of claims 1 to 6, wherein the organic electroluminescent device is a polyurethane represented by III-2).

[In the general formulas (III-1) and (III-2), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2), and R represents a hydrogen atom Represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, and T represents a divalent linear hydrocarbon group having 1 to 6 carbon atoms, or a divalent chain having 2 to 10 carbon atoms. , Y represents a diisocyanate residue, Z represents a dihydric alcohol residue, m represents 0 or 1, and p represents an integer of 5 to 5,000. ]

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