JP2004111133A - Organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element with sufficient brightness and excellent stability and durability, easy to manufacture, and capable of coping with enlargement of the luminous area. <P>SOLUTION: The organic EL element has one or a plurality of organic compound layers interposed between a pair of electrodes of which at least one electrode is transparent or translucent. At least one layer of the organic compound layers contains at least one kind of charge transporting polyurethane composed of repeating units at least containing one kind of structure selected from the structures denoted by general formulae (I-1) and (I-2). <P>COPYRIGHT: (C)2004,JPO

Description

〔一般式（Ｉ−１）および（Ｉ−２）中、Ａｒは、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芳香環数２〜１０の１価の多核芳香族炭化水素、置換もしくは未置換の芳香環数２〜１０の１価の縮合環芳香族炭化水素、置換もしくは未置換の１価の芳香族複素環、又は、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１価の芳香族基を表し、Ｘは下記構造式（１）〜（３）に示される２価の縮合環芳香族炭化水素の内少なくとも一種を部分構造として含む置換もしくは未置換の芳香環数３〜１０の２価の縮合芳香環を表し、ｋは０または１を表す。〕
【化５】

【００１２】
＜２＞　前記有機化合物層が、少なくとも発光層及び電子輸送層から構成され、前記発光層及び前記電子輸送層の少なくとも一方が、前記一般式（Ｉ−１）および（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。
【００１３】
＜３＞　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＞に記載の有機電界発光素子である。
【００１４】
＜４＞　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、前記ホール輸送層及び前記電子輸送層の少なくとも一方が、前記一般式（Ｉ−１）および（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。
【００１５】
＜５＞　前記有機化合物層が、発光層のみから構成され、前記発光層が、前記一般式（Ｉ−１）および（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。
【００１６】
＜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＜５＞に記載の有機電界発光素子である。
【００１７】
＜７＞　前記有機化合物層が、少なくともホール輸送層及び発光層から構成され、前記ホール輸送層及び前記発光層の少なくとも一方が、前記一般式（Ｉ−１）および（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】
＜８＞　前記発光層が、電荷輸送性材料を含むことを特徴とする＜７＞に記載の有機電界発光素子である。
【００１９】
＜９＞　前記一般式（Ｉ−１）および（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（ＩＩ−１）または（ＩＩ−２）で示される電荷輸送性ポリウレタンであ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。
【化６】

〔一般式（ＩＩ−１）及び（ＩＩ−２）中、Ａは前記一般式（Ｉ−１）および（Ｉ−２）で示される構造から選択される少なくとも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およびＺは２価のジイソシアネート、アルコール、または、アミン残基を表し、ｍは０または１を表し、ｐは５〜５，０００の整数を表す。〕
【００２０】
＜１０＞　前記一般式（Ｉ−１）および（Ｉ−２）において、Ａｒが２〜５個の芳香環を含み、Ｘが３〜５個の芳香環を含むことを特徴とする＜１＞に記載の有機電界発光素子である。
【００２１】
【発明の実施の形態】
本発明の有機電界発光素子は、少なくとも一方が透明又は半透明である一対の電極間に挾持された一つ又は複数の有機化合物層より構成される電界発光素子において、前記有機化合物層の少なくとも一層が、下記一般式（Ｉ−１）および（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」ということがある）を、少なくとも１種含有することを特徴とする。
【００２２】
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、安定性および耐久性に優れる。さらに、前記電荷輸送性ポリウレタンを用いることで、大面積化可能であり、容易に製造可能である。また、前記電荷輸送性ポリウレタンは、後述するような構造を適宜選択することで、ホール輸送能、電子輸送能のいずれの機能をも付与することができる。このため、目的に応じてホール輸送層、発光層、電荷輸送層等のいずれの層にも用いることができる。
【００２３】
【化７】

【００２４】
但し、一般式（Ｉ−１）および（Ｉ−２）中、Ａｒは、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芳香環数２〜１０の１価の多核芳香族炭化水素、置換もしくは未置換の芳香環数２〜１０の１価の縮合環芳香族炭化水素、置換もしくは未置換の１価の芳香族複素環、又は、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１価の芳香族基を表す。
【００２５】
一般式（Ｉ−１）および（Ｉ−２）中において、Ａｒを表す構造として選択される多核芳香族炭化水素および縮合環芳香族炭化水素を構成する芳香環数は特に限定されないが、芳香環数が２〜５のものが好ましく、縮合環芳香族炭化水素においては、全縮合環芳香族炭化水素が好ましい。なお、当該多核芳香族炭化水素および縮合環芳香族炭化水素とは、本発明においては、具体的には以下に定義される多環式芳香族のことを意味する。
【００２６】
即ち、「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、これらの芳香環同士が、炭素―炭素の単結合によって結合している炭化水素化合物を表す。具体例としては、ビフェニル、ターフェニル等が挙げられる。
また、「縮合環芳香族炭化水素」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、これらの芳香環同士が、１対の隣接して結合する炭素原子を共有している炭化水素化合物を表す。具体例としては、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。
なお、全ての芳香環が縮合環構造のより連続的に隣接してなる縮合環芳香族炭化水素を「全縮合環芳香族炭化水素」という。一方、これ以外の縮合環芳香族炭化水素を「部分縮合環芳香族炭化水素」という。
【００２７】
また、Ａｒを表す構造のひとつとして選択される芳香族複素環は、炭素と水素以外の元素も含む芳香環を表す。その環骨格を構成する原子数（Ｎｒ）は、Ｎｒ＝５及び／又は６が好ましく用いられる。また環骨格を構成するＣ以外の元素（異種元素）の種類及び数は特に限定されないが、例えば、Ｓ、Ｎ、Ｏ等が好ましく用いられ、前記環骨格中には２種類以上及び／又は２個以上の異種原子が含まれていてもよい。特に５員環構造を持つ複素環としては、チオフェン、チオフィン及びフランもしくはこれらの３位及び４位の炭素をさらに窒素で置換した複素環、ピロールもしくはこれらの３位及び４位の炭素をさらに窒素で置換した複素環が好ましく用いられ、６員環構造をもつ複素環として、ピリジンが好ましく用いられる。
【００２８】
さらに、Ａｒを表す構造のひとつとして選択される芳香族複素環を含む芳香族基は、骨格を構成する原子団中に、少なくとも１種の前記芳香族複素環を含む結合基を表す。これらは、すべてが共役系で構成されたもの、或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。
【００２９】
Ａｒを表す構造として選択されるベンゼン環、多核芳香族炭化水素、縮合環芳香族炭化水素または複素環の置換基としては、水素原子、アルキル基、アルコキシ基、フェノキシ基、アリール基、アラルキル基、置換アミノ基、ハロゲン原子等が挙げられる。アルキル基としては、炭素数１〜１０のものが好ましく、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。アルコキシル基としては、炭素数１〜１０のものが好ましく、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。アリール基としては、炭素数６〜２０のものが好ましく、例えば、フェニル基、トルイル基等が挙げられる、アラルキル基としては、炭素数７〜２０のものが好ましく、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。
【００３０】
一般式（Ｉ−１）および（Ｉ−２）中、Ｘは下記構造式（１）〜（３）に示される２価の縮合環芳香族炭化水素の内少なくとも一種を部分構造として含む置換もしくは未置換の芳香環数３〜１０の２価の縮合芳香環を表す。なお、Ｘは３〜５個の芳香環を含むことが好ましい。
【００３１】
【化８】

【００３２】
但し、式（１）〜（３）中、Ｒ^１は、それぞれ水素原子、炭素数１〜１０のアルキル基、炭素数１〜１０のアルコキシ基、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、ハロゲン原子を表す。
【００３３】
ここで、本発明における「縮合芳香環」とは、構造式（１）〜（３）に示される２価の縮合環芳香族炭化水素、または、構造式（１）〜（３）に示される２価の縮合環芳香族炭化水素から選択された少なくとも１種を部分構造として含み、それ以外の２価の置換基と直鎖状に隣接して結合した置換基を表す。
構造式（１）〜（３）に示される２価の縮合環芳香族炭化水素から選択された少なくとも１種を部分構造として含む置換基の場合、直鎖状に隣接して結合した２価の置換基の具体例としては、下記の式（４）〜（２２）で示される基より選択される。但し、２価の置換基としてはこれら具体例のみに限定されるわけではない。
【００３４】
【化９】

【００３５】
構造式（４）〜（２２）中、Ｒ^２は、それぞれ水素原子、炭素数１〜１０のアルキル基、炭素数１〜１０のアルコキシ基、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１以上の整数を意味する。また、一般式（Ｉ−１）および（Ｉ−２）中、ｋは０または１を表す。
【００３６】
以下、一般式（Ｉ−１）および（Ｉ−２）で示される構造の具体例を表１〜表２１に示す。但し、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１１に示す構造番号１〜６６は一般式（Ｉ−１）で示される構造の具体例を示し、表１２〜表２１に示す構造番号６７〜１２６は一般式（Ｉ−２）で示される構造の具体例を示す。
【００３７】
【表１】

【００３８】
【表２】

【００３９】
【表３】

【００４０】
【表４】

【００４１】
【表５】

【００４２】
【表６】

【００４３】
【表７】

【００４４】
【表８】

【００４５】
【表９】

【００４６】
【表１０】

【００４７】
【表１１】

【００４８】
【表１２】

【００４９】
【表１３】

【００５０】
【表１４】

【００５１】
【表１５】

【００５２】
【表１６】

【００５３】
【表１７】

【００５４】
【表１８】

【００５５】
【表１９】

【００５６】
【表２０】

【００５７】
【表２１】

【００５８】
本発明に用いられる電荷輸送性ポリウレタンは、前記一般式（Ｉ−１）および（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ものであれば特に限定されないが、下記一般式（ＩＩ−１）または（ＩＩ−２）で示されるものが好適に使用される。
【００５９】
【化１０】

【００６０】
但し、一般式（ＩＩ−１）および（ＩＩ−２）式中、Ａは前記一般式（Ｉ−１）および（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。
また、一般式（ＩＩ−１）および（ＩＩ−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１〜１０のものが好ましく、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。アリール基としては、炭素数６〜２０のものが好ましく、例えば、フェニル基、トルイル基等が挙げられる、アラルキル基としては、炭素数７〜２０のものが好ましく、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。
【００６１】
一般式（ＩＩ−１）および（ＩＩ−２）式中、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または炭素数３〜７の２価の分枝鎖状炭化水素基より選択される。以下にＴで表される構造の具体例を示す。
【００６２】
【化１１】

【００６３】
一般式（ＩＩ−１）および（ＩＩ−２）式中、ＹおよびＺは２価のジイソシアネート、アルコール、または、アミン残基を表す。ＹおよびＺは、具体的には下記の式（２３）〜（２９）から選択された基が挙げられる。
【００６４】
【化１２】

【００６５】
式（２３）〜（２９）中、Ｒ_３およびＲ_４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およびｅはそれぞれ１〜１０の整数を意味し、ｆは０、１または２の整数を意味し、ｈおよびｉはそれぞれ０または１を意味し、Ｖは式（４）〜（２２）で示される２価の置換基より選択される。
【００６６】
一般式（ＩＩ−１）および（ＩＩ−２）式中、ｍは０または１を表し、ｐは５〜５，０００の整数を表すが、好ましくは１０〜１，０００の範囲である。
【００６７】
以下、一般式（ＩＩ−１）および（ＩＩ−２）で示される電荷輸送性ポリウレタンの具体例を表２２〜２６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２２〜２６において、部分構造を示す「Ａ」の欄の番号は、表１〜２１の「構造」の欄の番号（構造番号）に対応する一般式（Ｉ−１）および（Ｉ−２）で表される構造の具体例に対応している。また、表２２〜２６において、「Ｚ」の欄が「−」と記載されている場合は一般式（ＩＩ−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「−」と記載されている場合は一般式（ＩＩ−２）で示される電荷輸送性ポリウレタンの具体例を示す。また、「化合物」の欄に記載された括弧付きの番号に対応する具体例は、例えば、１５の番号を付した具体例については以下、例示化合物（１５）と表現する。
【００６８】
【表２２】

【００６９】
【表２３】

【００７０】
【表２４】

【００７１】
【表２５】

【００７２】
【表２６】

【００７３】
以上に説明したような電荷輸送性ポリウレタンの重量平均分子量Ｍｗは、１０，０００〜３００，０００の範囲にあるのが好ましい。
電荷輸送性ポリウレタンは、下記一般式（ＩＩＩ−１）〜（ＩＩＩ−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、一般式（ＩＩＩ−１）〜（ＩＩＩ−４）中、ＡおよびＴで示される構造は、前記一般式（ＩＩ−１）および（ＩＩ−２）中において示される構造ＡおよびＴと同様であり、ｍも同様に０または１を表す。
【００７４】
【化１３】

【００７５】
具体的には、例えば、一般式（ＩＩＩ−１）および（ＩＩＩ−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（ＩＩＩ−１）で示される２価アルコールの場合には、ＯＣＮ−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（ＩＩＩ−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事ができる。これら有機金属化合物と第３アミンは触媒として混合して用いても良い。触媒の量は、電荷輸送性モノマー１重量部に対して、１／１０，０００〜１／１０重量部、好ましくは１／１，０００〜１／５０重量部の範囲で用いられる。溶剤は、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。溶剤の量は、電荷輸送性モノマー１重量部に対して、１〜１００重量部、好ましくは２〜５０重量部の範囲で用いられる。反応温度は任意に設定できる。
【００７６】
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。更に、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、効率よく撹拌しながら行うことが好ましい。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は、電荷輸送性ポリウレタン１重量部に対して、１〜１００重量部、好ましくは２〜５０重量部の範囲で用いられる。また、貧溶剤は電荷輸送性ポリウレタン１重量部に対して、１〜１，０００重量部、好ましくは１０〜５００重量部の範囲で用いられる。
【００７７】
一般式（ＩＩＩ−３）および（ＩＩＩ−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（ＩＩＩ−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（ＩＩＩ−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。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、電荷輸送性モノマー１重量部に対して、１〜１００重量部、好ましくは２〜５０重量部の範囲で用いられる。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。
【００７８】
また、_２ＨＮ−Ｙ−ＮＨ_２で示されるジアミン類が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述の一般式（ＩＩＩ−３）で示される当量の電荷輸送性モノマー溶液を加えることによって重合できる。この際、水はジアミン類１重量部に対して、１〜１，０００重量部、好ましくは１０〜５００重量部の範囲で用いられる。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。相間移動触媒は、電荷輸送性モノマー１重量部に対して、０．１〜１０重量部、好ましくは０．２〜５重量部の範囲で用いられる。
【００７９】
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、前記有機化合物層の少なくとも１層が、前記電荷輸送性ポリウレタンを含有してなるものであれば特に限定されない。
【００８０】
本発明の有機ＥＬ素子が、１つの有機化合物層を含む場合、この有機化合物層は発光層（キャリア輸送能を持つ発光層）を意味し、このキャリア輸送能を持つ発光層が前記電荷輸送性ポリウレタンを含有してなる。
一方、複数の有機化合物層を含む場合（機能分離型の場合）は、少なくともいずれか一の有機化合物層が発光層（この発光層はキャリア輸送能を持っていてもよいし、なくてもよい）である。また、発光層以外の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、又は、ホール輸送層及び電子輸送層よりなるものを意味し、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。
本発明の有機ＥＬ素子が複数の有機化合物層を含む場合の層構成の具体例としては、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場合、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場合、或いは、少なくともホール輸送層及び発光層から構成される場合等が挙げられるが、有機電界発光素子として発光可能な層構成であればこれに限定されるものではない。
【００８１】
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）を含有してもよい。詳しくは、後述する。
以下、図面を参照しつつ、より詳細に説明するが、これらに限定されるわけではない。
【００８２】
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の場合は、有機化合物層が複数の場合の一例であり、図３の場合は、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。
【００８３】
図１に示す有機ＥＬ素子は、透明絶縁体基板１上に、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上に、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上に、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上に、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。
【００８４】
なお、図１、図２に示す有機ＥＬ素子は、発光材料（発光層）が、明確な電子輸送性を示さないものを用いる場合に、有機ＥＬ素子の耐久性向上或いは発光効率の向上を図る目的で、発光層４（図２の場合）或いはキャリア輸送能を持つ発光層６（図１の場合）と、背面電極７と、の間に電子輸送層５を設けた層構成である。
【００８５】
本発明において前記電荷輸送性ポリウレタンを含有する有機化合物層は、その構造によっては、図１に示される有機ＥＬ素子の層構成の場合、電子輸送層５や、キャリア輸送能を持つ発光層６として機能することがき、図２に示される有機ＥＬ素子の層構成の場合、ホール輸送層３、電子輸送層５として機能することができ、図３に示される有機ＥＬ素子の層構成の場合、キャリア輸送能を持つ発光層６として機能することができ、図４に示される有機ＥＬ素子の層構成の場合、ホール輸送層３や、キャリア輸送能を持つ発光層６として機能することができる。
【００８６】
図１〜図４に示される有機ＥＬ素子の層構成の場合、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行うため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、および蒸着或いはスパッタされた金、白金、パラジウム等が用いられる。
【００８７】
図２及び図４に示される有機ＥＬ素子の層構成の場合、ホール輸送層３は、目的に応じて機能（ホール輸送能）が付与された電荷輸送性ポリウレタン単独で形成されていてもよいが、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を１重量％ないし５０重量％の範囲で混合分散して形成されていてもよい。このようなホール輸送材料としては、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挙げられ、特に好適な具体例として下記化合物（ＩＶ−１）〜（ＩＶ−８）が挙げられる。なお、化合物（ＩＶ−６）〜（ＩＶ−８）において、ｎは１以上の整数を意味する。
さらに、上記に列挙したホール輸送材料の中でも、電荷輸送性ポリウレタンとの相容性の良さの観点からは、テトラフェニレンジアミン誘導体が好ましい。また、他の汎用の樹脂等との混合でもよい。
なお、ホール輸送層３を構成する材料として前記電荷輸送性ポリウレタンを用いない場合には、ホール輸送層３は上記のホール輸送性材料単独で形成される。
【００８８】
【化１４】

【００８９】
【化１５】

【００９０】
図２に示される有機ＥＬ素子の層構成の場合、発光層４には、固体状態で高い蛍光量子収率を示す化合物が発光材料として用いられる。発光材料が有機低分子の場合、真空蒸着法により、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条件である。また、発光材料が高分子の場合、この高分子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。
発光材料が有機低分子の場合、キレート型有機金属錯体、多核または縮合芳香環化合物、ペリレン誘導体、クマリン誘導体、スチリルアリーレン誘導体、シロール誘導体、オキサゾール誘導体、オキサチアゾール誘導体、オキサジアゾール誘導体等が好適に用いられ、高分子の場合、ポリパラフェニレン誘導体、ポリパラフェニレンビニレン誘導体、ポリチオフェン誘導体、ポリアセチレン誘導体等が好適に用いられる。このような発光材料の好適な具体例としては、下記化合物（Ｖ−１）〜（Ｖ−１５）が挙げられるが、これらに限定されたものではない。なお、化合物（Ｖ−１３）〜（Ｖ−１５）中、ｎおよびｘは１以上の整数を示す。
【００９１】
【化１６】

【００９２】
【化１７】

【００９３】
また、発光層４には、有機ＥＬ素子の耐久性向上或いは発光効率の向上を目的として、上記発光材料中にゲスト材料として発光材料と異なる色素化合物をドーピングしてもよい。真空蒸着によって発光層を形成する場合、共蒸着によってドーピングを行い、溶液または分散液を塗布・乾燥することで発光層を形成する場合、溶液または分散液中に混合することでドーピングを行う。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０．００１重量％〜４０重量％程度、好ましくは０．０１重量％〜１０重量％程度である。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、発光材料との相容性が良く、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、好適には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挙げられる。好適な具体例として、下記の化合物（ＶＩ−１）〜（ＶＩ−４）が用いられるが、これらに限定されたものではない。
【００９４】
【化１８】

【００９５】
図１及び図２に示される有機ＥＬ素子の層構成の場合、電子輸送層５は、目的に応じて機能（電子輸送能）が付与された前記電荷輸送性ポリウレタン単独で形成されていてもよいが、電気的特性をさらに改善する等の目的で、電子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電子輸送材料を１重量％ないし５０重量％の範囲で混合分散して形成されていてもよい。このような電子輸送材料としては、好適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が挙げられる。好適な具体例として、下記化合物（ＶＩＩ−１）〜（ＶＩＩ−３）が挙げられるが、これらに限定されたものではない。なお、前記電荷輸送性ポリウレタンを用いない場合、これら電子輸送性材料単独で形成されることとなる。
【００９６】
【化１９】

【００９７】
図１、図３又は図４に示される有機ＥＬ素子の層構成の場合、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、或いは電子輸送能）が付与された前記電荷輸送性ポリウレタン中に発光材料を５０重量％以下の割合で分散させた有機化合物層であり、発光材料としては前記化合物（Ｖ−１）〜（Ｖ−１５）が好適に用いられるが、有機ＥＬ素子に注入されるホールと電子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１０重量％〜５０重量％分散させてもよい。
【００９８】
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が用いられることが好ましく、より好ましくは下記化合物（ＶＩＩＩ）が用いられるが、これに限定されるものではない。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適量同時に分散させて用いてもよい。また、図２で示される有機ＥＬ素子の発光層４と同様、発光材料と異なる色素化合物をドーピングしてもよい。
【００９９】
【化２０】

【０１００】
図１〜図４に示される有機ＥＬ素子の層構成の場合、背面電極７には、真空蒸着可能で、電子注入を行うため仕事関数の小さな金属が使用されるが、特に好ましくはマグネシウム、アルミニウム、銀、インジウムおよびこれらの合金が使用される。また、背面電極７上には、さらに有機ＥＬ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などの金属、ＭｇＯ、ＳｉＯ_２、ＴｉＯ_２棟の金属酸化物、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。
【０１０１】
これら図１〜図４に示される有機ＥＬ素子は、まず透明電極２の上に各有機ＥＬ素子の層構成に応じて、ホール輸送層３或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或いは分散し、得られた塗布液を用いて前記透明電極２上にスピンコーティング法、ディップ法等を用いて成膜することにより形成する。
【０１０２】
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或いはキャリア輸送能を持つ発光層６は、上記各材料を、真空蒸着法により成膜することにより、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上にスピンコーティング法、ディップ法等を用いて成膜することにより形成される。
【０１０３】
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より好ましい。また、キャリア輸送能を持つ発光層６の膜厚は、０．０３〜０．２μｍ程度が好ましい。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。塗布液を用いた成膜法の場合、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。
【０１０４】
そして、最後に、図１及び２に示す有機ＥＬ素子の場合には、電子輸送層５の上に背面電極７を、図３及び４に示す有機ＥＬ素子の場合には、キャリア輸送能を持つ発光層６の上に背面電極７を、真空蒸着法等により形成することにより本発明の有機ＥＬ素子が完成される。
このようにして作製された本発明の有機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発光させることができる。
【０１０５】
【実施例】
以下、実施例によって本発明を説明する。
まず、後述する実施例１〜１０に示す有機ＥＬ素子の作製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合成した。
【０１０６】
−合成例１〔例示化合物（１１）〕−
下記化合物（ＩＸ−１）２．０ｇおよびクロロベンゼン３０ｍｌを５０ｍｌのフラスコに入れて攪拌し溶解させ、この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、室温まで冷却した反応溶液を、メタノール３００ｍｌを撹拌している容器中に滴下してポリマーを析出させた。次に析出し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、テトラヒドロフラン（ＴＨＦ）３０ｍｌに溶解して得られた溶液を、上記と同様にメタノール３００ｍｌに析出させた。
このようなポリマーの濾過、洗浄、乾燥、溶解、析出操作を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〔例示化合物（１１）〕を得た。この電荷輸送性ポリウレタンの分子量をＧＰＣ（ゲルパーミエーションクロマトグラフィー）にて測定したところ、重量平均分子量Ｍｗは５．１５×１０^４（スチレン換算）であり、重量平均分子量Ｍｗをモノマー（一般式（ＩＩ−１）の繰り返し単位構造に相当）の分子量で割ることにより求めたｐ（数平均重合度）は約９０であった。
【０１０７】
【化２１】

【０１０８】
−合成例２〔例示化合物（４７）〕−
下記化合物（ＩＸ−２）２．０ｇおよびクロロベンゼン３０ｍｌを５０ｍｌのフラスコに入れて攪拌し溶解させ、この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、室温まで冷却した反応溶液を、メタノール３００ｍｌを撹拌している容器中に滴下してポリマーを析出させた。次に析出し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、テトラヒドロフラン（ＴＨＦ）３０ｍｌに溶解して得られた溶液を、上記と同様にメタノール３００ｍｌに析出させた。
このようなポリマーの濾過、洗浄、乾燥、溶解、析出操作を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〔例示化合物（４７）〕を得た。この電荷輸送性ポリウレタンの分子量をＧＰＣ（ゲルパーミエーションクロマトグラフィー）にて測定したところ、重量平均分子量Ｍｗは６．２３×１０^４（スチレン換算）であり、重量平均分子量Ｍｗをモノマー（一般式（ＩＩ−１）の繰り返し単位構造に相当）の分子量で割ることにより求めたｐ（数平均重合度）は約７０であった。
【０１０９】
【化２２】

【０１１０】
−合成例３〔例示化合物（４８）〕−
下記化合物（ＩＸ−３）２．０ｇおよびクロロベンゼン３０ｍｌを５０ｍｌのフラスコに入れて攪拌し溶解させ、この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、室温まで冷却した反応溶液を、メタノール３００ｍｌを撹拌している中に滴下してポリマーを析出させた。次に析出し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、テトラヒドロフラン（ＴＨＦ）３０ｍｌに溶解して得られた溶液を、上記と同様にメタノール３００ｍｌに析出させた。
このようなポリマーの濾過、洗浄、乾燥、溶解、析出操作を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〔例示化合物（４８）〕を得た。この電荷輸送性ポリウレタンの分子量をＧＰＣ（ゲルパーミエーションクロマトグラフィー）にて測定したところ、重量平均分子量Ｍｗは６．０８×１０^４（スチレン換算）であり、重量平均分子量Ｍｗをモノマー（一般式（ＩＩ−１）の繰り返し単位構造に相当）の分子量で割ることにより求めたｐ（数平均重合度）は約６０であった。
【０１１１】
【化２３】

【０１１２】
（実施例１）
ホール輸送性材料として電荷輸送性ポリウレタン〔例示化合物（１１）〕（Ｍｗ＝５．１５×１０^４）を５重量％含む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（ＰＴＦＥ）フィルターで濾過した。次に、２−プロパノール（電子工業用、関東化学社製）で超音波洗浄後乾燥させた短冊状のＩＴＯ電極付きガラス基板のＩＴＯ電極面側に、上記の溶液をディップ法により塗布し、膜厚約０．１μｍのホール輸送層を形成した。なお、使用したＩＴＯ電極付きガラス基板は、ガラス基板表面に２ｍｍ幅の短冊型ＩＴＯ電極をエッチング法等を利用して形成したものである（以下、「ＩＴＯ電極付き基板」と略す）。
【０１１３】
次に、ＩＴＯ電極付き基板上に形成したホール輸送層を十分乾燥させた後、発光材料として昇華精製した前記化合物（Ｖ−１）をタングステンボートに入れ、真空蒸着法によりホール輸送層表面に蒸着し、膜厚０．０５μｍの発光層を形成した。この時の真空度は１３３．３×１０^−５Ｐａ（１０^−５Ｔｏｒｒ）、ボート温度は３００℃であった。
続いて、短冊状の穴が設けられた金属マスクを用いて、Ｍｇ−Ａｇ合金を共蒸着により発光層表面に蒸着して、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。形成された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
【０１１４】
（実施例２）
ホール輸送性材料として電荷輸送性ポリウレタン〔例示化合物（１１）〕（Ｍｗ＝５．１５×１０^４）１重量部、発光材料として、前記化合物（Ｖ−１）１重量部を混合し、これらの混合物を１０重量％含む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。
次に、実施例１で用いたＩＴＯ電極付き基板のＩＴＯ電極面上に、上記の溶液を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、十分に乾燥させた。次に、キャリア輸送能を持つ発光層の表面に、実施例１と同様に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。形成された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
【０１１５】
（実施例３）
ホール輸送性材料として電荷輸送性ポリウレタン〔例示化合物（１１）〕（Ｍｗ＝５．１５×１０^４）を２重量部、発光材料として前記化合物（Ｖ−１０）を０．１重量部、電子輸送材料として前記化合物（ＶＩＩＩ）を１重量部混合し、これらの混合物を１０重量％含む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。
次に、実施例１で用いたＩＴＯ電極付き基板のＩＴＯ電極面上に、上記の溶液を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、十分乾燥させた。次に、キャリア輸送能を持つ発光層の表面に、実施例１と同様に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。形成された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった．
【０１１６】
（実施例４）
ホール輸送性材料として電荷輸送性ポリウレタン〔例示化合物（４７）〕（Ｍｗ＝６．２３×１０^４）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。
【０１１７】
（実施例５）
ホール輸送性材料として電荷輸送性ポリウレタン〔例示化合物（４７）〕（Ｍｗ＝６．２３×１０^４）を用いた以外は、実施例２と同にして有機ＥＬ素子を作製した。
【０１１８】
（実施例６）
ホール輸送性材料として電荷輸送性ポリウレタン〔例示化合物（４７）〕（Ｍｗ＝６．２３×１０^４）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。
【０１１９】
（実施例７）
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（１１）〕（Ｍｗ＝５．１５×１０^４）を１重量部、発光材料として前記化合物（Ｖ−１）を１重量部を混合し、これらの混合物を１０重量％含む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。
次に、実施例１で用いたＩＴＯ電極付き基板のＩＴＯ電極面上に、上記の溶液を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、十分乾燥させた。
【０１２０】
その後、キャリア輸送能を持つ発光層の表面に、電子輸送性材料として電荷輸送性ポリウレタン〔例示化合物（４８）〕（Ｍｗ＝６．０８×１０^４）を５重量％含むジクロロエタンを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溶液を、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。
最後に、電子輸送層の表面に、実施例１と同様に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。形成された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
【０１２１】
（実施例８）
実施例１で用いたＩＴＯ電極付き基板のＩＴＯ電極面上に、電荷輸送性ポリウレタン〔例示化合物（１１）〕（Ｍｗ＝５．１５×１０^４）を１重量部含む厚さ０．１μｍのホール輸送層をディップ法により形成し、十分乾燥させた後、さらに、このホール輸送層の表面に、発光材料として前記化合物（Ｖ−１）より構成される厚さ０．０６５μｍの発光層を真空蒸着法により形成した。
【０１２２】
次に、電子輸送性材料として電荷輸送性ポリウレタン〔例示化合物（４８）〕（Ｍｗ＝６．０８×１０^４）を５重量％含むジクロロエタンを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溶液を、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。
最後に、電子輸送層の表面に、実施例１と同様に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。形成された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
【０１２３】
（実施例９）
ホール輸送性材料として電荷輸送性ポリウレタン〔例示化合物（１１）〕（Ｍｗ＝５．１５×１０^４）１重量部、発光材料として前記化合物（Ｖ−１）１重量部、電子輸送性材料として電荷輸送性ポリウレタン〔例示化合物（４８）〕（Ｍｗ＝６．０８×１０^４）１重量部を用いて、キャリア輸送能を持つ発光層を形成した以外は、実施例２と同様にして有機ＥＬ素子を作製した。
【０１２４】
（実施例１０）
ホール輸送性材料として電荷輸送性ポリウレタン〔例示化合物（１１）〕（Ｍｗ＝５．１５×１０^４）１重量部、発光材料として前記化合物（Ｖ−１０）０．１重量部を混合し、電子輸送性材料として電荷輸送性ポリウレタン〔例示化合物（４８）〕（Ｍｗ＝６．０８×１０^４）１重量部を用いてキャリア輸送能を持つ発光層を形成した以外は、実施例３と同様にして有機ＥＬ素子を作製した。
【０１２５】
（比較例１）
実施例１で用いたＩＴＯ電極付き基板のＩＴＯ電極面上に、ホール輸送材料として前記化合物（ＩＶ−１）より構成される厚さ０．０５０μｍのホール輸送層と、発光材料として前記化合物（Ｖ−１）より構成される厚さ０．０６５μｍの発光層とを、順次真空蒸着法により形成した。最後に、発光層の表面に、実施例１と同様に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。形成された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
【０１２６】
（比較例２）
実施例１で用いたＩＴＯ電極付き基板のＩＴＯ電極面上に、発光材料として前記化合物（Ｖ−１）より構成される厚さ０．０６５μｍの発光層と、電子輸送材料として前記化合物（ＶＩＩ−１）より構成される厚さ０．０５０μｍの電子輸送層とを、順次真空蒸着法により形成した。最後に、電子輸送層の表面に、実施例１と同様に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。形成された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
【０１２７】
（比較例３）
ホール輸送材料として前記化合物（ＩＶ−１）を１重量部、発光材料として前記化合物（Ｖ−１）を１重量部、結着樹脂としてポリメチルメタクリレート（ＰＭＭＡ）を１重量部混合し、これらの混合物を１０重量％含む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。
次に、実施例１で用いたＩＴＯ電極付き基板のＩＴＯ電極面上に、上記の溶液を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、十分乾燥させた。最後に、ホール輸送層表面に、実施例１と同様に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。形成された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
【０１２８】
（比較例４）
ホール輸送材料として前記化合物（ＩＶ−６）を２重量部、発光材料として前記化合物（Ｖ−１０）を０．１重量部、電子輸送材料として前記化合物（ＶＩＩ−１）を１重量部混合し、これらの混合物を１０重量％含む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、実施例１で用いたＩＴＯ電極付き基板のＩＴＯ電極面上に、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十分乾燥させた。最後に、ホール輸送層表面に、実施例１と同様に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。形成された有機ＥＬ素子の有効面積は０．０４ｃｍ^２であった。
【０１２９】
（評価）
以上のように作製した有機ＥＬ素子を、真空中（１３３．３×１０^−３Ｐａ（１０^−３Ｔｏｒｒ））で、ＩＴＯ電極側をプラス、Ｍｇ−Ａｇ背面電極側をマイナスとして直流電圧を印加し、発光について測定を行い、このときの最高輝度、および発光色を評価した。それらの結果を表２７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２７に示す。
【０１３０】
【表２７】

【０１３１】
上記に説明したような各実施例および比較例から、上記一般式（Ｉ−１）および（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およびホール移動度を持ち、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、しかも向上した耐久性を有する。
【０１３２】
【発明の効果】
以上、本発明によれば、十分な輝度を有し、安定性および耐久性に優れ、且つ大面積化可能であり製造容易な有機ＥＬ素子を提供することができる。
【図面の簡単な説明】
【図１】本発明の有機電界発光素子の層構成の一例を示した概略構成図である。
【図２】本発明の有機電界発光素子の層構成の他の一例を示した概略構成図である。
【図３】本発明の有機電界発光素子の層構成の他の一例を示した概略構成図である。
【図４】本発明の有機電界発光素子の層構成の他の一例を示した概略構成図である。
【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 electroluminescent device using a specific charge transporting polymer.
[0002]
[Prior art]
BACKGROUND 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, a device using an inorganic phosphor is mainly used, but has a problem that an AC voltage of 200 V or more is required for driving, so that the manufacturing cost is high and the luminance is insufficient.
[0003]
On the other hand, research on EL devices using organic compounds started with the use of single crystals such as anthracene, but 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, attempts have been made to reduce the thickness by a vapor deposition method (see Non-Patent Document 1). However, the thin film obtained by this method still has a high driving voltage of 30 V, a low density of electron and hole carriers in the film, and a low probability of generating photons due to the recombination of carriers. I couldn't.
[0004]
However, recently, in a function separation type EL device in which a thin film 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 evaporation method, 1000 cd / m 2 at a low voltage of about 10 V. ² It has been reported that the above-described high luminance can be obtained (see Non-Patent Document 2), and since then, research and development of stacked EL elements have been actively conducted. These stacked devices are injected into the light-emitting layer made of a fluorescent organic compound from the electrode through the charge-transporting layer made of a charge-transporting organic compound while maintaining the carrier balance of holes and electrons, and confined in the light-emitting layer. High brightness light emission is realized by the recombination of the holes and electrons.
[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 apt to be generated. It is necessary to control. Therefore, there is a problem that productivity is low and it is difficult to increase the area. In addition, this EL device has several mA / cm. ² , It generates a large amount of Joule heat. For this reason, many hole transporting low molecular weight compounds and fluorescent organic low molecular weight compounds formed in an amorphous glass state by vapor deposition gradually crystallize and eventually melt, resulting in a decrease in brightness and dielectric breakdown. As a result, there was a problem that the life of the element was shortened.
[0006]
Therefore, in order to solve the problem relating to the thermal stability of the EL element, a starburst amine capable of obtaining a stable amorphous glass state can be used as a hole transport material (for example, see Non-Patent Document 3), or a polyphosphazene side chain. There has been reported an EL device using a polymer in which triphenylamine is introduced (see Non-Patent Document 4). However, these alone do not satisfy the hole injection property from the anode or the hole injection property into the light emitting layer because there is an energy barrier due to the ionization potential of the hole transport material. 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 is not obtained and sufficient luminance is obtained. There are also problems such as not having.
[0007]
On the other hand, with the aim of solving the problems related to productivity and large area of the stacked organic EL device, research and development of an organic EL device having a single layer structure have been promoted, and a conductive polymer such as poly (p-phenylenevinylene) has been developed. (For example, see Non-Patent Document 5) and a device in which an electron transporting material and a fluorescent dye are mixed in hole-transporting polyvinyl carbazole (see Non-Patent Document 6). Luminous efficiency and the like are not as high as those of a stacked organic EL device using an organic low-molecular compound. Further, in the manufacturing method, it is reported that a wet coating method is desirable from the viewpoints of simplification of manufacturing, workability, large area, cost, and the like, and it is reported that an element can be obtained by a casting method (Non-Patent Document 7). , Non-Patent Document 8). 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.
[0008]
[Non-patent document 1]
Thin Solid Films, Vol. 94, 171 (1982)
[Non-patent document 2]
Applied Physics Letter, Vol. 51, 913 (1987)
[Non-Patent Document 3]
Proceedings of the 40th Lecture Meeting on Applied Physics 30a-SZK-14 (1993)
[Non-patent document 4]
Proceedings of the 42nd Symposium on Polymers 20J21 (1993)
[Non-Patent Document 5]
Nature, Vol. 357, 477 (1992)
[Non-Patent Document 6]
Proceedings of the 38th JSAP Lecture Meeting on Applied Physics 31pg-12 (1991)
[Non-Patent Document 7]
Proc. Of the 50th Annual Meeting of the Japan Society of Applied Physics, 29p-ZP-5 (1989)
[Non-Patent Document 8]
Proceedings of the 51st Annual Meeting of the Japan Society of Applied Physics, 28a-PB-7 (1990)
[0009]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described conventional problems and achieve the following objects. 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 be made large in area, and is easy to manufacture.
[0010]
[Means for Solving the Problems]
As a result of intensive studies on the charge transporting material to achieve the above object, a charge transporting polyurethane containing at least one selected from the structures represented by the following general formulas (I-1) and (I-2) as a partial structure was obtained. The present inventors have found that the organic EL device has hole injection characteristics, hole mobility, and thin film forming ability suitable for an organic EL device, and have completed the present invention described below.
[0011]
That is, the organic electroluminescent device of the present invention comprises:
<1> An electroluminescent device comprising one or more organic compound layers sandwiched between a pair of electrodes, at least one of which is transparent or translucent,
At least one of the organic compound layers comprises a charge transporting polyurethane comprising 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. An organic electroluminescent device characterized by containing one kind.
Embedded image

[In the general formulas (I-1) and (I-2), Ar represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted monovalent polynuclear aromatic hydrocarbon having 2 to 10 aromatic rings, substituted or unsubstituted Unsubstituted monovalent condensed ring aromatic hydrocarbon having 2 to 10 aromatic rings, substituted or unsubstituted monovalent aromatic heterocycle, or substituted or unsubstituted including at least one aromatic heterocycle X represents a monovalent aromatic group, and X represents the number of substituted or unsubstituted aromatic rings containing at least one of divalent fused ring aromatic hydrocarbons represented by the following structural formulas (1) to (3) as a partial structure. Represents a 3 to 10 divalent condensed aromatic ring, and k represents 0 or 1. ]
Embedded image

[0012]
<2> The organic compound layer includes at least a light emitting layer and an electron transport layer, and at least one of the light emitting layer and the electron transport layer is 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 charge transporting polyurethane including a repeating unit containing at least one kind selected from structures as a partial structure.
[0013]
<3> The organic electroluminescent device according to <2>, wherein the light emitting layer contains a charge transporting material.
[0014]
<4> The organic compound layer includes at least a hole transport layer, a light-emitting layer, and an electron transport layer, and at least one of the hole transport layer and the electron transport layer has the general formulas (I-1) and (I- 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 selected from the structures shown in 2) as a partial structure. It is.
[0015]
<5> The organic compound layer includes only a light-emitting layer, and the light-emitting layer has at least one selected from the structures represented by the general formulas (I-1) and (I-2) as a partial structure. <1> The organic electroluminescent device according to <1>, wherein the organic electroluminescent device includes at least one kind of a charge transporting polyurethane including a repeating unit.
[0016]
<6> The organic electroluminescent device according to <5>, wherein the light emitting layer contains a charge transporting material.
[0017]
<7> The organic compound layer includes at least a hole transport layer and a light emitting layer, and at least one of the hole transport layer and the light emitting layer is 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 charge transporting polyurethane including a repeating unit containing at least one kind selected from structures as a partial structure.
[0018]
<8> The organic electroluminescent device according to <7>, wherein the light emitting layer contains a charge transporting material.
[0019]
<9> A 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 (II-1) The organic electroluminescent device according to <1>, which is a charge-transporting polyurethane represented by (II) or (II-2).
Embedded image

[In the general formulas (II-1) and (II-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 Represents a divalent branched hydrocarbon group, Y and Z represent a divalent diisocyanate, alcohol or amine residue, m represents 0 or 1, and p represents an integer of 5 to 5,000. Represent. ]
[0020]
<10> In the general formulas (I-1) and (I-2), Ar includes 2 to 5 aromatic rings, and X includes 3 to 5 aromatic rings. <1> 2. The organic electroluminescent device according to item 1.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
The organic electroluminescent device of the present invention is an electroluminescent device comprising at least one organic compound layer sandwiched between a pair of transparent or translucent electrodes, wherein at least one of the organic compound layers is provided. Is a charge-transporting polyurethane comprising 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") At least one of the following.
[0022]
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, it is possible to increase the area, and it is easy to manufacture. Further, the charge transporting polyurethane can have both functions of a hole transporting ability and an electron transporting ability by appropriately selecting a structure described below. For this reason, it can be used for any layer such as a hole transport layer, a light emitting layer, and a charge transport layer, depending on the purpose.
[0023]
Embedded image

[0024]
In the general formulas (I-1) and (I-2), Ar represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted monovalent polynuclear aromatic hydrocarbon having 2 to 10 aromatic rings, Or an unsubstituted monovalent condensed ring aromatic hydrocarbon having 2 to 10 aromatic rings, a substituted or unsubstituted monovalent aromatic heterocycle, or a substituted or unsubstituted group containing at least one aromatic heterocycle Represents a monovalent aromatic group.
[0025]
In the general formulas (I-1) and (I-2), the number of aromatic rings constituting the polynuclear aromatic hydrocarbon and the condensed-ring aromatic hydrocarbon selected as the structure representing Ar is not particularly limited, but is preferably an aromatic ring. Those having a number of 2 to 5 are preferable, and among condensed ring aromatic hydrocarbons, all condensed ring aromatic hydrocarbons are preferable. In the present invention, the polynuclear aromatic hydrocarbon and the condensed ring aromatic hydrocarbon specifically mean polycyclic aromatics defined below.
[0026]
That is, a “polynuclear aromatic hydrocarbon” is a hydrocarbon compound in which two or more aromatic rings composed of carbon and hydrogen exist, and these aromatic rings are bonded to each other by a single carbon-carbon bond. Represents Specific examples include biphenyl, terphenyl and the like.
Further, the “fused ring aromatic hydrocarbon” means that there are two or more aromatic rings composed of carbon and hydrogen, and these aromatic rings share a pair of adjacently bonded carbon atoms. Represents a hydrocarbon compound. Specific examples include naphthalene, anthracene, phenanthrene, and fluorene.
In addition, the condensed ring aromatic hydrocarbon in which all the aromatic rings are more continuously adjacent to each other in the condensed ring structure is referred to as “all condensed ring aromatic hydrocarbon”. On the other hand, other condensed ring aromatic hydrocarbons are referred to as "partially condensed ring aromatic hydrocarbons".
[0027]
Further, the aromatic heterocyclic ring selected as one of the structures representing Ar represents an aromatic ring containing elements other than carbon and hydrogen. Nr = 5 and / or 6 is preferably used as the number of atoms (Nr) constituting the ring skeleton. The type and number of elements (heterogeneous elements) other than C constituting the ring skeleton are not particularly limited, but, for example, S, N, O and the like are preferably used, and two or more and / or 2 More than one heteroatom may be included. Particularly, as the heterocyclic ring having a 5-membered ring structure, thiophene, thiofin, and furan, or a heterocyclic ring in which the 3- and 4-position carbons are further substituted with nitrogen, pyrrole, or a 3- or 4-position carbon further having a nitrogen atom Is preferably used, and pyridine is preferably used as the heterocyclic ring having a 6-membered ring structure.
[0028]
Further, the aromatic group containing an aromatic hetero ring selected as one of the structures representing Ar represents a bonding group containing at least one kind of the aromatic hetero ring in an atomic group constituting a skeleton. These may be all composed of conjugated systems or partially composed of non-conjugated systems, but those composed entirely of conjugated systems in terms of charge transportability and luminous efficiency. preferable.
[0029]
As a substituent of a benzene ring, a polynuclear aromatic hydrocarbon, a condensed ring aromatic hydrocarbon or a heterocyclic ring selected as a structure representing Ar, a hydrogen atom, an alkyl group, an alkoxy group, a phenoxy group, an aryl group, an aralkyl group, Examples include a substituted amino group and a halogen atom. The alkyl group preferably has 1 to 10 carbon atoms, and examples thereof include a methyl group, an ethyl group, a propyl group, and an isopropyl group. The alkoxyl group preferably has 1 to 10 carbon atoms, and examples thereof include a methoxy group, an ethoxy group, a propoxy group, and an isopropoxy group. The aryl group preferably has 6 to 20 carbon atoms, and examples thereof include a phenyl group and a toluyl group. The aralkyl group preferably has 7 to 20 carbon atoms, such as a benzyl group and a phenethyl group. Is mentioned. 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.
[0030]
In the general formulas (I-1) and (I-2), X represents a substituent containing at least one of divalent condensed ring aromatic hydrocarbons represented by the following structural formulas (1) to (3) as a partial structure or Represents an unsubstituted divalent fused aromatic ring having 3 to 10 aromatic rings. Preferably, X contains 3 to 5 aromatic rings.
[0031]
Embedded image

[0032]
However, in formulas (1) to (3), R ¹ Represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, or a halogen atom, respectively.
[0033]
Here, the “condensed aromatic ring” in the present invention is a divalent condensed ring aromatic hydrocarbon represented by the structural formulas (1) to (3) or represented by the structural formulas (1) to (3). It represents a substituent that contains at least one selected from divalent fused ring aromatic hydrocarbons as a partial structure and is linearly adjacently bonded to other divalent substituents.
In the case of a substituent containing at least one selected from divalent condensed ring aromatic hydrocarbons represented by the structural formulas (1) to (3) as a partial structure, a divalent bond adjacently bonded linearly Specific examples of the substituent are selected from groups represented by the following formulas (4) to (22). However, the divalent substituent is not limited to only these specific examples.
[0034]
Embedded image

[0035]
In the structural formulas (4) to (22), R ² Each represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted aralkyl group, or a halogen atom; It means the above integer. In the general formulas (I-1) and (I-2), k represents 0 or 1.
[0036]
Hereinafter, specific examples of the structures represented by the general formulas (I-1) and (I-2) are shown in Tables 1 to 21. However, the present invention is not limited to these specific examples. The structure numbers 1 to 66 shown in Tables 1 to 11 show specific examples of the structure represented by the general formula (I-1), and the structure numbers 67 to 126 shown in Tables 12 to 21 correspond to the general formulas (I- A specific example of the structure shown in 2) will be shown.
[0037]
[Table 1]

[0038]
[Table 2]

[0039]
[Table 3]

[0040]
[Table 4]

[0041]
[Table 5]

[0042]
[Table 6]

[0043]
[Table 7]

[0044]
[Table 8]

[0045]
[Table 9]

[0046]
[Table 10]

[0047]
[Table 11]

[0048]
[Table 12]

[0049]
[Table 13]

[0050]
[Table 14]

[0051]
[Table 15]

[0052]
[Table 16]

[0053]
[Table 17]

[0054]
[Table 18]

[0055]
[Table 19]

[0056]
[Table 20]

[0057]
[Table 21]

[0058]
The charge transporting polyurethane used in the present invention is not particularly limited as long as it comprises a repeating unit containing at least one selected from the structures represented by formulas (I-1) and (I-2) as a partial structure. Although not limited, those represented by the following general formula (II-1) or (II-2) are preferably used.
[0059]
Embedded image

[0060]
However, in the general formulas (II-1) and (II-2), A represents at least one selected from the structures represented by the general formulas (I-1) and (I-2). Two or more types of structure A may be included in the polymer.
In the general formulas (II-1) and (II-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 examples thereof include a methyl group, an ethyl group, a propyl group, and an isopropyl group. The aryl group preferably has 6 to 20 carbon atoms, and examples thereof include a phenyl group and a toluyl group. The aralkyl group preferably has 7 to 20 carbon atoms, such as a benzyl group and a phenethyl group. Is mentioned. 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.
[0061]
In the general formulas (II-1) and (II-2), T is a divalent linear hydrocarbon group having 1 to 6 carbon atoms or a divalent branched hydrocarbon group having 2 to 10 carbon atoms. And preferably a divalent straight-chain hydrocarbon group having 2 to 6 carbon atoms or a divalent branched-chain hydrocarbon group having 3 to 7 carbon atoms. Specific examples of the structure represented by T are shown below.
[0062]
Embedded image

[0063]
In the formulas (II-1) and (II-2), Y and Z represent a divalent diisocyanate, an alcohol, or an amine residue. Specific examples of Y and Z include groups selected from the following formulas (23) to (29).
[0064]
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[0065]
In the formulas (23) to (29), R ₃ And R ₄ 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, respectively, and d and e Each represents an integer of 1 to 10, f represents an integer of 0, 1 or 2, h and i each represent 0 or 1, and V represents 2 represented by the formulas (4) to (22). Selected from valency substituents.
[0066]
In the general formulas (II-1) and (II-2), m represents 0 or 1, and p represents an integer of 5 to 5,000, preferably 10 to 1,000.
[0067]
Hereinafter, specific examples of the charge transporting polyurethane represented by the general formulas (II-1) and (II-2) are shown in Tables 22 to 26, but the present invention is not limited to these specific examples. In Tables 22 to 26, the numbers in the column “A” indicating the partial structures correspond to the general formulas (I-1) and (I) corresponding to the numbers (structure numbers) in the column “Structure” in Tables 1 to 21. This corresponds to a specific example of the structure represented by -2). Further, in Tables 22 to 26, when the column of “Z” is described as “−”, it indicates a specific example of the charge transporting polyurethane represented by the general formula (II-1), and the column of “Y” is When "-" is described, specific examples of the charge transporting polyurethane represented by the general formula (II-2) are shown. Further, a specific example corresponding to the number in parentheses described in the column of “compound” is, for example, a specific example numbered 15 is hereinafter referred to as an exemplary compound (15).
[0068]
[Table 22]

[0069]
[Table 23]

[0070]
[Table 24]

[0071]
[Table 25]

[0072]
[Table 26]

[0073]
The weight average molecular weight Mw of the charge transporting polyurethane described above is preferably in the range of 10,000 to 300,000.
As the charge transporting polyurethane, charge transporting monomers represented by the following general formulas (III-1) to (III-4) are used, for example, in the fourth edition of Experimental Chemistry Lecture Vol. 28 (Maruzen, 1992), New Polymer Experimental Science Volume 2 (Kyoritsu Shuppan, 1995), etc., and can be synthesized by polymerizing by a known method. The structures represented by A and T in the general formulas (III-1) to (III-4) are the same as the structures A and T represented by the general formulas (II-1) and (II-2). And m also represents 0 or 1.
[0074]
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[0075]
Specifically, for example, in the case of the charge transporting monomers represented by the general formulas (III-1) and (III-2), the charge transporting polyurethane can be synthesized as follows. When the charge transporting monomer is a dihydric alcohol represented by the formula (III-1), the charge transporting monomer is mixed with a diisocyanate represented by OCN-Y-NCO in an equivalent amount, and the charge transporting monomer is represented by the formula (III-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 synthesizing a 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. The catalyst is used in an amount of 1 / 10,000 to 1/10 parts by weight, preferably 1/1000 to 1/50 parts by weight, based on 1 part by weight of the charge transporting monomer. 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 is formed between the solvent and the alcohol having a low polarity in terms of reactivity. Preferably, no solvent is used, and toluene, chlorobenzene, dichlorobenzene, 1-chloronaphthalene and the like are effective. The solvent is used in an amount of 1 to 100 parts by weight, preferably 2 to 50 parts by weight, based on 1 part by weight of the charge transporting monomer. The reaction temperature can be set arbitrarily.
[0076]
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 reprecipitation treatment of dissolving in a suitable organic solvent, dropping it into a poor solvent, and precipitating the charge transporting polyurethane may be repeated. In the case of the reprecipitation treatment, it is preferable to carry out the stirring with a mechanical stirrer or the like while stirring efficiently. The solvent for dissolving the charge transporting polyurethane during the reprecipitation treatment is used in an amount of 1 to 100 parts by weight, preferably 2 to 50 parts by weight, per 1 part by weight of the charge transporting polyurethane. The poor solvent is used in an amount of 1 to 1,000 parts by weight, preferably 10 to 500 parts by weight, based on 1 part by weight of the charge transporting polyurethane.
[0077]
In the case of the charge transporting monomers represented by the general formulas (III-3) and (III-4), the charge transporting polyurethane can be synthesized as follows. When the charge transporting monomer is bischloroformate represented by the general formula (III-3), ₂ HN-Y-NH ₂ In the case where the charge-transporting monomer is a diamine represented by the general formula (III-4), an equivalent amount thereof is mixed with a bischloroformate represented by ClOCO-Y-OCOCl. And polycondensation. As the solvent, methylene chloride, dichloroethane, trichloroethane, tetrahydrofuran (THF), toluene, chlorobenzene, 1-chloronaphthalene and the like are effective, and 1 to 100 parts by weight, preferably 2 to 100 parts by weight, per 1 part by weight of the charge transporting monomer. It is used in the range of ５０50 parts by weight. The reaction temperature can be set arbitrarily. After the polymerization, purification is performed by a reprecipitation treatment as described above.
[0078]
Also, ₂ HN-Y-NH ₂ In the case where the diamine represented by the formula (1) has a high basicity, 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 (III-3) are added with vigorous stirring. Can be polymerized. At this time, water is used in an amount of 1 to 1,000 parts by weight, preferably 10 to 500 parts by weight, based on 1 part by weight of the diamine. 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 phase transfer catalyst is used in an amount of 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, based on 1 part by weight of the charge transporting monomer.
[0079]
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 comprises 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. There is no particular limitation as long as at least one layer contains the charge transporting polyurethane.
[0080]
When the organic EL device of the present invention includes one organic compound layer, the organic compound layer means a light emitting layer (a light emitting layer having a carrier transporting ability). It contains polyurethane.
On the other hand, when a plurality of organic compound layers are included (in the case of a function separation type), at least one of the organic compound layers is a light-emitting layer (this light-emitting layer may or may not have a carrier transporting ability. ). Further, the organic compound layer other than the light emitting layer means a carrier transport layer, that is, a hole transport layer, an electron transport layer, or a layer composed of a hole transport layer and an electron transport layer, at least one of which is the charge transport layer. It comprises a transportable polyurethane.
Specific examples of the layer configuration when the organic EL device of the present invention includes a plurality of organic compound layers include, for example, at least a hole transport layer, a light emitting layer, and an electron transport layer when the organic EL device includes at least a light emitting layer and an electron transport layer. , Or at least a hole transport layer and a light-emitting layer. However, the present invention is not limited to this as long as it can emit light as an organic electroluminescent device.
[0081]
In the organic EL device of the present invention, the light emitting layer may contain a charge transporting material (a hole transporting material other than the charge transporting polyurethane, an electron transporting material). Details will be described later.
Hereinafter, the present invention will be described in more detail with reference to the drawings, but is not limited thereto.
[0082]
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 an example 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.
[0083]
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 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 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 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 a transparent insulator substrate 1. Hereinafter, each will be described in detail.
[0084]
Note that, when the organic EL element shown in FIGS. 1 and 2 uses a light-emitting material (light-emitting layer) that does not clearly show an electron transporting property, the organic EL element is improved in durability or luminous efficiency. For the purpose, the electron transport layer 5 is provided between the light emitting layer 4 (in the case of FIG. 2) or the light emitting layer 6 having the carrier transporting ability (in the case of FIG. 1) and the back electrode 7.
[0085]
In the present invention, the organic compound layer containing the charge transporting polyurethane may be, depending on its structure, an electron transporting layer 5 or a light emitting layer 6 having a carrier transporting ability in the case of the layer configuration of the organic EL device shown in FIG. It can function, and can function as the hole transport layer 3 and the electron transport layer 5 in the case of the layer configuration of the organic EL element shown in FIG. 2, and in the case of the layer configuration of the organic EL element shown in FIG. It can function as the light emitting layer 6 having a transporting ability. In the case of the layer structure of the organic EL device shown in FIG. 4, it can function as the hole transporting layer 3 or the light emitting layer 6 having a carrier transporting ability.
[0086]
In the case of the layer structure of the organic EL device 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 to extract light emission similarly to the transparent insulator substrate 1 and has a large work function for injecting holes. Indium tin oxide (ITO), tin oxide (NESA) ), An oxide film such as indium oxide and zinc oxide, and gold, platinum, palladium and the like which are deposited or sputtered.
[0087]
In the case of the layer structure of the organic EL device shown in FIGS. 2 and 4, the hole transport layer 3 may be formed of a charge transporting polyurethane having a function (hole transporting ability) according to the purpose. In order to adjust the hole mobility, a hole transport material other than the charge transporting polyurethane may be mixed and dispersed in the range of 1% by weight to 50% by weight. Examples of such a hole transport material include a tetraphenylenediamine derivative, a triphenylamine derivative, a carbazole derivative, a stilbene derivative, an arylhydrazone derivative, and a porphyrin-based compound. Particularly preferred specific examples include the following compound (IV-1) To (IV-8). In the compounds (IV-6) to (IV-8), n means an integer of 1 or more.
Further, among the hole transport materials listed above, a tetraphenylenediamine derivative is preferable from the viewpoint of good compatibility with the charge transporting polyurethane. Further, it may be mixed with other general-purpose resins.
When the charge transporting polyurethane is not used as a material constituting the hole transporting layer 3, the hole transporting layer 3 is formed of the above-described hole transporting material alone.
[0088]
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[0089]
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[0090]
In the case of the layer configuration of the organic EL device shown in FIG. 2, a compound exhibiting a high fluorescence quantum yield in a solid state is used for the light emitting layer 4 as a light emitting material. When the light emitting material is an organic low molecular weight, it is necessary that a good thin film can be formed by a vacuum evaporation method or by applying and drying a solution or a dispersion containing a low molecular weight and a binder resin. When the light emitting material is a polymer, it is a condition that a good thin film can be formed by applying and drying a solution or a dispersion containing the polymer itself.
When the light-emitting material is a low-molecular organic compound, a chelate-type organometallic complex, a polynuclear or condensed aromatic ring compound, a perylene derivative, a coumarin derivative, a styryl arylene derivative, a silole derivative, an oxazole derivative, an oxathiazole derivative, an oxadiazole derivative, and the like are preferably used. In the case of a polymer, a polyparaphenylene derivative, a polyparaphenylenevinylene derivative, a polythiophene derivative, a polyacetylene derivative, or the like is suitably used. Suitable specific examples of such a light emitting material include the following compounds (V-1) to (V-15), but are not limited thereto. In the compounds (V-13) to (V-15), n and x represent an integer of 1 or more.
[0091]
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[0092]
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[0093]
The light-emitting layer 4 may be doped with a dye compound different from the light-emitting material as a guest material in the light-emitting material for the purpose of improving the durability or luminous efficiency of the organic EL element. When the light emitting layer is formed by vacuum deposition, doping is performed by co-evaporation, and when the light emitting layer is formed by applying and drying a solution or a dispersion, doping is performed by mixing the solution or the dispersion with the solution or the dispersion. The doping ratio of the dye compound in the light emitting layer is about 0.001% to 40% by weight, preferably about 0.01% to 10% by weight. 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. Preferably, a DCM derivative, a quinacridone derivative, a rubrene derivative is used. And porphyrin compounds. As preferred specific examples, the following compounds (VI-1) to (VI-4) are used, but the invention is not limited thereto.
[0094]
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[0095]
In the case of the layer structure of the organic EL device shown in FIGS. 1 and 2, the electron transporting layer 5 may be formed of the charge transporting polyurethane alone having a function (electron transporting ability) according to the purpose. However, in order to further improve the electrical characteristics, the electron transport material other than the charge transporting polyurethane is mixed and dispersed in the range of 1% by weight to 50% by weight in order to adjust the electron mobility. You may. As such an electron transporting material, an oxadiazole derivative, a nitro-substituted fluorenone derivative, a diphenoquinone derivative, a thiopyrandioxide derivative, a fluorenylidenemethane derivative and the like are preferably mentioned. Preferred specific examples include the following compounds (VII-1) to (VII-3), but are not limited thereto. When the charge-transporting polyurethane is not used, the charge-transporting polyurethane is formed of these electron-transporting materials alone.
[0096]
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[0097]
In the case of the layer structure of the organic EL device shown in FIG. 1, FIG. 3, or FIG. 4, the light emitting layer 6 having a carrier transporting ability has a function (a hole transporting ability or an electron transporting ability) according to the purpose. An organic compound layer in which a light-emitting material is dispersed in a charge transporting polyurethane at a ratio of 50% by weight or less. As the light-emitting material, the compounds (V-1) to (V-15) are preferably used. In order to adjust the balance between holes and electrons injected into the EL element, an electron transporting material other than the charge transporting polyurethane may be dispersed in an amount of 10% by weight to 50% by weight.
[0098]
As such an electron transporting material, an organic compound that does not exhibit strong electron interaction with the charge transporting polyurethane is preferably used, and more preferably, the following compound (VIII) is used, but is not limited thereto. is not. 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 an appropriate amount. Further, similarly to the light emitting layer 4 of the organic EL element shown in FIG. 2, a dye compound different from the light emitting material may be doped.
[0099]
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[0100]
In the case of the layer structure of the organic EL element shown in FIGS. 1 to 4, the back electrode 7 is made of a metal that can be vacuum-deposited and has a small work function for performing electron injection. , Silver, indium and their alloys are used. Further, a protective layer may be further provided on the back electrode 7 in order to prevent the organic EL 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 Buildings include metal oxides, polyethylene resins, polyurea resins, and polyimide resins. 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.
[0101]
In the organic EL devices shown in FIGS. 1 to 4, first, a hole transport layer 3 or a light emitting layer 6 having a carrier transport ability is formed on the transparent electrode 2 depending on the layer configuration of each organic EL device. The hole transport layer 3 and the light emitting layer 6 having a carrier transport ability are formed by dissolving or dispersing each of the above materials in an organic solvent or an organic solvent, and spin coating the transparent electrode 2 on the transparent electrode 2 using the obtained coating solution. , By using a dipping method or the like.
[0102]
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 vacuum deposition of the above materials. Alternatively, it is formed by forming a film on the transparent electrode by using a coating solution obtained by dissolving or dispersing in an organic solvent by using a spin coating method, a dip method, or the like.
[0103]
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 more preferably in the range of 0.03 to 0.08 μm. The thickness of the light emitting layer 6 having a carrier transporting ability is preferably about 0.03 to 0.2 μm. 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 liquid, it is necessary to use a common solvent of each of the above materials as a dispersion solvent in order to obtain a molecular dispersion state, and to disperse the above materials in order to obtain a fine particle dispersion state. It is necessary to select in consideration of solubility and solubility. 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.
[0104]
Finally, in the case of the organic EL device shown in FIGS. 1 and 2, a back electrode 7 is provided on the electron transport layer 5, and in the case of the organic EL device shown in FIGS. By forming the back electrode 7 on the light emitting layer 6 by a vacuum evaporation method or the like, the organic EL device of the present invention is completed.
The organic EL device of the present invention thus manufactured has a current density of, for example, 4 to 20 V and a current density of 1 to 200 mA / cm between a pair of electrodes. ² Can be emitted by applying a DC voltage of
[0105]
【Example】
Hereinafter, the present invention will be described with reference to examples.
First, the charge transporting polyurethane used in the production of the organic EL devices shown in Examples 1 to 10 described later was synthesized, for example, as follows.
[0106]
-Synthesis Example 1 [Exemplified Compound (11)]-
2.0 g of the following compound (IX-1) and 30 ml of chlorobenzene are placed in a 50 ml flask and dissolved by stirring, and a solution prepared by dissolving 0.54 g of hexamethylene diisocyanate in 10 ml of chlorobenzene is dropped into this flask over 30 minutes. The mixture was heated and stirred at 150 ° C. for 2 hours under a nitrogen stream.
After completion of the reaction, the reaction solution cooled to room temperature was dropped into a vessel in which 300 ml of methanol was stirred to precipitate a polymer. Next, the precipitated polymer was filtered, sufficiently washed with methanol and dried, and dissolved in 30 ml of tetrahydrofuran (THF) to obtain a solution, which was precipitated in 300 ml of methanol in the same manner as described above.
By repeating such filtration, washing, drying, dissolving and precipitating operations of the polymer three times, 1.8 g of the charge transporting polyurethane [exemplified compound (11)] was obtained. When the molecular weight of this charge transporting polyurethane was measured by GPC (gel permeation chromatography), the weight average molecular weight Mw was 5.15 × 10 5 ⁴ (In terms of styrene), and p (number average degree of polymerization) obtained by dividing the weight average molecular weight Mw by the molecular weight of the monomer (corresponding to the repeating unit structure of the general formula (II-1)) was about 90.
[0107]
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[0108]
-Synthesis Example 2 [Exemplified Compound (47)]-
2.0 g of the following compound (IX-2) and 30 ml of chlorobenzene were placed in a 50 ml flask and dissolved by stirring, and a solution of 0.52 g of hexamethylene diisocyanate dissolved in 10 ml of chlorobenzene was dropped into this flask over 30 minutes. The mixture was heated and stirred at 150 ° C. for 2 hours under a nitrogen stream.
After completion of the reaction, the reaction solution cooled to room temperature was dropped into a vessel in which 300 ml of methanol was stirred to precipitate a polymer. Next, the precipitated polymer was filtered, sufficiently washed with methanol and dried, and dissolved in 30 ml of tetrahydrofuran (THF) to obtain a solution, which was precipitated in 300 ml of methanol in the same manner as described above.
By repeating such filtration, washing, drying, dissolving and precipitating operations of the polymer three times, 2.1 g of a charge transporting polyurethane [exemplified compound (47)] was obtained. When the molecular weight of this charge transporting polyurethane was measured by GPC (gel permeation chromatography), the weight average molecular weight Mw was 6.23 × 10 ⁴ (In terms of styrene), and p (number average degree of polymerization) obtained by dividing the weight average molecular weight Mw by the molecular weight of the monomer (corresponding to the repeating unit structure of the general formula (II-1)) was about 70.
[0109]
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[0110]
-Synthesis Example 3 [Exemplified Compound (48)]-
2.0 g of the following compound (IX-3) 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 dropped into this flask over 30 minutes. The mixture was heated and stirred at 150 ° C. for 3 hours under a nitrogen stream.
After completion of the reaction, the reaction solution cooled to room temperature was dropped into 300 ml of methanol while stirring to precipitate a polymer. Next, the precipitated polymer was filtered, sufficiently washed with methanol and dried, and dissolved in 30 ml of tetrahydrofuran (THF) to obtain a solution, which was precipitated in 300 ml of methanol in the same manner as described above.
By repeating such filtration, washing, drying, dissolving and precipitating operations of the polymer three times, 1.9 g of the charge transporting polyurethane [exemplified compound (48)] was obtained. When the molecular weight of this charge transporting polyurethane was measured by GPC (gel permeation chromatography), the weight average molecular weight Mw was 6.08 × 10 6 ⁴ (In terms of styrene), and p (number average degree of polymerization) obtained by dividing the weight average molecular weight Mw by the molecular weight of the monomer (corresponding to the repeating unit structure of the general formula (II-1)) was about 60.
[0111]
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[0112]
(Example 1)
Charge transporting polyurethane [Exemplified Compound (11)] as a hole transporting material (Mw = 5.15 × 10 ⁴ ) Was prepared at 5% by weight, and filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter. Next, the above solution was applied by dip method to the ITO electrode surface side of a strip-shaped glass substrate with an ITO electrode, which was dried after ultrasonic cleaning with 2-propanol (for the electronics industry, manufactured by Kanto Chemical Co., Ltd.). A hole transport layer having a thickness of about 0.1 μm was formed. The glass substrate with an ITO electrode used was formed by forming a strip-shaped ITO electrode having a width of 2 mm on the surface of the glass substrate by using an etching method or the like (hereinafter, abbreviated as “substrate with an ITO electrode”).
[0113]
Next, after sufficiently drying the hole transport layer formed on the substrate with the ITO electrode, the compound (V-1) purified by sublimation as a luminescent material is put into a tungsten boat, and vapor-deposited on the surface of the hole transport layer by a vacuum vapor deposition method. Thus, a light emitting layer having a thickness of 0.05 μm was formed. The degree of vacuum at this time is 133.3 × 10 ^-5 Pa (10 ^-5 Torr), the boat temperature was 300 ° C.
Subsequently, using a metal mask provided with strip-shaped holes, an Mg-Ag alloy is vapor-deposited on the surface of the light-emitting layer by co-deposition, so that a back electrode having a width of 2 mm and a thickness of 0.15 μm crosses the ITO electrode. Formed. The effective area of the formed organic EL element is 0.04 cm ² Met.
[0114]
(Example 2)
Charge transporting polyurethane [Exemplified Compound (11)] as a hole transporting material (Mw = 5.15 × 10 ⁴ 1) and 1 part by weight of the compound (V-1) as a luminescent material were mixed to prepare a dichloroethane solution containing 10% by weight of the mixture, and the solution was filtered through a 0.1 μm PTFE filter.
Next, on the ITO electrode surface of the substrate with the ITO electrode used in Example 1, the above solution was applied by a dipping method to form a 0.15 μm-thick light-emitting layer having a carrier transporting ability, and dried sufficiently. I let it. Next, a Mg-Ag alloy was co-evaporated on the surface of the light emitting layer having a carrier transporting ability in the same manner as in Example 1 so that the back electrode having a width of 2 mm and a thickness of 0.15 μm crossed the ITO electrode. Formed. The effective area of the formed organic EL element is 0.04 cm ² Met.
[0115]
(Example 3)
Charge transporting polyurethane [Exemplified Compound (11)] as a hole transporting material (Mw = 5.15 × 10 ⁴ ), 0.1 part by weight of the compound (V-10) as a luminescent material, and 1 part by weight of the compound (VIII) as an electron transporting material. A dichloroethane solution containing 10% by weight of the mixture is mixed. Prepared and filtered through a 0.1 μm PTFE filter.
Next, on the ITO electrode surface of the substrate with an ITO electrode used in Example 1, the above solution was applied by a dipping method to form a 0.15 μm-thick light-emitting layer having a carrier transporting ability, and then sufficiently dried. Was. Next, a Mg-Ag alloy was co-evaporated on the surface of the light emitting layer having a carrier transporting ability in the same manner as in Example 1 so that the back electrode having a width of 2 mm and a thickness of 0.15 μm crossed the ITO electrode. Formed. The effective area of the formed organic EL element is 0.04 cm ² Met.
[0116]
(Example 4)
Charge transporting polyurethane [Exemplified Compound (47)] as a hole transporting material (Mw = 6.23 × 10 ⁴ An organic EL device was produced in the same manner as in Example 1 except that the above was used.
[0117]
(Example 5)
Charge transporting polyurethane [Exemplified Compound (47)] as a hole transporting material (Mw = 6.23 × 10 ⁴ An organic EL device was produced in the same manner as in Example 2 except that the above was used.
[0118]
(Example 6)
Charge transporting polyurethane [Exemplified Compound (47)] as a hole transporting material (Mw = 6.23 × 10 ⁴ An organic EL device was produced in the same manner as in Example 3 except that the above was used.
[0119]
(Example 7)
Charge transporting polyurethane [Exemplified Compound (11)] as a hole transporting material (Mw = 5.15 × 10 ⁴ ) Was mixed with 1 part by weight of the compound (V-1) as a luminescent material to prepare a dichloroethane solution containing 10% by weight of the mixture, and the mixture was filtered through a 0.1 μm PTFE filter.
Next, on the ITO electrode surface of the substrate with an ITO electrode used in Example 1, the above solution was applied by a dipping method to form a 0.15 μm-thick light-emitting layer having a carrier transporting ability, and then sufficiently dried. Was.
[0120]
Then, on the surface of the light emitting layer having a carrier transporting ability, a charge transporting polyurethane [exemplified compound (48)] (Mw = 6.08 × 10 4) as an electron transporting material. ⁴ ) Was filtered by a 0.1 μm polytetrafluoroethylene (PTFE) filter containing 5% by weight of dichloroethane, and the solution was applied by a spin coating method to form a 0.1 μm thick electron transport layer.
Finally, a Mg-Ag alloy was co-evaporated on the surface of the electron transport layer in the same manner as in Example 1 to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect with the ITO electrode. The effective area of the formed organic EL element is 0.04 cm ² Met.
[0121]
(Example 8)
On the ITO electrode surface of the substrate with an ITO electrode used in Example 1, a charge transporting polyurethane [exemplified compound (11)] (Mw = 5.15 × 10 ⁴ ) Was formed by dipping and a hole-transporting layer containing 1 part by weight of the compound (V-1) was formed on the surface of the hole-transporting layer by using the compound (V-1) as a luminescent material. A light emitting layer having a thickness of 0.065 μm was formed by a vacuum evaporation method.
[0122]
Next, a charge transporting polyurethane [exemplified compound (48)] (Mw = 6.08 × 10 3) as an electron transporting material. ⁴ ) Was filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter containing 5% by weight of dichloroethane, and the solution was applied to the surface of the light emitting layer by spin coating to form an electron transport layer having a thickness of 0.1 μm.
Finally, a Mg-Ag alloy was co-evaporated on the surface of the electron transport layer in the same manner as in Example 1 to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect with the ITO electrode. The effective area of the formed organic EL element is 0.04 cm ² Met.
[0123]
(Example 9)
Charge transporting polyurethane [Exemplified Compound (11)] as a hole transporting material (Mw = 5.15 × 10 ⁴ 1), 1 part by weight of the compound (V-1) as a light emitting material, and a charge transporting polyurethane [exemplified compound (48)] as an electron transporting material (Mw = 6.08 × 10 ⁴ ) An organic EL device was manufactured in the same manner as in Example 2 except that a light emitting layer having a carrier transporting ability was formed using 1 part by weight.
[0124]
(Example 10)
Charge transporting polyurethane [Exemplified Compound (11)] as a hole transporting material (Mw = 5.15 × 10 ⁴ 1) and 0.1 part by weight of the compound (V-10) as a light emitting material, and a charge transporting polyurethane [exemplified compound (48)] (Mw = 6.08 × 10 4) as an electron transporting material. ⁴ An organic EL device was produced in the same manner as in Example 3, except that 1 part by weight of the light emitting layer having a carrier transporting ability was formed.
[0125]
(Comparative Example 1)
On the ITO electrode surface of the substrate with an ITO electrode used in Example 1, a hole transport layer having a thickness of 0.050 μm composed of the compound (IV-1) as a hole transport material and the compound (V) as a light emitting material -1) and a light-emitting layer having a thickness of 0.065 μm were sequentially formed by a vacuum evaporation method. Finally, a Mg-Ag alloy was co-evaporated on the surface of the light emitting layer in the same manner as in Example 1 to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect with the ITO electrode. The effective area of the formed organic EL element is 0.04 cm ² Met.
[0126]
(Comparative Example 2)
On the ITO electrode surface of the substrate with an ITO electrode used in Example 1, a 0.065 μm-thick luminescent layer composed of the compound (V-1) as a luminescent material, and the compound (VII- An electron transport layer having a thickness of 0.050 μm constituted by 1) was sequentially formed by a vacuum evaporation method. Finally, a Mg-Ag alloy was co-evaporated on the surface of the electron transport layer in the same manner as in Example 1 to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect with the ITO electrode. The effective area of the formed organic EL element is 0.04 cm ² Met.
[0127]
(Comparative Example 3)
One part by weight of the compound (IV-1) as a hole transport material, 1 part by weight of the compound (V-1) as a light emitting material, and 1 part by weight of polymethyl methacrylate (PMMA) as a binder resin are mixed. A dichloroethane solution containing 10% by weight of the mixture was prepared, and filtered with a 0.1 μm PTFE filter.
Next, the above solution was applied on the ITO electrode surface of the substrate with an ITO electrode used in Example 1 by a dipping method to form a hole transport layer having a thickness of 0.15 μm, and the film was sufficiently dried. Finally, a Mg-Ag alloy was co-evaporated on the surface of the hole transport layer in the same manner as in Example 1 to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect with the ITO electrode. The effective area of the formed organic EL element is 0.04 cm ² Met.
[0128]
(Comparative Example 4)
2 parts by weight of the compound (IV-6) as a hole transport material, 0.1 part by weight of the compound (V-10) as a light emitting material, and 1 part by weight of the compound (VII-1) as an electron transport material are mixed. A dichloroethane solution containing 10% by weight of these mixtures was prepared and filtered with a 0.1 μm PTFE filter.
Using this solution, a hole transport layer having a thickness of 0.15 μm was formed by applying a dip method on the ITO electrode surface of the substrate with an ITO electrode used in Example 1 and dried sufficiently. Finally, a Mg-Ag alloy was co-evaporated on the surface of the hole transport layer in the same manner as in Example 1 to form a back electrode having a width of 2 mm and a thickness of 0.15 μm so as to intersect with the ITO electrode. The effective area of the formed organic EL element is 0.04 cm ² Met.
[0129]
(Evaluation)
The organic EL device manufactured as described above was placed in a vacuum (133.3 × 10 ^-3 Pa (10 ^-3 (Torr)), a DC voltage was applied with the ITO electrode side plus and the Mg-Ag back electrode side minus, and the emission was measured to evaluate the maximum brightness and emission color at this time. Table 27 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 27 shows the drive current density at this time together with the element life.
[0130]
[Table 27]

[0131]
From each of the examples and the comparative examples as described above, a charge composed of a repeating structural unit containing, as a partial structure, at least one selected from the structures represented by the general formulas (I-1) and (I-2). The transportable polyurethane has an ionization potential and a hole mobility suitable for an organic EL device, and can form a good thin film by using a spin coating method, a dip method, or the like. The organic EL device of the present invention exhibits a sufficiently high luminance and has a relatively large thickness, so that there are few defects such as pinholes, the area can be easily increased, and the durability is improved. Having.
[0132]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an organic EL device which has sufficient luminance, is excellent in stability and durability, can have a large area, and is easy to manufacture.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a layer configuration of an organic electroluminescent device of the present invention.
FIG. 2 is a schematic configuration diagram showing another example of the layer configuration of the organic electroluminescent element of the present invention.
FIG. 3 is a schematic configuration diagram showing another example of the layer configuration of the organic electroluminescent device of the present invention.
FIG. 4 is a schematic configuration diagram showing another example of the layer configuration of the organic electroluminescent 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 (9)

An electroluminescent device comprising one or more organic compound layers sandwiched between a pair of electrodes, at least one of which is transparent or translucent,
At least one of the organic compound layers comprises a charge transporting polyurethane comprising 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. An organic electroluminescent device comprising one kind.

[In the general formulas (I-1) and (I-2), Ar represents a substituted or unsubstituted phenyl group, a substituted or unsubstituted monovalent polynuclear aromatic hydrocarbon having 2 to 10 aromatic rings, substituted or unsubstituted Unsubstituted monovalent condensed ring aromatic hydrocarbon having 2 to 10 aromatic rings, substituted or unsubstituted monovalent aromatic heterocycle, or substituted or unsubstituted including at least one aromatic heterocycle X represents a monovalent aromatic group, and X represents the number of substituted or unsubstituted aromatic rings containing at least one of divalent fused ring aromatic hydrocarbons represented by the following structural formulas (1) to (3) as a partial structure. Represents a 3 to 10 divalent condensed aromatic ring, and k represents 0 or 1. ]

The organic compound layer includes at least a light emitting layer and an electron transport layer, and at least one of the light emitting layer and the electron transport layer is 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 at least one kind as a partial structure. The organic electroluminescent device according to claim 2, wherein the light emitting layer includes a charge transporting material. The organic compound layer includes at least a hole transport layer, a light emitting layer, and an electron transport layer, and at least one of the hole transport layer and the electron transport layer is 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 at least one kind selected from the structures shown as a partial structure. A repeating unit in which the organic compound layer is composed of only a light-emitting layer, and wherein the light-emitting layer includes, as a partial structure, at least one selected from the structures represented by 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. The organic electroluminescent device according to claim 5, wherein the light emitting layer includes a charge transporting material. The organic compound layer includes at least a hole transport layer and a light emitting layer, and at least one of the hole transport layer and the light emitting layer is 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 at least one kind as a partial structure. The organic electroluminescent device according to claim 7, wherein the light emitting layer includes a charge transporting material. The 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 (II-1) or ( The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device is a charge transporting polyurethane represented by II-2).

[In the general formulas (II-1) and (II-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 Represents a divalent branched hydrocarbon group, Y and Z represent a divalent diisocyanate, alcohol or amine residue, m represents 0 or 1, and p represents an integer of 5 to 5,000. Represent. ]

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