JP2004087393A - Organic electroluminescent element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element which has sufficient brightness, which is superior in stability and durability, and in which realization of a large area is possible and manufacturing is easy. <P>SOLUTION: This organic electroluminescent element is constituted of one or a plurality of organic compound layers pinched between a pair of electrodes consisting of a positive electrode and a negative electrode at least one being transparent or semi-transparent. At least one layer of the organic compound layers contains one or more kinds of electric charge transfer polyurethanes composed of repeated units containing as a partial substructure at least one kind selected from the structure shown by the following general formulae (I-1) and (I-2). <P>COPYRIGHT: (C)2004,JPO

Description

【００１３】
一般式（Ｉ−１）及び（Ｉ−２）中、Ｘは置換または未置換の２価の芳香族基を表す。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価の分枝状炭化水素基を表し、ｋは０または１を表す。Ｒ_１は炭素数１〜１０の飽和もしくは不飽和炭化水素基、または置換もしくは未置換の芳香族基を表し、Ｒ_２は水素原子、炭素数１〜１０の飽和もしくは不飽和炭化水素基、炭素数１〜４のアルコキシ基、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す。
【００１４】
＜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。
【００１５】
＜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。
【００１６】
＜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。
【００１７】
＜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、前記発光層もしくはホール輸送層のうち少なくとも１つの層が、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】
＜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＞に記載の有機電界発光素子である。
【００１９】
＜７＞　前記発光層が、電荷輸送性材料を含むことを特徴とする＜３＞に記載の有機電界発光素子である。
【００２０】
＜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＜４＞に記載の有機電界発光素子である。
【００２１】
＜９＞　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。
【００２２】
＜１０＞　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（ＩＩ−１）または（ＩＩ−２）で示される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。
【００２３】
【化４】

【００２４】
一般式（ＩＩ−１）及び（ＩＩ−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、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、ｐは５〜５０００の整数を表す。
【００２５】
＜１１＞　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、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリウレタンであることを特徴とする＜２＞に記載の有機電界発光素子である。
【００２６】
＜１２＞　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、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリウレタンであることを特徴とする＜３＞に記載の有機電界発光素子である。
【００２７】
＜１３＞　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、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリウレタンであることを特徴とする＜４＞に記載の有機電界発光素子である。
【００２８】
＜１４＞　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、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリウレタンであることを特徴とする＜５＞に記載の有機電界発光素子である。
【００２９】
＜１５＞　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、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリウレタンであることを特徴とする＜６＞に記載の有機電界発光素子である。
【００３０】
＜１６＞　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、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリウレタンであることを特徴とする＜７＞に記載の有機電界発光素子である。
【００３１】
＜１７＞　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、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリウレタンであることを特徴とする＜８＞に記載の有機電界発光素子である。
【００３２】
＜１８＞　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、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリウレタンであることを特徴とする＜９＞に記載の有機電界発光素子である。
【００３３】
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電荷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もよい。
【００３４】
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、該発光層には、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）を含んでもよい。
【００３５】
【発明の実施の形態】
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」ということがある）を１種以上含有することを特徴とする。
【００３６】
【化５】

【００３７】
一般式（Ｉ−１）及び（Ｉ−２）中、Ｘは置換または未置換の２価の芳香族基を表す。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価の分枝状炭化水素基を表し、ｋは０または１を表す。Ｒ_１は炭素数１〜１０の飽和もしくは不飽和炭化水素基、または置換もしくは未置換の芳香族基を表し、Ｒ_２は水素原子、炭素数１〜１０の飽和もしくは不飽和炭化水素基、炭素数１〜４のアルコキシ基、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す。
【００３８】
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。
【００３９】
具体的には、上記電荷輸送性ポリウレタンを有機化合物層の少なくとも一層に用いることにより、電荷の移動度を大きくすることができるため、低電流で高い発光輝度を有する有機ＥＬ素子を得ることができる。また、電荷輸送層形成にあたり、低分子の電荷輸送材料を高分子材料中に分散（相溶）させる必要がないため、高分子材料のガラス転移温度を低下させることがなく、有機ＥＬ素子の耐熱性、耐久性を向上させることができる。
【００４０】
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、具体的な例としては下記の式（１）〜（１３）が挙げられる。
【００４１】
【化６】

【００４２】
式（１）〜（１３）中、Ｒ_３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_４〜Ｒ_１２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、ｂは０または１を表し、Ｖは下記の式（１４）〜（３１）から選択される基を表す。
【００４３】
【化７】

【００４４】
式（１４）〜（３１）中、ｃ、ｄ、ｅは１〜１０の整数、ｆ、ｇ、ｈは０〜１０の整数を表す。
【００４５】
これらの中でも、前記Ｘが下記構造式（３２）または（３３）で示されるビフェニレン構造を有する場合、「Ｔｈｅ　Ｓｉｘｔｈ　ＩｎｔｅｒｎａｔｉｏｎａｌＣｏｎｇｒｅｓｓ　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。
【００４６】
【化８】

【００４７】
なお、一般式（Ｉ−１）及び（Ｉ−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価の分枝状炭化水素基を表し、具体的な例としては以下の構造を挙げることができる。
【００４８】
【化９】

【００４９】
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１７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９における構造番号１〜７６は一般式（Ｉ−１）で示される構造の具体例を示し、表１０〜表１７における構造番号７７〜１４０は一般式（Ｉ−２）で示される構造の具体例を示す。
【００５０】
【表１】

【００５１】
【表２】

【００５２】
【表３】

【００５３】
【表４】

【００５４】
【表５】

【００５５】
【表６】

【００５６】
【表７】

【００５７】
【表８】

【００５８】
【表９】

【００５９】
【表１０】

【００６０】
【表１１】

【００６１】
【表１２】

【００６２】
【表１３】

【００６３】
【表１４】

【００６４】
【表１５】

【００６５】
【表１６】

【００６６】
【表１７】

【００６７】
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（ＩＩ−１）または（ＩＩ−２）で示されるものが好適に使用される。
【００６８】
【化１０】

【００６９】
一般式（ＩＩ−１）及び（ＩＩ−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、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、ｐは５〜５０００の整数を表す。
【００７０】
一般式（ＩＩ−１）または（ＩＩ−２）中の、Ｙ及びＺの具体的な例としては下記の式（３４）〜（４０）から選択された基が挙げられる。
【００７１】
【化１１】

【００７２】
式（３４）〜（４０）中、Ｒ_１３及びＲ_１４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、α及びβはそれぞれ１〜１０の整数を、γ及びδはそれぞれ０、１または２の整数を、η及びρはそれぞれ０または１を表す。また、Ｖの具体例としては、前記式（１４）〜（３１）を挙げることができる。
【００７３】
以下、表１８〜表２５に、一般式（ＩＩ−１）及び（ＩＩ−２）で示される電荷輸送性ポリウレタンの具体的な例を示すが、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１８〜表２５において、モノマー列のＡ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１７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（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、Ｚの欄が「−」以外であるものは一般式（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。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。
【００７４】
【表１８】

【００７５】
【表１９】

【００７６】
【表２０】

【００７７】
【表２１】

【００７８】
【表２２】

【００７９】
【表２３】

【００８０】
【表２４】

【００８１】
【表２５】

【００８２】
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、５０，０００〜２００，０００の範囲にあることがより好ましい。
【００８３】
前記電荷輸送性ポリウレタンは、下記構造式（ＩＩＩ−１）〜（ＩＶ−２）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、下記構造式（ＩＩＩ−１）及び（ＩＩＩ−２）中、Ａ、Ｔは、前記一般式（ＩＩ−１）または（ＩＩ−２）におけるＡ、前記一般式（Ｉ−１）または（Ｉ−２）におけるＴと同様である。
【００８４】
【化１２】

【００８５】
具体的には、例えば、一般式（ＩＩＩ−１）及び（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。例えば、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、また例えば、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。
【００８６】
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。
【００８７】
上記触媒の添加量は、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。
【００８８】
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。
【００８９】
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。
【００９０】
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。
【００９１】
次に、下記構造式（ＩＶ−１）及び（ＩＶ−２）で示される電荷輸送性モノマーを用いた場合の電荷輸送性ポリウレタンの合成について説明する。なお、構造式（ＩＶ−１）及び（ＩＶ−２）におけるＡ、Ｔも、前記一般式（ＩＩ−１）または（ＩＩ−２）におけるＡ、前記一般式（Ｉ−１）または（Ｉ−２）におけるＴと同様である。
【００９２】
【化１３】

【００９３】
電荷輸送性モノマーが一般式（ＩＶ−１）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−２）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。
【００９４】
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。
【００９５】
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−１）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。
【００９６】
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。
【００９７】
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。
【００９８】
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。
【００９９】
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。さらに、例えば、有機化合物層が発光層のみから構成されてなり、該発光層が前記電荷輸送性ポリウレタンを含有してなるものも挙げることができる。
【０１００】
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。
【０１０１】
以下、図面を参照しつつ、本発明の有機ＥＬ素子の構成を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。
【０１０２】
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。
【０１０３】
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。
【０１０４】
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、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、ホール輸送層３としていずれにも用いることができるが、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。
【０１０５】
前記電荷輸送性ポリウレタンを有機化合物層として用いる本発明の有機ＥＬ素子としては、上記各層構成の中で図３、図４の構成が、素子として作製が容易であり、電荷輸送性ポリウレタンの特性を反映でき、十分な輝度、安定性、耐久性を達成できる点で好ましい構成である。
【０１０６】
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。
【０１０７】
【化１４】

【０１０８】
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。
【０１０９】
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。
【０１１０】
【化１５】

【０１１１】
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。
【０１１２】
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。
【０１１３】
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）を挙げることができるが、これらに限定されるものではない。
【０１１４】
【化１６】

【０１１５】
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。
【０１１６】
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。
【０１１７】
【化１７】

【０１１８】
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。該電荷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、ホール輸送能を示す電荷輸送性材料が高分子の場合には、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。
【０１１９】
ホール輸送能を示す電荷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。
【０１２０】
【化１８】

【０１２１】
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。
【０１２２】
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。
【０１２３】
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、ディップ法等を用いることによって形成される。
【０１２４】
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、０．０５〜０．１μｍの範囲であることがより好ましい。
【０１２５】
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。
【０１２６】
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。
【０１２７】
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、１００ｃｄ／ｍ^２程度以上に十分発光させることができる。
【０１２８】
【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。
【０１２９】
−合成例１〔例示化合物（４）〕−
表１の１７に記載のモノマー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、１．７ｇ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＝８．８２×１０^４（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１０３であった。
【０１３０】
−合成例２〔例示化合物（１３）〕−
表１の３２に記載のモノマー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、１．７ｇ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＝１．５２×１０^５（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１７０であった。
【０１３１】
−合成例３〔例示化合物（３８）〕−
表１の５８に記載のモノマー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、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＝１．２１×１０^５（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１４０であった。
【０１３２】
（実施例１）
合成例１に記載の電荷輸送性ポリウレタンの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（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、膜厚約０．１μｍのホール輸送層を形成した。十分乾燥させたこのホール輸送層の表面に、発光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のキャリア輸送能を持つ発光層を形成した。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。
【０１３３】
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１０Ｖ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２６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３５０ｃｄ／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２６に示す。
【０１３４】
（実施例２）
合成例１に記載の電荷輸送性ポリウレタン９９質量部と、発光材料として化合物（ＶＩＩ−３）１質量部とを混合し、１０質量％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、ディップ法により膜厚約０．１５μｍのキャリア輸送能を持つ発光層を形成した。充分乾燥させた後、該キャリア輸送能を持つ発光層表面に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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１３５】
（実施例３）
合成例１に記載の電荷輸送性ポリウレタンを２質量部と、発光材料として化合物（ＶＩＩ−１）を０．１質量部と、電子輸送材料として前記化合物（ＶＩ）を１質量部とを混合し、１０質量％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、膜厚約０．１５μｍのキャリア輸送能を持つ発光層を形成した。十分乾燥させた後、該キャリア輸送能を持つ発光層表面に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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１３６】
（実施例４）
合成例１に記載の電荷輸送性ポリウレタンの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（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、膜厚約０．１μｍのキャリア輸送能を持つ発光層を形成した。十分乾燥させた後、該キャリア輸送能を持つ発光層表面に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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１３７】
（実施例５）
合成例１の電荷輸送性ポリウレタンの代わりに、合成例２の電荷輸送性ポリウレタン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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１３８】
（実施例６）
合成例１の電荷輸送性ポリウレタンの代わりに、合成例２の電荷輸送性ポリウレタン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素子について実施例１と同様の評価を行った。結果を表２６示す。
【０１３９】
（実施例７）
合成例１の電荷輸送性ポリウレタンの代わりに、合成例２の電荷輸送性ポリウレタン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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１４０】
（実施例８）
合成例１の電荷輸送性ポリウレタンの代わりに、合成例２の電荷輸送性ポリウレタンを用いた以外は実施例４と同様にして有機ＥＬ素子を作製した。
上記有機ＥＬ素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１４１】
（実施例９）
合成例１の電荷輸送性ポリウレタンの代わりに、合成例３の電荷輸送性ポリウレタン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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１４２】
（実施例１０）
合成例１の電荷輸送性ポリウレタンの代わりに、合成例３の電荷輸送性ポリウレタン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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１４３】
（実施例１１）
合成例１の電荷輸送性ポリウレタンの代わりに、合成例３の電荷輸送性ポリウレタン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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１４４】
（実施例１２）
合成例１の電荷輸送性ポリウレタンの代わりに、合成例３の電荷輸送性ポリウレタンを用いた以外は実施例４と同様にして有機ＥＬ素子を作製した。
上記有機ＥＬ素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１４５】
（比較例１）
前記ホール輸送能を示す化合物（ＩＸ−２）を１質量部と、発光材料として前記の化合物（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％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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１４６】
（比較例２）
ホール輸送性高分子化合物として、ポリビニルカルバゾール（ＰＶＫ）を２質量部、発光材料として前記化合物（Ｖ−１）を０．１質量部、電子輸送材料として前記化合物（ＶＩ）を１質量部混合し、１０質量％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、該ホール輸送層表面に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素子について実施例１と同様の評価を行った。結果を表２６に示す。
【０１４７】
【表２６】

【０１４８】
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２、６、９、１２においては、８００ｃｄ／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、十分な最高輝度、素子寿命が得られなかった。
【０１４９】
【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. It has been reported that a high luminance of 1000 cd / m ² or more can be obtained (Appl. Phys. Lett., Vol. 51, 913 (1987), JP-A-59-194393). Research and development of devices are being 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. Further, since this EL element is driven at a high current density of 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]
Therefore, in order to solve the above-mentioned problem concerning the thermal stability of the EL element, a star-burst amine, which can obtain a stable amorphous glass state as a hole transporting material, is used (for example, the 40th Applied Physics Related Conference, 30a-SZK-14 (1993), etc.), and EL devices using a polymer in which triphenylamine is introduced into the side chain of polyphosphazene (Preprints of the 42nd Polymer Symposium, 20J21 (1993)). ing.
[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. (Nature, Vol. 357, 477 (1992), Nature, Vol. 397, 121 (1999)), or a device in which an electron transporting material and a fluorescent dye are mixed in a hole transporting polyvinyl carbazole (No. 38). Proceedings of the Lectures of the Joint Lecture on Applied Physics, 31p-G-12 (1991)), but the luminance, luminous efficiency, etc., are still inferior to those of stacked EL devices using organic low-molecular compounds. 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), X represents a substituted or unsubstituted divalent aromatic group. 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, and k represents 0 or 1. R ₁ represents a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms or a substituted or unsubstituted aromatic group; R ₂ represents a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, Represents 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 represented by Formulas 1 to 4.
[0014]
<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.
[0015]
<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.
[0016]
<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.
[0017]
<5> The organic compound layer includes at least a hole transporting layer and a light emitting layer having a carrier transporting ability, and at least one of the light emitting layer and the hole transporting layer has the general formula (I-1) or (I) <2> The organic electroluminescence according to <1>, comprising at least one kind of charge transporting polyurethane composed of a repeating unit containing at least one kind selected from the structures represented by -2 as a partial structure. Element.
[0018]
<6> The organic electroluminescent device according to <2>, wherein the light emitting layer contains a charge transporting material.
[0019]
<7> The organic electroluminescent device according to <3>, wherein the light emitting layer contains a charge transporting material.
[0020]
<8> The organic electroluminescent device according to <4>, wherein the light emitting layer contains a charge transporting material.
[0021]
<9> The organic electroluminescent device according to <5>, wherein the light emitting layer contains a charge transporting material.
[0022]
<10> 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 (II-1) The organic electroluminescent device according to <1>, which is a polyurethane represented by (II) or (II-2).
[0023]
Embedded image

[0024]
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), R represents a hydrogen atom, Represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, Y represents a diisocyanate residue, Z represents a dihydric alcohol residue, and p represents an integer of 5 to 5,000.
[0025]
<11> 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 general formula (II-1) The organic electroluminescent device according to <2>, which is a polyurethane represented by (II) or (II-2).
[0026]
<12> 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 formula (II-1). The organic electroluminescent device according to <3>, which is a polyurethane represented by (II) or (II-2).
[0027]
<13> 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 general formula (II-1) The organic electroluminescent device according to <4>, which is a polyurethane represented by (II) or (II-2).
[0028]
<14> 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 general formula (II-1). The organic electroluminescent device according to <5>, wherein the organic electroluminescent device is a polyurethane represented by (II) or (II-2).
[0029]
<15> 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 formula (II-1). The organic electroluminescent device according to <6>, which is a polyurethane represented by (II) or (II-2).
[0030]
<16> 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 formula (II-1). The organic electroluminescent device according to <7>, wherein the organic electroluminescent device is a polyurethane represented by (II) or (II-2).
[0031]
<17> 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 general formula (II-1). The organic electroluminescent device according to <8>, wherein the organic electroluminescent device is a polyurethane represented by (II) or (II-2).
[0032]
<18> 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 general formula (II-1) The organic electroluminescent device according to <9>, which is a polyurethane represented by (II) or (II-2).
[0033]
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 charge-transporting polyurethane composed of a repeating unit containing at least one selected from the structures represented by -2 as a partial structure, and those having both carrier-transporting ability and light-emitting ability, that is, organic compounds The layer is composed of only a light-emitting layer, and the light-emitting layer is a charge composed 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 a transportable polyurethane may be used.
[0034]
In the organic EL device of the present invention, when the organic compound layer is composed only of 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). May be.
[0035]
BEST MODE FOR CARRYING OUT THE INVENTION
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") ) May be included.
[0036]
Embedded image

[0037]
In the general formulas (I-1) and (I-2), X represents a substituted or unsubstituted divalent aromatic group. 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, and k represents 0 or 1. R ₁ represents a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms or a substituted or unsubstituted aromatic group; R ₂ represents a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, Represents 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 represented by Formulas 1 to 4.
[0038]
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.
[0039]
Specifically, by using the charge-transporting polyurethane for at least one of the organic compound layers, charge mobility can be increased, so that an organic EL device having low current and high light emission luminance can be obtained. . Further, in forming the charge transport layer, it is not necessary to disperse (compatible) a low-molecular charge transport material in the polymer material, so that the glass transition temperature of the polymer material is not lowered and the heat resistance of the organic EL element is reduced. Properties and durability can be improved.
[0040]
In the general formulas (I-1) and (I-2), X represents a substituted or unsubstituted divalent aromatic group, and specific examples include the following formulas (1) to (13). Can be
[0041]
Embedded image

[0042]
In the formulas (1) to (13), R ₃ 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, and R _{4 to} R ₁₂ Each 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; Represents 0 or 1, and V represents a group selected from the following formulas (14) to (31).
[0043]
Embedded image

[0044]
In the formulas (14) to (31), c, d, and e represent integers of 1 to 10, and f, g, and h represent integers of 0 to 10.
[0045]
Among them, when X has a biphenylene structure represented by the following structural formula (32) or (33), 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, which is particularly preferable.
[0046]
Embedded image

[0047]
In the general formulas (I-1) and (I-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. Represents a group, and specific examples include the following structures.
[0048]
Embedded image

[0049]
Hereinafter, specific examples of the structures represented by the general formulas (I-1) and (I-2) are shown in Tables 1 to 17, but the present invention is not limited to these specific examples. Structure numbers 1 to 76 in Tables 1 to 9 show specific examples of the structure represented by the general formula (I-1), and structure numbers 77 to 140 in Tables 10 to 17 correspond to the general formula (I-2) A specific example of the structure represented by is shown.
[0050]
[Table 1]

[0051]
[Table 2]

[0052]
[Table 3]

[0053]
[Table 4]

[0054]
[Table 5]

[0055]
[Table 6]

[0056]
[Table 7]

[0057]
[Table 8]

[0058]
[Table 9]

[0059]
[Table 10]

[0060]
[Table 11]

[0061]
[Table 12]

[0062]
[Table 13]

[0063]
[Table 14]

[0064]
[Table 15]

[0065]
[Table 16]

[0066]
[Table 17]

[0067]
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 (II-1) or ( What is shown by II-2) is used suitably.
[0068]
Embedded image

[0069]
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), R represents a hydrogen atom, Represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group, Y represents a diisocyanate residue, Z represents a dihydric alcohol residue, and p represents an integer of 5 to 5,000.
[0070]
Specific examples of Y and Z in the general formula (II-1) or (II-2) include groups selected from the following formulas (34) to (40).
[0071]
Embedded image

[0072]
In the formulas (34) to (40), R ₁₃ and R ₁₄ each represent 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 Represents a substituted aralkyl group or a halogen atom, α and β each represent an integer of 1 to 10, γ and δ each represent an integer of 0, 1 or 2, and η and ρ each represent 0 or 1. Further, specific examples of V include the above formulas (14) to (31).
[0073]
Hereinafter, Tables 18 to 25 show specific examples of the charge transporting polyurethanes represented by the general formulas (II-1) and (II-2), but the present invention is not limited to these specific examples. Absent. In Tables 18 to 25, the numbers in column A of the monomer column are the structures shown in Tables 1 to 17 which are specific examples of the structures represented by the general formulas (I-1) and (I-2). It corresponds to the number. Further, those in which the column of Z is "-" indicate specific examples of the charge transporting polyurethane represented by the general formula (II-1), and those in which the column of Z is other than "-" indicate those of the general formula (II-). 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).
[0074]
[Table 18]

[0075]
[Table 19]

[0076]
[Table 20]

[0077]
[Table 21]

[0078]
[Table 22]

[0079]
[Table 23]

[0080]
[Table 24]

[0081]
[Table 25]

[0082]
The mass 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 50,000 to 200,000.
[0083]
The charge-transporting polyurethane is prepared by using charge-transporting monomers represented by the following structural formulas (III-1) to (IV-2), 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 following structural formulas (III-1) and (III-2), A and T represent A in the general formula (II-1) or (II-2), the general formula (I-1) or ( It is the same as T in I-2).
[0084]
Embedded image

[0085]
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. For example, when the charge transporting monomer is a dihydric alcohol represented by the general formula (III-1), the charge transporting monomer is mixed with an equivalent amount of a diisocyanate represented by OCN-Y-NCO. In the case of the diisocyanates represented by (III-2), the diisocyanates are mixed with polyhydric alcohols represented by HO-Y-OH in an equivalent amount and polyaddition is performed.
[0086]
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.
[0087]
The amount of the catalyst to be added is preferably in the range of 1 / 10,000 to 1/10 parts by mass, and more preferably in the range of 1 / 1,000 to 1/50 parts by mass, per 1 part by mass of the charge transporting monomer. Is more preferable.
[0088]
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.
[0089]
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.
[0090]
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.
[0091]
Next, the synthesis of the charge transporting polyurethane using the charge transporting monomers represented by the following structural formulas (IV-1) and (IV-2) will be described. In addition, A and T in the structural formulas (IV-1) and (IV-2) are also A in the general formula (II-1) or (II-2), and A or T in the general formula (I-1) or (I- Same as T in 2).
[0092]
Embedded image

[0093]
When the charge transporting monomer is a bischloroformate represented by the general formula (IV-1), the charge transporting monomer is mixed with a diamine represented by ₂ HN—Y—NH ₂ in an equivalent amount, and the charge transporting monomer is represented by the general formula (IV-1). In the case of diamines represented by (IV-2), equivalents are mixed with bischloroformates represented by ClOCO-Y-OCOCl and polycondensed.
[0094]
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.
[0095]
Further, when the high basicity of the diamine represented by ₂ HN-Y-NH ₂ may also be used interfacial polymerization method. That is, a diamine is added to water, an equivalent amount of an acid is added and dissolved, and then the diamine and an equivalent amount of the charge transporting monomer solution represented by the general formula (IV-1) 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.
[0096]
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. .
[0097]
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.
[0098]
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.
[0099]
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. Furthermore, for example, there can also be mentioned those in which the organic compound layer is constituted only by the light emitting layer, and the light emitting layer contains the charge transporting polyurethane.
[0100]
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.
[0101]
Hereinafter, the configuration of the organic EL device of 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.
[0102]
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.
[0103]
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.
[0104]
The organic compound layer containing the charge transporting polyurethane in the present invention is preferably used as, for example, 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. In the case of the layer configuration of the organic EL device shown in FIG. 2, the organic compound layer containing the charge transporting polyurethane can be used as both the light emitting layer 4 and the hole transport layer 3, It is preferable to use it 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.
[0105]
As the organic EL device of the present invention using the charge-transporting polyurethane as the organic compound layer, the structure shown in FIGS. This is a preferable configuration because it can be reflected and sufficient luminance, stability and durability can be achieved.
[0106]
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).
[0107]
Embedded image

[0108]
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.
[0109]
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.
[0110]
Embedded image

[0111]
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.
[0112]
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.
[0113]
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. Specific examples include the following compounds (VII-1) to (VII-4), but are not limited thereto.
[0114]
Embedded image

[0115]
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.
[0116]
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.
[0117]
Embedded image

[0118]
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 charge-transporting material is a low-molecular organic material, it is preferable that a good thin film can be formed by vacuum evaporation, or by applying and drying a solution or dispersion containing a low-molecular compound and a binder resin. Condition. When the charge transporting material having hole transporting ability is a polymer, the condition for selecting a material is that a good thin film can be formed by applying and drying a solution or dispersion containing itself. .
[0119]
As the charge transporting material having a hole transporting ability, a tetraphenylenediamine derivative, a triphenylamine derivative, a carbazole derivative, a stilbene derivative, an arylhydrazone derivative, a porphyrin compound, and the like are preferably used. Illustrative compounds (IX-1) to (IX-8) can be mentioned, 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.
[0120]
Embedded image

[0121]
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 examples of the material of the protective layer include metals such as In, Sn, Pb, Au, Cu, Ag, and Al; metal oxides such as MgO, SiO ₂ , and TiO ₂ ; polyethylene resins, polyurea resins, and polyimide resins. 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.
[0122]
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 transporting layer 3 and the light emitting layer 6 having a carrier transporting 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. that spin coating is formed by dipping or the like.
[0123]
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 dissolving or dispersing in the inside, and using a spin coating method, a dipping method, or the like in which a film is formed on the surface of the transparent electrode 2 using the obtained coating solution.
[0124]
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 0.05 to 0.1 μm.
[0125]
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.
[0126]
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.
[0127]
The organic EL element of the present invention can emit light sufficiently to about 100 cd / m ² or more by applying a DC voltage of 1 to 200 mA / cm ² at a current density of 4 to 20 V between a pair of electrodes. it can.
[0128]
【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.
[0129]
-Synthesis Example 1 [Exemplified Compound (4)]-
2.0 g of the monomer described in 17 of Table 1 and 30 ml of chlorobenzene were placed in a 50-ml flask and stirred to dissolve. A solution of 0.54 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 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 measured by GPC was Mw = 8.82 × 10 ⁴ (in terms of styrene), and the value of p determined from the molecular weight of the monomer was about 103.
[0130]
-Synthesis Example 2 [Exemplified Compound (13)]-
2.0 g of the monomer described in 32 of Table 1 and 30 ml of chlorobenzene were placed in a 50-ml flask and stirred for dissolution, 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 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. When measured by GPC, the molecular weight was Mw = 1.52 × 10 ⁵ (in terms of styrene), and the value of p obtained from the molecular weight of the monomer was about 170.
[0131]
-Synthesis Example 3 [Exemplified Compound (38)]-
2.0 g of the monomer described in 58 of Table 1 and 30 ml of chlorobenzene were placed in a 50-ml flask and stirred to dissolve, and a solution obtained 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 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, washed sufficiently 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 measured by GPC was Mw = 1.21 × 10 ⁵ (in terms of styrene), and the value of p determined from the molecular weight of the monomer was about 140.
[0132]
(Example 1)
A 5% by mass solution of the charge-transporting polyurethane described in Synthesis Example 1 in dichloroethane was prepared and filtered with a 0.1 μm polytetrafluoroethylene (PTFE) filter. Using this solution, a strip-shaped ITO electrode having a width of 2 mm was applied to the surface of the glass substrate formed by etching by a dipping method to form a hole transport layer having a thickness of about 0.1 μm. The exemplary compound (V-1), which was sublimated and purified as a light emitting material, was placed in a tungsten boat on the sufficiently dried surface of the hole transport layer, and was vapor-deposited by a vacuum vapor deposition method. A light emitting layer was formed. At this time, the degree of vacuum was 1.33 × 10 ⁻³ Pa, and the boat temperature was 300 ° C. Subsequently, a Mg-Ag alloy was 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 intersect the ITO electrode. The effective area of the manufactured organic EL device was 0.04 cm ² .
[0133]
The organic EL device manufactured as described above was measured for light emission by applying a DC voltage of 10 V with the ITO electrode side plus and the Mg-Ag back electrode minus in vacuum (1.33 × 10 ^-1 Pa). Then, the maximum luminance and the emission color at this time were evaluated. Table 26 shows the results. The emission lifetime of the organic EL device was measured in dry nitrogen. In the evaluation of the light emission lifetime, the current value was set so that the initial luminance was 350 cd / m ^2, and the time until the luminance was reduced to half from the initial value by constant current driving was defined as the element life (hour). Table 26 shows the drive current density at this time together with the element life.
[0134]
(Example 2)
99 parts by mass of the charge-transporting polyurethane described in Synthesis Example 1 and 1 part by mass of the compound (VII-3) as a luminescent material were mixed to prepare a 10% by mass dichloroethane solution, and the solution was filtered through a 0.1 μm PTFE filter. . Using this solution, a light emitting layer having a carrier transporting ability with a thickness of about 0.15 μm was formed by dipping on the surface of a glass substrate on which a rectangular ITO electrode having a width of 2 mm was formed by etching. After sufficient drying, a Mg-Ag alloy was co-evaporated on the surface of the light emitting layer having the carrier transporting ability 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 was 0.04 cm ² .
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0135]
(Example 3)
2 parts by mass of the charge-transporting polyurethane described in Synthesis Example 1, 0.1 part by mass of the compound (VII-1) as a light emitting material, and 1 part by mass of the compound (VI) as an electron transporting material were mixed. A 10% by mass dichloroethane solution was prepared, and filtered with a 0.1 μm PTFE filter. Using this solution, a strip-shaped ITO electrode having a width of 2 mm was etched and applied to the surface of the glass substrate formed by etching to form a light-emitting layer having a carrier transporting ability with a thickness of about 0.15 μm. After drying sufficiently, a Mg-Ag alloy was co-evaporated on the surface of the light emitting layer having the carrier transporting ability 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 was 0.04 cm ² .
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0136]
(Example 4)
A 5% by mass solution of the charge-transporting polyurethane described in Synthesis Example 1 in dichloroethane was prepared and filtered with a 0.1 μm polytetrafluoroethylene (PTFE) filter. Using this solution, a strip-shaped ITO electrode having a width of 2 mm was applied to the surface of the glass substrate formed by etching by a dipping method to form a light-emitting layer having a carrier transporting ability with a thickness of about 0.1 μm. After drying sufficiently, a Mg-Ag alloy was co-evaporated on the surface of the light emitting layer having the carrier transporting ability 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 was 0.04 cm ² .
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0137]
(Example 5)
An organic EL device was produced in the same manner as in Example 1 except that the charge transporting polyurethane of Synthesis Example 2 was used instead of the charge transporting polyurethane of Synthesis Example 1.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0138]
(Example 6)
An organic EL device was produced in the same manner as in Example 2 except that the charge transporting polyurethane of Synthesis Example 2 was used instead of the charge transporting polyurethane of Synthesis Example 1.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0139]
(Example 7)
An organic EL device was produced in the same manner as in Example 3, except that the charge transporting polyurethane of Synthesis Example 2 was used instead of the charge transporting polyurethane of Synthesis Example 1.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0140]
(Example 8)
An organic EL device was produced in the same manner as in Example 4, except that the charge transporting polyurethane of Synthesis Example 2 was used instead of the charge transporting polyurethane of Synthesis Example 1.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0141]
(Example 9)
An organic EL device was produced in the same manner as in Example 1 except that the charge transporting polyurethane of Synthesis Example 3 was used instead of the charge transporting polyurethane of Synthesis Example 1.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0142]
(Example 10)
An organic EL device was produced in the same manner as in Example 2 except that the charge transporting polyurethane of Synthesis Example 3 was used instead of the charge transporting polyurethane of Synthesis Example 1.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0143]
(Example 11)
An organic EL device was produced in the same manner as in Example 3, except that the charge transporting polyurethane of Synthesis Example 3 was used instead of the charge transporting polyurethane of Synthesis Example 1.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0144]
(Example 12)
An organic EL device was produced in the same manner as in Example 4 except that the charge transporting polyurethane of Synthesis Example 3 was used instead of the charge transporting polyurethane of Synthesis Example 1.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0145]
(Comparative Example 1)
1 part by mass of the compound (IX-2) exhibiting the hole transporting ability, 1 part by mass of the compound (V-1) as a light emitting material, and 1 part by mass of polymethyl methacrylate (PMMA) as a binder resin. Was mixed to prepare a 10% by mass dichloroethane solution, which was filtered through a 0.1 μm PTFE filter. Using this solution, a 0.15 μm-thick hole transport layer was formed by applying a dip method on the surface of a glass substrate on which a strip-shaped ITO electrode having a width of 2 mm was formed by etching. 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 cross the ITO electrode. The effective area of the manufactured organic EL device was 0.04 cm ² .
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0146]
(Comparative Example 2)
2 parts by mass of polyvinyl carbazole (PVK) as a hole transporting polymer compound, 0.1 part by mass of the compound (V-1) as a light emitting material, and 1 part by mass of the compound (VI) as an electron transporting material are mixed. A 10% by mass dichloroethane solution was prepared, and filtered with a 0.1 μm PTFE filter. Using this solution, a 0.15 μm-thick hole transport layer was formed by applying a dip method on the surface of a glass substrate on which a strip-shaped ITO electrode having a width of 2 mm was formed by etching. After sufficient drying, a Mg-Ag alloy was co-evaporated on the 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 with the ITO electrode. The effective area of the manufactured organic EL device was 0.04 cm ² .
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 26.
[0147]
[Table 26]

[0148]
As shown in the above Examples, the organic EL device of the present invention exhibits high maximum luminance despite the low drive current density, and in Examples 2, 6, 9 and 12, particularly, 800 cd / m ² or more. The highest brightness was obtained. On the other hand, in the organic EL device of the comparative example, sufficient maximum luminance and device life could not be obtained.
[0149]
【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]
REFERENCE SIGNS LIST 1 transparent insulator substrate 2 transparent electrode 3 hole transport layer 4 light emitting layer 5 electron transport layer 6 light emitting layer having carrier transporting ability 7 back electrode

Claims (18)

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 general formulas (I-1) and (I-2), X represents a substituted or unsubstituted divalent aromatic group. 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, and k represents 0 or 1. R ₁ represents a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms or a substituted or unsubstituted aromatic group; R ₂ represents a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, Represents 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 represented by Formulas 1 to 4. ] 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 at least one of the light emitting layer and the hole transporting layer has the general formula (I-1) or (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 at least one kind selected from the following structures as a partial structure. The organic electroluminescent device according to claim 2, wherein the light emitting layer includes a charge transporting material. The organic electroluminescent device according to claim 3, wherein the light emitting layer includes a charge transporting material. The organic electroluminescent device according to claim 4, wherein the light emitting layer includes a charge transporting material. The organic electroluminescent device according to claim 5, 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 the general formulas (I-1) and (I-2) as a partial structure is represented by the following general formula (II-1) or ( The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device is a polyurethane represented by II-2).

[In 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, Y represents a diisocyanate residue, Z represents a dihydric alcohol residue, and p represents an integer of 5 to 5000. . ] The charge-transporting polyurethane composed of 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 general formula (II-1) or ( The organic electroluminescent device according to claim 2, wherein the organic electroluminescent device is a polyurethane represented by II-2). The charge-transporting polyurethane composed of 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 general formula (II-1) or ( The organic electroluminescent device according to claim 3, which is a polyurethane represented by II-2). The charge-transporting polyurethane composed of 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 general formula (II-1) or ( The organic electroluminescent device according to claim 4, wherein the organic electroluminescent device is a polyurethane represented by II-2). The charge-transporting polyurethane composed of 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 general formula (II-1) or ( The organic electroluminescent device according to claim 5, wherein the organic electroluminescent device is a polyurethane represented by II-2). The charge-transporting polyurethane composed of 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 general formula (II-1) or ( The organic electroluminescent device according to claim 6, wherein the organic electroluminescent device is a polyurethane represented by II-2). The charge-transporting polyurethane composed of 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 general formula (II-1) or ( The organic electroluminescent device according to claim 7, wherein the organic electroluminescent device is a polyurethane represented by II-2). The charge-transporting polyurethane composed of 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 general formula (II-1) or ( The organic electroluminescent device according to claim 8, wherein the organic electroluminescent device is a polyurethane represented by II-2). The charge-transporting polyurethane composed of 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 general formula (II-1) or ( The organic electroluminescent device according to claim 9, which is a polyurethane represented by II-2).

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