JP2004087396A - 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 polyesters composed of repeated units containing as a partial substructure at least one kind selected from the structure shown in the following general formulae (I-1) and (I-2). <P>COPYRIGHT: (C)2004,JPO

Description

【００１４】
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、または炭素数２〜１０の分枝状炭化水素を表し、ｉ、ｊ、ｋは０または１を表す。Ｒ_１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。
【００１５】
＜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エステルを、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】
＜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エステルを、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】
＜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エステルを、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】
＜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エステルを、少なくとも１種含有してなることを特徴とする＜１＞に記載の有機電界発光素子である。
【００１９】
＜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。
【００２０】
＜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。
【００２１】
＜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。
【００２２】
＜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。
【００２３】
＜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エステルが、下記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリエステル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。
【００２４】
【化４】

【００２５】
式中、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２価のアルコール残基を表し、Ｚは２価のカルボン酸残基を表し、ｍは１〜５の整数を表し、ｐは５〜５０００の整数を表す。Ｂ及びＢ’は、それぞれ独立に−Ｏ−（Ｙ−Ｏ）_ｍ−Ｒまたは−Ｏ−（Ｙ−Ｏ）_ｍ−ＣＯ−Ｚ−ＣＯ−Ｏ−Ｒ’（ここで、Ｒ、Ｙ、Ｚ、ｍ、ｐは上記と同様であり、Ｒ’はアルキル基、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。）を表す。
【００２６】
＜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エステルが、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリエステル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。
【００２７】
＜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エステルが、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリエステル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。
【００２８】
＜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エステルが、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリエステル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。
【００２９】
＜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エステルが、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリエステル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。
【００３０】
＜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エステルが、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリエステル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。
【００３１】
＜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エステルが、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリエステル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。
【００３２】
＜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エステルが、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリエステル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。
【００３３】
＜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エステルが、上記一般式（ＩＩ−１）または（ＩＩ−２）で示されるポリエステル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。
【００３４】
なお、本発明の有機ＥＬ素子において、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エステルは、機能分離された複数の層が積層されたもの、例えば、少なくともホール輸送層及び発光層が積層された積層型、あるいは有機化合物層がキャリア輸送能と発光能を兼ね備えた単層型のいずれにも用いられる。また、積層型の発光層、あるいは単層型の有機化合物層に含有される場合には、他に電荷輸送性材料や発光性化合物を同時に含有してもよい。
【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エステル（以下、単に「電荷輸送性ポリエステル」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、または炭素数２〜１０の分枝状炭化水素を表し、ｉ、ｊ、ｋは０または１を表す。Ｒ_１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】
上記電荷輸送性ポリエステル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。
【００３９】
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。
【００４０】
【化６】

【００４１】
式（１）〜（１３）中、Ｒ_２〜Ｒ_１０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０〜１０の整数を表し、Ｖは下記の式（１４）〜（３１）から選択される基を表す。
【００４２】
【化７】

【００４３】
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。
【００４４】
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。
【００４５】
【化８】

【００４６】
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、または炭素数２〜１０の分枝状炭化水素を表し、具体的な例としては以下の構造を挙げることができる。
【００４７】
【化９】

【００４８】
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１４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７における構造番号１〜５９は一般式（Ｉ−１）で示される構造の具体例を示し、表８〜表１４における構造番号６０〜１１４は一般式（Ｉ−２）で示される構造の具体例を示す。
【００４９】
【表１】

【００５０】
【表２】

【００５１】
【表３】

【００５２】
【表４】

【００５３】
【表５】

【００５４】
【表６】

【００５５】
【表７】

【００５６】
【表８】

【００５７】
【表９】

【００５８】
【表１０】

【００５９】
【表１１】

【００６０】
【表１２】

【００６１】
【表１３】

【００６２】
【表１４】

【００６３】
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エステルとしては、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。
【００６４】
【化１０】

【００６５】
式中、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２価のアルコール残基を表し、Ｚは２価のカルボン酸残基を表し、ｍは１〜５の整数を表し、ｐは５〜５０００の整数を表すが、ｐは１０〜１０００の範囲であることが好ましい。Ｂ及びＢ’は、それぞれ独立に−Ｏ−（Ｙ−Ｏ）_ｍ−Ｒまたは−Ｏ−（Ｙ−Ｏ）_ｍ−ＣＯ−Ｚ−ＣＯ−Ｏ−Ｒ’（ここで、Ｒ、Ｙ、Ｚ、ｍ、ｐは上記と同様であり、Ｒ’はアルキル基、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。）を表す。
【００６６】
一般式（ＩＩ−１）または（ＩＩ−２）式中の、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。
【００６７】
【化１１】

【００６８】
式（３４）〜（４０）中、Ｒ_１１及び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、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。
【００６９】
以下、表１５〜表２１に、一般式（ＩＩ−１）及び（ＩＩ−２）で示される電荷輸送性ポリエステル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１５〜表２１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１４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エステルの具体例を示し、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エステルの具体例を示す。以下、各番号を付した具体例、例えば、１５の番号を付した具体例は例示化合物（１５）という。
【００７０】
【表１５】

【００７１】
【表１６】

【００７２】
【表１７】

【００７３】
【表１８】

【００７４】
【表１９】

【００７５】
【表２０】

【００７６】
【表２１】

【００７７】
前記電荷輸送性ポリエステルの質量平均分子量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。
【００７８】
前記電荷輸送性ポリエステルは、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。
【００７９】
なお、構造式（ＩＩＩ−１）〜（ＩＶ−２）中、Ｔ、ｍは、各々前記一般式（Ｉ−１）、（Ｉ−２）、（ＩＩ−１）、及び（ＩＩ−２）におけるＴ、ｍと各々同様である。また、Ａ’は脱アルコールにより重合（エステル結合形成）させるため、前記モノマー末端をアルコール化するための２価アルコール等との反応基を表す。
【００８０】
【化１２】

【００８１】
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、電荷輸送性ポリエステルは、次のようにして合成することができる。
まず、上記（ＩＩＩ−１）式及び（ＩＩＩ−２）式におけるＡ’が水酸基の場合には、ＨＯ−（Ｙ−Ｏ）_ｍ−Ｈで示される２価アルコール類をほぼ当量混合し、酸触媒を用いて重合する。
【００８２】
酸触媒としては、硫酸、トルエンスルホン酸、トリフルオロ酢酸等、通常のエステル化反応に用いるものが使用でき、触媒量としては、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。
【００８３】
重合中に生成する水を除去するために、水と共沸可能な溶剤を用いることが好ましく、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質量部に対して、１〜１００質量部、好ましくは２〜５０質量部の範囲で用いられる。反応温度は任意に設定できるが、重合中に生成する水を除去するために、溶剤の沸点で反応させることが好ましい。
【００８４】
反応終了後、溶剤を用いなかった場合には溶解可能な溶剤に溶解させる。溶剤を用いた場合には、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、電荷輸送性ポリエステルを析出させ、電荷輸送性ポリエステルを分離した後、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、電荷輸送性ポリエステル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。
【００８５】
上記再沈殿処理の際に電荷輸送性ポリエステルを溶解させる溶剤の量は、電荷輸送性ポリエステル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、貧溶剤の量は、電荷輸送性ポリエステル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。
【００８６】
前記Ａ’がハロゲンの場合には、ＨＯ−（Ｙ−Ｏ）_ｍ−Ｈで示される２価アルコール類をほぼ当量混合し、ピリジンやトリエチルアミン等の有機塩基性触媒を用いて重合する。上記有機塩基性触媒の量は、電荷輸送性モノマー１当量に対して、１〜１０当量の範囲であることが好ましく、２〜５当量の範囲であることがより好ましい。
【００８７】
溶剤としては、塩化メチレン、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、前述のように再沈殿処理し、精製する。
【００８８】
また、ビスフェノール等の酸性度の高い２価アルコール類の場合には、界面重合法も用いることができる。すなわち、２価アルコール類を水に加え、当量の塩基を加えて溶解させた後、激しく撹拌しながら２価アルコール類と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することができる。この際、水の量は、２価アルコール類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、２〜５００質量部の範囲であることがより好ましい。
【００８９】
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。
【００９０】
前記Ａ’がアルコキシル基の場合には、前述の構造式（ＩＩＩ−１）及び（ＩＩＩ−２）で示される電荷輸送性ポリマーに、ＨＯ−（Ｙ−Ｏ）_ｍ−Ｈで示される２価アルコール類を過剰に加え、硫酸、リン酸等の無機酸、チタンアルコキシド、カルシウム及びコバルト等の酢酸塩あるいは炭酸塩、亜鉛や鉛の酸化物を触媒に用いて加熱し、エステル交換により合成することができる。
【００９１】
前記２価アルコール類の量は、電荷輸送性モノマー１当量に対して、２〜１００当量の範囲であることが好ましく、３〜５０当量の範囲であることがより好ましい。また、触媒の量は、ホール輸送性モノマー１質量部に対して１／１０，０００〜１質量部の範囲であることが好ましく、１／１，０００〜１／２質量部の範囲であることがより好ましい。
【００９２】
反応は、反応温度２００〜３００℃の範囲で行い、前記アルコキシル基から−Ｏ−（Ｙ−Ｏ）_ｍ−Ｈへのエステル交換終了後は、ＨＯ−（Ｙ−Ｏ）_ｍ−Ｈの脱離による重合を促進するため、減圧下で反応させることが好ましい。また、ＨＯ−（Ｙ−Ｏ）_ｍ−Ｈと共沸可能な１−クロロナフタレン等の高沸点溶剤を用いて、常圧下でＨＯ−（Ｙ−Ｏ）_ｍ−Ｈを共沸で除きながら反応させることもできる。
【００９３】
また、一般式（ＩＩ−２）で示される電荷輸送性ポリエステルは、次のようにして合成することができる。上記の一般式（ＩＩ−１）で示される電荷輸送性ポリエステルの合成におけるそれぞれの場合において、２価アルコール類を過剰に加えて反応させることによって、下記構造式（ＩＶ−１）及び（ＩＶ−２）で示される化合物を生成した後、これを電荷輸送性モノマーとして用いて上記と同様の方法で、２価カルボン酸または２価カルボン酸ハロゲン化物等と反応させればよく、それによって電荷輸送性ポリエステルを得ることができる。
【００９４】
【化１３】

【００９５】
なお、上記式中、Ｒ_１、Ｘ、Ｙ、Ｔ、ｉ、ｊ、ｍ及びｋは前述の通りである。
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とから構成され、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エステルを含有してなる。
【００９６】
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、有機化合物層はキャリア輸送能を持つ発光層を意味し、該発光層が前記電荷輸送性ポリエステルを含有してなる。また、有機化合物層が複数の場合（機能分離型の場合）は、その少なくとも１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よりなるものを意味し、これらの少なくとも１層が前記電荷輸送性ポリエステルを含有してなる。
【００９７】
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エステルを含有してなるもの等が挙げられる。
【００９８】
本発明の有機ＥＬ素子においては、発光層が、低分子の電荷輸送性材料（前記電荷輸送性ポリエステル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。
【００９９】
以下、図面を参照しつつ、より詳細に説明するが、本発明の有機ＥＬ素子は、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。
【０１００】
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。
【０１０１】
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。
【０１０２】
本発明における前記電荷輸送性ポリエステル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エステルを含有してなる有機化合物層を発光層４として用いることが好ましい。また、図３に示される有機ＥＬ素子の層構成の場合には、前記電荷輸送性ポリエステル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エステル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工程数を大きく削減できるため、コスト的に好ましい。
【０１０３】
前記電荷輸送性ポリエステル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、電荷輸送性ポリエステルの特性を反映でき、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。
【０１０４】
なお、本発明における前記電荷輸送性ポリエステルが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で表される有機ＥＬ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記（Ｖ−１〜９）に示される化合物を挙げることができる。
【０１０５】
【化１４】

【０１０６】
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エステルを含有する有機化合物層であることが好ましい。
【０１０７】
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エステル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エステル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エステル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。
【０１０８】
【化１５】

【０１０９】
同様にホール移動度を調節するために、電荷輸送性ポリエステル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。
【０１１０】
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エステル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。
【０１１１】
このようなドーピングに用いられる色素化合物としては、発光材料との相溶性がよく、かつ発光層の良好な薄膜形成を妨げない有機化合物が用いられ、ＤＣＭ誘導体、キナクリドン誘導体、ルブレン誘導体、ポルフィリン系化合物等が好適に用いられる。具体例として、下記の化合物（ＶＩＩ−１）〜（ＶＩＩ−４）が用いられるが、これらに限定されたものではない。
【０１１２】
【化１６】

【０１１３】
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。
【０１１４】
図１及び図２に示される層構成の有機ＥＬ素子の場合、電子輸送層５には、電子輸送能を示す化合物が電荷輸送性材料として用いられる。このような電子輸送層に用いられる電子輸送性材料としては、有機低分子の場合、真空蒸着法により良好な薄膜形成が可能な有機化合物が好ましく用いられ、具体的にはオキサジアゾール誘導体、ニトロ置換フルオレノン誘導体、ジフェノキノン誘導体、チオピランジオキシド誘導体、フルオレニリデンメタン誘導体等を挙げることができる。また、高分子の場合、それ自身を含む溶液または分散液を塗布・乾燥することにより良好な薄膜形成が可能であることが条件である。電子輸送性材料としては、具体的に下記の化合物（ＶＩＩＩ−１）〜（ＶＩＩＩ−３）が好ましく用いられるが、これらに限定されるものではない。また、他の汎用の樹脂等と混合して用いてもよい。
【０１１５】
【化１７】

【０１１６】
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、前記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。
【０１１７】
前記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、電荷輸送性ポリエステル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が、これらに限定されるものではない。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。
【０１１８】
【化１８】

【０１１９】
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。
【０１２０】
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。
【０１２１】
次に、各有機ＥＬ素子の層構成に応じて、ホール輸送層３、発光層４、電子輸送層５あるいはキャリア輸送能を持つ発光層６は、上記各材料を、真空蒸着法、もしくは有機溶媒中に溶解或いは分散し、得られた塗布液を用いて前記透明電極２表面に製膜するスピンコーティング法、ディップ法等を用いることによって形成される。
【０１２２】
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。
【０１２３】
上記各材料（前記電荷輸送性ポリエステル、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。
【０１２４】
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。
【０１２５】
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。
【０１２６】
【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エステルは、例えば以下のようにして得た。
【０１２７】
−合成例１〔例示化合物（７）〕−
表１の１４に記載のモノマー２．０ｇ、エチレングリコール８．０ｇ及びテトラブトキシチタン０．１ｇを、容量５０ｍｌのフラスコに入れ、窒素気流下、２００℃で３時間加熱攪拌した。原料モノマーが消費されたことを確認した後、６６．６６Ｐａに減圧してエチレングリコールを留去しながら２００℃に加熱し、４時間反応を続けた。その後、室温まで冷却し、反応物をトルエン５０ｍｌに溶解して不溶物を０．１μｍのポリテトラフルオロエチレン（ＰＴＦＥ）フィルターにて濾過し、その濾液を撹拌されたメタノール２５０ｍｌ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、１．９ｇの電荷輸送性ポリエステル（例示化合物７）を得た。分子量はＧＰＣにて測定したところ、Ｍｗ＝７．８９×１０^４（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１２２であった。
【０１２８】
−合成例２〔例示化合物（３３）〕−
表１の４３に記載のモノマー２．０ｇ、エチレングリコール８．０ｇ及びテトラブトキシチタン０．１ｇを、容量５０ｍｌのフラスコに入れ、窒素気流下、２００℃で３時間加熱攪拌した。原料モノマーが消費されたことを確認した後、６６．６６Ｐａに減圧してエチレングリコールを留去しながら２００℃に加熱し、４時間反応を続けた。その後、室温まで冷却し、トルエン５０ｍｌに溶解して不溶物を０．１μｍのＰＴＦＥフィルターにて濾過し、その濾液を撹拌されてメタノール２５０ｍｌ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、１．８ｇの電荷輸送性ポリエステル（例示化合物３３）を得た。分子量はＧＰＣにて測定したところ、Ｍｗ＝５．９８×１０^４（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８８であった。
【０１２９】
−合成例３〔例示化合物（９３）〕−
表１の９９に記載のモノマー２．０ｇ、エチレングリコール８．０ｇ及びテトラブトキシチタン０．１ｇを、容量５０ｍｌのフラスコに入れ、窒素気流下、２００℃で３時間加熱攪拌した。原料モノマーが消費されたことを確認した後、６６．６６Ｐａに減圧してエチレングリコールを留去しながら２００℃に加熱し、４時間反応を続けた。その後、室温まで冷却し、トルエン５０ｍｌに溶解して不溶物を０．１μｍのＰＴＦＥフィルターにて濾過し、その濾液を撹拌されたメタノール２５０ｍｌ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、１．８ｇの電荷輸送性ポリエステル（例示化合物９３）を得た。分子量はＧＰＣにて測定したところ、Ｍｗ＝１．０１×１０^５（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１０３であった。
【０１３０】
（実施例１）
合成例１に記載の電荷輸送性ポリエステルの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。
【０１３１】
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２２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２２に示す。
【０１３２】
（実施例２）
合成例１に記載の電荷輸送性ポリエステル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２２に示す。
【０１３３】
（実施例３）
合成例１に記載の電荷輸送性ポリエステルを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２２に示す。
【０１３４】
（実施例４）
合成例１に記載の電荷輸送性ポリエステルの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２２に示す。
【０１３５】
（実施例５）
合成例２の電荷輸送性ポリエステル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２２に示す。
【０１３６】
（実施例６）
合成例２の電荷輸送性ポリエステル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２２に示す。
【０１３７】
（実施例７）
合成例２の電荷輸送性ポリエステル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２２に示す。
【０１３８】
（実施例８）
合成例２の電荷輸送性ポリエステル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２２に示す。
【０１３９】
（実施例９）
合成例３の電荷輸送性ポリエステル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２２に示す。
【０１４０】
（実施例１０）
合成例３の電荷輸送性ポリエステル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２２に示す。
【０１４１】
（実施例１１）
合成例３の電荷輸送性ポリエステル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２２に示す。
【０１４２】
（実施例１２）
合成例３の電荷輸送性ポリエステル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２２に示す。
【０１４３】
（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２２に示す。
【０１４４】
（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例示化合物（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２２に示す。
【０１４５】
【表２２】

【０１４６】
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３、９、１２においては、９００ｃｄ／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。
【０１４７】
【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エステルは、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.
[0009]
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.
[0010]
[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.
[0011]
[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 polyester containing not only has a charge injection property, a charge mobility and a thin film forming ability suitable as an organic EL element, but also has an extremely good light-emitting property in a solid state, when 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.
[0012]
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 polyester comprising 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.
[0013]
Embedded image

[0014]
In the general formulas (I-1) and (I-2), X represents a substituted or unsubstituted divalent aromatic group. T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched hydrocarbon having 2 to 10 carbon atoms, and i, j, and k represent 0 or 1. R ₁ is a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a halogen atom, a substituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aryl group. Represents an unsubstituted aralkyl group.
[0015]
<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 a charge transporting polyester comprising a repeating unit containing at least one kind as a partial structure.
[0016]
<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>, wherein the organic electroluminescent device includes at least one kind of a charge transporting polyester including a repeating unit containing at least one kind as a partial structure.
[0017]
<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 polyester including a repeating unit containing, as a partial structure.
[0018]
<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) The organic electroluminescence according to <1>, comprising at least one kind of a charge transporting polyester comprising a repeating unit containing at least one kind selected from the structures represented by -2) as a partial structure. Element.
[0019]
<6> The organic electroluminescent device according to <2>, wherein the light emitting layer contains a charge transporting material.
[0020]
<7> The organic electroluminescent device according to <3>, wherein the light emitting layer contains a charge transporting material.
[0021]
<8> The organic electroluminescent device according to <4>, wherein the light emitting layer contains a charge transporting material.
[0022]
<9> The organic electroluminescent device according to <5>, wherein the light emitting layer contains a charge transporting material.
[0023]
<10> A charge-transporting polyester 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>, wherein the organic electroluminescent device is a polyester represented by (II) or (II-2).
[0024]
Embedded image

[0025]
In the formula, A represents at least one selected from the structures represented by formulas (I-1) and (I-2), and R represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or Represents a substituted or unsubstituted aralkyl group, Y represents a divalent alcohol residue, Z represents a divalent carboxylic acid residue, m represents an integer of 1 to 5, p is an integer of 5 to 5000 Represents B and B ′ are each independently —O— (YO) _m —R or —O— (YO) _m —CO—Z—CO—OR ′ (where R, Y, Z , M and p are as defined above, and R ′ represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.)
[0026]
<11> The charge-transporting polyester 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). ) Or the polyester represented by (II-2).
[0027]
<12> The charge-transporting polyester 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) ) Or the polyester represented by (II-2).
[0028]
<13> The charge-transporting polyester 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 polyester represented by (II) or (II-2).
[0029]
<14> The charge-transporting polyester 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 <5>, which is a polyester represented by (II-2).
[0030]
<15> The charge-transporting polyester 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). ) Or the polyester represented by (II-2).
[0031]
<16> The charge-transporting polyester 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 <7>, wherein the organic electroluminescent device is a polyester represented by (II) or (II-2).
[0032]
<17> The charge-transporting polyester 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). ) Or the polyester represented by (II-2).
[0033]
<18> The charge-transporting polyester 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 polyester represented by (II) or (II-2).
[0034]
In the organic EL device of the present invention, the charge transporting polyester 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: A stack of a plurality of functionally separated layers, such as a stacked type in which at least a hole transport layer and a light emitting layer are stacked, or a single layer type in which an organic compound layer has both carrier transporting ability and light emitting ability Used. In the case where the light-emitting layer is contained in a stacked light-emitting layer or a single-layer organic compound layer, a charge-transporting material or a light-emitting compound may be additionally contained.
[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 polyester 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 polyester") ) 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 having 1 to 6 carbon atoms or a branched hydrocarbon having 2 to 10 carbon atoms, and i, j, and k represent 0 or 1. R ₁ is a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a halogen atom, a substituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aryl group. Represents an unsubstituted aralkyl group.
[0038]
By using the charge transporting polyester for at least one of the organic compound layers, the mobility of charges 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.
[0039]
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
[0040]
Embedded image

[0041]
In the formulas (1) to (13), R _{2 to} R ₁₀ each represent a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxyl group having 1 to 10 carbon atoms, a substituted or unsubstituted phenyl group, a substituted or unsubstituted Represents a substituted aralkyl group or a halogen atom, a and b represent an integer of 0 to 10, and V represents a group selected from the following formulas (14) to (31).
[0042]
Embedded image

[0043]
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.
[0044]
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.
[0045]
Embedded image

[0046]
In the general formulas (I-1) and (I-2), T represents a divalent linear hydrocarbon having 1 to 6 carbon atoms or a branched hydrocarbon having 2 to 10 carbon atoms. Typical examples include the following structures.
[0047]
Embedded image

[0048]
Hereinafter, specific examples of the structures represented by formulas (I-1) and (I-2) are shown in Tables 1 to 14, but the present invention is not limited to these specific examples. In addition, the structural numbers 1 to 59 in Tables 1 to 7 show specific examples of the structure represented by the general formula (I-1), and the structural numbers 60 to 114 in Tables 8 to 14 correspond to the general formula (I-2) A specific example of the structure represented by is shown.
[0049]
[Table 1]

[0050]
[Table 2]

[0051]
[Table 3]

[0052]
[Table 4]

[0053]
[Table 5]

[0054]
[Table 6]

[0055]
[Table 7]

[0056]
[Table 8]

[0057]
[Table 9]

[0058]
[Table 10]

[0059]
[Table 11]

[0060]
[Table 12]

[0061]
[Table 13]

[0062]
[Table 14]

[0063]
As the charge transporting polyester 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.
[0064]
Embedded image

[0065]
In the formula, A represents at least one selected from the structures represented by formulas (I-1) and (I-2), and R represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, or Represents a substituted or unsubstituted aralkyl group, Y represents a divalent alcohol residue, Z represents a divalent carboxylic acid residue, m represents an integer of 1 to 5, p is an integer of 5 to 5000 Wherein p is preferably in the range of 10 to 1,000. B and B ′ are each independently —O— (YO) _m —R or —O— (YO) _m —CO—Z—CO—OR ′ (where R, Y, Z , M and p are as defined above, and R ′ represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.)
[0066]
Specific examples of Y and Z in the formula (II-1) or (II-2) include groups selected from the following formulas (34) to (40).
[0067]
Embedded image

[0068]
In the formulas (34) to (40), R ₁₁ and R ₁₂ 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).
[0069]
Hereinafter, Tables 15 to 21 show specific examples of the charge transporting polyesters represented by the general formulas (II-1) and (II-2), but the present invention is not limited to these specific examples. Absent. In Tables 15 to 21, the numbers in column A of the monomer column are the structures shown in Tables 1 to 14 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 polyester 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 polyester represented by 2) are shown. Hereinafter, specific examples assigned with respective numbers, for example, specific examples assigned with a number of 15 are referred to as Exemplified Compound (15).
[0070]
[Table 15]

[0071]
[Table 16]

[0072]
[Table 17]

[0073]
[Table 18]

[0074]
[Table 19]

[0075]
[Table 20]

[0076]
[Table 21]

[0077]
The weight average molecular weight Mw of the charge transporting polyester is preferably in the range of 10,000 to 300,000, and more preferably in the range of 50,000 to 200,000.
[0078]
The charge-transporting polyester 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 Lecture 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).
[0079]
In the structural formulas (III-1) to (IV-2), T and m are the general formulas (I-1), (I-2), (II-1), and (II-2), respectively. Are the same as T and m, respectively. A ′ represents a reactive group with a dihydric alcohol or the like for alcoholizing the terminal of the monomer for polymerization (ester bond formation) by dealcoholation.
[0080]
Embedded image

[0081]
Specifically, for example, in the case of the charge transporting monomers represented by the general formulas (III-1) and (III-2), the charge transporting polyester can be synthesized as follows.
First, when A ′ in the formulas (III-1) and (III-2) is a hydroxyl group, dihydric alcohols represented by HO— (YO) _m —H are mixed in substantially equivalent amounts, and the acid is added. Polymerize using a catalyst.
[0082]
As the acid catalyst, those used in ordinary esterification reactions such as sulfuric acid, toluenesulfonic acid, and trifluoroacetic acid can be used. The amount of the catalyst is 1 / 10,000 to 1 part by mass of the charge transporting monomer. It is preferably in the range of 1/10 parts by mass, and more preferably in the range of 1/1000 to 1/50 parts by mass.
[0083]
In order to remove water generated during the polymerization, it is preferable to use a solvent that can be azeotropic with water, and toluene, chlorobenzene, 1-chloronaphthalene, and the like are effective. It is used in the range of 1 to 100 parts by mass, preferably 2 to 50 parts by mass. The reaction temperature can be arbitrarily set, but the reaction is preferably performed at the boiling point of the solvent in order to remove water generated during the polymerization.
[0084]
After the completion of the reaction, if no solvent is used, the solvent is dissolved in a soluble solvent. When a solvent is used, the reaction solution is directly dropped into a poor solvent in which a polymer such as alcohol such as methanol and ethanol or acetone is difficult to dissolve, thereby precipitating a charge-transporting polyester. After being separated, it is sufficiently washed with water or an organic solvent and dried. Further, if necessary, the re-precipitation treatment of dissolving in a suitable organic solvent and dropping it into a poor solvent to precipitate a charge transporting polyester 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.
[0085]
The amount of the solvent for dissolving the charge transporting polyester 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 relative to 1 part by mass of the charge transporting polyester. Is more preferable. 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 polyester.
[0086]
When A 'is a halogen, dihydric alcohols represented by HO- (YO) _m -H are mixed in approximately equivalent amounts, and polymerized using an organic basic catalyst such as pyridine or triethylamine. The amount of the organic basic catalyst is preferably in the range of 1 to 10 equivalents, more preferably in the range of 2 to 5 equivalents, per equivalent of the charge transporting monomer.
[0087]
As the solvent, methylene chloride, tetrahydrofuran (THF), toluene, chlorobenzene, 1-chloronaphthalene and the like are effective, and the amount of the solvent is in the range of 1 to 100 parts by mass with respect to 1 part by mass of the charge transporting monomer. It is more preferable that it is in the range of 2 to 50 parts by mass. The reaction temperature can be set arbitrarily. After the polymerization, reprecipitation treatment and purification are performed as described above.
[0088]
In the case of a dihydric alcohol having a high acidity such as bisphenol, an interfacial polymerization method can also be used. That is, polymerization can be carried out by adding a dihydric alcohol to water, adding an equivalent of a base and dissolving the same, and then adding an equivalent of a charge transporting monomer solution to the dihydric alcohol with vigorous stirring. At this time, the amount of water is preferably in the range of 1 to 1,000 parts by mass, more preferably in the range of 2 to 500 parts by mass, per 1 part by mass of the dihydric alcohol.
[0089]
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 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.
[0090]
When A ′ is an alkoxyl group, the charge-transporting polymer represented by the aforementioned structural formulas (III-1) and (III-2) is added to the divalent compound represented by HO— (YO) _m —H Addition of alcohols in excess, synthesis using inorganic acids such as sulfuric acid and phosphoric acid, acetates or carbonates such as titanium alkoxide, calcium and cobalt, oxides of zinc and lead as catalysts, and transesterification. Can be.
[0091]
The amount of the dihydric alcohol is preferably in the range of 2 to 100 equivalents, more preferably in the range of 3 to 50 equivalents, per equivalent of the charge transporting monomer. The amount of the catalyst is preferably in the range of 1 / 10,000 to 1 part by mass, and more preferably in the range of 1/1000 to 1/2 part by mass, per 1 part by mass of the hole transporting monomer. Is more preferred.
[0092]
The reaction is carried out in the range of reaction temperature 200 to 300 [° C., the -O- from alkoxyl groups _(Y-O) transesterification after the end of the m -H is, HO- _(Y-O) elimination of m -H The reaction is preferably performed under reduced pressure in order to promote the polymerization by the reaction. Also, HO- _(Y-O) with m -H and high boiling point solvent such as azeotropic 1-chloronaphthalene under normal pressure HO- _(Y-O) with the exception of m -H azeotropically reaction It can also be done.
[0093]
The charge transporting polyester represented by the general formula (II-2) can be synthesized as follows. In each case in the synthesis of the charge-transporting polyester represented by the above general formula (II-1), an excess amount of a dihydric alcohol is added and reacted to obtain the following structural formulas (IV-1) and (IV- After producing the compound represented by 2), the compound may be reacted with a divalent carboxylic acid or a divalent carboxylic acid halide in the same manner as described above using the compound as a charge transporting monomer. Can be obtained.
[0094]
Embedded image

[0095]
In the above formula, R ₁ , X, Y, T, i, j, m, and k are as described above.
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 a plurality of organic compound layers including a light emitting layer sandwiched between the electrodes. At least one layer contains the charge transporting polyester.
[0096]
In the organic EL device of the present invention, when there is one organic compound layer, the organic compound layer means a light emitting layer having a carrier transporting ability, and the light emitting layer contains the charge transporting polyester. 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 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, and at least one of these layers has the charge transport property. It contains polyester.
[0097]
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 polyester.
[0098]
In the organic EL device of the present invention, it is preferable that the light emitting layer contains a low molecular charge transporting material (a hole transporting material other than the charge transporting polyester and an electron transporting material). Details will be described later.
[0099]
Hereinafter, the present invention will be described in more detail with reference to the drawings, but the organic EL device of 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.
[0100]
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.
[0101]
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.
[0102]
In the case of the layer structure of the organic EL device shown in FIG. 1, the organic compound layer containing the charge transporting polyester in the present invention is preferably used, for example, as the light emitting layer 6 having a carrier transporting ability. In the case of the layer configuration of the organic EL element shown in FIG. 2, it is preferable to use an organic compound layer containing the charge transporting polyester 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 polyester 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 polyester may be used as, for example, the hole transport layer 3 or the light emitting layer 6 having carrier transport ability. Although it can be used, it is preferable in terms of cost to use it as the light emitting layer 6 having a carrier transporting ability because the number of steps can be greatly reduced.
[0103]
As the organic EL device of the present invention using the charge-transporting polyester 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.
[0104]
The organic compound layer containing the charge transporting polyester in the present invention has good hole transporting ability. For example, as described above, the organic compound layer also has a hole transporting layer 3 of the organic EL device shown in FIG. Can be used. 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 (V-1 to 9).
[0105]
Embedded image

[0106]
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 polyester is preferable.
[0107]
The organic compound layer in this case is basically formed of the charge-transporting polyester alone, but in order to adjust the balance between holes and electrons injected into the organic EL device, other than the charge-transportable polyester. 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 polyester, and more preferably, the following exemplified compound (VI), but is not limited thereto. is not.
[0108]
Embedded image

[0109]
Similarly, in order to adjust the hole mobility, a hole transporting material other than the charge transporting polyester, 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.
[0110]
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 polyester for the purpose of improving the durability or 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.
[0111]
As the dye compound used for such doping, an organic compound having good compatibility with the light-emitting material and not hindering formation of a good thin film of the light-emitting layer is used. DCM derivatives, quinacridone derivatives, rubrene derivatives, porphyrin-based compounds Etc. are preferably used. As specific examples, the following compounds (VII-1) to (VII-4) are used, but are not limited thereto.
[0112]
Embedded image

[0113]
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.
[0114]
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.
[0115]
Embedded image

[0116]
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 is a polymer, a condition for selecting a material is that a good thin film can be formed by applying and drying a solution or dispersion containing the charge transporting material itself.
[0117]
As the charge transporting material exhibiting the hole transporting ability, a tetraphenylenediamine derivative, a triphenylamine derivative, a carbazole derivative, a stilbene derivative, an arylhydrazone derivative, a porphyrin-based compound, and the like are preferably used. Examples of the compounds (IX-1) to (IX-8) include tetraphenylenediamine derivatives, which are preferably used because of their good compatibility with the charge transporting polyester. It is not limited. Further, the above compound may be used as a mixture with another general-purpose resin or the like.
[0118]
Embedded image

[0119]
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.
[0120]
Each layer of the organic EL device shown in FIGS. 1 to 4 is formed as follows. First, a hole transport layer 3 or a light emitting layer 6 having a carrier transport ability is formed on the surface of the transparent electrode 2 according to the layer configuration of each organic EL element. The hole transport layer 3 and the light emitting layer 6 having a carrier transport ability are formed on the surface of the transparent electrode 2 using the obtained coating solution by dissolving or dispersing each of the above materials in a vacuum evaporation method or an organic solvent. It is formed by a spin coating method, a dipping method, or the like.
[0121]
Next, depending on the layer configuration of each organic EL element, the hole transporting layer 3, the light emitting layer 4, the electron transporting layer 5, or the light emitting layer 6 having a carrier transporting ability is formed by applying the above materials to each other by a vacuum evaporation method or an organic solvent. It is formed by using a spin coating method, a dip method, or the like in which the transparent electrode 2 is dissolved or dispersed therein and a film is formed on the surface of the transparent electrode 2 using the obtained coating liquid.
[0122]
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.
[0123]
The dispersion state of each of the above materials (the charge transporting polyester, 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.
[0124]
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.
[0125]
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.
[0126]
【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 polyester used in each example was obtained, for example, as follows.
[0127]
-Synthesis Example 1 [Exemplary Compound (7)]-
2.0 g of the monomers described in Table 1, 14 g, 8.0 g of ethylene glycol, and 0.1 g of tetrabutoxytitanium were put in a flask having a capacity of 50 ml, and heated and stirred at 200 ° C. for 3 hours under a nitrogen stream. After confirming that the raw material monomer was consumed, the pressure was reduced to 66.66 Pa, and the mixture was heated to 200 ° C. while distilling off ethylene glycol, and the reaction was continued for 4 hours. Thereafter, the reaction product was cooled to room temperature, the reaction product was dissolved in 50 ml of toluene, the insoluble material was filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter, and the filtrate was dropped into 250 ml of stirred methanol to give a polymer. Was precipitated. The obtained polymer was filtered, sufficiently washed with methanol, and dried to obtain 1.9 g of a charge-transporting polyester (exemplary compound 7). The molecular weight measured by GPC was Mw = 7.89 × 10 ⁴ (in terms of styrene), and the value of p determined from the molecular weight of the monomer was about 122.
[0128]
-Synthesis Example 2 [Exemplified Compound (33)]-
2.0 g of the monomer, 43 g of ethylene glycol and 0.1 g of tetrabutoxytitanium described in 43 of Table 1 were put in a flask having a capacity of 50 ml, and heated and stirred at 200 ° C. for 3 hours under a nitrogen stream. After confirming that the raw material monomer was consumed, the pressure was reduced to 66.66 Pa, and the mixture was heated to 200 ° C. while distilling off ethylene glycol, and the reaction was continued for 4 hours. Thereafter, the mixture was cooled to room temperature, dissolved in 50 ml of toluene, and the insolubles were filtered through a 0.1 μm PTFE filter. The filtrate was stirred and dropped into 250 ml of methanol to precipitate a polymer. The obtained polymer was filtered, sufficiently washed with methanol, and dried to obtain 1.8 g of a charge-transporting polyester (Exemplary Compound 33). The molecular weight measured by GPC was Mw = 5.98 × 10 ⁴ (in terms of styrene), and the value of p determined from the molecular weight of the monomer was about 88.
[0129]
-Synthesis Example 3 [Exemplified Compound (93)]-
2.0 g of the monomer, 99 g of ethylene glycol, and 0.1 g of tetrabutoxytitanium described in 99 in Table 1 were placed in a 50-ml flask, and heated and stirred at 200 ° C. for 3 hours under a nitrogen stream. After confirming that the raw material monomer was consumed, the pressure was reduced to 66.66 Pa, and the mixture was heated to 200 ° C. while distilling off ethylene glycol, and the reaction was continued for 4 hours. Thereafter, the mixture was cooled to room temperature, dissolved in 50 ml of toluene, the insolubles were filtered through a 0.1 μm PTFE filter, and the filtrate was dropped into 250 ml of stirred methanol to precipitate a polymer. The obtained polymer was filtered, washed sufficiently with methanol, and then dried to obtain 1.8 g of a charge-transporting polyester (Exemplary Compound 93). When measured by GPC, the molecular weight was Mw = 1.01 × 10 ⁵ (in terms of styrene), and the value of p obtained from the molecular weight of the monomer was about 103.
[0130]
(Example 1)
A 5% by mass solution of the charge transporting polyester 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 .
[0131]
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 22 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 22 shows the drive current density at this time together with the element life.
[0132]
(Example 2)
99 parts by mass of the charge-transporting polyester 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 22.
[0133]
(Example 3)
2 parts by mass of the charge transporting polyester 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 22.
[0134]
(Example 4)
A 5% by mass solution of the charge transporting polyester 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 22.
[0135]
(Example 5)
An organic EL device was produced in the same manner as in Example 1 except that the charge transporting polyester of Synthesis Example 2 was used.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 22.
[0136]
(Example 6)
An organic EL device was prepared in the same manner as in Example 2 except that the charge transporting polyester of Synthesis Example 2 was used.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 22.
[0137]
(Example 7)
An organic EL device was produced in the same manner as in Example 3 except that the charge transporting polyester of Synthesis Example 2 was used.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 22.
[0138]
(Example 8)
An organic EL device was produced in the same manner as in Example 4, except that the charge transporting polyester of Synthesis Example 2 was used.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 22.
[0139]
(Example 9)
An organic EL device was produced in the same manner as in Example 1 except that the charge transporting polyester of Synthesis Example 3 was used.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 22.
[0140]
(Example 10)
An organic EL device was produced in the same manner as in Example 2 except that the charge transporting polyester of Synthesis Example 3 was used.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 22.
[0141]
(Example 11)
An organic EL device was produced in the same manner as in Example 3 except that the charge transporting polyester of Synthesis Example 3 was used.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 22.
[0142]
(Example 12)
An organic EL device was produced in the same manner as in Example 4, except that the charge transporting polyester of Synthesis Example 3 was used.
The same evaluation as in Example 1 was performed for the above organic EL element. The results are shown in Table 22.
[0143]
(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 22.
[0144]
(Comparative Example 2)
As a hole transporting polymer compound, 2 parts by mass of polyvinyl carbazole (PVK), 0.1 parts by mass of the exemplified compound (V-1) as a light emitting material, and 1 part by mass of the compound (VI) as an electron transporting material are mixed. Then, 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 22.
[0145]
[Table 22]

[0146]
As shown in the above examples, the organic EL device of the present invention, the drive current density indicates a low despite high maximum brightness, in particular embodiments 3,9,12, 900cd / ^{m 2} or more of the highest luminance was gotten. On the other hand, in the organic EL device of the comparative example, sufficient maximum luminance and device life could not be obtained.
[0147]
【The invention's effect】
The charge transporting polyester comprising 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 more 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 has the following structure. An organic electric field comprising at least one charge-transporting polyester comprising a repeating unit containing at least one 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 having 1 to 6 carbon atoms or a branched hydrocarbon having 2 to 10 carbon atoms, and i, j, and k represent 0 or 1. R ₁ represents a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a halogen atom, a substituted amino group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aryl group. Represents an unsubstituted aralkyl group. ] 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 a charge transporting polyester comprising 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 polyester 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). 2. The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device comprises at least one kind of a charge transporting polyester comprising 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 polyester comprising 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 polyester 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 polyester represented by II-2).

[Wherein, A represents at least one selected from the structures represented by formulas (I-1) and (I-2) above, and R represents a hydrogen atom, an alkyl group, a substituted or unsubstituted aryl group, Or represents a substituted or unsubstituted aralkyl group, Y represents a divalent alcohol residue, Z represents a divalent carboxylic acid residue, m represents an integer of 1 to 5, and p represents 5 to 5000. Represents an integer. B and B ′ are each independently —O— (YO) _m —R or —O— (YO) _m —CO—Z—CO—OR ′ (where R, Y, Z , M and p are as defined above, and R ′ represents an alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted aralkyl group.) ] The charge-transporting polyester 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) or ( The organic electroluminescent device according to claim 2, which is a polyester represented by II-2). The charge-transporting polyester 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) or ( The organic electroluminescent device according to claim 3, which is a polyester represented by II-2). The charge-transporting polyester 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) or ( The organic electroluminescent device according to claim 4, wherein the organic electroluminescent device is a polyester represented by II-2). The charge-transporting polyester 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) or ( The organic electroluminescent device according to claim 5, which is a polyester represented by II-2). The charge-transporting polyester 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) or ( The organic electroluminescent device according to claim 6, which is a polyester represented by II-2). The charge-transporting polyester 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) or ( The organic electroluminescent device according to claim 7, which is a polyester represented by II-2). The charge-transporting polyester 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) or ( The organic electroluminescent device according to claim 8, which is a polyester represented by II-2). The charge-transporting polyester 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) or ( The organic electroluminescent device according to claim 9, which is a polyester represented by II-2).

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