JP3817957B2 - Organic fluorescent material and organic electroluminescence device - Google Patents

Description

〔ここで、Ａｒ₆は、共役結合に関与する炭素原子数が４個以上２０個以下からなるアリーレン基または複素環化合物基を示す。Ｒ₇〜Ｒ₁₀は、それぞれ独立に、水素、炭素数１〜２０のアルキル基、炭素数６〜２０のアリール基、炭素数４〜２０の複素環化合物基およびシアノ基からなる群から選ばれる基を示す。Ｒ₁₁〜Ｒ₁₈は、それぞれ独立に、水素または下記式（６）で示される置換基を示す。
【００１４】
【化１４】
−（Ｒ₁₉）_m−（Ｘ）_n−Ｒ₂₀ ・・・・（６）
（ここで、Ｒ₁₉は、炭素数１〜２０の炭化水素基を示す。Ｒ₂₀は、炭素数１〜２０の炭化水素基、共役結合に関与する炭素原子数が４〜２０のアリール基および複素環化合物基、ならびに環を構成する炭素原子数が６〜２０の脂肪族環状炭化水素基からなる群から選ばれる基である。Ｘは、−Ｏ−、−Ｓ−、−ＣＯ−、−ＣＯ−Ｏ−および−Ｏ−ＣＯ−からなる群から選ばれる基を示す。ｍおよびｎは、それぞれ独立に０または１である。）〕
〔７〕固体状態で蛍光を有し、下記式（７）で表わされる構造を含む有機蛍光材料。
【００１５】
【化１５】
Ａｒ₇−ＣＲ₂₁＝ＣＲ₂₂−Ａｒ₈−Ａｒ₉−ＣＲ₂₃＝ＣＲ₂₄−Ａｒ₁₀．．．（７）
〔ここで、Ａｒ₇およびＡｒ₁₀は、それぞれ独立に、共役結合に関与する炭素数が４〜２０のアリール基、または一官能の複素環化合物基を示す。
Ｒ₂₁〜Ｒ₂₄は、それぞれ独立に、水素、シアノ基、炭素数１〜２０のアルキル基、アルコキシ基およびアルキルチオ基；炭素数６〜２０のアリール基およびアリールオキシ基；ならびに炭素数４〜２０の複素環化合物基からなる群から選ばれる基を示す。Ａｒ₈およびＡｒ₉は、それぞれ独立に、隣接する基と炭素−炭素結合を形成する２個の結合手を有する基であり、共役結合に関与する炭素数６〜２２の芳香族化合物基、またはヘテロ原子を含有する炭素数４〜２０の六員環以上の複素環化合物基から選ばれ、それぞれ基の化学構造式において２本の結合手を有する炭素原子の間で最短の経路に連続して存在する原子の個数が１、３または５のいずれかであるものを示す。〕
〔８〕固体状態で可視の蛍光を有し、下記式（８）で示される有機蛍光材料。
【００１６】
【化１６】

〔ここで、Ａｒ₁₁、Ａｒ₁₂は、共役結合に関与する炭素原子数が４個以上２０個以下からなるアリール基または複素環化合物基を示す。Ｒ₂₅〜Ｒ₂₈は、それぞれ独立に水素、炭素数１〜２０のアルキル基、炭素数６〜２０のアリール基、炭素数４〜２０の複素環化合物基およびシアノ基からなる群から選ばれる基を示す。Ｒ₂₉〜Ｒ₃₆は、水素または上記〔６〕記載の式（６）で示される置換基を示す〕〔９〕少なくとも一方が透明または半透明である一対の陽極および陰極からなる電極間に、少なくとも発光層を有する有機エレクトロルミネッセンス素子において、該発光層が〔１〕、〔２〕、〔３〕、〔４〕、〔５〕もしくは〔６〕記載の高分子蛍光体から選ばれる１種類以上の高分子蛍光体および／または〔７〕もしくは〔８〕記載の有機蛍光材料を含む有機エレクトロルミネッセンス素子。
〔１０〕少なくとも一方が透明または半透明である一対の陽極および陰極からなる電極間に、少なくとも発光層および正孔輸送層を有する有機エレクトロルミネッセンス素子において、該発光層および／または正孔輸送層が〔１〕、〔２〕、〔３〕、〔４〕、〔５〕もしくは〔６〕記載の高分子蛍光体から選ばれる１種類以上の高分子蛍光体および／または〔７〕もしくは〔８〕記載の有機蛍光材料を含む有機エレクトロルミネッセンス素子。
〔１１〕陽極と発光層との間に、該発光層に隣接して正孔輸送性化合物を含む層を設けた〔１０〕記載の有機エレクトロルミネッセンス素子。
〔１２〕少なくとも一方が透明または半透明である一対の陽極および陰極からなる電極間に、少なくとも発光層および電子輸送層を有する有機エレクトロルミネッセンス素子において、該発光層および／または電子輸送層が〔１〕、〔２〕、〔３〕、〔４〕、〔５〕もしくは〔６〕記載の高分子蛍光体から選ばれる１種類以上の高分子蛍光体および／または〔７〕もしくは〔８〕記載の有機蛍光材料を含む有機エレクトロルミネッセンス素子。
〔１３〕陰極と発光層との間に、該発光層に隣接して電子輸送性化合物を含む層を設けた〔１２〕記載の有機エレクトロルミネッセンス素子
〔１４〕少なくとも一方が透明または半透明である一対の陽極および陰極からなる電極間に、少なくとも正孔輸送層、発光層および電子輸送層を有する有機エレクトロルミネッセンス素子において、該正孔輸送層、発光層、電子輸送層のうち少なくとも１つの層が〔１〕、〔２〕、〔３〕、〔４〕、〔５〕もしくは〔６〕記載の高分子蛍光体から選ばれる１種類以上の高分子蛍光体および／または〔７〕もしくは〔８〕記載の有機蛍光材料を含む有機エレクトロルミネッセンス素子。
〔１５〕陰極と発光層との間に、該発光層に隣接して電子輸送性化合物を含む層、および陽極と発光層との間に、該発光層に隣接して正孔輸送性化合物を含む層を設けた〔１４〕記載の有機エレクトロルミネッセンス素子。
【００１７】
【発明の実施の形態】
以下、本発明について詳細に説明する。
本発明の高分子蛍光体は、固体状態で蛍光を有し、ポリスチレン換算の数平均分子量が１０³〜１０⁷であり、上記式（１）で表わされる繰り返し単位を１種類以上含み、式（１）で示される繰り返し単位が、繰り返し単位数で全体の２〜１００％含まれることを特徴とする。
【００１８】
該式（１）におけるＡｒ₁およびＡｒ₂としては、それぞれ隣接する基と炭素−炭素結合を形成する２本の結合手を有する基であり、共役結合に関与する炭素数が６〜２２の芳香族化合物基、またはヘテロ原子を含有する炭素数４〜２０の六員環以上の複素環化合物基であり、それぞれの基の化学構造式において２本の結合手を有する炭素原子の間で最短の経路に連続して存在する原子の個数が１、３または５のいずれかであるものから独立に選ばれる。
【００１９】
また、該繰り返し単位（１）は、式（２）で示されるビニレン基を介して、隣接する基と結合していることが好ましい。
【００２０】
具体的には、該Ａｒ₁、Ａｒ₂としては、それぞれ独立に、下記化１７に示す芳香族化合物基もしくはその誘導体基、または、複素環化合物基もしくはその誘導体基が例示される。
【００２１】
【化１７】

〔ここでＲは、上記式（６）で示される置換基またはシアノ基であり、炭素数１〜２０のアルキル基、アルコキシ基およびアルキルチオ基；炭素数６〜１８のアリール基およびアリールオキシ基；炭素数４〜１４の複素環化合物基、ならびにシアノ基からなる群から選ばれた基であることが好ましい。また、ａ〜ｆは置換基の数を表わし、ａは、０から４の整数、ｂは、０から３の整数、ｃは、０から２の整数、ｄは、０から６の整数、ｅは、０から８の整数、ｆは、０から５の整数から選ばれた数である。また、置換基の数ａ〜ｆが複数のときには、当該置換基Ｒは互いに同一でも異なっても良い。〕
【００２２】
これらのなかで１，３−フェニレン基、２，５−ナフタレニレン基、２，６−ピリジン−ジイル基、２，５−キノリン−ジイル基もしくはそれらの核置換誘導体が好ましい。これらのうちから一種類または二種類以上を選ぶことができる。
【００２３】
該式（２）におけるビニレン基に結合するＲ₁とＲ₂としては、それぞれ独立に、水素、シアノ基、炭素数１〜２０のアルキル基、アルコキシ基およびアルキルチオ基；炭素数６〜２０のアリール基およびアリールオキシ基；ならびに炭素数４〜２０の複素環化合物基からなる群から選ばれた基である。
炭素数１〜２０のアルキル基としては、具体的には、メチル基、エチル基、プロピル基、ブチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基、デシル基、ドデシル基などが挙げられ、メチル基、エチル基、ペンチル基、ヘキシル基、ヘプチル基、オクチル基が好ましい。
アリール基としては、フェニル基、Ｃ₁〜Ｃ₁₄アルコキシフェニル基（Ｃ₁〜Ｃ₁₄は、炭素数１〜１４であることを示す。以下も、同様である。）、Ｃ₁〜Ｃ₁₄アルキルフェニル基、１−ナフチル基、２−ナフチル基などが例示される。複素環化合物基としては、２−ピリジル基、２−キノリル基、チエニル基などが例示される。
これらのなかで、水素やシアノ基がさらに好ましい。
【００２４】
また、本発明の高分子蛍光体は、固体状態で蛍光を有し、ポリスチレン換算の数平均分子量が１０³〜１０⁷であり、上記式（１）および上記式（３）で表わされる繰り返し単位をそれぞれ１種類以上含み、式（１）で示される繰り返し単位が、繰り返し単位数で全体の２〜５０％含まれるものであることが好ましい。
【００２５】
上記式（３）におけるＡｒ₃としては、それぞれ隣接する基と炭素−炭素結合を形成する２本の結合手を有する基であり、共役結合に関与する炭素数６〜２２の芳香族化合物基またはヘテロ原子を含有する炭素数４〜２０の複素環化合物基で示される群から選ばれる基であり、式（２）で示されるビニレン基を介して隣接する基と結合していることがさらに好ましい。
【００２６】
具体的には、該Ａｒ₃としては、上記化１７に例示された基、または下記化１８に示す芳香族化合物基もしくはその誘導体基、または複素環化合物基もしくはその誘導体基が例示される。
【００２７】
【化１８】

〔ここでＲは、上記式（６）で示される置換基またはシアノ基であり、炭素数１〜２０のアルキル基、アルコキシ基およびアルキルチオ基；炭素数６〜１８のアリール基およびアリールオキシ基；炭素数４〜１４の複素環化合物基；ならびにシアノ基からなる群から選ばれた基であることが好ましい。また、ａ〜ｆは、置換基の数を表わし、ａは、０から４の整数、ｂは、０から３の整数、ｃは、０から２の整数、ｄは、０から６の整数、ｅは、０から８の整数、ｆは、０から５の整数から選ばれた数である。また、置換基の数ａ〜ｆが複数のときには、当該置換基Ｒは，互いに同一でも異なっても良い。〕
【００２８】
これらのなかで１，４−フェニレン基、２，６−ナフタレニレン基、４，４’−ビフェニレン基、９，１０−アントリレン基、２，５−ピリジン−ジイル基、２，５−チエニレン基もしくはそれらの核置換誘導体；または１，３−フェニレン基、２，５−ナフタレニレン基、３，３’−ビフェニレン基、２，６−ピリジン−ジイル基、２，６−キノリン−ジイル基もしくはそれらの誘導体が好ましい。さらに好ましくは１，４−フェニレン基、２，５−ピリジン−ジイル基、２，５−チエニレン基、４、４’−ビフェニレン基、３，３’−ビフェニレン基、１，３−フェニレン基、２，６−ピリジン−ジイル基、２，４−キノリン−ジイル基、またはそれらの誘導体が挙げられる。これらのうちから一種類または二種類以上を選ぶことができる。
【００２９】
また、本発明の高分子蛍光体は、固体状態で蛍光を有し、ポリスチレン換算の数平均分子量が１０³〜１０⁷であり、上記式（４）で表わされる繰り返し単位を１種類以上含み、式（４）で示される繰り返し単位が、繰り返し単位数で全体の４〜１００％含まれるものである。
該式（４）におけるＡｒ₄は、上記式（３）で示される基と同じ基を示す。また、Ａｒ₅は、上記式（１）で示される繰り返し単位と同じ繰り返し単位を示す。
また、式（４）のビニレン基に結合したＲ₃〜Ｒ₆は、それぞれ独立に、水素、シアノ基、炭素数１〜２０のアルキル基、アルコキシ基およびアルキルチオ基；炭素数６〜２０のアリール基およびアリールオキシ基；ならびに炭素数４〜２０の複素環化合物基からなる群から選ばれる基である。
具体的には、式（２）のビニレン基に結合したＲ₁やＲ₂と同じ基が例示される。
【００３０】
該式（１）で示される繰り返し単位の合計は、全繰り返し単位の２〜１００モル％であり、繰り返し単位の構造にもよるが、１０〜１００モル％であることが好ましい。
【００３１】
該式（３）で示される繰り返し単位の合計は、全繰り返し単位の５０モル％を超え９８モル％未満であることが好ましく、繰り返し単位の構造にもよるが、５０モル％を超え９０モル％未満であることがさらに好ましい。
【００３２】
該式（４）で示される繰り返し単位の合計は、全繰り返し単位の４〜１００モル％であり、繰り返し単位の構造にもよるが、２０〜１００モル％であることがさらに好ましい。
【００３３】
また、本発明の高分子蛍光体は、固体状態で可視の蛍光を有し、ポリスチレン換算の数平均分子量が１０³から１０⁷である高分子蛍光体において、下記式（５）で示される繰り返し単位を１種類以上含み、かつそれらの繰り返し単位の合計が全繰り返し単位の１０モル％以上１００モル％以下であることを特徴とする。
【００３４】
【化１９】

【００３５】
Ａｒ₆としては、共役結合に関与する炭素原子数が４個以上２０個以下からなるアリーレン基または複素環化合物基を示す。具体的には、上記化１７、化１８に示す化合物基またはその誘導体基が例示される。
Ｒ₇〜Ｒ₁₀は、それぞれ独立に水素、炭素数１〜２０のアルキル基、炭素数６〜２０のアリール基、炭素数４〜２０の複素環化合物基およびシアノ基からなる群から選ばれる基を示す。具体的には、式（２）のビニレン基に結合したＲ₁やＲ₂と同じ基が例示される。また、Ｒ₁₁〜Ｒ₁₈は、水素または上記式（６）で示される置換基を示す。
【００３６】
本発明に用いる高分子蛍光体の末端基は、特に限定されないが、重合活性基がそのまま残っていると、素子にしたときの発光特性や寿命が低下する可能性があるので、安定な基で保護されていることが好ましい。主鎖の共役構造と連続した共役結合を有しているものがより好ましく、例えば、ビニレン基を介してアリール基または複素環化合物基と結合している構造が例示される。
具体的には、上記式（７）で示されるＡｒ₇またはＡｒ₁₀基と同じ芳香族化合物基またはその誘導体基、およびそれらとビニレン基が結合した基が例示される
【００３７】
これらのなかで、フェニル基、１−ナフチル基、９−アントリル基、２−ピリジル基、２−チエニル基、オキサジアゾリル基、ベンゾオキサゾリル基、４−（Ｎ，Ｎ−ジフェニルアミノ）フェニル基、１−ピレニル基、２−フルオレニル基、２−キノリル基、４−（９−カルバゾリル）フェニル基、９−フェニル−３−カルバゾリル基、３−ペリレニル基またはそれらの誘導体が好ましい。
さらに好ましくは、１−ナフチル基、９−アントリル基、オキサジアゾリル基、４−（Ｎ，Ｎ−ジフェニルアミノ）フェニル基、１−ピレニル基、２−フルオレニル基、２−キノリル基、４−（９−カルバゾリル）フェニル基、９−フェニル−３−カルバゾリル基、３−ペリレニル基またはそれらの誘導体が挙げられ、特に好ましくは１−ナフチル基、９−アントリル基、１−ピレニル基、２−フルオレニル基、３−ペリレニル基が挙げられる。
【００３８】
本発明の高分子蛍光体の重合度は、分子量がポリスチレン換算で１０³〜１０⁷であれば特に限定されず、繰り返し構造やその割合によっても変わる。成膜性の点から一般には繰り返し構造の合計数は、好ましくは２〜１００００、さらに好ましくは３〜３０００、特に好ましくは４〜２０００である。ここで、分子量はクロロホルムを溶媒として、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）により求めたポリスチレン換算の数平均分子量である。
【００３９】
なお、本発明の高分子蛍光体は、式（１）、（３）、（４）、（５）それぞれで示される繰り返し単位からなる重合体または共重合体であり、共重合体の場合にはランダム、ブロックまたはグラフト共重合体であってもよいし、それらの中間的な構造を有する高分子、例えばブロック性を帯びたランダム共重合体であってもよい。蛍光の量子収率の高い共重合体を得る観点からは完全なランダム共重合体よりブロック性を帯びたランダム共重合体やブロックまたはグラフト共重合体が好ましく、主鎖に枝分かれがあり、末端が三つ以上ある場合も含まれる。
【００４０】
一方、本発明の有機蛍光材料は、固体状態で蛍光を有し、上記式（７）で表わされる構造を含むことを特徴とする。
該式（７）におけるＡｒ₇、Ａｒ₁₀としては、それぞれ独立に、共役結合に関与する炭素数が４〜２０のアリール基または一官能の複素環化合物基である。
【００４１】
具体的には、該Ａｒ₇、Ａｒ₁₀としては、それぞれ独立に、下記化２０に示す芳香族化合物基もしくはその誘導体基、または、複素環化合物基もしくはその誘導体基が例示される。
【００４２】
【化２０】

〔ここでＲは、上記式（６）で示される置換基またはシアノ基であり、炭素数１〜２０のアルキル基、アルコキシ基およびアルキルチオ基；炭素数６〜１８のアリール基およびアリールオキシ基；炭素数４〜１４の複素環化合物基；ならびにシアノ基からなる群から選ばれた基であることが好ましい。また、ａ〜ｉは置換基の数を表わし、ａは、０から４の整数、ｂは、０から３の整数、ｄは、０から６の整数、ｆは、０から５の整数、ｇは、０から７の整数、ｈは、０から９の整数、ｉは、０から１１の整数から選ばれた数である。また、置換基の数ａ〜ｉが複数のときには、当該置換基Ｒは互いに同一でも異なっても良い。〕
【００４３】
これらのなかで、フェニル基、１−ナフチル基、９−アントリル基、２−ピリジル基、２−チエニル基、４−（Ｎ，Ｎ−ジフェニルアミノ）フェニル基、１−ピレニル基、２−キノリル基、４−（９−カルバゾリル）フェニル基、３−ペリレニル基またはそれらの誘導体が好ましい。
さらに好ましくは、１−ナフチル基、９−アントリル基、４−（Ｎ，Ｎ−ジフェニルアミノ）フェニル基、１−ピレニル基、２−フルオレニル基、２−キノリル基、３−ペリレニル基またはそれらの誘導体が挙げられ、特に好ましくは１−ナフチル基、９−アントリル基、１−ピレニル基、２−フルオレニル基、３−ペリレニル基が挙げられる。これらのうちから一種類または二種類以上を選ぶことができる。
【００４４】
該式（７）におけるＡｒ₈、Ａｒ₉としては、それぞれ独立に、上記式（１）で示されるＡｒ₁またはＡｒ₂と同じ基である。
【００４５】
該式（７）におけるＲ₂₁〜Ｒ₂₄としては、それぞれ独立に、水素またはシアノ基、炭素数１〜２０のアルキル基、アルコキシ基およびアルキルチオ基；炭素数６〜２０のアリール基およびアリールオキシ基；ならびに炭素数４〜２０の複素環化合物基からなる群から選ばれる基である。
具体的には、式（２）のビニレン基に結合したＲ₁やＲ₂と同じ基が例示される。
【００４６】
また、本発明の有機蛍光材料は、固体状態で可視の蛍光を有し、上記式（８）で示されるものである。
Ａｒ₁₁、Ａｒ₁₂は、共役結合に関与する炭素原子数が４個以上２０個以下からなるアリール基または複素環化合物基を示す。
Ａｒ₁₁、Ａｒ₁₂は、それぞれ独立に、上記式（７）のＡｒ₇またはＡｒ₁₀と同じ基であり、具体的には、上記化２０に示す芳香族化合物基もしくはその誘導体基、または複素環化合物基もしくはその誘導体基が例示される。
Ｒ₂₅〜Ｒ₂₈は、それぞれ独立に水素、炭素数１〜２０のアルキル基、炭素数６〜２０のアリール基、炭素数４〜２０の複素環化合物基およびシアノ基からなる群から選ばれる基を示す。具体的には、式（２）のビニレン基に結合したＲ₁やＲ₂と同じ基が例示される。Ｒ₂₉〜Ｒ₃₆は、水素または上記式（６）で示される置換基を示す。
【００４７】
本発明の有機蛍光材料および高分子蛍光体は、溶剤に溶解させて成膜することができる。
該有機蛍光材料および該高分子蛍光体に対する良溶媒としては、クロロホルム、塩化メチレン、ジクロロエタン、テトラヒドロフラン、トルエン、キシレンなどが例示される。有機蛍光材料および高分子蛍光体の構造や分子量にもよるが、通常は、これらの溶媒に０．１ｗｔ％以上溶解させることができる。
有機ＥＬ素子作成の際に、これらの有機溶媒可溶性の有機蛍光材料および／または高分子蛍光体を用いることにより、溶液から成膜する場合、この溶液を塗布後乾燥により溶媒を除去するだけでよく、また後述する電荷輸送材料を混合した場合においても同様な手法が適用でき、製造上非常に有利である。
【００４８】
本発明の有機蛍光材料および高分子蛍光体の製造方法としては、例えば、炭素−炭素二重結合形成反応により、式（５）で示される化合物または式（１）、（３）、（４）で示される繰り返し単位を含む高分子を合成する。高分子蛍光体の合成において、末端基を特定の安定な基にする場合は、引き続き末端基を形成するモノマーと反応させればよい。また、末端基を形成するモノマーの存在下、重合反応を行うことで末端基を導入することもできる。本発明で用いる炭素−炭素二重結合を形成する反応には、Ｗｉｔｔｉｇ反応、脱ハロゲン化水素法、スルホニウム塩分解法、Ｈｅｃｋ法やＫｎｏｅｖｅｎａｇｅｌ反応などが例示される。これらのうち、Ｗｉｔｔｉｇ反応による方法が反応の制御や収率の点で好ましい。
【００４９】
Ｗｉｔｔｉｇ反応での有機蛍光材料の合成では、例えば式（９）で示すモノアルデヒド化合物と式（１０）で示すジホスホニウム塩化合物を反応させる。Ａｒ₁₃は、同一の基でも異なる基でもよい。二種類以上のモノアルデヒド化合物および／または二種類以上のジホスホニウム塩化合物を用いてもよい。
【００５０】
【化２１】
Ａｒ₁₃−ＣＨＯ ・・・・（９）
【００５１】
【化２２】

・・・・（１０）
〔ここで、Ａｒ₁₃は、共役結合に関与する炭素原子数が４個以上２０個以下からなるアリール基または複素環化合物基を示す。また、Ｒは、上記式（６）で示される置換基またはシアノ基であり、炭素数１〜２０のアルキル基、アルコキシ基およびアルキルチオ基；炭素数６〜１８のアリール基およびアリールオキシ基；炭素数４〜１４の複素環化合物基；ならびにシアノ基からなる群から選ばれた基であることが好ましい。 また、ａは、置換基の数を示し、０から４の整数から選ばれた数である。また、置換基の数ａが複数のときには、当該置換基Ｒは，互いに同一でも異なっても良い。Ｘ₁は、対イオンでハロゲン化物イオンなどが例示される。Ｐｈは、フェニル基である。〕
【００５２】
Ｗｉｔｔｉｇ反応での高分子蛍光体の合成では、例えば式（１１）で示すジアルデヒド化合物と式（１２）で示すジホスホニウム塩化合物を反応させる。Ａｒ₁₄は、同一の基でも異なる基でもよい。さらに、二種類以上のジアルデヒド化合物および／または二種類以上のジホスホニウム塩化合物を用いればそれらすべての共重合体が得られる。
【００５３】
【化２３】
ＯＨＣ−Ａｒ₁₄−ＣＨＯ ・・・・（１１）
【００５４】
【化２４】

・・・・（１１）
〔ここで、Ａｒ₁₄は、式（２）中のＡｒ₃で示される基から選ばれる。Ｒは、上記式（６）で示される置換基またはシアノ基であり、炭素数１〜２０のアルキル基、アルコキシ基およびアルキルチオ基；炭素数６〜１８のアリール基およびアリールオキシ基；炭素数４〜１４の複素環化合物基；ならびにシアノ基からなる群から選ばれた基であることが好ましい。また、ａは、置換基の数を示し、０から４の整数から選ばれた数である。また、置換基の数ａが複数のときには、当該置換基Ｒは、互いに同一でも異なっても良い。Ｘ₂は、対イオンでハロゲン化物イオンなどが例示される。Ｐｈは、フェニル基である。〕
【００５５】
高分子蛍光体の合成では、末端基を特定の安定な基にする場合は、一官能化合物の存在下、重合させるか、または、重合した後、引き続き末端基を形成する一官能化合物と反応させればよい。この一官能化合物は、用いる反応、または官能基の異なる２種類のモノマーを重縮合した場合には、反応に用いたモノマーの多少により適宜選択する。すなわち、Ｗｉｔｔｉｇ反応では、一官能化合物の存在下、ジアルデヒドとジホスホニウム塩とを反応させるか、ジアルデヒドとジホスホニウム塩とを反応させ、重合した後、引き続き末端基を形成する一官能化合物と反応させればよい。具体的には、Ｗｉｔｔｉｇ反応では、末端がホスホニウム塩またはアルデヒドであるので、それぞれに対してアルデヒド基またはホスホニウム塩が選ばれる。
【００５６】
さらに具体的に、本発明の高分子蛍光体の１つの例であるアリーレンビニレン系共重合体の合成法を説明する。
Ｗｉｔｔｉｇ反応によりアリーレンビニレン系共重合体を得る場合として、具体的には、まず、ビス（ハロゲン化メチル）化合物、例えば、４，４’−ビス（３−フェニルプロピルオキシ）−３，３’−ビス（ブロモメチル）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させてホスホニウム塩を合成し、これとジアルデヒド化合物、例えば、テレフタルアルデヒドとを、エチルアルコール中、リチウムエトキシドを用いて縮合させるＷｉｔｔｉｇ反応により、アリーレンビニレン系共重合体が得られる例が挙げられる。二種類以上のジホスホニウム塩および／または二種類以上のジアルデヒド化合物を反応させればそれらすべての共重合体が得られる。
【００５７】
さらに、モノアルデヒド化合物、例えば、１−ピレンカルボキシアルデヒド存在下、ジホスホニウム塩とジアルデヒドを、ジホスホニウム塩過剰の条件で、例えばエチルアルコール中、リチウムエトキシドを用いて縮合させるＷｉｔｔｉｇ反応により、末端を置換された共重合体が得られる例が挙げられる。
また、これらの重合体を有機ＥＬ素子の発光材料として用いる場合、その純度が発光特性に影響を与えるため、合成後、再沈精製、クロマトグラフィーによる分別等の純化処理をすることが望ましい。
【００５８】
本発明の有機蛍光材料または高分子蛍光体を用いて作成される有機ＥＬ素子の構造については、少なくとも一方が透明または半透明である一対の電極間に設ける発光層中に、本発明の有機蛍光材料または高分子蛍光体からなる発光材料が用いられておれば、特に制限はなく、公知の構造が採用される。
例えば、該有機蛍光材料または該高分子蛍光体からなる発光層、もしくは該有機蛍光材料または該高分子蛍光体と電荷輸送材料（電子輸送材料と正孔輸送材料の総称を意味する）との混合物からなる発光層の両面に一対の電極を有する構造のもの、さらに陰極と発光層の間に電子輸送材料を含む電子輸送層および／または陽極と発光層の間に正孔輸送材料を含む正孔輸送層を積層したものが例示される。
【００５９】
また、発光層や電荷輸送層は、１層の場合と複数の層を組み合わせる場合も本発明に含まれる。さらに、発光層に例えば下記に述べる該高分子蛍光体以外の発光材料を混合使用してもよい。また、該有機蛍光材料または該高分子蛍光体および／または電荷輸送材料を高分子化合物に分散させた層とすることもできる。
【００６０】
本発明の有機蛍光材料または高分子蛍光体とともに使用される電荷輸送材料、すなわち、電子輸送材料または正孔輸送材料としては公知のものが使用でき、特に限定されないが、正孔輸送材料としてはピラゾリン誘導体、アリールアミン誘導体、スチルベン誘導体、トリフェニルジアミン誘導体等が例示され、電子輸送材料としてはオキサジアゾール誘導体、アントラキノジメタンもしくはその誘導体、ベンゾキノンもしくはその誘導体、ナフトキノンもしくはその誘導体、アントラキノンもしくはその誘導体、テトラシアノアンスラキノジメタンもしくはその誘導体、フルオレノン誘導体、ジフェニルジシアノエチレンもしくはその誘導体、ジフェノキノン誘導体、または８−ヒドロキシキノリンもしくはその誘導体の金属錯体等が例示される。
【００６１】
具体的には、特開昭６３−７０２５７号、同６３−１７５８６０号公報、特開平２−１３５３５９号、同２−１３５３６１号、同２−２０９９８８号、同３−３７９９２号、同３−１５２１８４号公報に記載されているもの等が例示される。正孔輸送材料としては、トリフェニルジアミン誘導体、電子輸送材料としてはオキサジアゾール誘導体、ベンゾキノンもしくはその誘導体、アントラキノンもしくはその誘導体、または８−ヒドロキシキノリンもしくはその誘導体の金属錯体が好ましい。特に、正孔輸送材料としては、４，４’−ビス（Ｎ（３−メチルフェニル）−Ｎ−フェニルアミノ）ビフェニル、電子輸送材料としては２−（４−ビフェニリル）−５−（４−ｔ−ブチルフェニル）−１，３，４−オキサジアゾール、ベンゾキノン、アントラキノン、トリス（８−キノリノール）アルミニウムが好ましい。
【００６２】
これらのうち、電子輸送性の化合物と正孔輸送性の化合物のいずれか一方、または両方を同時に使用すればよい。これらは単独で用いてもよいし、２種類以上を混合して用いてもよい。
発光層と電極の間に電荷輸送層（正孔輸送層および電子輸送層の総称を意味する。）を設ける場合、これらの電荷輸送材料を使用して電荷輸送層を形成すればよい。
【００６３】
また、電荷輸送材料を発光層に混合して使用する場合、電荷輸送材料の使用量は使用する化合物の種類等によっても異なるので、十分な成膜性と発光特性を阻害しない量範囲でそれらを考慮して適宜決めればよい。通常、発光材料に対して１〜４０重量％が好ましく、さらに好ましくは２〜３０重量％である。
【００６４】
本発明の有機蛍光材料または高分子蛍光体と共に使用できる公知の発光材料としては特に限定されないが、例えば、ナフタレン誘導体、アントラセンもしくはその誘導体、ペリレンもしくはその誘導体；ポリメチン系、キサンテン系、クマリン系、シアニン系などの色素類；８−ヒドロキシキノリンもしくはその誘導体の金属錯体；芳香族アミン、テトラフェニルシクロペンタジエンもしくはその誘導体；またはテトラフェニルブタジエンもしくはその誘導体などを用いることができる。具体的には、例えば特開昭５７−５１７８１号、同５９−１９４３９３号公報に記載されているもの等、公知のものが使用可能である。
【００６５】
次に、本発明の有機蛍光材料または高分子蛍光体を用いた有機ＥＬ素子の代表的な作製方法について述べる。
陽極および陰極からなる一対の電極で、透明または半透明な電極としては、ガラス、透明プラスチック等の透明基板の上に、透明または半透明の電極を形成したものが用いられる。
陽極の材料としては、導電性の金属酸化物膜、半透明の金属薄膜等が用いられる。具体的にはインジウム・スズ・オキサイド（ＩＴＯ）、酸化スズ等からなる導電性ガラスを用いて作成された膜（ＮＥＳＡなど）、Ａｕ、Ｐｔ、Ａｇ、Ｃｕ等が用いられる。作製方法としては真空蒸着法、スパッタリング法、メッキ法などが用いられる。
【００６６】
次いで、この陽極上に発光材料として、上記有機蛍光材料および／または高分子蛍光体、または該発光材料と電荷輸送材料を含む発光層を形成する。形成方法としては、これら材料の溶融液、溶液または混合液を使用するスピンコーティング法、キャスティング法、ディッピング法、バーコート法、ロールコート法、グラビアコート法、フレキソ印刷法、スプレーコート法等の塗布法が例示される。溶液または混合液をスピンコーティング法、キャスティング法、ディッピング法、バーコート法、ロールコート法、グラビアコート法、フレキソ印刷法、スプレーコート法等の塗布法により成膜することが特に好ましい。
【００６７】
発光層の膜厚としては、好ましくは１ｎｍ〜１μｍ、さらに好ましくは２ｎｍ〜５００ｎｍである。電流密度を上げて発光効率を上げるためには５〜２００ｎｍの範囲が好ましい。
なお、塗布法により薄膜化した場合には、好ましくは溶媒を除去するため、減圧下または不活性雰囲気下、好ましくは３０〜３００℃、さらに好ましくは６０〜２００℃の温度で加熱乾燥することが望ましい。
また、該発光層と電荷輸送層とを積層する場合には、上記の成膜方法で発光層を設ける前に陽極の上に正孔輸送層を形成する、および／または発光層を設けた後にその上に電子輸送層を形成することが好ましい。
【００６８】
電荷輸送層の成膜方法としては、特に限定されないが、粉末状態からの真空蒸着法、または溶液に溶かした後のスピンコーティング法、キャスティング法、ディッピング法、バーコート法、ロールコート法等の塗布法、または高分子化合物と電荷輸送材料とを溶液状態または溶融状態で混合し分散させた後のスピンコーティング法、キャスティング法、ディッピング法、バーコート法、ロールコート法等の塗布法を用いることができる。
混合する高分子化合物としては、特に限定されないが、電荷輸送を極度に阻害しないものが好ましく、また、可視光に対する吸収が強くないものが好適に用いられる。
電荷輸送性の高分子化合物であれば、低分子電荷輸送材料と混合しなくても電荷輸送層に用いることができる。
【００６９】
該高分子化合物としては、例えば、ポリ（Ｎ−ビニルカルバゾール）、ポリアニリンもしくはその誘導体、ポリチオフェンもしくはその誘導体、ポリ（ｐ−フェニレンビニレン）もしくはその誘導体、ポリ（２，５−チエニレンビニレン）もしくはその誘導体、ポリカーボネート、ポリアクリレート、ポリメチルメタクリレート、ポリスチレン、ポリ塩化ビニル、またはポリシロキサンなどが例示される。成膜が容易に行なえるという点では、塗布法を用いることが好ましい。
【００７０】
電荷輸送層の厚さについては、少なくともピンホールが発生しないような厚さが必要であるが、あまり厚いと、素子の抵抗が増加し、高い駆動電圧が必要となり好ましくない。したがって、電荷輸送層の厚さは、好ましくは１ｎｍ〜１μｍ、さらに好ましくは２ｎｍ〜５００ｎｍ、特に好ましくは５ｎｍ〜２００ｎｍである。
【００７１】
次いで、発光層または電子輸送層の上に電極を設ける。この電極は電子注入陰極となる。その材料としては、特に限定されないが、イオン化エネルギーの小さい材料が好ましい。例えば、Ａｌ、Ｉｎ、Ｍｇ、Ｃａ、Ｌｉ、Ｍｇ−Ａｇ合金、Ｉｎ−Ａｇ合金、Ｍｇ−Ｉｎ合金、Ｍｇ−Ａｌ合金、Ｍｇ−Ｌｉ合金、Ａｌ−Ｌｉ合金、Ａｌ−Ｃａ合金、グラファイト薄膜等が用いられる。陰極の作製方法としては真空蒸着法、スパッタリング法等が用いられる。
【００７２】
【作用】
本発明において、該有機蛍光材料または該高分子蛍光体が発光材料として優れているのは、３，３’―ビアリーレンの特定の構造を有するので強い蛍光、とりわけ強い青色〜緑色の蛍光になるものと考えられる。また、塗布法により容易に均一性に優れた発光層を形成できることから、非常に容易に高発光効率で高耐熱性、長寿命の有機ＥＬ素子を作製することができる。
【００７３】
【実施例】
以下、本発明をさらに詳細に説明するために実施例を示すが、本発明はこれらに限定されるものではない。
ここで、数平均分子量については、クロロホルムを溶媒として、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）によりポリスチレン換算の数平均分子量を求めた。
【００７４】
実施例１
＜有機蛍光材料１の合成＞
３，３’−ビス（ブロモメチル）−４，４’−ビス（３−フェニルプロピルオキシ）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させてホスホニウム塩を合成した。得られたホスホニウム塩４．５３ｇと１−ピレンカルボキシアルデヒド１．９６ｇとを、エタノール／トルエン（１／１）混合溶媒８０ｇに溶解させた。このホスホニウム塩とアルデヒドのエタノール／トルエン混合溶液に、１２％リチウムメトキシドメタノール溶液５ｍｌとエチルアルコール２０ｍｌとをあらかじめ混合した溶液２５ｍｌを、室温で滴下した。引き続き、室温で４時間反応させた。
【００７５】
室温で一夜放置した後、沈殿を回収した。次に、この沈殿をエタノールで洗浄、続いてエタノール／水混合溶媒で洗浄、さらにエタノールで洗浄した。これを減圧乾燥して、有機蛍光材料２．６ｇを得た。この有機蛍光材料を有機蛍光材料１と呼ぶ。
該有機蛍光材料１の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００７６】
実施例２
＜高分子蛍光体１の合成＞
３，３’―ビス（ブロモメチル）―４，４’―ビス（３−フェニルプロピルオキシ）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させてホスホニウム塩を合成した。得られたホスホニウム塩５．６６ｇとテレフタルアルデヒド０．５４ｇと１−ピレンカルボキシアルデヒド０．６９ｇとを、エタノール／トルエン（１／１）混合溶媒８０ｇに溶解させた。このホスホニウム塩とアルデヒドのエタノール／トルエン混合溶液に、１２％リチウムメトキシドメタノール溶液５ｍｌとエチルアルコール２０ｍｌとをあらかじめ混合した溶液２５ｍｌを、室温で滴下した。引き続き、室温で５時間反応させた。
【００７７】
室温で一夜放置した後、生成した沈殿を回収した。次に、この沈殿をエタノールで洗浄した。次に、この沈殿をトルエンに溶解し、これにエタノールを加えて再沈精製した。再沈精製は２回行った。これを減圧乾燥して、重合体１．４ｇを得た。得られた重合体を高分子蛍光体１と呼ぶ。
該高分子蛍光体１のポリスチレン換算の数平均分子量は、３．３×１０³であった。該高分子蛍光体１の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００７８】
実施例３
＜高分子蛍光体２の合成＞
３，３’―ビス（ブロモメチル）―４，４’―ビス（３−フェニルプロピルオキシ）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させてホスホニウム塩を合成した。得られたホスホニウム塩５．６６ｇとイソフタルアルデヒド０．５４ｇと１−ピレンカルボキシアルデヒド０．５１ｇとを、エタノール／トルエン（１／１）混合溶媒８０ｇに溶解させた。次に、このホスホニウム塩とアルデヒドのエタノール／トルエン混合溶液に、１２％リチウムメトキシドメタノール溶液５ｍｌとエチルアルコール２０ｍｌとをあらかじめ混合した溶液２５ｍｌを、室温で滴下した。引き続き、室温で５時間反応させた。
【００７９】
室温で一夜放置した後、生成した沈殿を回収した。次に、この沈殿をエタノールで洗浄した。次に、この沈殿をトルエンに溶解し、これにエタノールを加えて再沈精製した。再沈精製は２回行った。これを減圧乾燥して、重合体１．７ｇを得た。得られた重合体を高分子蛍光体２と呼ぶ。
該高分子蛍光体２のポリスチレン換算の数平均分子量は、２．１×１０³であった。該高分子蛍光体２の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００８０】
実施例４
＜高分子蛍光体３の合成＞
３，３’―ビス（ブロモメチル）―４，４’―ビス（３−フェニルプロピルオキシ）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させてホスホニウム塩を合成した。得られたホスホニウム塩４．５３ｇと、前記と同様にして合成して得た、２，５−ジオクチルオキシ−ｐ−キシリレンジクロライドのホスホニウム塩０．９６ｇとテレフタルアルデヒド０．５８ｇと１−ピレンカルボキシアルデヒド０．３５ｇとを、エタノール／トルエン（１／１）混合溶媒８０ｇに溶解させた。次に、このホスホニウム塩とアルデヒドのエタノール／トルエン混合溶液に、１２％リチウムメトキシドメタノール溶液５ｍｌとエチルアルコール２０ｍｌとをあらかじめ混合した溶液２５ｍｌを、室温で滴下した。引き続き、室温で５時間反応させた。
【００８１】
室温で一夜放置した後、生成した沈殿を回収した。次に、この沈殿をエタノールで洗浄した。次に、この沈殿をトルエンに溶解し、これにエタノールを加えて再沈精製した。再沈精製は２回行った。これを減圧乾燥して、重合体１．４ｇを得た。得られた重合体を高分子蛍光体３と呼ぶ。
該高分子蛍光体３のポリスチレン換算の数平均分子量は、２．７×１０³であった。該高分子蛍光体３の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００８２】
実施例５
＜高分子蛍光体４の合成＞
３，３’―ビス（ブロモメチル）―４，４’―ビス（３−フェニルプロピルオキシ）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させてホスホニウム塩を合成した。得られたホスホニウム塩２．２６ｇと、同じようにして合成して得た、２，５−ジオクチルオキシ−ｐ−キシリレンジクロライドのホスホニウム塩２．８７ｇとテレフタルアルデヒド０．５８ｇと１−ピレンカルボキシアルデヒド０．３５ｇとを、エタノール／トルエン（１／１）混合溶媒８０ｇに溶解させた。次に、このホスホニウム塩とアルデヒドのエタノール／トルエン混合溶液に、１２％リチウムメトキシドメタノール溶液５ｍｌとエチルアルコール２０ｍｌとをあらかじめ混合した溶液２５ｍｌを、室温で滴下した。引き続き、室温で５時間反応させた。
【００８３】
室温で一夜放置した後、生成した沈殿を回収した。次に、この沈殿をエタノールで洗浄した。次に、この沈殿をトルエンに溶解し、これにエタノールを加えて再沈精製した。再沈精製は２回行った。これを減圧乾燥して、重合体１．４ｇを得た。得られた重合体を高分子蛍光体４と呼ぶ。
該高分子蛍光体４のポリスチレン換算の数平均分子量は、２．９×１０³であった。該高分子蛍光体４の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００８４】
実施例６
＜高分子蛍光体５の合成＞
３、３’―ビス（ブロモメチル）―２，２’―ビス（３−フェニルプロピルオキシ）−１，１’−ビナフチルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させてホスホニウム塩を合成した。得られたホスホニウム塩３．９４ｇと、同じようにして合成して得た、２，５−ジオクチルオキシ−ｐ−キシリレンジクロライドのホスホニウム塩０．７６ｇとテレフタルアルデヒド０．４７ｇと１−ピレンカルボキシアルデヒド０．２５ｇとを、エタノール／トルエン（１／１）混合溶媒８０ｇに溶解させた。次に、このホスホニウム塩とアルデヒドのエタノール／トルエン混合溶液に、１２％リチウムメトキシドメタノール溶液５ｍｌとエチルアルコール２０ｍｌとをあらかじめ混合した溶液２５ｍｌを、室温で滴下した。引き続き、室温で５時間反応させた。
【００８５】
この反応液にエタノール１００ｍｌを加え、室温で一夜放置した後、生成した沈殿を回収した。次に、この沈殿をエタノールで洗浄した。洗浄後、この沈殿をトルエンに溶解し、これにエタノールを加えて再沈精製した。再沈精製は２回行った。これを減圧乾燥して、重合体１．３ｇを得た。得られた重合体を高分子蛍光体５と呼ぶ。
該高分子蛍光体５のポリスチレン換算の数平均分子量は、３．２×１０³であった。該高分子蛍光体５の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００８６】
実施例７
＜高分子蛍光体６の合成＞
３，３’―ビス（ブロモメチル）―４，４’―ビス（３−フェニルプロピルオキシ）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させてホスホニウム塩を合成した。得られたホスホニウム塩６．４５ｇと、同じようにして合成して得た、２，５−ジオクチルオキシ−ｐ−キシリレンジクロライドのホスホニウム塩１．３６ｇとテレフタルアルデヒド０．７２ｇと４−（Ｎ，Ｎ−ジフェニルアミノ）ベンズアルデヒド０．９８ｇとを、エタノール／トルエン（１／１）混合溶媒１２０ｇに溶解させた。次に、このホスホニウム塩とアルデヒドのエタノール／トルエン混合溶液に、１２％リチウムメトキシドメタノール溶液８ｍｌとエチルアルコール３２ｍｌとをあらかじめ混合した溶液４０ｍｌを、室温で滴下した。引き続き、室温で３時間反応させた。
【００８７】
一夜室温で放置した後、生成した沈殿を回収した。次に、この沈殿をエタノールで洗浄した。洗浄後、この沈殿をトルエンに溶解し、これにエタノールを加えて再沈精製した。再沈精製は２回行った。これを減圧乾燥して、重合体２．５ｇを得た。得られた重合体を高分子蛍光体６と呼ぶ。
該高分子蛍光体６のポリスチレン換算の数平均分子量は、３．２×１０³であった。該高分子蛍光体６の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００８８】
実施例８
＜高分子蛍光体７の合成＞
３，３’―ビス（ブロモメチル）―４，４’―ビス（３−フェニルプロピルオキシ）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させてホスホニウム塩を合成した。得られたホスホニウム塩２．２６ｇと、同じようにして合成して得た、２，５−ジオクチルオキシ−ｐ−キシリレンジクロライドのホスホニウム塩２．８７ｇとテレフタルアルデヒド０．５８ｇと４−（Ｎ，Ｎ−ジフェニルアミノ）ベンズアルデヒド０．４１ｇとを、エタノール／トルエン（１／１）混合溶媒８０ｇに溶解させた。次に、このホスホニウム塩とアルデヒドのエタノール／トルエン混合溶液に、１２％リチウムメトキシドメタノール溶液５ｍｌとエチルアルコール２０ｍｌとをあらかじめ混合した溶液２５ｍｌを、室温で滴下した。引き続き、室温で３時間反応させた。
【００８９】
一夜室温で放置した後、生成した沈殿を回収した。次に、この沈殿をエタノールで洗浄した。洗浄後、この沈殿をトルエンに溶解し、これにエタノールを加えて再沈精製した。再沈精製は２回行った。これを減圧乾燥して、重合体２．５ｇを得た。得られた重合体を高分子蛍光体７と呼ぶ。
該高分子蛍光体７のポリスチレン換算の数平均分子量は、４．２×１０³であった。該高分子蛍光体７の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００９０】
比較例１
＜有機蛍光材料２の合成＞
３，３’―ビス（ブロモメチル）―４，４’―ビス（３−フェニルプロピルオキシ）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させて得たホスホニウム塩の代わりに、２，５−ジオクチルオキシ−ｐ−キシリレンジクロリドのホスホニウム塩３．８２ｇを用いた以外は、実施例１と同じ方法で反応、精製、乾燥を行い、有機蛍光材料２ｇを得た。得られた化合物を有機蛍光材料２と呼ぶ。
該有機蛍光材料２の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００９１】
比較例２
＜高分子発光体８の合成＞
３，３’―ビス（ブロモメチル）―４，４’―ビス（３−フェニルプロピルオキシ）ビフェニルをＮ，Ｎ−ジメチルホルムアミド溶媒中、トリフェニルホスフィンと反応させて得たホスホニウム塩の代わりに、２，５−ジオクチルオキシ−ｐ−キシリレンジクロリドのホスホニウム塩３．８ｇを用いた以外は、実施例２と同じ方法で重合、精製、乾燥を行い、高分子蛍光体１．７重量部を得た。得られた重合体を高分子蛍光体８と呼ぶ。
該高分子蛍光体８のポリスチレン換算の数平均分子量は、３．７×１０³であった。該高分子蛍光体８の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで確認した。
【００９２】
実施例９
＜吸収スペクトル、蛍光スペクトルの測定＞
有機蛍光材料１、２および高分子蛍光体１〜８は、クロロホルムに容易に溶解させることができた。その０．４％クロロホルム溶液を石英板上にスピンコートして重合体の薄膜を作成した。この薄膜の紫外可視吸収スペクトルと蛍光スペクトルをそれぞれ島津製作所製自記分光光度計ＵＶ３６５および日立製作所製蛍光分光光度計８５０を用いて測定した。得られた蛍光の量子収率を表１、表２に示す。有機蛍光材料１は、表１に示すとおり、有機蛍光材料２よりも強かった。また、高分子蛍光体１〜７は、表２に示すとおり、高分子蛍光体８よりも強かった。
【００９３】
実施例１０
＜示差走査熱量分析（ＤＳＣ）による耐熱性の評価＞
セイコー電子製示差走査熱量分析計ＤＳＣ２００を用いて、高分子蛍光体１〜８の熱分析を行った。いずれも高分子の軟化に対応すると思われる吸熱ピークが見られた。高分子蛍光体１〜７は、表２に示すとおり、高分子蛍光体８よりも高い温度で吸熱ピークを示した。
【００９４】
【表１】

【００９５】
【表２】

【００９６】
実施例１１
＜素子の作成および評価＞
スパッタリングによって、４０ｎｍの厚みでＩＴＯ膜を付けたガラス基板に、ポリ（Ｎービニルカルバゾール）の１重量％ジクロロエタン溶液を用いて、スピンコートにより６０ｎｍの厚みで成膜した。次に、実施例２で得た高分子蛍光体１の２重量％メシチレン溶液を用いて、スピンコートにより６０ｎｍの厚みで成膜した。その上に、電子輸送材料を含有する有機層として、トリス（８−キノリノール）アルミニウムを４０ｎｍ蒸着した。最後に、その上に陰極として、アルミニウムリチウム合金（Ａｌ：Ｌｉ＝約２００：１重量比）を１００ｎｍ蒸着して、有機ＥＬ素子を作成した。蒸着のときの真空度は、すべて１×１０^-5Ｔｏｒｒ以下であった。この素子に１０Ｖの電圧を印加したところ、高分子蛍光体１の蛍光と同じスペクトルを有するＥＬ発光が観察された。
同様にして、実施例１で得た有機蛍光材料１、また実施例３〜８で得た高分子蛍光体２〜７を用いれば、それぞれの蛍光スペクトルと同じスペクトルを有するＥＬ発光が観察される。
【００９７】
【発明の効果】
本発明の有機蛍光材料および／または高分子蛍光体は、短波長の蛍光、とりわけ青色〜緑色の強い蛍光と熱的安定性を兼ね備えており、溶媒可溶性で、有機ＥＬ素子用の材料として優れている。また、該有機蛍光体および／または該高分子蛍光体を用いた有機ＥＬ素子は、塗布法により作成が容易で、また優れた発光特性、耐熱性を示すので、バックライトとしての面状光源，フラットパネルディスプレイ等の装置として好ましく使用できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic fluorescent material and a polymeric fluorescent material that emit blue to green light and has a high fluorescence yield, and an organic electroluminescent device that is produced using the organic fluorescent material and / or the polymeric fluorescent material ( Hereinafter, it may be referred to as an organic EL element).
[0002]
[Prior art]
Inorganic electroluminescence elements using inorganic phosphors as light emitting materials (hereinafter sometimes referred to as inorganic EL elements) are used for display devices such as planar light sources and flat panel displays as backlights, for example. In order to emit light, high voltage alternating current was required.
From the viewpoint of improving such an inorganic EL device, a device having a two-layer structure in which an organic fluorescent dye is used as a light emitting layer and this is stacked with an organic charge transport compound (Japanese Patent Laid-Open No. 59-194393), a polymer An element using a light emitting material (WO90113148, JP-A-3-244630) has been reported. Electroluminescent elements using these organic materials are characterized in that multi-color light emission can be easily obtained in addition to low-voltage direct current drive and high luminance, as compared with inorganic EL elements.
[0003]
As an organic fluorescent material having a distyryl structure reported so far, JP-A-8-239655 exemplifies a distyryl compound having a 4,4′-biphenylene skeleton. Further, as a polymer light-emitting material, WO90113148 discloses a poly-p-phenylene vinylene thin film converted into a conjugated polymer by forming a soluble precursor on an electrode and performing a heat treatment. JP-A-3-244630 discloses a conjugated polymer such as poly-2,5-dialkoxy-p-phenylene vinylene, which is itself soluble in a solvent and does not require heat treatment. Is illustrated. Further, JP-A-10-36487 discloses that a fluorene polymer in which fluorene is bonded to a phenylene group via a vinylene group exhibits blue EL emission.
[0004]
In addition, in polythiophene, an attempt to shorten the emission wavelength by introducing a bulky substituent at the 3-position has been reported (Synthetic Metals, Vol. 71, p. 2121 (1995)).
In addition, as a polymer light-emitting material, a polymer fluorescent substance containing a conjugated system and a non-conjugated system in the molecule, and a poly-p-phenylene vinylene derivative in which a cyano group is introduced into a vinylene group have been reported [Nature (Nature). 365, 628 (1993)]. As a polymeric fluorescent substance having a conjugated system and a non-conjugated system in the molecule, a random copolymer of 2,5-dimethoxy-p-phenyleneethylene structure and p-phenylene vinylene [Nature 356, 47 (1992)] and a polymer [Macromolecules, Vol. 26, 1188 (1993)] in which a phenylene vinylene structure and an aliphatic hydrocarbon are linked by an ether bond. JP-A-3-33183 exemplifies oligomers having a p-phenylene skeleton. Further, poly (p-phenylene) derivatives are reported in [Advanced Materials, vol. 4, page 36 (1992)].
[0005]
However, a derivative that is soluble in a solvent and has strong fluorescence, for example, having a 3,3′-biphenylene skeleton is not known. In addition, the poly (arylene vinylene) polymer fluorescent substance used in the organic EL elements reported so far needs to be heat-treated when passing through a solvent-soluble intermediate. There was a restriction that it could not be used. In addition, in order to obtain a solvent-soluble polymeric fluorescent substance, it is necessary to introduce a flexible repeating unit into the main chain or a flexible side chain having a high affinity with the solvent. There is a problem that the heat resistance of the element is lowered because the phosphor is easily softened.
[0006]
In addition, in order to obtain a polymer fluorescent substance having a blue emission color, it is necessary to introduce a group having a non-conjugated bond such as an aliphatic hydrocarbon group into the main chain, which complicates the synthesis process. was there. In addition, in polymers in which aromatic compound groups are bonded alternately with vinylene groups, there are attempts to increase the wavelength by the electronic action of the nuclear substituent, but introducing an aromatic ring with a specific structure into the main chain Thus, there is no known compound that shortens the fluorescence wavelength and increases the quantum yield of fluorescence. Thus, there is a demand for a polyarylene vinylene-based light emitting material that has high quantum yield of fluorescence and light emission efficiency of an organic EL element, is thermally stable, and can be easily synthesized.
[0007]
[Problems to be solved by the invention]
The object of the present invention is to provide a solvent-soluble organic fluorescent material and polymer fluorescent material having strong fluorescence with a short wavelength, particularly blue to green, excellent in heat resistance, and excellently prepared by a coating method using the same. Another object is to provide an organic EL element having the above characteristics.
[0008]
[Means for Solving the Problems]
In view of such circumstances, the present inventors have found that the emission efficiency, heat resistance, and heat resistance of an organic EL device using a blue to green organic fluorescent material and / or a polymeric fluorescent substance having a short emission wavelength as a light emitting layer. As a result of diligent studies to improve the device lifetime, a distyryl derivative having a biarylene skeleton at a specific bonding position and a polymer phosphor having an aromatic ring of a specific structure at the position of the main chain in the molecular structural formula An organic EL device that exhibits strong blue to green fluorescence, exhibits high fluorescence quantum yield and high heat resistance, and can easily be applied by a coating method by using the organic fluorescent material and / or the polymer fluorescent material. In addition, the present inventors have found that this organic EL element exhibits excellent characteristics, and have reached the present invention.
[0009]
That is, the present invention relates to the following [1] to [15].
[1] It has fluorescence in the solid state and has a polystyrene-reduced number average molecular weight of 10 ^Three -10 ⁷ The polymeric fluorescent substance contains at least one type of repeating unit represented by the following formula (1), and the repeating unit represented by the formula (1) is contained in 2 to 100% of the total number of repeating units.
[Chemical 9]
-Ar ₁ -Ar ₂ −. . . (1)
[Where Ar ₁ And Ar ₂ Is a group having two bonds each forming a carbon-carbon bond with an adjacent group, and an aromatic compound group having 6 to 22 carbon atoms involved in the conjugated bond or a carbon number of 4 containing a hetero atom A heterocyclic compound group of ˜20-membered ring or more, wherein the number of atoms present continuously in the shortest path between the carbon atoms having two bonds in the chemical structural formula of each group is 1, It is independently selected from those that are either 3 or 5. ]
[2] The polymeric fluorescent substance according to [1], wherein the repeating unit represented by the formula (1) described in [1] is bonded to an adjacent group via a vinylene group represented by the formula (2) .
[0010]
[Chemical Formula 10]
-CR ₁ = CR ₂ −. . . (2)
[Where R ₁ And R ₂ Each independently represents hydrogen, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and aryloxy group having 6 to 20 carbon atoms; and a heterocyclic compound group having 4 to 20 carbon atoms A group selected from the group consisting of ]
[3] In addition to the repeating unit represented by the formula (1) described in the above [1], the repeating unit represented by the following formula (3) includes one or more kinds of repeating units, and the repeating unit represented by the formula (1) is a repeating unit. The polymeric fluorescent substance according to [1] or [2], which is contained in an amount of 2 to 50% of the whole.
[0011]
Embedded image
-Ar _Three −. . . (3)
[Where Ar _Three Is a group having two bonds that form a carbon-carbon bond with an adjacent group, an aromatic compound group having 6 to 22 carbon atoms involved in the conjugated bond, or a carbon number of 4 to 4 containing a hetero atom It is a group selected from the group represented by 20 heterocyclic compound groups. ]
[4] The repeating unit represented by the formula (3) described in the above [3] is bonded to an adjacent group via a vinylene group represented by the formula (2) described in [1]. Polymer phosphor.
[5] It has fluorescence in a solid state and has a polystyrene-equivalent number average molecular weight of 10 ^Three -10 ⁷ A polymeric fluorescent substance containing at least one type of repeating unit represented by the following formula (4), wherein the repeating unit represented by the formula (4) is contained in 4 to 100% of the total number of repeating units.
[0012]
Embedded image
-Ar _Four -CR _Three = CR _Four -Ar _Five -CR _Five = CR ₆ −. . . (4)
[Where Ar _Four Represents the same group as the group represented by the formula (3) according to claim 3. Ar _Five Represents the same repeating unit as the repeating unit represented by the formula (1) according to claim 1. R _Three ~ R ₆ Each independently represents hydrogen, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and aryloxy group having 6 to 20 carbon atoms; and a heterocyclic compound group having 4 to 20 carbon atoms A group selected from the group consisting of
[6] It has visible fluorescence in the solid state and has a polystyrene-reduced number average molecular weight of 10 ^Three -10 ⁷ In the polymeric fluorescent substance, the polymeric fluorescent substance contains at least one type of repeating unit represented by the following formula (5), and the total of these repeating units is 10 mol% or more and 100 mol% or less of all the repeating units .
[0013]
Embedded image

[Where Ar ₆ Represents an arylene group or a heterocyclic compound group having 4 to 20 carbon atoms involved in a conjugated bond. R ₇ ~ R _Ten Each independently represents a group selected from the group consisting of hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group. R ₁₁ ~ R ₁₈ Each independently represents hydrogen or a substituent represented by the following formula (6).
[0014]
Embedded image
-(R ₁₉ ) _m -(X) _n -R ₂₀ .... (6)
(Where R ₁₉ Represents a hydrocarbon group having 1 to 20 carbon atoms. R ₂₀ Is a hydrocarbon group having 1 to 20 carbon atoms, an aryl group and a heterocyclic compound group having 4 to 20 carbon atoms involved in the conjugated bond, and an aliphatic cyclic carbonization having 6 to 20 carbon atoms constituting the ring It is a group selected from the group consisting of hydrogen groups. X represents a group selected from the group consisting of —O—, —S—, —CO—, —CO—O— and —O—CO—. m and n are each independently 0 or 1. )]
[7] An organic fluorescent material having fluorescence in a solid state and including a structure represented by the following formula (7).
[0015]
Embedded image
Ar ₇ -CR _{twenty one} = CR _{twenty two} -Ar ₈ -Ar ₉ -CR _{twenty three} = CR _{twenty four} -Ar _Ten . . . (7)
[Where Ar ₇ And Ar _Ten Each independently represents an aryl group having 4 to 20 carbon atoms involved in a conjugated bond or a monofunctional heterocyclic compound group.
R _{twenty one} ~ R _{twenty four} Each independently represents hydrogen, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and aryloxy group having 6 to 20 carbon atoms; and a heterocyclic compound group having 4 to 20 carbon atoms A group selected from the group consisting of Ar ₈ And Ar ₉ Are each independently a group having two bonds that form a carbon-carbon bond with an adjacent group, and contains an aromatic compound group having 6 to 22 carbon atoms involved in a conjugated bond, or a heteroatom. The number of atoms selected continuously from a heterocyclic compound group having 4 to 20 carbon atoms and having 6 or more members, each continuously present in the shortest path between the carbon atoms having two bonds in the chemical structure of each group Is one of 1, 3 or 5. ]
[8] An organic fluorescent material having visible fluorescence in a solid state and represented by the following formula (8).
[0016]
Embedded image

[Where Ar ₁₁ , Ar ₁₂ Represents an aryl group or a heterocyclic compound group having 4 to 20 carbon atoms involved in the conjugated bond. R _{twenty five} ~ R ₂₈ Each independently represents a group selected from the group consisting of hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group. R ₂₉ ~ R ₃₆ Represents hydrogen or a substituent represented by the formula (6) described in [6] above. [9] At least a light emitting layer is provided between an electrode composed of a pair of an anode and a cathode, at least one of which is transparent or translucent. In the organic electroluminescence device, the light emitting layer is one or more polymer phosphors selected from the polymer phosphors described in [1], [2], [3], [4], [5] or [6] And / or an organic electroluminescent device comprising the organic fluorescent material according to [7] or [8].
[10] In an organic electroluminescence device having at least a light emitting layer and a hole transport layer between a pair of anodes and cathodes, at least one of which is transparent or translucent, the light emitting layer and / or the hole transport layer are [1], [2], [3], [4], [5] or [6] one or more polymer phosphors selected from the polymer phosphors described in [6] and / or [7] or [8] An organic electroluminescent device comprising the organic fluorescent material described.
[11] The organic electroluminescence device according to [10], wherein a layer containing a hole transporting compound is provided adjacent to the light emitting layer between the anode and the light emitting layer.
[12] In an organic electroluminescence device having at least a light-emitting layer and an electron transport layer between a pair of anodes and cathodes, at least one of which is transparent or translucent, the light-emitting layer and / or the electron transport layer is [1 ], [2], [3], [4], [5] or one or more polymeric fluorescent substances selected from the polymeric fluorescent substances described in [6] and / or [7] or [8] An organic electroluminescence device including an organic fluorescent material.
[13] The organic electroluminescence device according to [12], wherein a layer containing an electron transporting compound is provided adjacent to the light emitting layer between the cathode and the light emitting layer.
[14] In an organic electroluminescence device having at least a hole transport layer, a light emitting layer, and an electron transport layer between an electrode composed of a pair of an anode and a cathode, at least one of which is transparent or translucent, the hole transport layer, light emission At least one of the layers and the electron transport layer is at least one polymer selected from the polymeric fluorescent substances according to [1], [2], [3], [4], [5] or [6] An organic electroluminescence device comprising a phosphor and / or the organic fluorescent material according to [7] or [8].
[15] A layer containing an electron transporting compound adjacent to the light emitting layer between the cathode and the light emitting layer, and a hole transporting compound adjacent to the light emitting layer between the anode and the light emitting layer. [14] The organic electroluminescence device according to [14], wherein a layer containing the organic electroluminescence device is provided.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The polymeric fluorescent substance of the present invention has fluorescence in a solid state and has a number average molecular weight of 10 in terms of polystyrene. ^Three -10 ⁷ It contains at least one type of repeating unit represented by the above formula (1), and the repeating unit represented by the formula (1) is contained in 2 to 100% of the total number of repeating units.
[0018]
Ar in the formula (1) ₁ And Ar ₂ Is a group having two bonds that form a carbon-carbon bond with an adjacent group, respectively, and an aromatic compound group having 6 to 22 carbon atoms involved in the conjugated bond, or carbon containing a heteroatom. It is a heterocyclic compound group having a number of 4 to 20 or more, and the number of atoms present continuously in the shortest path between carbon atoms having two bonds in the chemical structural formula of each group. It is independently selected from any one of 1, 3 and 5.
[0019]
Moreover, it is preferable that this repeating unit (1) is couple | bonded with the adjacent group through the vinylene group shown by Formula (2).
[0020]
Specifically, the Ar ₁ , Ar ₂ As each of them, an aromatic compound group represented by the following chemical formula 17 or a derivative group thereof, or a heterocyclic compound group or a derivative group thereof is exemplified.
[0021]
Embedded image

[Wherein R is a substituent represented by the above formula (6) or a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and aryloxy group having 6 to 18 carbon atoms; It is preferably a group selected from the group consisting of a heterocyclic compound group having 4 to 14 carbon atoms and a cyano group. A to f represent the number of substituents, a is an integer from 0 to 4, b is an integer from 0 to 3, c is an integer from 0 to 2, d is an integer from 0 to 6, e Is an integer from 0 to 8, and f is a number selected from integers from 0 to 5. When the number of substituents af is plural, the substituents R may be the same as or different from each other. ]
[0022]
Among these, 1,3-phenylene group, 2,5-naphthalenylene group, 2,6-pyridine-diyl group, 2,5-quinoline-diyl group or a nucleus-substituted derivative thereof is preferable. One or more types can be selected from these.
[0023]
R bonded to the vinylene group in the formula (2) ₁ And R ₂ As, independently, hydrogen, cyano group, alkyl group having 1 to 20 carbon atoms, alkoxy group and alkylthio group; aryl group and aryloxy group having 6 to 20 carbon atoms; and heterocyclic compounds having 4 to 20 carbon atoms It is a group selected from the group consisting of groups.
Specific examples of the alkyl group having 1 to 20 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a decyl group, and a dodecyl group. A methyl group, an ethyl group, a pentyl group, a hexyl group, a heptyl group, and an octyl group are preferred.
As the aryl group, a phenyl group, C ₁ ~ C ₁₄ Alkoxyphenyl group (C ₁ ~ C ₁₄ Indicates that it has 1 to 14 carbon atoms. The same applies to the following. ), C ₁ ~ C ₁₄ Examples thereof include an alkylphenyl group, a 1-naphthyl group, and a 2-naphthyl group. Examples of the heterocyclic compound group include a 2-pyridyl group, a 2-quinolyl group, and a thienyl group.
Of these, hydrogen and cyano groups are more preferable.
[0024]
The polymeric fluorescent substance of the present invention has fluorescence in a solid state and has a number average molecular weight of 10 in terms of polystyrene. ^Three -10 ⁷ One or more of each of the repeating units represented by the above formula (1) and the above formula (3), and the repeating unit represented by the formula (1) is contained in 2 to 50% of the total number of repeating units. It is preferable that
[0025]
Ar in the above formula (3) _Three Is a group having two bonds that form a carbon-carbon bond with an adjacent group, respectively, and an aromatic compound group having 6 to 22 carbon atoms or a heteroatom that is involved in a conjugated bond. It is a group selected from the group represented by ˜20 heterocyclic compound groups, and is more preferably bonded to an adjacent group via a vinylene group represented by the formula (2).
[0026]
Specifically, the Ar _Three Examples thereof include the group exemplified in Chemical Formula 17 above, the aromatic compound group shown in Chemical Formula 18 below or a derivative group thereof, or the heterocyclic compound group or the derivative group thereof.
[0027]
Embedded image

[Wherein R is a substituent represented by the above formula (6) or a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and aryloxy group having 6 to 18 carbon atoms; It is preferably a group selected from the group consisting of a heterocyclic compound group having 4 to 14 carbon atoms; and a cyano group. A to f represent the number of substituents, a is an integer from 0 to 4, b is an integer from 0 to 3, c is an integer from 0 to 2, d is an integer from 0 to 6, e is an integer from 0 to 8, and f is a number selected from integers from 0 to 5. In addition, when the number of substituents af is plural, the substituents R may be the same as or different from each other. ]
[0028]
Among these, 1,4-phenylene group, 2,6-naphthalenylene group, 4,4′-biphenylene group, 9,10-anthrylene group, 2,5-pyridine-diyl group, 2,5-thienylene group or the like Or a 1,3-phenylene group, a 2,5-naphthalenylene group, a 3,3′-biphenylene group, a 2,6-pyridine-diyl group, a 2,6-quinoline-diyl group, or a derivative thereof. preferable. More preferably, a 1,4-phenylene group, a 2,5-pyridine-diyl group, a 2,5-thienylene group, a 4,4′-biphenylene group, a 3,3′-biphenylene group, a 1,3-phenylene group, 2 , 6-pyridine-diyl group, 2,4-quinoline-diyl group, or derivatives thereof. One or more types can be selected from these.
[0029]
The polymeric fluorescent substance of the present invention has fluorescence in a solid state and has a number average molecular weight of 10 in terms of polystyrene. ^Three -10 ⁷ And one or more repeating units represented by the above formula (4) are contained, and the repeating unit represented by the formula (4) is contained in 4 to 100% of the total number of repeating units.
Ar in the formula (4) _Four Represents the same group as the group represented by the above formula (3). Ar _Five Represents the same repeating unit as the repeating unit represented by the above formula (1).
In addition, R bonded to the vinylene group of the formula (4) _Three ~ R ₆ Each independently represents hydrogen, a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and aryloxy group having 6 to 20 carbon atoms; and a heterocyclic compound group having 4 to 20 carbon atoms A group selected from the group consisting of
Specifically, R bonded to the vinylene group of formula (2) ₁ Or R ₂ The same groups are exemplified.
[0030]
The total number of repeating units represented by the formula (1) is 2 to 100 mol% of all repeating units, and it is preferably 10 to 100 mol% although it depends on the structure of the repeating units.
[0031]
The total of repeating units represented by the formula (3) is preferably more than 50 mol% and less than 98 mol% of all repeating units, and more than 50 mol% and more than 90 mol% depending on the structure of the repeating units. More preferably, it is less than.
[0032]
The total number of repeating units represented by the formula (4) is 4 to 100 mol% of all repeating units, and more preferably 20 to 100 mol%, although it depends on the structure of the repeating units.
[0033]
The polymeric fluorescent substance of the present invention has visible fluorescence in a solid state and has a number average molecular weight of 10 in terms of polystyrene. ^Three To 10 ⁷ The polymeric fluorescent substance is characterized in that it contains one or more repeating units represented by the following formula (5), and the total of these repeating units is 10 mol% or more and 100 mol% or less of all repeating units. To do.
[0034]
Embedded image

[0035]
Ar ₆ Represents an arylene group or a heterocyclic compound group having 4 to 20 carbon atoms involved in the conjugated bond. Specifically, the compound groups represented by the above chemical formulas 17 and 18 or their derivative groups are exemplified.
R ₇ ~ R _Ten Each independently represents a group selected from the group consisting of hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group. Specifically, R bonded to the vinylene group of formula (2) ₁ Or R ₂ The same groups are exemplified. R ₁₁ ~ R ₁₈ Represents hydrogen or a substituent represented by the above formula (6).
[0036]
The terminal group of the polymeric fluorescent substance used in the present invention is not particularly limited. However, if the polymerization active group remains as it is, there is a possibility that the light emission characteristics and life when the device is made may be reduced. It is preferably protected. Those having a conjugated bond continuous with the conjugated structure of the main chain are more preferable, and examples thereof include a structure bonded to an aryl group or a heterocyclic compound group via a vinylene group.
Specifically, Ar represented by the above formula (7) ₇ Or Ar _Ten Examples are the same aromatic compound group as the group or a derivative group thereof, and a group in which the vinylene group is bonded to the group.
[0037]
Among these, phenyl group, 1-naphthyl group, 9-anthryl group, 2-pyridyl group, 2-thienyl group, oxadiazolyl group, benzoxazolyl group, 4- (N, N-diphenylamino) phenyl group, A 1-pyrenyl group, 2-fluorenyl group, 2-quinolyl group, 4- (9-carbazolyl) phenyl group, 9-phenyl-3-carbazolyl group, 3-perylenyl group or derivatives thereof are preferred.
More preferably, 1-naphthyl group, 9-anthryl group, oxadiazolyl group, 4- (N, N-diphenylamino) phenyl group, 1-pyrenyl group, 2-fluorenyl group, 2-quinolyl group, 4- (9- Carbazolyl) phenyl group, 9-phenyl-3-carbazolyl group, 3-perylenyl group or derivatives thereof, particularly preferably 1-naphthyl group, 9-anthryl group, 1-pyrenyl group, 2-fluorenyl group, 3 -A perylenyl group is mentioned.
[0038]
The degree of polymerization of the polymeric fluorescent substance of the present invention is such that the molecular weight is 10 in terms of polystyrene. ^Three -10 ⁷ If it is, it will not specifically limit, It changes also with a repeating structure and its ratio. In general, the total number of repeating structures is preferably 2 to 10,000, more preferably 3 to 3000, and particularly preferably 4 to 2000 from the viewpoint of film formability. Here, the molecular weight is a polystyrene-equivalent number average molecular weight determined by gel permeation chromatography (GPC) using chloroform as a solvent.
[0039]
The polymeric fluorescent substance of the present invention is a polymer or copolymer composed of repeating units represented by formulas (1), (3), (4), and (5). May be a random, block or graft copolymer, or may be a polymer having an intermediate structure thereof, such as a random copolymer having a block property. From the viewpoint of obtaining a copolymer having a high fluorescence quantum yield, a random copolymer or block or graft copolymer having a block property is preferable to a complete random copolymer, the main chain is branched, and the terminal is terminated. This includes cases where there are more than two.
[0040]
On the other hand, the organic fluorescent material of the present invention is characterized by having fluorescence in a solid state and including a structure represented by the above formula (7).
Ar in the formula (7) ₇ , Ar _Ten Are each independently an aryl group having 4 to 20 carbon atoms or a monofunctional heterocyclic compound group involved in a conjugated bond.
[0041]
Specifically, the Ar ₇ , Ar _Ten Examples of the compound are each independently an aromatic compound group represented by the following chemical formula 20 or a derivative group thereof, or a heterocyclic compound group or a derivative group thereof.
[0042]
Embedded image

[Wherein R is a substituent represented by the above formula (6) or a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group and aryloxy group having 6 to 18 carbon atoms; It is preferably a group selected from the group consisting of a heterocyclic compound group having 4 to 14 carbon atoms; and a cyano group. A to i represent the number of substituents, a is an integer from 0 to 4, b is an integer from 0 to 3, d is an integer from 0 to 6, f is an integer from 0 to 5, g Is an integer from 0 to 7, h is an integer from 0 to 9, and i is a number selected from integers from 0 to 11. When the number of substituents ai is plural, the substituents R may be the same as or different from each other. ]
[0043]
Among these, phenyl group, 1-naphthyl group, 9-anthryl group, 2-pyridyl group, 2-thienyl group, 4- (N, N-diphenylamino) phenyl group, 1-pyrenyl group, 2-quinolyl group 4- (9-carbazolyl) phenyl group, 3-perylenyl group or derivatives thereof are preferred.
More preferably, 1-naphthyl group, 9-anthryl group, 4- (N, N-diphenylamino) phenyl group, 1-pyrenyl group, 2-fluorenyl group, 2-quinolyl group, 3-perylenyl group or derivatives thereof Particularly preferred are 1-naphthyl group, 9-anthryl group, 1-pyrenyl group, 2-fluorenyl group and 3-perylenyl group. One or more types can be selected from these.
[0044]
Ar in the formula (7) ₈ , Ar ₉ Each independently represents Ar represented by the above formula (1). ₁ Or Ar ₂ Is the same group.
[0045]
R in the formula (7) _{twenty one} ~ R _{twenty four} Each independently represents hydrogen or a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group and an alkylthio group; an aryl group having 6 to 20 carbon atoms and an aryloxy group; and a heterocyclic compound having 4 to 20 carbon atoms It is a group selected from the group consisting of groups.
Specifically, R bonded to the vinylene group of formula (2) ₁ Or R ₂ The same groups are exemplified.
[0046]
In addition, the organic fluorescent material of the present invention has visible fluorescence in a solid state and is represented by the above formula (8).
Ar ₁₁ , Ar ₁₂ Represents an aryl group or a heterocyclic compound group having 4 to 20 carbon atoms involved in the conjugated bond.
Ar ₁₁ , Ar ₁₂ Each independently represents Ar in the above formula (7). ₇ Or Ar _Ten Specifically, an aromatic compound group represented by the above chemical formula 20 or a derivative group thereof, or a heterocyclic compound group or a derivative group thereof is specifically exemplified.
R _{twenty five} ~ R ₂₈ Each independently represents a group selected from the group consisting of hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group. Specifically, R bonded to the vinylene group of formula (2) ₁ Or R ₂ The same groups are exemplified. R ₂₉ ~ R ₃₆ Represents hydrogen or a substituent represented by the above formula (6).
[0047]
The organic fluorescent material and polymeric fluorescent substance of the present invention can be formed by dissolving in a solvent.
Examples of the good solvent for the organic fluorescent material and the polymeric fluorescent substance include chloroform, methylene chloride, dichloroethane, tetrahydrofuran, toluene, xylene and the like. Although depending on the structure and molecular weight of the organic fluorescent material and the polymeric fluorescent substance, it can usually be dissolved in these solvents in an amount of 0.1 wt% or more.
In forming an organic EL element, when using these organic solvent-soluble organic fluorescent materials and / or polymer fluorescent materials to form a film from a solution, it is only necessary to remove the solvent by drying after coating the solution. In addition, the same technique can be applied to the case where a charge transport material described later is mixed, which is very advantageous in production.
[0048]
Examples of the method for producing the organic fluorescent material and the polymeric fluorescent substance of the present invention include a compound represented by the formula (5) or a formula (1), (3), (4) by a carbon-carbon double bond forming reaction. A polymer containing a repeating unit represented by is synthesized. In the synthesis of the polymeric fluorescent substance, when the terminal group is to be a specific stable group, it may be subsequently reacted with a monomer that forms the terminal group. Moreover, a terminal group can also be introduce | transduced by performing a polymerization reaction in presence of the monomer which forms a terminal group. Examples of the reaction for forming a carbon-carbon double bond used in the present invention include Wittig reaction, dehydrohalogenation method, sulfonium salt decomposition method, Heck method and Knoevenagel reaction. Among these, the method by Wittig reaction is preferable in terms of reaction control and yield.
[0049]
In the synthesis of the organic fluorescent material by the Wittig reaction, for example, a monoaldehyde compound represented by the formula (9) and a diphosphonium salt compound represented by the formula (10) are reacted. Ar ₁₃ May be the same or different groups. Two or more kinds of monoaldehyde compounds and / or two or more kinds of diphosphonium salt compounds may be used.
[0050]
Embedded image
Ar ₁₃ -CHO (9)
[0051]
Embedded image

(10)
[Where Ar ₁₃ Represents an aryl group or a heterocyclic compound group having 4 to 20 carbon atoms involved in the conjugated bond. R is a substituent represented by the above formula (6) or a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group, and an alkylthio group; an aryl group having 6 to 18 carbon atoms and an aryloxy group; carbon It is preferably a group selected from the group consisting of a heterocyclic compound group of 4 to 14; and a cyano group. A represents the number of substituents, and is a number selected from an integer of 0 to 4. When the number of substituents a is plural, the substituents R may be the same as or different from each other. X ₁ Examples of the counter ion include halide ions. Ph is a phenyl group. ]
[0052]
In the synthesis of the polymeric fluorescent substance by the Wittig reaction, for example, a dialdehyde compound represented by the formula (11) and a diphosphonium salt compound represented by the formula (12) are reacted. Ar ₁₄ May be the same or different groups. Furthermore, if two or more kinds of dialdehyde compounds and / or two or more kinds of diphosphonium salt compounds are used, copolymers of all of them can be obtained.
[0053]
Embedded image
OHC-Ar ₁₄ -CHO (11)
[0054]
Embedded image

(11)
[Where Ar ₁₄ Is Ar in formula (2) _Three Is selected from the group represented by R is a substituent represented by the above formula (6) or a cyano group, an alkyl group having 1 to 20 carbon atoms, an alkoxy group, and an alkylthio group; an aryl group having 6 to 18 carbon atoms and an aryloxy group; It is preferably a group selected from the group consisting of -14 heterocyclic compound groups; and a cyano group. A represents the number of substituents, and is a number selected from an integer of 0 to 4. When the number of substituents a is plural, the substituents R may be the same as or different from each other. X ₂ Examples of the counter ion include halide ions. Ph is a phenyl group. ]
[0055]
In the synthesis of polymeric fluorescent substances, when a terminal group is to be a specific stable group, it is polymerized in the presence of a monofunctional compound, or after polymerization, it is reacted with a monofunctional compound that forms a terminal group. Just do it. This monofunctional compound is appropriately selected depending on the amount of monomers used in the reaction when polycondensation of two types of monomers with different reactions or functional groups. That is, in the Wittig reaction, a dialdehyde and a diphosphonium salt are reacted in the presence of a monofunctional compound, or a dialdehyde and a diphosphonium salt are reacted and polymerized, and then a monofunctional compound that subsequently forms a terminal group and What is necessary is just to make it react. Specifically, in the Wittig reaction, since the terminal is a phosphonium salt or an aldehyde, an aldehyde group or a phosphonium salt is selected for each.
[0056]
More specifically, a method for synthesizing an arylene vinylene copolymer, which is one example of the polymeric fluorescent substance of the present invention, will be described.
In order to obtain an arylene vinylene copolymer by Wittig reaction, specifically, first, a bis (halogenated methyl) compound, for example, 4,4′-bis (3-phenylpropyloxy) -3,3′- Bis (bromomethyl) biphenyl is reacted with triphenylphosphine in an N, N-dimethylformamide solvent to synthesize a phosphonium salt, and this is combined with a dialdehyde compound such as terephthalaldehyde using lithium ethoxide in ethyl alcohol. An example in which an arylene vinylene copolymer is obtained by a Wittig reaction to be condensed. If two or more kinds of diphosphonium salts and / or two or more kinds of dialdehyde compounds are reacted, a copolymer of all of them can be obtained.
[0057]
Furthermore, the terminal is obtained by a Wittig reaction in which diphosphonium salt and dialdehyde are condensed with lithium ethoxide in, for example, ethyl alcohol in the presence of a monoaldehyde compound such as 1-pyrenecarboxaldehyde in excess of diphosphonium salt. An example in which a copolymer substituted with is obtained is given.
Further, when these polymers are used as a light emitting material of an organic EL device, the purity affects the light emitting characteristics, and therefore it is desirable to perform purification treatment such as reprecipitation purification and fractionation by chromatography after synthesis.
[0058]
Regarding the structure of the organic EL device produced using the organic fluorescent material or polymer fluorescent substance of the present invention, the organic fluorescent substance of the present invention is provided in a light emitting layer provided between a pair of electrodes, at least one of which is transparent or translucent. If the light emitting material which consists of material or polymeric fluorescent substance is used, there will be no restriction | limiting in particular and a well-known structure will be employ | adopted.
For example, a light emitting layer comprising the organic fluorescent material or the polymeric fluorescent substance, or a mixture of the organic fluorescent material or the polymeric fluorescent substance and a charge transporting material (which means a generic term of an electron transporting material and a hole transporting material) A structure having a pair of electrodes on both sides of the light emitting layer, and an electron transport layer including an electron transport material between the cathode and the light emitting layer and / or a hole including a hole transport material between the anode and the light emitting layer. Examples in which the transport layer is laminated are exemplified.
[0059]
Further, the present invention includes a case where the light emitting layer and the charge transport layer are a single layer and a combination of a plurality of layers. Furthermore, for example, a light emitting material other than the polymeric fluorescent substance described below may be mixed and used in the light emitting layer. Moreover, it can also be set as the layer which disperse | distributed this organic fluorescent material or this polymeric fluorescent substance, and / or charge transport material to the high molecular compound.
[0060]
A charge transport material used together with the organic fluorescent material or polymeric fluorescent substance of the present invention, that is, an electron transport material or a hole transport material may be a known one, and is not particularly limited. Derivatives, arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives, etc. are exemplified, and electron transport materials include oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinones or derivatives thereof, naphthoquinones or derivatives thereof, anthraquinones or derivatives thereof , Tetracyanoanthraquinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof. That.
[0061]
Specifically, JP-A-63-70257, JP-A-63-175860, JP-A-2-135359, JP-A-2-135361, JP-A-2-209998, JP-A-3-37992, and JP-A-3-152184. The thing etc. which are described in the gazette are illustrated. The hole transport material is preferably a triphenyldiamine derivative, and the electron transport material is preferably an oxadiazole derivative, benzoquinone or a derivative thereof, anthraquinone or a derivative thereof, or a metal complex of 8-hydroxyquinoline or a derivative thereof. In particular, 4,4′-bis (N (3-methylphenyl) -N-phenylamino) biphenyl is used as the hole transport material, and 2- (4-biphenylyl) -5- (4-t is used as the electron transport material. -Butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone and tris (8-quinolinol) aluminum are preferred.
[0062]
Of these, one or both of an electron transporting compound and a hole transporting compound may be used simultaneously. These may be used singly or in combination of two or more.
In the case where a charge transport layer (which means a general term for a hole transport layer and an electron transport layer) is provided between the light emitting layer and the electrode, the charge transport layer may be formed using these charge transport materials.
[0063]
In addition, when the charge transport material is mixed with the light emitting layer, the amount of the charge transport material varies depending on the type of the compound used, etc. It may be determined as appropriate in consideration. Usually, it is preferably 1 to 40% by weight, more preferably 2 to 30% by weight, based on the light emitting material.
[0064]
Although it does not specifically limit as a well-known luminescent material which can be used with the organic fluorescent material or polymeric fluorescent substance of this invention, For example, a naphthalene derivative, anthracene or its derivative, perylene or its derivative; Polymethine type, xanthene type, coumarin type, cyanine Dyes such as the above systems; metal complexes of 8-hydroxyquinoline or derivatives thereof; aromatic amines, tetraphenylcyclopentadiene or derivatives thereof; or tetraphenylbutadiene or derivatives thereof can be used. Specifically, for example, known ones such as those described in JP-A-57-51781 and 59-194393 can be used.
[0065]
Next, a typical method for producing an organic EL element using the organic fluorescent material or polymer fluorescent material of the present invention will be described.
As a pair of electrodes composed of an anode and a cathode, a transparent or translucent electrode is formed by forming a transparent or translucent electrode on a transparent substrate such as glass or transparent plastic.
As the material for the anode, a conductive metal oxide film, a translucent metal thin film, or the like is used. Specifically, a film (NESA etc.) made of conductive glass made of indium tin oxide (ITO), tin oxide or the like, Au, Pt, Ag, Cu or the like is used. As a manufacturing method, a vacuum deposition method, a sputtering method, a plating method, or the like is used.
[0066]
Next, a light emitting layer containing the organic fluorescent material and / or polymer fluorescent material or the light emitting material and a charge transport material is formed on the anode as the light emitting material. As a forming method, a spin coating method, a casting method, a dipping method, a bar coating method, a roll coating method, a gravure coating method, a flexographic printing method, a spray coating method or the like using a melt, solution or mixed solution of these materials is used. The law is exemplified. It is particularly preferable to form a solution or a mixed solution by a coating method such as a spin coating method, a casting method, a dipping method, a bar coating method, a roll coating method, a gravure coating method, a flexographic printing method, or a spray coating method.
[0067]
The thickness of the light emitting layer is preferably 1 nm to 1 μm, more preferably 2 nm to 500 nm. In order to increase the current density and increase the light emission efficiency, the range of 5 to 200 nm is preferable.
In addition, when it thins by the apply | coating method, in order to remove a solvent preferably, it is heat-dried under the pressure of pressure reduction or an inert atmosphere, Preferably it is 30-300 degreeC, More preferably, it is 60-200 degreeC. desirable.
In addition, when laminating the light emitting layer and the charge transport layer, the hole transport layer is formed on the anode before the light emitting layer is provided by the above film forming method, and / or after the light emitting layer is provided. It is preferable to form an electron transport layer thereon.
[0068]
The method for forming the charge transport layer is not particularly limited, but it can be applied by vacuum deposition from a powder state, or spin coating method after being dissolved in a solution, casting method, dipping method, bar coating method, roll coating method, etc. Or a coating method such as a spin coating method, a casting method, a dipping method, a bar coating method, or a roll coating method after mixing and dispersing a polymer compound and a charge transport material in a solution state or a molten state. it can.
The polymer compound to be mixed is not particularly limited, but those that do not extremely inhibit charge transport are preferable, and those that do not strongly absorb visible light are preferably used.
Any charge transporting polymer compound can be used in the charge transport layer without being mixed with a low molecular charge transport material.
[0069]
Examples of the polymer compound include poly (N-vinylcarbazole), polyaniline or a derivative thereof, polythiophene or a derivative thereof, poly (p-phenylene vinylene) or a derivative thereof, poly (2,5-thienylene vinylene) or a derivative thereof. Derivatives, polycarbonate, polyacrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, polysiloxane and the like are exemplified. In view of easy film formation, it is preferable to use a coating method.
[0070]
As for the thickness of the charge transport layer, at least a thickness that does not cause pinholes is necessary. However, if the thickness is too large, the resistance of the device increases and a high driving voltage is required, which is not preferable. Therefore, the thickness of the charge transport layer is preferably 1 nm to 1 μm, more preferably 2 nm to 500 nm, and particularly preferably 5 nm to 200 nm.
[0071]
Next, an electrode is provided on the light emitting layer or the electron transport layer. This electrode becomes an electron injection cathode. The material is not particularly limited, but a material having a small ionization energy is preferable. For example, Al, In, Mg, Ca, Li, Mg—Ag alloy, In—Ag alloy, Mg—In alloy, Mg—Al alloy, Mg—Li alloy, Al—Li alloy, Al—Ca alloy, graphite thin film, etc. Is used. As a method for producing the cathode, a vacuum deposition method, a sputtering method, or the like is used.
[0072]
[Action]
In the present invention, the organic fluorescent material or the polymeric fluorescent substance is excellent as a light emitting material because it has a specific structure of 3,3′-biarylene, and thus becomes strong fluorescent, especially strong blue to green fluorescent. it is conceivable that. In addition, since a light emitting layer having excellent uniformity can be easily formed by a coating method, an organic EL element having a high light emission efficiency, a high heat resistance and a long life can be produced very easily.
[0073]
【Example】
Examples will be shown below for illustrating the present invention in more detail, but the present invention is not limited to these examples.
Here, for the number average molecular weight, the number average molecular weight in terms of polystyrene was determined by gel permeation chromatography (GPC) using chloroform as a solvent.
[0074]
Example 1
<Synthesis of organic fluorescent material 1>
3,3′-bis (bromomethyl) -4,4′-bis (3-phenylpropyloxy) biphenyl was reacted with triphenylphosphine in an N, N-dimethylformamide solvent to synthesize a phosphonium salt. 4.53 g of the obtained phosphonium salt and 1.96 g of 1-pyrenecarboxaldehyde were dissolved in 80 g of an ethanol / toluene (1/1) mixed solvent. 25 ml of a solution prepared by previously mixing 5 ml of a 12% lithium methoxide methanol solution and 20 ml of ethyl alcohol was added dropwise to the phosphonium salt / aldehyde ethanol / toluene mixed solution at room temperature. Then, it was made to react at room temperature for 4 hours.
[0075]
After standing overnight at room temperature, the precipitate was collected. Next, this precipitate was washed with ethanol, subsequently with an ethanol / water mixed solvent, and further washed with ethanol. This was dried under reduced pressure to obtain 2.6 g of an organic fluorescent material. This organic fluorescent material is called organic fluorescent material 1.
Regarding the structure of the organic fluorescent material 1 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0076]
Example 2
<Synthesis of polymeric fluorescent substance 1>
3,3′-bis (bromomethyl) -4,4′-bis (3-phenylpropyloxy) biphenyl was reacted with triphenylphosphine in an N, N-dimethylformamide solvent to synthesize a phosphonium salt. 5.66 g of the obtained phosphonium salt, 0.54 g of terephthalaldehyde, and 0.69 g of 1-pyrenecarboxaldehyde were dissolved in 80 g of an ethanol / toluene (1/1) mixed solvent. 25 ml of a solution prepared by previously mixing 5 ml of a 12% lithium methoxide methanol solution and 20 ml of ethyl alcohol was added dropwise to the phosphonium salt / aldehyde ethanol / toluene mixed solution at room temperature. Then, it was made to react at room temperature for 5 hours.
[0077]
After standing at room temperature overnight, the resulting precipitate was collected. The precipitate was then washed with ethanol. Next, this precipitate was dissolved in toluene, and ethanol was added thereto for reprecipitation purification. Reprecipitation purification was performed twice. This was dried under reduced pressure to obtain 1.4 g of a polymer. The obtained polymer is referred to as polymeric fluorescent substance 1.
The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 1 is 3.3 × 10 ^Three Met. Regarding the structure of the polymeric fluorescent substance 1 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0078]
Example 3
<Synthesis of polymeric fluorescent substance 2>
3,3′-bis (bromomethyl) -4,4′-bis (3-phenylpropyloxy) biphenyl was reacted with triphenylphosphine in an N, N-dimethylformamide solvent to synthesize a phosphonium salt. 5.66 g of the obtained phosphonium salt, 0.54 g of isophthalaldehyde, and 0.51 g of 1-pyrenecarboxaldehyde were dissolved in 80 g of an ethanol / toluene (1/1) mixed solvent. Next, 25 ml of a solution in which 5 ml of 12% lithium methoxide methanol solution and 20 ml of ethyl alcohol were mixed in advance in an ethanol / toluene mixed solution of the phosphonium salt and aldehyde was dropped at room temperature. Then, it was made to react at room temperature for 5 hours.
[0079]
After standing at room temperature overnight, the resulting precipitate was collected. The precipitate was then washed with ethanol. Next, this precipitate was dissolved in toluene, and ethanol was added thereto for reprecipitation purification. Reprecipitation purification was performed twice. This was dried under reduced pressure to obtain 1.7 g of a polymer. The obtained polymer is referred to as polymeric fluorescent substance 2.
The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 2 is 2.1 × 10 ^Three Met. Regarding the structure of the polymeric fluorescent substance 2 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0080]
Example 4
<Synthesis of polymeric fluorescent substance 3>
3,3′-bis (bromomethyl) -4,4′-bis (3-phenylpropyloxy) biphenyl was reacted with triphenylphosphine in an N, N-dimethylformamide solvent to synthesize a phosphonium salt. 4.53 g of the obtained phosphonium salt, 0.96 g of a phosphonium salt of 2,5-dioctyloxy-p-xylylene dichloride, 0.58 g of terephthalaldehyde, and 1-pyrenecarboxy obtained by synthesis in the same manner as described above. 0.35 g of aldehyde was dissolved in 80 g of a mixed solvent of ethanol / toluene (1/1). Next, 25 ml of a solution in which 5 ml of 12% lithium methoxide methanol solution and 20 ml of ethyl alcohol were mixed in advance in an ethanol / toluene mixed solution of the phosphonium salt and aldehyde was dropped at room temperature. Then, it was made to react at room temperature for 5 hours.
[0081]
After standing at room temperature overnight, the resulting precipitate was collected. The precipitate was then washed with ethanol. Next, this precipitate was dissolved in toluene, and ethanol was added thereto for reprecipitation purification. Reprecipitation purification was performed twice. This was dried under reduced pressure to obtain 1.4 g of a polymer. The resulting polymer is referred to as polymeric fluorescent substance 3.
The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 3 is 2.7 × 10 ^Three Met. Regarding the structure of the polymeric fluorescent substance 3 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0082]
Example 5
<Synthesis of polymeric fluorescent substance 4>
3,3′-bis (bromomethyl) -4,4′-bis (3-phenylpropyloxy) biphenyl was reacted with triphenylphosphine in an N, N-dimethylformamide solvent to synthesize a phosphonium salt. 2.87 g of the obtained phosphonium salt, 2.87 g of phosphonium salt of 2,5-dioctyloxy-p-xylylene dichloride, 0.58 g of terephthalaldehyde, and 1-pyrenecarboxaldehyde obtained by synthesizing in the same manner. 0.35 g was dissolved in 80 g of ethanol / toluene (1/1) mixed solvent. Next, 25 ml of a solution in which 5 ml of 12% lithium methoxide methanol solution and 20 ml of ethyl alcohol were mixed in advance in an ethanol / toluene mixed solution of the phosphonium salt and aldehyde was dropped at room temperature. Then, it was made to react at room temperature for 5 hours.
[0083]
After standing at room temperature overnight, the resulting precipitate was collected. The precipitate was then washed with ethanol. Next, this precipitate was dissolved in toluene, and ethanol was added thereto for reprecipitation purification. Reprecipitation purification was performed twice. This was dried under reduced pressure to obtain 1.4 g of a polymer. The resulting polymer is referred to as polymeric fluorescent substance 4.
The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 4 is 2.9 × 10 ^Three Met. Regarding the structure of the polymeric fluorescent substance 4 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0084]
Example 6
<Synthesis of polymeric fluorescent substance 5>
3,3′-bis (bromomethyl) -2,2′-bis (3-phenylpropyloxy) -1,1′-binaphthyl is reacted with triphenylphosphine in N, N-dimethylformamide solvent to give a phosphonium salt. Synthesized. 3.94 g of the obtained phosphonium salt, 0.76 g of phosphonium salt of 2,5-dioctyloxy-p-xylylene dichloride, 0.47 g of terephthalaldehyde, and 1-pyrenecarboxaldehyde obtained by synthesizing in the same manner. 0.25 g was dissolved in 80 g of ethanol / toluene (1/1) mixed solvent. Next, 25 ml of a solution in which 5 ml of 12% lithium methoxide methanol solution and 20 ml of ethyl alcohol were mixed in advance in an ethanol / toluene mixed solution of the phosphonium salt and aldehyde was dropped at room temperature. Then, it was made to react at room temperature for 5 hours.
[0085]
100 ml of ethanol was added to this reaction solution and left overnight at room temperature, and then the produced precipitate was recovered. The precipitate was then washed with ethanol. After washing, this precipitate was dissolved in toluene, and ethanol was added thereto for reprecipitation purification. Reprecipitation purification was performed twice. This was dried under reduced pressure to obtain 1.3 g of a polymer. The resulting polymer is referred to as polymeric fluorescent substance 5.
The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 5 is 3.2 × 10. ^Three Met. Regarding the structure of the polymeric fluorescent substance 5 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0086]
Example 7
<Synthesis of polymeric fluorescent substance 6>
3,3′-bis (bromomethyl) -4,4′-bis (3-phenylpropyloxy) biphenyl was reacted with triphenylphosphine in an N, N-dimethylformamide solvent to synthesize a phosphonium salt. 6.45 g of the obtained phosphonium salt, 1.36 g of phosphonium salt of 2,5-dioctyloxy-p-xylylene dichloride, 0.72 g of terephthalaldehyde and 4- (N, N-diphenylamino) benzaldehyde (0.98 g) was dissolved in an ethanol / toluene (1/1) mixed solvent (120 g). Next, 40 ml of a solution prepared by previously mixing 8 ml of 12% lithium methoxide methanol solution and 32 ml of ethyl alcohol was added dropwise to the ethanol / toluene mixed solution of the phosphonium salt and aldehyde at room temperature. Then, it was made to react at room temperature for 3 hours.
[0087]
After standing overnight at room temperature, the resulting precipitate was collected. The precipitate was then washed with ethanol. After washing, this precipitate was dissolved in toluene, and ethanol was added thereto for reprecipitation purification. Reprecipitation purification was performed twice. This was dried under reduced pressure to obtain 2.5 g of a polymer. The obtained polymer is referred to as polymeric fluorescent substance 6.
The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 6 is 3.2 × 10 ^Three Met. Regarding the structure of the polymeric fluorescent substance 6 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0088]
Example 8
<Synthesis of polymeric fluorescent substance 7>
3,3′-bis (bromomethyl) -4,4′-bis (3-phenylpropyloxy) biphenyl was reacted with triphenylphosphine in an N, N-dimethylformamide solvent to synthesize a phosphonium salt. 2.87 g of the obtained phosphonium salt, 2.87 g of phosphonium salt of 2,5-dioctyloxy-p-xylylene dichloride, 0.58 g of terephthalaldehyde and 4- (N, N-diphenylamino) benzaldehyde (0.41 g) was dissolved in an ethanol / toluene (1/1) mixed solvent (80 g). Next, 25 ml of a solution in which 5 ml of 12% lithium methoxide methanol solution and 20 ml of ethyl alcohol were mixed in advance in an ethanol / toluene mixed solution of the phosphonium salt and aldehyde was dropped at room temperature. Then, it was made to react at room temperature for 3 hours.
[0089]
After standing overnight at room temperature, the resulting precipitate was collected. The precipitate was then washed with ethanol. After washing, this precipitate was dissolved in toluene, and ethanol was added thereto for reprecipitation purification. Reprecipitation purification was performed twice. This was dried under reduced pressure to obtain 2.5 g of a polymer. The resulting polymer is referred to as polymeric fluorescent substance 7.
The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 7 is 4.2 × 10 ^Three Met. Regarding the structure of the polymeric fluorescent substance 7 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0090]
Comparative Example 1
<Synthesis of organic fluorescent material 2>
Instead of the phosphonium salt obtained by reacting 3,3′-bis (bromomethyl) -4,4′-bis (3-phenylpropyloxy) biphenyl with triphenylphosphine in N, N-dimethylformamide solvent, 2 , 5-Dioctyloxy-p-xylylene dichloride except for using 3.82 g of phosphonium salt, reaction, purification and drying were carried out in the same manner as in Example 1 to obtain 2 g of an organic fluorescent material. The obtained compound is referred to as organic fluorescent material 2.
Regarding the structure of the organic fluorescent material 2 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0091]
Comparative Example 2
<Synthesis of polymer light emitter 8>
Instead of the phosphonium salt obtained by reacting 3,3′-bis (bromomethyl) -4,4′-bis (3-phenylpropyloxy) biphenyl with triphenylphosphine in N, N-dimethylformamide solvent, 2 , 5-Dioctyloxy-p-xylylene dichloride except for using 3.8 g of phosphonium salt was polymerized, purified and dried in the same manner as in Example 2 to obtain 1.7 parts by weight of a polymeric fluorescent substance. . The resulting polymer is referred to as polymeric fluorescent substance 8.
The number average molecular weight in terms of polystyrene of the polymeric fluorescent substance 8 is 3.7 × 10 ^Three Met. Regarding the structure of the polymeric fluorescent substance 8 ¹ This was confirmed by 1 H-NMR and IR spectrum.
[0092]
Example 9
<Measurement of absorption spectrum and fluorescence spectrum>
Organic fluorescent materials 1 and 2 and polymeric fluorescent substances 1 to 8 could be easily dissolved in chloroform. The 0.4% chloroform solution was spin-coated on a quartz plate to form a polymer thin film. The ultraviolet-visible absorption spectrum and fluorescence spectrum of this thin film were measured using a self-recording spectrophotometer UV365 manufactured by Shimadzu Corporation and a fluorescence spectrophotometer 850 manufactured by Hitachi, Ltd., respectively. Tables 1 and 2 show the quantum yields of the obtained fluorescence. The organic fluorescent material 1 was stronger than the organic fluorescent material 2 as shown in Table 1. Moreover, as shown in Table 2, the polymeric fluorescent substances 1 to 7 were stronger than the polymeric fluorescent substance 8.
[0093]
Example 10
<Evaluation of heat resistance by differential scanning calorimetry (DSC)>
Thermal analysis of the polymeric fluorescent substances 1 to 8 was performed using a differential scanning calorimeter DSC200 manufactured by Seiko Electronics. In both cases, an endothermic peak that seems to correspond to the softening of the polymer was observed. As shown in Table 2, polymeric fluorescent substances 1 to 7 showed endothermic peaks at a higher temperature than polymeric fluorescent substance 8.
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[Table 1]

[0095]
[Table 2]

[0096]
Example 11
<Creation and evaluation of device>
A glass substrate with an ITO film having a thickness of 40 nm was formed by sputtering using a 1 wt% dichloroethane solution of poly (N-vinylcarbazole) to a thickness of 60 nm by spin coating. Next, a 2 wt% mesitylene solution of polymeric fluorescent substance 1 obtained in Example 2 was used to form a film with a thickness of 60 nm by spin coating. On top of that, 40 nm of tris (8-quinolinol) aluminum was deposited as an organic layer containing an electron transport material. Finally, an aluminum lithium alloy (Al: Li = about 200: 1 weight ratio) was vapor-deposited with a thickness of 100 nm as a cathode thereon to produce an organic EL device. The degree of vacuum at the time of vapor deposition is 1 × 10 ^-Five It was below Torr. When a voltage of 10 V was applied to the device, EL light emission having the same spectrum as the fluorescence of the polymeric fluorescent substance 1 was observed.
Similarly, when the organic fluorescent material 1 obtained in Example 1 and the polymeric fluorescent substances 2 to 7 obtained in Examples 3 to 8 are used, EL emission having the same spectrum as each fluorescence spectrum is observed. .
[0097]
【The invention's effect】
The organic fluorescent material and / or polymeric fluorescent substance of the present invention combines short-wave fluorescence, particularly strong blue-green fluorescence and thermal stability, is solvent-soluble, and is excellent as a material for organic EL devices. Yes. In addition, an organic EL element using the organic phosphor and / or the polymer phosphor is easy to produce by a coating method, and exhibits excellent light emission characteristics and heat resistance. Therefore, a planar light source as a backlight, It can be preferably used as a device such as a flat panel display.

Claims (8)

Polymer fluorescent substance which has visible fluorescence in a solid state and has a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁷ , contains one or more kinds of repeating units represented by the following formula (5), and repeats them A polymeric fluorescent substance, wherein the total of the units is 10 mol% or more and 100 mol% or less of all repeating units.

[Ar ₆ represents an arylene group or a heterocyclic compound group having 4 to 20 carbon atoms involved in the conjugated bond. R _{7 to} R ₁₀ are each independently selected from the group consisting of hydrogen, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a heterocyclic compound group having 4 to 20 carbon atoms, and a cyano group. Indicates a group. R _{11 to} R ₁₈ each independently represent hydrogen or a substituent represented by the following formula (6).

(Here, R ₁₉ represents a hydrocarbon group having 1 to ₂₀ carbon atoms. R ₂₀ represents a hydrocarbon group having 1 to ₂₀ carbon atoms, an aryl group having 4 to 20 carbon atoms involved in a conjugated bond, and X is a group selected from the group consisting of a heterocyclic compound group and an aliphatic cyclic hydrocarbon group having 6 to 20 carbon atoms constituting the ring, X is —O—, —S—, —CO—, — A group selected from the group consisting of CO-O- and -O-CO-, wherein m and n are each independently 0 or 1.)] Between at least one of a pair of an anode and a cathode is transparent or semi-transparent electrode, an organic electroluminescent device having at least a light emitting layer, characterized in that the light emitting layer comprises a polymeric fluorescent substance according to claim 1 Symbol placement An organic electroluminescence element. In the organic electroluminescent device having at least a light emitting layer and a hole transport layer between a pair of anode and cathode electrodes, at least one of which is transparent or translucent, the light emitting layer and / or the hole transport layer are claimed in claim 1. the organic electroluminescence device which comprises a polymeric fluorescent substance of the serial placement. 4. The organic electroluminescent device according to claim 3 , wherein a layer containing a hole transporting compound is provided adjacent to the light emitting layer between the anode and the light emitting layer. At least one of between the electrode made of a transparent or a pair of anode and cathode is translucent, an organic electroluminescence device having at least a light emitting layer and an electron transport layer, light emitting layer and / or electron transport layer is placing claim 1 Symbol An organic electroluminescence device comprising a polymer fluorescent material of: 6. The organic electroluminescence device according to claim 5 , wherein a layer containing an electron transporting compound is provided adjacent to the light emitting layer between the cathode and the light emitting layer . In an organic electroluminescence device having at least a hole transport layer, a light-emitting layer and an electron transport layer between a pair of anodes and cathodes, at least one of which is transparent or translucent, the hole transport layer, light-emitting layer, electron the organic electroluminescent device in which at least one layer, characterized in that it comprises a polymeric fluorescent substance according to claim 1 Symbol placement of the transport layer. A layer containing an electron transporting compound adjacent to the light emitting layer between the cathode and the light emitting layer, and a layer containing a hole transporting compound adjacent to the light emitting layer between the anode and the light emitting layer. 8. The organic electroluminescence device according to claim 7 , wherein the organic electroluminescence device is provided.