JP4048653B2 - Polymer phosphor and polymer light emitting device - Google Patents

Description

・・・・・（１）
〔ここで、Ａｒ₁、Ａｒ₂は、それぞれ独立に、共役結合に関与する炭素原子数が６個以上６０個以下からなるアリーレン基、または共役結合に関与する炭素原子数が４個以上６０個以下からなる複素環化合物基を示す。Ｒ₁〜Ｒ₈は、それぞれ独立に、水素原子または下記式（２）で示される置換基を示す。Ｒ₉〜Ｒ₁₀は、それぞれ独立に水素原子、炭素数１〜２０のアルキル基、炭素数６〜６０のアリール基、炭素数４〜６０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。ｎは、０または１である。〕
【化６】
−（Ｒ₁₁）_l−（Ｘ）_m−Ｒ₁₂ ・・・・（２）
〔ここで、Ｒ₁₁は、炭素数１〜２０の炭化水素基を示す。Ｒ₁₂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６〜６０のアリール基、共役結合に関与する炭素原子数が４〜６０の複素環化合物基、ならびに環を構成する炭素原子数が６〜６０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。ｌおよびｍは、それぞれ独立に０または１である。〕また、本発明は、〔２〕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１０⁸である高分子蛍光体において、上記式（１）および下記式（３）で示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全繰り返し単位の２モル％以上、かつ式（１）および式（３）で示される繰り返し単位の合計が全繰り返し単位の５０モル％以上１００モル％以下である高分子蛍光体に関するものである。
【化７】

・・・・・（３）
〔ここで、Ａｒ₃は、共役結合に関与する炭素原子数が６個以上６０個以下からなるアリーレン基、または共役結合に関与する炭素原子数が４個以上６０個以下からなる複素環化合物基を示す。Ｒ₁₃、Ｒ₁₄は、それぞれ独立に水素原子、炭素数１〜２０のアルキル基、炭素数６〜６０のアリール基、炭素数４〜６０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。ｋは、０または１である。〕
さらに本発明は、〔３〕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１０⁸である高分子蛍光体において、下記式（４）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％以下である高分子蛍光体に関するものである。
【化８】

・・・・（４）
〔ここで、Ａｒ₄、Ａｒ₅、Ａｒ₆は、それぞれ独立に、共役結合に関与する炭素原子数が６個以上６０個以下からなるアリーレン基、または共役結合に関与する炭素原子数が４個以上６０個以下からなる複素環化合物基を示す。 Ｒ₁₅〜Ｒ₂₂は、水素原子または上記式（２）で示される置換基を示す。Ｒ₂₃〜Ｒ₂₆は、それぞれ独立に水素原子、炭素数１〜２０のアルキル基、炭素数６〜６０のアリール基、炭素数４〜６０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。ｉおよびｊは、それぞれ独立に０または１である。〕
【００１２】
次に、本発明は、〔４〕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高分子発光素子において、該発光層が〔１〕〜〔３〕記載の高分子蛍光体を含む高分子発光素子に関するものである。
【００１３】
【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〔１〕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１０⁸である高分子蛍光体において、前記式（１）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５０モル％以上１００モル％以下であることを特徴とする。また、本発明〔２〕の高分子蛍光体は、前記式（１）で示される繰り返し単位と前記式（３）で示される繰り返し単位とをそれぞれ１種類以上含み含み、前記式（１）で示される繰り返し単位が全繰り返し単位の２モル％以上で、かつ前記式（１）で示される繰り返し単位と、前記式（３）で示される繰り返し単位との合計が全繰り返し単位の５０モル％以上１００モル％以下であることを特徴とする。さらに、本発明〔３〕の高分子蛍光体は、前記式（４）で示される繰り返し単位を１種類以上含み、その合計が全繰り返し単位の１０モル％以上１００モル％以上であることを特徴とする。
【００１４】
該式（１）におけるＡｒ₁、Ａｒ₂、式（３）におけるＡｒ₃、式（４）におけるＡｒ₄、Ａｒ₅、Ａｒ₆は、共役結合に関与する炭素原子数が６個以上６０個以下からなるアリーレン基、または共役結合に関与する炭素原子数が４個以上６０個以下からなる複素環化合物基である。
【００１５】
具体的には、該Ａｒ₁〜Ａｒ₆としては、それぞれ独立に、下記に示す芳香族化合物基もしくはその誘導体基が例示される。
【００１６】
【化９】

【化１０】

【化１１】

【化１２】

〔ここでＲは、それぞれ独立に、水素原子、炭素数１〜２０のアルキル基、炭素数１〜２０のアルコキシ基、炭素数１〜２０のアルキルチオ基、炭素数１〜６０のアルキルシリル基、炭素数１〜４０のアルキルアミノ基、炭素数６〜６０のアリール基、炭素数６〜６０のアリールオキシ基、炭素数７〜６０のアリールアルキル基、炭素数７〜６０のアリールアルコキシ基、炭素数８〜６０のアリールアルケニル基、炭素数８〜６０のアリールアルキニル基、炭素数６〜６０のアリールアミノ基、炭素数４〜６０の複素環化合物基、シアノ基からなる群から選ばれる基を示す。〕
【００１７】
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、アントラセン−９，１０−ジイル基、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、１，３−ナフタレニレン基、３，３’−ビフェニレン基、２，４−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。
上記の例において、１つの構造式中に複数のＲを有しているが、それらは同一であってもよいし、異なる基であってもよく、それぞれ独立に選択される。Ａｒ₂が複数の置換基を有する場合、それらは同一であってもよいし、それぞれ異なっていてもよい。溶媒への溶解性を高めるためには、水素原子でない置換基を１つ以上有していることが好ましく、また置換基を含めた繰り返し単位の形状の対称性が少ないことが好ましい。
【００１８】
Ａｒ₁〜Ａｒ₆として、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。合成の容易さという観点からは、Ａｒ₁とＡｒ₂、あるいはＡｒ₄とＡｒ₅はそれぞれ同じものであることが好ましい。
【００１９】
Ｒが、水素原子またはシアノ基以外の置換基である場合について述べると、炭素数１〜２０のアルキル基としては、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、ノニル基、デシル基、ラウリル基などが挙げられ、ペンチル基、ヘキシル基、オクチル基、デシル基が好ましい。
【００２０】
炭素数１〜２０のアルコキシ基としては、メトキシ基、エトキシ基、プロピルオキシ基、ブトキシ基、ペンチルオキシ基、ヘキシルオキシ基、ヘプチルオキシ基、オクチルオキシ基、ノニルオキシ基、デシルオキシ基、ラウリルオキシ基などが挙げられ、ペンチルオキシ基、ヘキシルオキシ基、オクチルオキシ基、デシルオキシ基が好ましい。
【００２１】
炭素数１〜２０のアルキルチオ基としては、メチルチオ基、エチルチオ基、プロピルチオ基、ブチルチオ基、ペンチルチオ基、ヘキシルチオ基、ヘプチルチオ基、オクチルチオ基、ノニルチオ基、デシルチオ基、ラウリルチオ基などが挙げられ、ペンチルチオ基、ヘキシルチオ基、オクチルチオ基、デシルチオ基が好ましい。
【００２２】
炭素数１〜６０のアルキルシリル基としては、メチルシリル基、エチルシリル基、プロピルシリル基、ブチルシリル基、ペンチルシリル基、ヘキシルシリル基、ヘプチルシリル基、オクチルシリル基、ノニルシリル基、デシルシリル基、ラウリルシリル基、トリメチルシリル基、エチルジメチルシリル基、プロピルジメチルシリル基、ブチルジメチルシリル基、ペンチルジメチルシリル基、ヘキシルジメチルシリル基、ヘプチルジメチルシリル基、オクチルジメチルシリル基、ノニルジメチルシリル基、デシルジメチルシリル基、ラウリルジメチルシリル基などが挙げられ、ペンチルシリル基、ヘキシルシリル基、オクチルシリル基、デシルシリル基、ペンチルジメチルシリル基、ヘキシルジメチルシリル基、オクチルジメチルシリル基、デシルジメチルシリル基が好ましい。
【００２３】
炭素数１〜４０のアルキルアミノ基としては、メチルアミノ基、ジメチルアミノ基、エチルアミノ基、プロピルアミノ基、ブチルアミノ基、ペンチルアミノ基、ヘキシルアミノ基、ヘプチルアミノ基、オクチルアミノ基、ノニルアミノ基、デシルアミノ基、ラウリルアミノ基などが挙げられ、ペンチルアミノ基、ヘキシルアミノ基、オクチルアミノ基、デシルアミノ基が好ましい。
【００２４】
炭素数６〜６０のアリール基としては、フェニル基、Ｃ₁〜Ｃ₁₂アルコキシフェニル基（Ｃ₁〜Ｃ₁₂は、炭素数１〜１２であることを示す。以下も同様である。）、Ｃ₁〜Ｃ₁₂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、 Ｃ₁〜Ｃ₁₂アルコキシフェニル基、Ｃ₁〜Ｃ₁₂アルキルフェニル基が好ましい。
【００２５】
炭素数６〜６０のアリールオキシ基としては、フェノキシ基、Ｃ₁〜Ｃ₁₂アルコキシフェノキシ基、Ｃ₁〜Ｃ₁₂アルキルフェノキシ基、１−ナフチルオキシ基、２−ナフチルオキシ基などが例示され、 Ｃ₁〜Ｃ₁₂アルコキシフェノキシ基、Ｃ₁〜Ｃ₁₂アルキルフェノキシ基が好ましい。
【００２６】
炭素数６〜６０のアリールアルキル基としては、フェニル−Ｃ₁〜Ｃ₁₂アルキル基、Ｃ₁〜Ｃ₁₂アルコキシフェニル−Ｃ₁〜Ｃ₁₂アルキル基、Ｃ₁〜Ｃ₁₂アルキルフェニル−Ｃ₁〜Ｃ₁₂アルキル基、１−ナフチル−Ｃ₁〜Ｃ₁₂アルキル基、２−ナフチル−Ｃ₁〜Ｃ₁₂アルキル基などが例示され、Ｃ₁〜Ｃ₁₂アルコキシフェニル−Ｃ₁〜Ｃ₁₂アルキル基、Ｃ₁〜Ｃ₁₂アルキルフェニル−Ｃ₁〜Ｃ₁₂アルキル基が好ましい。
【００２７】
炭素数６〜６０のアリールアルコキシ基としては、フェニル−Ｃ₁〜Ｃ₁₂アルコキシ基、Ｃ₁〜Ｃ₁₂アルコキシフェニル−Ｃ₁〜Ｃ₁₂アルコキシ基、Ｃ₁〜Ｃ₁₂アルキルフェニル−Ｃ₁〜Ｃ₁₂アルコキシ基、１−ナフチル−Ｃ₁〜Ｃ₁₂アルコキシ基、２−ナフチル−Ｃ₁〜Ｃ₁₂アルコキシ基などが例示され、Ｃ₁〜Ｃ₁₂アルコキシフェニル−Ｃ₁〜Ｃ₁₂アルコキシ基、Ｃ₁〜Ｃ₁₂アルキルフェニル−Ｃ₁〜Ｃ₁₂アルコキシ基が好ましい。
【００２８】
炭素数６〜６０のアリールアミノ基としては、フェニルアミノ基、ジフェニルアミノ基、Ｃ₁〜Ｃ₁₂アルコキシフェニルアミノ基、ジ（Ｃ₁〜Ｃ₁₂アルコキシフェニル）アミノ基、ジ（Ｃ₁〜Ｃ₁₂アルキルフェニル）アミノ基、１−ナフチルアミノ基、２−ナフチルアミノ基などが例示され、Ｃ₁〜Ｃ₁₂アルキルフェニルアミノ基、ジ（Ｃ₁〜Ｃ₁₂アルキルフェニル）アミノ基が好ましい。
【００２９】
炭素数４〜６０の複素環化合物基としては、チエニル基、Ｃ₁〜Ｃ₁₂アルキルチエニル基、ピロリル基、フリル基、ピリジル基、Ｃ₁〜Ｃ₁₂アルキルピリジル基などが例示され、チエニル基、Ｃ₁〜Ｃ₁₂アルキルチエニル基、ピリジル基、Ｃ₁〜Ｃ₁₂アルキルピリジル基が好ましい。
【００３０】
Ｒの例のうち、アルキル鎖を含む置換基においては、それらは直鎖、分岐または環状のいずれかまたはそれらの組み合わせであってもよく、直鎖でない場合、例えば、イソアミル基、２−エチルヘキシル基、３，７−ジメチルオクチル基、シクロヘキシル基、４−Ｃ₁〜Ｃ₁₂アルキルシクロヘキシル基などが例示される。
【００３１】
式（１）のＲ₉〜Ｒ₁₀、式（３）のＲ₁₃〜Ｒ₁₄、式（４）のＲ₂₃〜Ｒ₂₆は、それぞれ独立に水素原子、炭素数１〜２０のアルキル基、炭素数６〜６０のアリール基、炭素数４〜６０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である。
【００３２】
具体的には、炭素数１〜２０のアルキル基としては、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、４−Ｃ₁〜Ｃ₁₄アルコキシフェニル基（Ｃ₁〜Ｃ₁₄は、炭素数が１〜１４であることを示す。以下の記載もこれに準じる。）、４−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−キノリル基などが例示される。
【００３３】
式（１）のＲ₁〜Ｒ₈、式（４）のＲ₁₅〜Ｒ₂₂は、水素原子または前記式（２）で示される置換基である。
【００３４】
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５０モル％以上１００モル％以下であり、繰り返し単位の構造にもよるが、６０モル％以上１００モル％以下であることが好ましく、７０モル％以上１００モル％以下であることがさらに好ましい。該式（１）および式（３）で示される繰り返し単位からなる重合体の場合は、該式（１）で示される繰り返し単位を２モル％以上含む共重合体であり、式（１）で示される繰り返し単位は２０モル％以下であることが好ましく、式（１）で示される繰り返し単位と式（３）で示される繰り返し単位との合計は、全繰り返し単位の５０モル％以上１００モル％以下であり、繰り返し単位の構造にもよるが、６０モル％以上１００モル％以下であることが好ましく、７０モル％以上１００モル％以下であることがさらに好ましい。また、繰り返し単位が式（４）で示される場合、式（４）で示される繰り返し単位のみからなる重合体以外の場合は、該式（４）で示される繰り返し単位を１０モル％以上含む共重合体であり、５０モル％以上であることが好ましく、７０モル％以上であることがさらに好ましい。式（１）、（３）、（４）で示される繰り返し単位以外の共重合相手としては、上記の条件を満たしていれば特に限定されないが、溶解性および／または蛍光強度を低下させることのない構造を有するものが好ましい。
【００３５】
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、特開平９−４５４７８号公報の化１０に記載の置換基およびそれらとビニレン基が結合した基等が例示される。
【００３６】
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１０³〜１０⁸であり、溶解性および成膜性の観点からは、１０⁴〜１０⁶が好ましく、５×１０⁴〜１０⁶が特に好ましい。それらの重合度は、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。
【００３７】
なお、本発明の高分子蛍光体は、式（１）で示される繰り返し単位の合計が全繰り返し単位の５０モル％以上である重合体または共重合体、式（１）および式（３）で示される繰り返し単位の合計が全繰り返し単位の５０モル％以上である共重合体、式（４）で示される繰り返し単位が全繰り返し単位の１０モル％以上である重合体または共重合体である。該高分子蛍光体が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。
【００３８】
本発明の高分子蛍光体は、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。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。
高分子発光素子作成の際に、これらの有機溶媒可溶性の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。
【００３９】
本発明の高分子蛍光体の製造方法としては、炭素−炭素二重結合形成反応により、式（１）または式（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。また、高分子量化が容易という点では、脱ハロゲン化水素法が好ましい。
【００４０】
Ｗｉｔｔｉｇ反応での高分子蛍光体の合成では、例えば式（５）で示すジアルデヒド化合物と式（６）で示すジホスホニウム塩化合物を反応させる。この場合、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。
【化１３】
ＯＨＣ−Ａｒ₇−ＣＨＯ ・・・・（５）
【化１４】

・・・・（６）
〔ここで、Ａｒ₇は、式（３）中のＡｒ₃または式（４）中のＡｒ₆で示される基から選ばれ、また、Ａｒ₈、Ａｒ₉は、式（１）中のＡｒ₁、Ａｒ₂または式（４）中のＡｒ₄、Ａｒ₅で示される基から選ばれる。Ｘは、対イオンで塩化物イオン、臭化物イオンなどのハロゲン化物イオンが例示される。Ｐｈは、フェニル基である。〕
【００４１】
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、１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１官能化合物と反応させればよい。この１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、１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１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。
【００４２】
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、フルオレン誘導体のビス（ハロゲン化メチル）化体を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。
【００４３】
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、ジホスホニウム塩をジアルデヒドに対して、等モルより過剰に用いる条件で、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、これらの重合体を高分子ＬＥＤ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。
【００４４】
本発明の高分子蛍光体を用いて作成される高分子ＬＥＤ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、該高分子蛍光体からなる発光層、もしく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。
【００４５】
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。
【００４６】
本発明の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。
【００４７】
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。
【００４８】
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。
【００４９】
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。
【００５０】
本発明の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。
【００５１】
次に、本発明の高分子蛍光体を用いた高分子ＬＥＤ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。
【００５２】
次いで、この陽極上に発光材料として、上記高分子蛍光体、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。
【００５３】
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。
【００５４】
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。
【００５５】
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。
【００５６】
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。
【００５７】
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、また金属薄膜を熱圧着するラミネート法等が用いられる。
陰極作製後、該高分子ＬＥＤを保護する保護層を装着していてもよい。該高分子ＬＥＤを長期安定的に用いるためには、素子を外部から保護するために、保護層および／または保護カバーを装着することが好ましい。
該保護層としては、高分子化合物、金属酸化物、金属フッ化物、金属ホウ化物などを用いることができる。また、保護カバーとしては、ガラス板、表面に低透水率処理を施したプラスチック板などを用いることができ、該カバーを熱効果樹脂や光硬化樹脂で素子基板と貼り合わせて密閉する方法が好適に用いられる。スペーサーを用いて空間を維持すれば、素子が傷つくのを防ぐことが容易である。該空間に窒素やアルゴンのような不活性なガスを封入すれば、陰極の酸化を防止することができ、さらに酸化バリウム等の乾燥剤を該空間内に設置することにより製造工程で吸着した水分が素子にタメージを与えるのを抑制することが容易となる。これらのうち、いずれか１つ以上の方策をとることが好ましい。
本発明の高分子ＬＥＤを用いて面状の素子を得るためには、面状の陽極と陰極が重なり合うように配置すればよい。また、パターン状の発光を得るためには、前記面状の発光素子の表面にパターン状の窓を設けたマスクを設置する方法、非発光部の有機層を極端に厚く形成し実質的に非発光とする方法、陽極または陰極のいずれか一方、または両方の電極をパターン状に形成する方法が挙げられる。更に、ドットマトリックス素子とするためには、陽極と陰極をともにストライプ状に形成して直交するように配置する方法、片方の電極をＴＦＴで選択駆動できるようにする方法が挙げられる。複数の種類の発光色の異なる高分子蛍光体を塗り分けることにより、部分カラー表示、マルチカラー表示が可能となる。
【００５８】
【作用】
本発明において、該高分子蛍光体が発光材料として優れているのは、フルオレンとジスチリルの特定の構造を有するので強い蛍光を示すものと考えられる。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、長寿命の高分子ＬＥＤを作製することができる。
【００５９】
【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。
【００６０】
実施例１
＜高分子蛍光体１の合成＞
９、９−ビス｛（３’−ブロモメチル−４’−オクチルオキシ）フェニル｝フルオレンを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５．１４ｇとテレフタルアルデヒド０．５４ｇとを、エタノール１００ｍｌに溶解させた。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との混合溶液をホスホニウム塩とアルデヒドのエタノール溶液に滴下した。引き続き、室温で３時間反応させた。
【００６１】
エタノール１００ｍｌを添加し、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後、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。これを減圧乾燥して、重合体０．５ｇ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、３．１×１０³であった。該高分子蛍光体１の構造については¹Ｈ−ＮＭＲ、ＩＲスペクトルで相当するスペクトルを得た。
【００６２】
＜吸収スペクトル、蛍光スペクトルの測定＞
高分子蛍光体１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。吸収のピーク波長は３６８．５ｎｍであり、蛍光のピーク波長は４６４ｎｍで、青色だった。
【００６３】
＜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の熱分析を行った。高分子の軟化に対応すると思われる吸熱ピークが４３℃に見られた。
【００６４】
実施例２
＜素子の作成および評価＞
スパッタリングによって、２００ｎｍの厚みでＩＴＯ膜を付けたガラス基板に、実施例１で得た高分子蛍光体１のトルエン溶液を用いて、スピンコートにより８０ｎｍの厚みで成膜した。その上に真空度８×１０^-6Ｔｏｒｒ以下でフッ化リチウムを２．５ｍｍ、次いでアルミニウムを５０ｎｍ蒸着して陰極を形成し、高分子ＬＥＤを作製した。この素子に電圧を１０Ｖ印加すると、高分子蛍光体の蛍光と同じスペクトルを有する青色のＥＬ発光が観察された。
【００６５】
【発明の効果】
本発明の高分子蛍光体は、強い蛍光を有し、比較的容易に蛍光波長を調節することができ、耐熱性に優れ、溶媒可溶性なので高分子ＬＥＤ用の材料として優れている。また、該高分子蛍光体を用いた高分子ＬＥＤは、塗布法により容易に作成でき、発光効率が高く、耐熱性に優れているので、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 a polymer phosphor and a polymer light-emitting device produced using the polymer phosphor.
[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.
[0003]
From the viewpoint of improvement of such an inorganic EL element, an element having a two-layer structure in which an organic phosphor is used for a light emitting layer and this is stacked with an organic charge transport compound (Japanese Patent Laid-Open No. 59-194393), A device using a molecular phosphor (WO90113148, JP-A-3-244630) has been reported. Electroluminescent elements using these organic phosphors (hereinafter sometimes referred to as organic EL elements) are characterized by being capable of multicolor light emission in addition to low-voltage direct current drive and high brightness, compared to inorganic EL elements. is there. Among organic EL elements, an element using a polymeric phosphor as a light emitting material is particularly called a polymer light emitting element (hereinafter sometimes referred to as polymer LED).
[0004]
As a polymer phosphor, WO90113148 discloses a polymer phosphor composed of poly-p-phenylene vinylene which is converted into a conjugated polymer by forming a film of a soluble precursor on an electrode and performing a heat treatment. The thin film is described. Japanese Patent Application Laid-Open No. 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. A polymeric fluorescent substance consisting of is described. Further, JP-A-8-510483 describes a polymeric fluorescent substance comprising a highly soluble poly-p-phenylene vinylene copolymer having a cholesteryloxy group in the nucleus substitution side chain.
[0005]
In the polymeric fluorescent substance, the emission wavelength is changed by changing the chemical structure of the polymeric fluorescent substance, and multicolor emission is attempted.
For example, in polythiophene, an attempt to shorten the emission wavelength by introducing a bulky substituent at the 3-position has been reported (Synthetic Metals 71, 2121 (1995)).
In addition, in order to obtain multicolor light emission, a polymeric 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.
[0006]
On the other hand, as an organic phosphor having a distyryl structure, JP-A-8-239655 exemplifies a distyryl compound having a 4,4′-biphenylene skeleton. JP-A-5-320635 exemplifies a polymer light emitter in which distyryl derivatives are linked by a non-conjugated bond. Furthermore, [Macromolecular Symposia, Vol. 125, p. 133 (1997)] exemplifies polyarylene vinylene derivatives having a fluorene skeleton in the main chain.
[0007]
However, the poly (arylene vinylene) polymer fluorescent substance used for the polymer LED reported so far needs to be heat-treated when passing through a solvent-soluble intermediate, and only a substrate having high heat resistance is required. 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 device is lowered because the phosphor is easily softened.
[0008]
In addition, in order to achieve multicolor emission, it may be desired to adjust the fluorescence wavelength. For example, in order to obtain a polymeric fluorescent substance having a blue emission color, a non-aliphatic hydrocarbon group or the like is included in the main chain. There is a problem that the synthesis process becomes complicated, such as the need to introduce a group having a conjugated bond. In addition, in polymers in which aromatic compound groups are alternately bonded with vinylene groups, there is an attempt to increase the wavelength by the electronic action of the nuclear substituent, but the introduction of a compound having an aromatic ring of a specific structure 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 solvent-soluble polymeric fluorescent substance that has strong fluorescence, can adjust the fluorescence wavelength relatively easily, and has excellent heat resistance.
[0009]
[Problems to be solved by the invention]
The object of the present invention is to have a strong fluorescence, can adjust the fluorescence wavelength relatively easily, can be easily prepared by a coating method using a solvent-soluble polymer phosphor excellent in heat resistance, and The object is to provide a polymer LED having high luminous efficiency and excellent heat resistance.
[0010]
[Means for Solving the Problems]
In view of such circumstances, the present inventors have intensively studied to improve the luminous efficiency and heat resistance of a polymer LED using a polymer phosphor as a light emitting layer and to adjust the fluorescence wavelength relatively easily. As a result, the polymer fluorescent substance having a fluorene ring having a specific structure exhibits strong fluorescence and high heat resistance, and can adjust the fluorescence wavelength relatively easily. The polymer LED can be easily prepared by the method, and the polymer LED is found to have high luminous efficiency and excellent heat resistance, leading to the present invention.
[0011]
That is, the present invention [1] has visible fluorescence in the solid state and has a polystyrene-equivalent number average molecular weight of 10 ^Three To 10 ⁸ The polymeric fluorescent substance is characterized in that it contains one or more types of repeating units represented by the following formula (1), and the total of these repeating units is 50 mol% or more and 100 mol% or less of all repeating units. The present invention relates to a polymeric fluorescent substance.
[Chemical formula 5]

(1)
[Where Ar ₁ , Ar ₂ Each independently represents an arylene group having 6 to 60 carbon atoms involved in a conjugated bond, or a heterocyclic compound group having 4 to 60 carbon atoms involved in a conjugated bond. . R ₁ ~ R ₈ Each independently represents a hydrogen atom or a substituent represented by the following formula (2). R ₉ ~ R _Ten Each independently represents a group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms and a cyano group. n is 0 or 1. ]
[Chemical 6]
-(R ₁₁ ) _l -(X) _m -R ₁₂ (2)
[Where R ₁₁ Represents a hydrocarbon group having 1 to 20 carbon atoms. R ₁₂ Comprises a hydrocarbon group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms involved in a conjugated bond, a heterocyclic compound group having 4 to 60 carbon atoms involved in a conjugated bond, and a ring And a group selected from the group consisting of aliphatic cyclic hydrocarbon groups having 6 to 60 carbon atoms. X represents a group selected from the group consisting of —O—, —S—, —CO—, —CO—O— and —O—CO—. l and m are each independently 0 or 1. In addition, the present invention [2] has visible fluorescence in the solid state and has a polystyrene-equivalent number average molecular weight of 10 ^Three To 10 ⁸ In the polymeric fluorescent substance, the compound contains at least one type of repeating unit represented by the above formula (1) and the following formula (3), and the repeating unit represented by the formula (1) is 2 mol% or more of all repeating units, In addition, the present invention relates to a polymeric fluorescent substance in which the total of repeating units represented by formula (1) and formula (3) is 50 mol% or more and 100 mol% or less of all repeating units.
[Chemical 7]

(3)
[Where Ar _Three Represents an arylene group having 6 to 60 carbon atoms involved in a conjugated bond, or a heterocyclic compound group having 4 to 60 carbon atoms involved in a conjugated bond. R ₁₃ , R ₁₄ Each independently represents a group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms and a cyano group. k is 0 or 1. ]
Furthermore, the present invention [3] has visible fluorescence in the solid state and has a polystyrene-equivalent number average molecular weight of 10 ^Three To 10 ⁸ In the polymeric fluorescent substance, the polymeric fluorescent substance contains at least one repeating unit represented by the following formula (4), and the total of those repeating units is 10 mol% or more and 100 mol% or less of all repeating units. It is about.
[Chemical 8]

.... (4)
[Where Ar _Four , Ar _Five , Ar ₆ Each independently represents an arylene group having 6 to 60 carbon atoms involved in a conjugated bond, or a heterocyclic compound group having 4 to 60 carbon atoms involved in a conjugated bond. . R ₁₅ ~ R _{twenty two} Represents a hydrogen atom or a substituent represented by the above formula (2). R _{twenty three} ~ R ₂₆ Each independently represents a group selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms and a cyano group. i and j are each independently 0 or 1. ]
[0012]
Next, the present invention provides: [4] In a polymer light emitting device having at least a light emitting layer between a pair of anodes and cathodes, at least one of which is transparent or translucent, the light emitting layer comprises [1] to [ 3] A polymer light-emitting device comprising the polymeric fluorescent substance according to [3].
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The polymeric fluorescent substance of the present invention [1] has visible fluorescence in a solid state and has a number average molecular weight of 10 in terms of polystyrene. ^Three To 10 ⁸ The polymeric fluorescent substance is characterized in that it contains one or more repeating units represented by the formula (1), and the total of these repeating units is 50 mol% or more and 100 mol% or less of all repeating units. To do. In addition, the polymeric fluorescent substance of the present invention [2] includes one or more repeating units represented by the formula (1) and the repeating unit represented by the formula (3), each having the formula (1) The repeating unit shown is 2 mol% or more of all repeating units, and the total of the repeating unit represented by the formula (1) and the repeating unit represented by the formula (3) is 50 mol% or more of all repeating units. It is characterized by being 100 mol% or less. Furthermore, the polymeric fluorescent substance of the present invention [3] contains one or more types of repeating units represented by the formula (4), and the total is 10 mol% or more and 100 mol% or more of all repeating units. And
[0014]
Ar in the formula (1) ₁ , Ar ₂ Ar in formula (3) _Three , Ar in formula (4) _Four , Ar _Five , Ar ₆ Is an arylene group having 6 to 60 carbon atoms involved in the conjugated bond, or a heterocyclic compound group having 4 to 60 carbon atoms involved in the conjugated bond.
[0015]
Specifically, the Ar ₁ ~ Ar ₆ As each of them, the following aromatic compound groups or derivative groups thereof are exemplified.
[0016]
[Chemical 9]

[Chemical Formula 10]

Embedded image

Embedded image

[Wherein R is independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an alkylthio group having 1 to 20 carbon atoms, an alkylsilyl group having 1 to 60 carbon atoms, An alkylamino group having 1 to 40 carbon atoms, an aryl group having 6 to 60 carbon atoms, an aryloxy group having 6 to 60 carbon atoms, an arylalkyl group having 7 to 60 carbon atoms, an arylalkoxy group having 7 to 60 carbon atoms, carbon A group selected from the group consisting of an arylalkenyl group having 8 to 60 carbon atoms, an arylalkynyl group having 8 to 60 carbon atoms, an arylamino group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms, and a cyano group. Show. ]
[0017]
Among these, 1,4-phenylene group, 2,6-naphthalenylene group, 4,4′-biphenylene group, anthracene-9,10-diyl group, 2,5-pyridinediyl group, 2,5-thienylene group or Those nucleus-substituted derivatives; or 1,3-phenylene group, 1,3-naphthalenylene group, 3,3′-biphenylene group, 2,4-pyridinediyl group, 2,5-quinolinediyl group or derivatives thereof are preferable. More preferably, 1,4-phenylene group, 2,5-pyridinediyl group, 2,5-thienylene group, 4,4′-biphenylene group, 3,3′-biphenylene group, 1,3-phenylene group, 2, Examples include 6-pyridinediyl group, 2,4-quinolinediyl group, and derivatives thereof.
In the above example, a plurality of Rs are contained in one structural formula, but they may be the same or different groups, and are independently selected. Ar ₂ When has a plurality of substituents, they may be the same or different. In order to increase the solubility in a solvent, it is preferable to have one or more substituents that are not hydrogen atoms, and it is preferable that the shape of the repeating unit including the substituents has little symmetry.
[0018]
Ar ₁ ~ Ar ₆ From these, one or more types can be selected. From the viewpoint of ease of synthesis, Ar ₁ And Ar ₂ Or Ar _Four And Ar _Five Are preferably the same.
[0019]
When R is a substituent other than a hydrogen atom or a cyano group, the alkyl group having 1 to 20 carbon atoms includes a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, and a heptyl group. Octyl group, nonyl group, decyl group, lauryl group and the like, and pentyl group, hexyl group, octyl group and decyl group are preferable.
[0020]
Examples of the alkoxy group having 1 to 20 carbon atoms include methoxy group, ethoxy group, propyloxy group, butoxy group, pentyloxy group, hexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, decyloxy group, lauryloxy group, etc. And a pentyloxy group, a hexyloxy group, an octyloxy group, and a decyloxy group are preferable.
[0021]
Examples of the alkylthio group having 1 to 20 carbon atoms include methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, hexylthio group, heptylthio group, octylthio group, nonylthio group, decylthio group, laurylthio group, and the like, and pentylthio group , A hexylthio group, an octylthio group, and a decylthio group are preferable.
[0022]
Examples of the alkylsilyl group having 1 to 60 carbon atoms include methylsilyl group, ethylsilyl group, propylsilyl group, butylsilyl group, pentylsilyl group, hexylsilyl group, heptylsilyl group, octylsilyl group, nonylsilyl group, decylsilyl group, laurylsilyl group , Trimethylsilyl group, ethyldimethylsilyl group, propyldimethylsilyl group, butyldimethylsilyl group, pentyldimethylsilyl group, hexyldimethylsilyl group, heptyldimethylsilyl group, octyldimethylsilyl group, nonyldimethylsilyl group, decyldimethylsilyl group, lauryl Dimethylsilyl group and the like, such as pentylsilyl group, hexylsilyl group, octylsilyl group, decylsilyl group, pentyldimethylsilyl group, hexyldimethylsilyl group, octyldimethylsilyl group, Le butyldimethylsilyl group is preferred.
[0023]
Examples of the alkylamino group having 1 to 40 carbon atoms include methylamino group, dimethylamino group, ethylamino group, propylamino group, butylamino group, pentylamino group, hexylamino group, heptylamino group, octylamino group, and nonylamino group. Decylamino group, laurylamino group and the like, and pentylamino group, hexylamino group, octylamino group and decylamino group are preferable.
[0024]
Examples of the aryl group having 6 to 60 carbon atoms include a phenyl group and C ₁ ~ C ₁₂ Alkoxyphenyl group (C ₁ ~ C ₁₂ Indicates that the number of carbon atoms is 1 to 12. The same applies to the following. ), C ₁ ~ C ₁₂ Examples include alkylphenyl group, 1-naphthyl group, 2-naphthyl group and the like. ₁ ~ C ₁₂ Alkoxyphenyl group, C ₁ ~ C ₁₂ Alkylphenyl groups are preferred.
[0025]
Examples of the aryloxy group having 6 to 60 carbon atoms include a phenoxy group and C ₁ ~ C ₁₂ Alkoxyphenoxy group, C ₁ ~ C ₁₂ Examples include alkylphenoxy group, 1-naphthyloxy group, 2-naphthyloxy group, and the like. ₁ ~ C ₁₂ Alkoxyphenoxy group, C ₁ ~ C ₁₂ Alkylphenoxy groups are preferred.
[0026]
As the arylalkyl group having 6 to 60 carbon atoms, phenyl-C ₁ ~ C ₁₂ Alkyl group, C ₁ ~ C ₁₂ Alkoxyphenyl-C ₁ ~ C ₁₂ Alkyl group, C ₁ ~ C ₁₂ Alkylphenyl-C ₁ ~ C ₁₂ Alkyl group, 1-naphthyl-C ₁ ~ C ₁₂ Alkyl group, 2-naphthyl-C ₁ ~ C ₁₂ Examples include alkyl groups and the like, and C ₁ ~ C ₁₂ Alkoxyphenyl-C ₁ ~ C ₁₂ Alkyl group, C ₁ ~ C ₁₂ Alkylphenyl-C ₁ ~ C ₁₂ Alkyl groups are preferred.
[0027]
As the arylalkoxy group having 6 to 60 carbon atoms, phenyl-C ₁ ~ C ₁₂ Alkoxy group, C ₁ ~ C ₁₂ Alkoxyphenyl-C ₁ ~ C ₁₂ Alkoxy group, C ₁ ~ C ₁₂ Alkylphenyl-C ₁ ~ C ₁₂ Alkoxy group, 1-naphthyl-C ₁ ~ C ₁₂ Alkoxy group, 2-naphthyl-C ₁ ~ C ₁₂ An alkoxy group etc. are illustrated and C ₁ ~ C ₁₂ Alkoxyphenyl-C ₁ ~ C ₁₂ Alkoxy group, C ₁ ~ C ₁₂ Alkylphenyl-C ₁ ~ C ₁₂ Alkoxy groups are preferred.
[0028]
Examples of the arylamino group having 6 to 60 carbon atoms include phenylamino group, diphenylamino group, C ₁ ~ C ₁₂ Alkoxyphenylamino group, di (C ₁ ~ C ₁₂ Alkoxyphenyl) amino group, di (C ₁ ~ C ₁₂ Alkylphenyl) amino group, 1-naphthylamino group, 2-naphthylamino group, etc. ₁ ~ C ₁₂ Alkylphenylamino group, di (C ₁ ~ C ₁₂ Alkylphenyl) amino groups are preferred.
[0029]
Examples of the heterocyclic compound group having 4 to 60 carbon atoms include thienyl group, C ₁ ~ C ₁₂ Alkylthienyl group, pyrrolyl group, furyl group, pyridyl group, C ₁ ~ C ₁₂ Examples include alkylpyridyl group, thienyl group, C ₁ ~ C ₁₂ Alkyl thienyl group, pyridyl group, C ₁ ~ C ₁₂ Alkylpyridyl groups are preferred.
[0030]
Among the examples of R, in the substituent containing an alkyl chain, they may be linear, branched or cyclic, or a combination thereof, and when not linear, for example, isoamyl group, 2-ethylhexyl group 3,7-dimethyloctyl group, cyclohexyl group, 4-C ₁ ~ C ₁₂ Examples thereof include an alkylcyclohexyl group.
[0031]
R in formula (1) ₉ ~ R _Ten , R in formula (3) ₁₃ ~ R ₁₄ , R in formula (4) _{twenty three} ~ R ₂₆ Are groups independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms and a cyano group.
[0032]
Specifically, 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, 4-C ₁ ~ C ₁₄ Alkoxyphenyl group (C ₁ ~ C ₁₄ Indicates that the number of carbon atoms is 1-14. The following description is based on this. ), 4-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 and a 2-quinolyl group.
[0033]
R in formula (1) ₁ ~ R ₈ , R in formula (4) ₁₅ ~ R _{twenty two} Is a hydrogen atom or a substituent represented by the formula (2).
[0034]
The total of repeating units represented by the formula (1) is 50 mol% or more and 100 mol% or less of all repeating units, and it is preferably 60 mol% or more and 100 mol% or less depending on the structure of the repeating units. More preferably, it is 70 mol% or more and 100 mol% or less. In the case of a polymer composed of the repeating units represented by the formula (1) and the formula (3), it is a copolymer containing 2 mol% or more of the repeating unit represented by the formula (1). The repeating unit shown is preferably 20 mol% or less, and the total of the repeating unit represented by formula (1) and the repeating unit represented by formula (3) is 50 mol% or more and 100 mol% of all repeating units. Although it depends on the structure of the repeating unit, it is preferably 60 mol% or more and 100 mol% or less, and more preferably 70 mol% or more and 100 mol% or less. In addition, when the repeating unit is represented by the formula (4), in the case other than the polymer consisting only of the repeating unit represented by the formula (4), a copolymer containing 10 mol% or more of the repeating unit represented by the formula (4) is used. It is a polymer, preferably 50 mol% or more, and more preferably 70 mol% or more. The copolymerization partner other than the repeating units represented by the formulas (1), (3), and (4) is not particularly limited as long as the above conditions are satisfied, but the solubility and / or fluorescence intensity may be reduced. Those having no structure are preferred.
[0035]
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.
Specific examples include substituents described in Chemical formula 10 of JP-A-9-45478 and groups in which they are bonded to a vinylene group.
[0036]
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 ⁸ From the viewpoint of solubility and film formability, 10 ^Four -10 ⁶ Is preferred, 5 × 10 ^Four -10 ⁶ Is particularly preferred. Their degree of polymerization also varies depending on the repeating structure and its proportion. 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.
[0037]
The polymeric fluorescent substance of the present invention is a polymer or copolymer in which the total of repeating units represented by formula (1) is 50 mol% or more of all repeating units, and is represented by formulas (1) and (3). It is a copolymer in which the total of the repeating units shown is 50 mol% or more of all repeating units, and a polymer or copolymer in which the repeating units of formula (4) are 10 mol% or more of all repeating units. When the polymeric fluorescent substance is a copolymer, it may be a random, block or graft copolymer, or a polymer having an intermediate structure thereof, such as a random copolymer having a block property. There may be. 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.
[0038]
The polymeric fluorescent substance of the present invention can be formed by dissolving in a solvent.
Examples of the good solvent for 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 polymeric fluorescent substance, it can usually be dissolved in these solvents in an amount of 0.1 wt% or more.
When forming a polymer light-emitting device by using these organic solvent-soluble polymer fluorescent substances, when forming a film from a solution, it is only necessary to remove the solvent by drying after applying the solution, and the charge described later The same technique can be applied to the case where the transport material is mixed, which is very advantageous in production.
[0039]
As a method for producing the polymeric fluorescent substance of the present invention, a polymer containing a repeating unit represented by formula (1) or formula (4) is synthesized by a carbon-carbon double bond forming reaction. 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 and Knoevenagel reaction. Among these, the method by Wittig reaction is preferable in terms of reaction control and yield. In addition, the dehydrohalogenation method is preferable in terms of easy high molecular weight.
[0040]
In the synthesis of the polymeric fluorescent substance by the Wittig reaction, for example, a dialdehyde compound represented by the formula (5) and a diphosphonium salt compound represented by the formula (6) are reacted. In this case, if two or more kinds of dialdehyde compounds and / or two or more kinds of diphosphonium salt compounds are used, all of these copolymers can be obtained.
Embedded image
OHC-Ar ₇ -CHO (5)
Embedded image

.... (6)
[Where Ar ₇ Is Ar in formula (3) _Three Or Ar in formula (4) ₆ Or a group represented by Ar ₈ , Ar ₉ Is Ar in formula (1) ₁ , Ar ₂ Or Ar in formula (4) _Four , Ar _Five Is selected from the group represented by X is exemplified by halide ions such as chloride ions and bromide ions as counter ions. Ph is a phenyl group. ]
[0041]
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. The monofunctional compound is appropriately selected depending on the reaction used, or when two types of monomers having different functional groups are polycondensed, depending on the number of monomers used in the reaction. That is, in the Wittig reaction, the dialdehyde and diphosphonium salt are reacted in the presence of the monofunctional compound, or the dialdehyde and diphosphonium salt are reacted and polymerized, and then the monofunctional compound that subsequently forms a terminal group 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.
[0042]
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) fluorene derivative is reacted with triphenylphosphine in an N, N-dimethylformamide solvent to obtain a phosphonium salt. And an arylene vinylene copolymer can be obtained by a Wittig reaction in which this is condensed with a dialdehyde compound such as terephthalaldehyde using lithium ethoxide in ethyl alcohol. 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.
[0043]
Furthermore, in the presence of a monoaldehyde compound, for example, 1-pyrenecarboxaldehyde, diphosphonium salt and dialdehyde, diphosphonium salt is used in excess of equimolar amount to dialdehyde, for example, lithium ethoxylate in ethyl alcohol. An example in which a terminal-substituted copolymer is obtained by a Wittig reaction in which condensation is performed using a catalyst.
Further, when these polymers are used as light emitting materials for polymer LEDs, the purity affects the light emission characteristics. Therefore, it is desirable to perform purification treatment such as reprecipitation purification and fractionation by chromatography after synthesis.
[0044]
The structure of the polymer LED produced using the polymer phosphor of the present invention is composed of the polymer phosphor of the present invention in a light emitting layer provided between a pair of electrodes, at least one of which is transparent or translucent. If a luminescent material is used, there is no restriction | limiting in particular and a well-known structure is employ | adopted.
For example, a pair of electrodes on both sides of a light emitting layer made of the polymer fluorescent material or a light emitting layer made of a mixture of the polymer fluorescent material and a charge transport material (meaning a generic name of an electron transport material and a hole transport material) And a structure in which an electron transport layer including an electron transport material and / or a hole transport layer including a hole transport material are stacked between an anode and a light emitting layer are exemplified. .
[0045]
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 polymeric fluorescent substance and / or charge transport material to the high molecular compound.
[0046]
A charge transport material used with the polymeric fluorescent substance of the present invention, that is, a known material can be used as the electron transport material or the hole transport material, and is not particularly limited, but examples of the hole transport material include pyrazoline derivatives, arylamines. Derivatives, stilbene derivatives, triphenyldiamine derivatives, etc. are exemplified. Electron transport materials include oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyanoanthra Examples include quinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof.
[0047]
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.
[0048]
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.
[0049]
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.
[0050]
Known light-emitting materials that can be used with the polymeric fluorescent substance of the present invention are not particularly limited. For example, naphthalene derivatives, anthracene or derivatives thereof, perylene or derivatives thereof; dyes such as polymethine, xanthene, coumarin, and cyanine A metal complex of 8-hydroxyquinoline or a derivative thereof; an aromatic amine, tetraphenylcyclopentadiene or a derivative thereof; or tetraphenylbutadiene or a derivative thereof. Specifically, for example, known ones such as those described in JP-A-57-51781 and 59-194393 can be used.
[0051]
Next, a typical method for producing a polymer LED using the polymeric fluorescent substance 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.
[0052]
Next, a light emitting layer containing the polymeric fluorescent substance 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.
[0053]
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.
[0054]
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.
[0055]
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.
[0056]
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.
[0057]
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, a laminating method in which a metal thin film is thermocompression-bonded, or the like is used.
A protective layer for protecting the polymer LED may be attached after the cathode is produced. In order to use the polymer LED stably for a long period of time, it is preferable to attach a protective layer and / or protective cover in order to protect the element from the outside.
As the protective layer, a polymer compound, metal oxide, metal fluoride, metal boride and the like can be used. Further, as the protective cover, a glass plate, a plastic plate having a low water permeability treatment on the surface, or the like can be used, and a method of sealing the cover by bonding it to the element substrate with a heat effect resin or a photo-curing resin is preferable. Used for. If a space is maintained using a spacer, it is easy to prevent the element from being damaged. If an inert gas such as nitrogen or argon is sealed in the space, the cathode can be prevented from being oxidized, and moisture adsorbed in the manufacturing process by installing a desiccant such as barium oxide in the space. It becomes easy to suppress giving an image to an element. Of these, it is preferable to take one or more measures.
In order to obtain a planar element using the polymer LED of the present invention, the planar anode and cathode may be arranged so as to overlap each other. In addition, in order to obtain pattern-like light emission, a method in which a mask having a pattern-like window is provided on the surface of the planar light-emitting element, an organic layer of a non-light-emitting portion is formed extremely thick and substantially non-light-emitting. Examples thereof include a method of emitting light, and a method of forming either one of the anode or the cathode or both electrodes in a pattern. Further, in order to obtain a dot matrix element, there are a method in which both the anode and the cathode are formed in stripes and arranged so as to be orthogonal, and a method in which one electrode can be selectively driven by a TFT. By separately coating a plurality of types of polymer fluorescent substances having different emission colors, partial color display and multi-color display are possible.
[0058]
[Action]
In the present invention, it is considered that the polymeric fluorescent substance is excellent as a luminescent material because it has a specific structure of fluorene and distyryl and thus exhibits strong fluorescence. In addition, since a light emitting layer having excellent uniformity can be easily formed by a coating method, a polymer LED having a high light emission efficiency, a high heat resistance and a long life can be produced very easily.
[0059]
【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.
[0060]
Example 1
<Synthesis of polymeric fluorescent substance 1>
9,9-bis {(3′-bromomethyl-4′-octyloxy) phenyl} fluorene was reacted with triphenylphosphine in a N, N-dimethylformamide solvent to synthesize a phosphonium salt. 5.14 g of the obtained phosphonium salt and 0.54 g of terephthalaldehyde were dissolved in 100 ml of ethanol. A mixed solution of 5 ml of 12% lithium methoxide methanol solution and 20 ml of ethyl alcohol was added dropwise to an ethanol solution of phosphonium salt and aldehyde. Then, it was made to react at room temperature for 3 hours.
[0061]
After adding 100 ml of ethanol and allowing to stand overnight at room temperature, the produced precipitate was recovered. Next, the precipitate was washed with ethanol, dissolved in toluene, and ethanol was added to the precipitate for reprecipitation purification. This was dried under reduced pressure to obtain 0.5 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 3.1 × 10 ^Three Met. Regarding the structure of the polymeric fluorescent substance 1 ¹ The corresponding spectra were obtained by H-NMR and IR spectra.
[0062]
<Measurement of absorption spectrum and fluorescence spectrum>
The polymeric fluorescent substance 1 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. The absorption peak wavelength was 368.5 nm, and the fluorescence peak wavelength was 464 nm, which was blue.
[0063]
<Evaluation of heat resistance by differential scanning calorimetry (DSC)>
The polymeric fluorescent substance 1 was subjected to thermal analysis using a differential scanning calorimeter DSC200 manufactured by Seiko Electronics. An endothermic peak believed to correspond to the softening of the polymer was observed at 43 ° C.
[0064]
Example 2
<Creation and evaluation of device>
Using a toluene solution of the polymeric fluorescent substance 1 obtained in Example 1, a glass substrate having an ITO film with a thickness of 200 nm was formed by sputtering to a thickness of 80 nm. On top of that, the degree of vacuum 8 × 10 ^-6 A cathode was formed by vapor-depositing lithium fluoride at 2.5 mm below Torr and then 50 nm of aluminum, to produce a polymer LED. When a voltage of 10 V was applied to this element, blue EL emission having the same spectrum as the fluorescence of the polymeric fluorescent substance was observed.
[0065]
【The invention's effect】
The polymeric fluorescent substance of the present invention is excellent as a material for a polymer LED because it has strong fluorescence, can adjust the fluorescence wavelength relatively easily, has excellent heat resistance and is soluble in a solvent. In addition, a polymer LED using the polymer fluorescent substance can be easily produced by a coating method, has high luminous efficiency, and is excellent in heat resistance. Therefore, a planar light source as a backlight, a device such as a flat panel display, etc. Can be preferably used.

Claims (11)

Polymer fluorescent substance having visible fluorescence in a solid state and having a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ , containing one or more repeating units represented by the following formula (1), and repeating them A polymeric fluorescent substance characterized in that the total of units is 50 mol% or more and 100 mol% or less of all repeating units.

(1)
[Ar ₁ and Ar ₂ each independently represents an arylene group having an alkoxy group having 1 to 20 carbon atoms and having 6 to 60 carbon atoms involved in the conjugated bond. R _{1 to} R ₈ each independently represent a hydrogen atom or a substituent represented by the following formula (2). R _{9 to} R ₁₀ are each independently selected from the group consisting of a hydrogen atom , an alkyl group having 1 to 20 carbon atoms , an aryl group having 6 to 60 carbon atoms , a heterocyclic compound group having 4 to 60 carbon atoms, and a cyano group. Indicates a group. n is 0 . ]

[Wherein R ₁₁ represents a hydrocarbon group having 1 to 20 carbon atoms. R ₁₂ is a hydrocarbon group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms involved in a conjugated bond, a heterocyclic compound group having 4 to 60 carbon atoms involved in a conjugated bond, and a ring Is a group selected from the group consisting of aliphatic cyclic hydrocarbon groups having 6 to 60 carbon atoms. X represents a group selected from the group consisting of —O—, —S—, —CO—, —CO—O— and —O—CO—. l and m are each independently 0 or 1. ] In the polymeric fluorescent substance having visible fluorescence in the solid state and having a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ , the repeating unit represented by the formula (1) according to claim 1 and the following formula (3): Each of which has a repeating unit represented by formula (1) of 2 mol% or more of all repeating units, and the total of repeating units represented by formulas (1) and (3) is 50 mol of all repeating units. % To 100 mol% of a polymeric fluorescent substance,

(3)
[Wherein Ar ₃ represents an arylene group having 6 to 60 carbon atoms involved in the conjugated bond, or a heterocyclic compound group having 4 to 60 carbon atoms involved in the conjugated bond. Indicates. R ₁₃ and R ₁₄ are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms, and a cyano group. Indicates a group. k is 0 or 1. ] Polymer fluorescent substance having visible fluorescence in a solid state and having a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ , containing one or more repeating units represented by the following formula (4), and repeating 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.

.... (4)
[Here, Ar _4, Ar ₅ each independently have an alkoxy group having 1 to 20 carbon atoms, an arylene group carbon atoms of 60 or less 6 or more involved in conjugated bonds. Ar ₆ represents an arylene group having 6 to 60 carbon atoms involved in the conjugated bond , or a heterocyclic compound group having 4 to 60 carbon atoms involved in the conjugated bond. R _{15 to} R ₂₂ represent a hydrogen atom or a substituent represented by the formula (2) according to claim 1. R _{23 to} R ₂₆ are each independently selected from the group consisting of a hydrogen atom , an alkyl group having 1 to 20 carbon atoms , an aryl group having 6 to 60 carbon atoms , a heterocyclic compound group having 4 to 60 carbon atoms, and a cyano group. Indicates a group. i is 0 . j is 0 or 1. ] Polymer fluorescent substance having visible fluorescence in a solid state and having a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ , containing one or more repeating units represented by the following formula (1), and repeating them A polymeric fluorescent substance characterized in that the total of units is 50 mol% or more and 100 mol% or less of all repeating units.

(1)
[Ar ₁ and Ar ₂ each independently represents an arylene group having 6 to 60 carbon atoms involved in the conjugated bond. R _{1 to} R ₈ each independently represent a hydrogen atom or a substituent represented by the following formula (2). R _{9 to} R ₁₀ are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms, and a cyano group. Indicates a group. n is 1. ]
-(R ₁₁ ) _l- (X) _m -R ₁₂ (2)
[Wherein R ₁₁ represents a hydrocarbon group having 1 to 20 carbon atoms. R ₁₂ is a hydrocarbon group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms involved in a conjugated bond, a heterocyclic compound group having 4 to 60 carbon atoms involved in a conjugated bond, and a ring Is a group selected from the group consisting of aliphatic cyclic hydrocarbon groups having 6 to 60 carbon atoms. X represents a group selected from the group consisting of —O—, —S—, —CO—, —CO—O— and —O—CO—. l and m are each independently 0 or 1. ] In a polymer fluorescent substance having visible fluorescence in a solid state and having a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ , the repetition represented by the formula (1) according to claim 4 and the following formula (3) Each repeating unit represented by formula (1) is 2 mol% or more of all repeating units, and the total of repeating units represented by formulas (1) and (3) is the total repeating unit. The polymeric fluorescent substance characterized by being 50 mol% or more and 100 mol% or less.

(3)
[Wherein Ar ₃ represents an arylene group having 6 to 60 carbon atoms involved in the conjugated bond, or a heterocyclic compound group having 4 to 60 carbon atoms involved in the conjugated bond. Indicates. R ₁₃ and R ₁₄ are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms, and a cyano group. Indicates a group. k is 0 or 1. ] Polymer fluorescent substance having visible fluorescence in a solid state and having a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ , containing one or more repeating units represented by the following formula (4), and repeating 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.

.... (4)
[Ar ₄ and Ar ₅ each independently represents an arylene group having 6 to 60 carbon atoms involved in the conjugated bond. Ar ₆ represents an arylene group having 6 to 60 carbon atoms involved in the conjugated bond, or a heterocyclic compound group having 4 to 60 carbon atoms involved in the conjugated bond. R _{15 to} R ₂₂ represent a hydrogen atom or a substituent represented by the formula (2) according to claim 4. R _{23 to} R ₂₆ are each independently selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group having 6 to 60 carbon atoms, a heterocyclic compound group having 4 to 60 carbon atoms, and a cyano group. Indicates a group. i is 1. j is 0 or 1. ] Ar ₁ , Ar ₂ , Ar _Four And Ar _Five Each independently represents an arylene group having an alkoxy group having 1 to 20 carbon atoms and having 6 to 60 carbon atoms involved in the conjugated bond. Polymer phosphor. The polymer phosphor according to any one of claims 1 to 7 , wherein the light emitting layer is a polymer light emitting device having at least a light emitting layer between a pair of anode and cathode electrodes, at least one of which is transparent or translucent. A polymer light emitting device comprising: 9. The polymer light emitting device according to claim 8 , wherein a layer containing an electron transporting compound is provided adjacent to the light emitting layer between the cathode and the light emitting layer. 9. The polymer light emitting device according to claim 8 , wherein a layer containing a hole transporting compound is provided adjacent to the light emitting layer between the anode and the light emitting 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. The polymer light emitting device according to claim 8 , wherein the polymer light emitting device is provided.