JP2004039317A - Organic el element, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To protect an organic EL against moisture/oxygen in the atmospheric air to restrain a dark spot or the like from being generated over a long period. <P>SOLUTION: A fluoro-elastomer is used as a material for a sealing layer, in a thin-filmlike organic EL structure having two electrode layers of which at least one is transparent, and having an organic EL layer sandwiched by the electrode layers, and in an organic EL element having the sealing layer for coating one face or both faces of an outer surface of the organic EL structure. <P>COPYRIGHT: (C)2004,JPO

Description

【００２５】
上記の化学式において、Ｒｆは炭素数１〜１２の酸素および／または水素を部分的に含んでも良いフルオロアルキル基を示し、水素原子の５０％以上、特に７０％以上がフッ素原子に置換されており、残りはフッ素原子以外の塩素原子または水素原子を有していてもよくかつエーテル性酸素原子を有していてもよい。特に、７０％以上の水素がフッ素に置換されエーテル性酸素原子を有していてもよいペルフルオロアルキル基が好ましく、エーテル性酸素原子が存在する場合は炭素原子４個に対して１個から炭素原子２個に対して１個の割合であるものが好ましい。中でも特に水素が全てフッ素に置換されたものあるいは、分子末端もしくは側鎖のみＣＦ_２Ｈ基が含まれ、他はすべてフッ素原子が結合した炭素数１〜１２のものが好ましい。
【００２６】
好ましいＲｆ基の具体例としては、ＣＦ_３（ＣＦ_２）_ｎ、
ＨＣＦ_２（ＣＦ_２）_ｎＣＦ_３Ｏ、ＣＦ_３（ＣＦ_２）_２（ＯＣＦ（ＣＦ_３））_ｎＯＣＦ（ＣＦ_３）、（ここでｎは０〜１１の整数）などが挙げられる。
上記の芳香族単位が全芳香族の８０％以上、特に好ましくは１００％であるポリマーが好ましい。また、ポリマーとしては、その安定性や、合成のしやすさから、芳香族単位が直接連結しているポリマー、又は、エーテル結合若しくはカルボニル結合を介して結合しているポリマーが特に好ましい。
【００２７】
これらの好ましいポリマーは公知の方法で合成することができるが、特に含フッ素量の高いポリマーの合成方法としては以下の文献を例示できる。
１．　Ｊ．　Ｐｏｌｙｍ．　Ｓｃｉ．　ＰａｒｔＡ：　Ｐｏｌｙｍ．　Ｃｈｅｍ．　Ｖｏｌ３０　（１９９２）　ｐ１６７５
２．特開平１０−１５８３９１号公報及び特開平１０−１５８３８２号公報
【００２８】
含フッ素芳香族環がパーフルオロアルキレン基で連結されたブロック、溶媒可溶の含フッ素ポリイミド、又は含フッ素ポリベンズイミダゾール等のブロックもガラス転移温度の高いブロックとして使用することができる。
【００２９】
Ａ−２．主鎖骨格にフッ素置換エチレン性不飽和化合物の付加重合構造を有するポリマー
テトラフルオロエチレン、ヘキサフルオロプロピレン、トリフルオロエチレン、クロロトリフルオロエチレン、ペルフルオロシクロペンテン、ペルフルオロ（３−ブテニルビニルエーテル）、ペルフルオロ（アリルビニルエーテル）、ペルフルオロ（２，２−ジメチル−１，３−ジオキソール）、ペルフルオロ（１，３−ジオキソール）、ペルフルオロ（２−メチレン−４−メチル−１，３−ジオキソラン）、ペルフルオロ（３，５−ジオキサ−１，６−ヘプタジエン）、ふっ化ビニリデン、ふっ化ビニル、１，２ジフルオロエチレン、ジクロロジフルオロエチレン、等の単独および／または共重合体。
これらの中では特に含フッ素溶媒への溶解性の点からアモルファス性の高分子が好ましい。特にガラス転移温度を高くすることができる点でペルフルオロ（３−ブテニルビニルエーテル）、ペルフルオロ（アリルビニルエーテル）、ペルフルオロ（２，２−ジメチル−１，３−ジオキソール）、ペルフルオロ（１，３−ジオキソール）、ペルフルオロ（２−メチレン−４−メチル−１，３−ジオキソラン）、ペルフルオロ（３，５−ジオキサ−１，６−ヘプタジエン）等の環状モノマーおよび／または環化重合モノマー等から選ばれる少なくとも１つのモノマーを必須成分とする単独および／または共重合体が好ましい。特に好ましいのはペルフルオロ（３−ブテニルビニルエーテル）、ペルフルオロ（２，２−ジメチル−１，３−ジオキソール）の単独重合体および／またはテトラフルオロエチレンとの共重合体である。これら重合体の末端には官能基が存在していてもよく、この官能基の存在は重合体の密着性向上に効果がある。
【００３０】
ガラス転移温度が低いブロック成分としては例えば下記の構造が例示できる。Ｂ−１．下記一般式で表される繰り返し単位を主成分として含有するペルフルオロポリエーテルの分子末端に反応性部位が導入されたもの
−（ＣＦ_２−ＣＦ（ＣＦ_３）−Ｏ）_ｎ−
−（ＣＦ_２−ＣＦ_２−Ｏ−）_ｎ−
−（ＣＦ_２−ＣＦ_２−Ｏ−）_ｎ−（ＣＦ_２Ｏ）_ｍ−
−（ＣＦ_２−ＣＦ（ＣＦ_３）−Ｏ）_ｎ−（ＣＦ（ＣＦ_３）Ｏ）_ｍ−
−（ＣＦ_２−ＣＦ_２−ＣＨ_２−Ｏ）_ｎ−
−（ＣＦ_２−ＣＦ_２−ＣＦ_２−Ｏ）_ｎ−
【００３１】
Ｂ−２．下記（式１）〜（式３）で示される含フッ素モノマーの単独重合体又は共重合体の分子末端に反応性部位が導入されたもの
【００３２】
【化２】
ＲｆＯＣＦ＝ＣＦ_２　　　　（式１）
ＲｆＣＨ_２ＯＣＦ＝ＣＦ_２　　（式２）
ＲｆＣＦ＝ＣＨ_２　　　　　（式３）
【００３３】
式中、Ｒｆは、エーテル性酸素原子を炭素原子間に有していてもよいポリフルオロアルキル基を表す。このポリフルオロアルキル基は２以上のフッ素原子を有し、フッ素原子以外のハロゲン原子や水素原子を有していてもよい。ポリフルオロアルキル基の炭素数は１〜１５が適当であり、２〜１２が好ましい。ポリフルオロアルキル基はフッ素原子以外のハロゲン原子や水素原子を有していてもよい。また、エーテル性酸素原子はポリフルオロアルキレン基の炭素原子間に存在することができ、その酸素原子の数は炭素原子１ないし４個に対し１個の割合であることが好ましい。
【００３４】
共重合体としては、（式１）〜（式３）で表される含フッ素モノマーを必須成分とし、これにテトラフルオロエチレン、ヘキサフルオロプロピレン、トリフルオロエチレン、クロロトリフルオロエチレン、ふっ化ビニリデン、ふっ化ビニル、１，２−ジフルオロエチレン、ジクロロジフルオロエチレン、ペルフルオロシクロペンテン、ペルフルオロ（３−ブテニルビニルエーテル）、ペルフルオロ（アリルビニルエーテル）、ペルフルオロ（２，２−ジメチル−１，３−ジオキソール）、ペルフルオロ（１，３−ジオキソール）、ペルフルオロ（２−メチレン−４−メチル−１，３−ジオキソラン）、ペルフルオロ（３，５−ジオキサ−１，６−ヘプタジエン）、等の含フッ素ビニル化合物とを必要により共重合して得られるポリマーが例示できる。
【００３５】
この場合前記（式１）〜（式３）で表されている含フッ素モノマーの含量が１０ｍｏｌ％以上、好ましくは３０ｍｏｌ％以上、特に好ましくは５０ｍｏｌ％以上含有されることによりガラス転移温度の低いエラストマーが得られるため好ましい。また、含フッ素溶媒への溶解性や、化学的安定性等の観点から前記Ｒｆ中の炭素に結合されている水素の全てがフッ素に置換されているものが好ましい。
【００３６】
Ｂ−３．ふっ化ビニリデンの単独重合体又はその共重合体
ふっ化ビニリデンを必須成分とし、これにテトラフルオロエチレン、ヘキサフルオロプロピレン、トリフルオロエチレン、クロロトリフルオロエチレン、前記Ｂ―２に挙げた（式１）〜（式３）で表される含フッ素モノマー、ふっ化ビニル、１，２−ジフルオロエチレン、ジクロロジフルオロエチレン、ペルフルオロシクロペンテン、ペルフルオロ（３−ブテニルビニルエーテル）、ペルフルオロ（アリルビニルエーテル）、ペルフルオロ（２，２−ジメチル−１，３−ジオキソール）、ペルフルオロ（１，３−ジオキソール）、　ペルフルオロ（２−メチレン−４−メチル−１，３−ジオキソラン）、ペルフルオロ（３，５−ジオキサ−１，６−ヘプタジエン）、等の含フッ素ビニル化合物とを必要により共重合して得られるポリマー。
この場合、ふっ化ビニリデンは１０〜９０ｍｏｌ％の含量、好ましく２０〜８０ｍｏｌ％であることがガラス転移温度の低いエラストマーを得るために好ましく、さらに共重合成分としてヘキサフルオロプロピレンを含有していることが好ましい。
【００３７】
Ｂ−４．　前記Ｂ−２、Ｂ−３における単独重合体又は共重合体の重合度が１〜１０の末端に反応性を有するオリゴマーを単独で、および／または前記Ａの重合体と鎖延長させたブロックも挙げられる。
【００３８】
これらの中でも、Ｂ−１、Ｂ―２中のテトラフルオロエチレンおよび／またはクロロトリフルオロエチレンと前記（式１）のＲｆ中の炭素に結合されている水素の全てがフッ素に置換されている含フッ素モノマーとの共重合体、Ｂ−３中のフッ化ビニリデンとヘキサフルオロプロピレンおよび／または前記（式１）〜（式３）の含フッ素モノマーに必要によりテトラフルオロエチレンを共重合したもの等が含フッ素溶媒への溶解性、ガラス転移温度を低くできるなどの点で好ましい。
【００３９】
以上に例示したガラス転移温度が高いポリマーとガラス転移温度が低いポリマーのブロック共重合体は公知の方法で合成することができる。以下（ａ）〜（ｃ）にその具体例を例示する。
【００４０】
（ａ）両ブロック成分が反応部位を有しており、それらの反応でブロック共重合体を合成する方法。
反応部位の導入や反応部位の反応方法は公知のものを使用することができる。反応部位の導入については、例えば前記Ｂ−１の場合、テトラフルオロエチレンやヘキサフルオロプロピレンの酸素による酸化反応で合成したものは、末端がＣＯＦ基になるものが得られる。これをアミノ基、水酸基、メルカプト基等を有する化合物で処理する方法、加水分解や還元反応を利用してＣＯＯＨ基や水酸基末端にする方法などで、末端に反応性部位を導入したり、鎖延長反応で高分子量化しながら末端に反応性部位を導入することができる。
具体的な例としては、特開昭６２−１２０３３５、特公昭５０−７０５４、特開昭６０−３４９２４、米国特許第３８４５０５１号、米国特許第３３１７４８４号、特開平２−２０２９１９、特開平４−８５３２８、特開平８−１９９０７０などに記載されている。また、具体的な化合物としては、アウシモント社製「Ｆｏｍｂｌｉｎ　Ｚｄｏｌ」（商品名）、「Ｆｏｍｂｌｉｎ　Ｚｄｉａｃ」（商品名）などのペルフルオロポリエーテル、アリル末端ペルフルオロポリエーテル、トリアジン鎖延長ペルフルオロポリエーテルなどがある。
前記Ａ−２、Ｂ−２，Ｂ−３のビニル化合物の重合でポリマーを得る場合、反応性部位を有するモノマーを共重合する方法、ヨウ素移動重合法（詳細は下記（ｂ）記載）や反応性部位を有する重合開始剤および／またはポリマー型重合開始剤（詳細は下記（ｃ）記載）などの方法でポリマーを合成後、必要により分子末端を公知の方法で処理する方法などが、反応性部位の導入方法として例示できる。
前記Ａ−１の芳香族ポリマーの縮合反応を利用する場合は、公知の方法で末端に反応部位を導入することが可能である。
【００４１】
２種以上のポリマーの各反応性部位の反応によるブロック共重合体の合成反応も公知の方法で行うことができる。具体例として下記に挙げるがこれらに限られるものではない。
（ｉ）反応性部位として芳香環の水素結合がハロゲンに置換された部位を有するポリマーと、水酸基を末端に有するポリマーを縮合することでエーテル結合を介してブロック共重合体を合成する方法。
（ｉｉ）水酸基末端を有する２種以上のポリマーを分子内に２個以上のイソシアナート、エポキシ基、ハロゲン化アルキル等を有する化合物と同時にもしくは逐次的に反応してブロック共重合体を合成する方法。もしくは、水酸基末端を有するポリマーをトシル化反応や硫酸を用いて縮合反応によりエーテル結合を介してブロック共重合体にする方法。
（ｉｉｉ）カルボニルハライドおよび／またはカルボキシル基を有するポリマーを分子内に２個以上のアミノ基を有する化合物を利用してブロック共重合体にする方法等が挙げられる。
【００４２】
（ｂ）含フッ素モノマーを用いてヨウ素移動重合を用い、ブロック共重合体を逐次合成する方法。
この場合、例えば（Ｂ−２）または（Ｂ−３）で例示したモノマーをペルフルオロアルキルポリヨウ素化合物存在下重合した後さらに（Ａ−２）で例示したモノマーを重合する方法、（Ｂ−１）の骨格の末端をヨウ素化し、ヨウ素移動重合開始剤とし、この化合物の存在下ガラス転移温度の高いビニル化合物を重合することによっても得ることができる。これらの具体例としては、例えば高分子論文集Ｖｏｌ．４９、Ｎｏ．１０（１９９２）Ｐ７６５に記載されている。
【００４３】
（ｃ）ポリマー型パーオキサイド（例えば特公昭５５−３３４４６号公報）や、重合開始活性を有するビニル化合物を用いる方法（例えば特開平５−１９４６２５、特開平８−６７７１７、特開平８−６７７２０）などが挙げられる。
【００４４】
また、本発明における含フッ素エラストマーからなる層の形成方法としては他に、前記ガラス転移温度が低い反応性部位を有する含フッ素ポリマーのみを該反応部位と反応することで架橋しうる架橋剤とともに含フッ素溶媒に溶解および／または分散し、コーティング前および／またはコーティング後に該含フッ素ポリマーを架橋することでゴム弾性を有する含フッ素エラストマーの層を形成することもできる。架橋剤は２以上の官能基を有し、含フッ素ポリマーの反応性部位に対して反応しうる官能基の種類は公知のものが使用できる。例えば、水酸基を有する含フッ素ポリマーにはイソシアナート化合物やポリエポキシ化合物が使用され、エポキシ基を有する含フッ素ポリマーにはアミノ基、カルボキシル基、メルカプト基等を有する化合物や、光および／または熱で酸を発生するエポキシ硬化剤が使用される。また、加水分解性珪素基を有する含フッ素ポリマーには該加水分解性珪素基を縮合硬化させうる硬化触媒（有機錫化合物や、有機酸チタン塩等）が使用され、末端不飽和基を有する含フッ素ポリマーにはラジカル開始剤あるいは水素化珪素化合物（および必要により付加反応触媒）が使用されるが、これらに限られるものではない。
【００４５】
含フッ素エラストマーを製造するための反応部位を有する含フッ素ポリマーは、前記の重合・合成過程の途中および／または最後に公知の方法（再沈洗浄、カラムクロマトグラフによる精製、熱処理等）で反応残分や重合開始剤等を除去されたものであることが好ましい。特に重合後２００℃以上好ましくは２５０℃以上、さらに好ましくは３００℃以上の温度で熱処理することが、低分子の不安定成分を分解除去できるため好ましい処理方法である。
【００４６】
また、前記含フッ素エラストマーをフッ素ガスによりフッ素化処理することは、例えばペルフルオロエラストマーは反応および／または重合時生成する末端基を最終的にペルフルオロ化すると同時に、エラストマーに含まれる不純物が全てフッ素化のエネルギーで分解除去できるため、好ましい前処理である。またペルフルオロでない含フッ素エラストマーはフッ素化により、フッ素含有量が向上し、安定性、含フッ素溶媒への溶解性が向上し、さらにペルフルオロエラストマーのフッ素化時に期待される効果と同様の効果も期待できるため好ましい前処理方法である。
【００４７】
また、含フッ素エラストマーの溶液や分散液には、基板、有機ＥＬ構造体、上層の樹脂層などとの密着性向上のためにシランカップリング剤や、エポキシ化合物等の公知の密着性付与剤を少量添加しても良い。
【００４８】
これらの含フッ素エラストマーの含フッ素溶媒に溶解または分散した溶液の有機ＥＬ構造体へのコーティング方法としては特に限定されないが、スピンコート、ダイコート、ブレードコート、スクリーン印刷、インクジェット、スプレーコート、カーテンコート等の公知の方法が使用できる。但し、例えば電極配線の取り出し・実装する場合や、含フッ素エラストマー層の上にさらに合成樹脂層を積層する場合、接着性を確保するため基板と合成樹脂層の接着部位を確保する場合等において、含フッ素エラストマー層は有機ＥＬ構造体の上部のみにコーティングすることが好ましい。この場合全面にスピンコート等を用いてコーティング後含フッ素エラストマー層を所定位置を除いて機械的および／またはレーザー等により除去する方法、インクジェット法による特定エリアの選択的コート法、ダイコート等でダイを加工し特定エリアのみをコートする方法、スプレーコートやカーテンコート等においてマスクを用いて特定エリアのみをコートする方法等が好ましい。
【００４９】
含フッ素エラストマー層の厚みとしては、特に制限されるものではないが、薄すぎると表面保護効果および／または上層に合成樹脂層等が積層される場合の応力緩和効果等が低下するため好ましくない。また厚すぎると含フッ素エラストマー層自体の総応力が高くなり有機ＥＬ構造体に影響を及ぼす、あるいは、コーティング後の乾燥が不完全になりやすい等の問題が出る可能性があり好ましくない。好ましくは１０ｎｍ〜２ｍｍ、より好ましく５０ｎｍ〜５００μｍ、特に好ましくは０．１μｍ〜１００μｍである。
【００５０】
また、本発明における封止層として含フッ素エラストマー層の外表面にさらに防湿性や素子保護等の目的で他の有機化合物、金属、金属酸化物および／または窒化物、無機酸化物および／または窒化物、合成樹脂層などからなる外層を設けることができる。封止層の外側には、さらに、ガラス板、プラスチックフィルム等を設置しても良い。このような場合でも、含フッ素エラストマー層が挿入されることで、合成樹脂層などの封止層外層やガラス板などと、下層有機ＥＬ構造体層との線膨張差や応力が緩和され、素子が安定して発光することができる。具体的には合成樹脂からなる封止層外層を介してガラス板やプラスチック板等を接着する方法が機械的保護や防湿性の観点で好ましい。また、含フッ素エラストマー層上に合成樹脂層および無機および／または金属層を順次積層した構造も素子の薄型化および防湿性の観点で好ましい方法といえる。
【００５１】
このような封止層外層の材料である合成樹脂層としては、一般の光硬化性樹脂、熱可塑性樹脂、熱硬化性樹脂等が挙げられる。中でも硬化性樹脂の場合はアウトガスの観点で熱もしくは光カチオン硬化系のエポキシ樹脂および／またはオキセタン系樹脂が好ましい。また、熱可塑性樹脂も硬化反応による副生物等の問題が少なく好ましい。この場合均一に低温で被覆が可能であることから溶媒に可溶な熱可塑性樹脂をコーティングによりコートすることが好ましい。また、この際の溶媒としては炭化水素系溶媒もしくは前記フッ素含量が４０ｗｔ％以上の含フッ素溶剤に可溶な熱可塑性樹脂が有機ＥＬ構造体への溶媒の影響の観点で好ましいと言える。
【００５２】
２つの電極層によって挟持された有機ＥＬ層としては公知のものを使用することができる。具体的な構造を例示すると、透明電極層、背面電極層に挟まれる有機ＥＬ層からなっており、いずれか一方の電極上にＴＦＴアレイが形成されたり、透明電極上にカラーフィルターや、青色発光の素子の場合青色変換フィルターが設置されている場合もある。これらの構造がガラス基板やプラスチック基板、プラスチックフィルム、シリコン等の金属基板や金属フィルム上に形成されている。
【００５３】
２つの電極はいずれかが負極（電子注入用電極）で他方が正極（正孔注入電極）となり、少なくとも一方が透明な電極である。
通常は正極として使用される透明電極層の材料としては、通常、インジウムスズ酸化物（ＩＴＯ）薄膜、アンチモンまたはフッ素をドープしたスズ酸化物、３Ｂ族元素をドープした酸化亜鉛等を使用できる。また、仕事関数の大きい金等の金属、ヨウ化銅などの無機化合物導電性物質、ポリ（３−メチルチオフェン）、ポリ（３，４−エチレンジオキシチオフェン）、ポリピロール、ポリアニリン等の有機化合物導電性物質、これらにポリスチレンスルホン酸やパラトルエンスルホン酸、ルイス酸性金属等をドープしたもの等により構成されてもよい。
この電極は、真空蒸着法、スパッタリング法等により作成されることが一般的であるが、有機化合物導電性物質の場合には適当なバインダーとの溶液を基板上に塗布したり、電解重合したりすることにより直接基板上に薄膜を作製できる。陽極の膜厚は、必要とする透明性に依存するが、可視光の透過率が６０％以上、好ましくは８０％以上とされるように選定される。通常、この膜厚は５〜１０００ｎｍ程度とされ、好ましくは１０〜５００ｎｍである。
【００５４】
正極層の上には有機ＥＬ層が積層され、有機ＥＬ層の上には第２の電極層が積層されている。第２の電極層は通常負極であり、Ｌｉ、Ｎａ、Ｃｓ、Ｃａ、Ｍｇなどの低仕事関数金属および／またはこれらの酸化物、水酸化物、フッ化物、塩化物等をＡｌ、Ａｇ等の低抵抗金属と積層あるいは合金化したものなどの材料からなる。この負極は、正極と対向して所定の形状や、直交するストライプ状等に形成されている。以上の正極と負極とそれらに挟まれた有機ＥＬ層が基本的な有機ＥＬ構造体を形成する。
【００５５】
負極を透明電極として使用する場合は前記低仕事関数金属を使用することが一般的であり、この場合は光透過性が確保できる程度に負極層を薄膜化し、必要により補助電極等を併用することが好ましい。
有機ＥＬ層と正極層の間にはホール注入層や、ホール輸送層が設けられてもよく、有機ＥＬ層と負極層の間には、電子輸送層や、電子注入層が設けられてもよい。これらの層は、要求される有機ＥＬ層の特性から、必要でないものは省かれても良いし、層構成の順序が変更されても良い。
【００５６】
具体的な正孔輸送層用材料としては、電極からの正孔注入障壁が低く、さらに正孔移動度が高い材料が使用できる。このような材料としては公知の正孔輸送材料が使用できる。たとえば、Ｎ，Ｎ’−ジフェニル−Ｎ，Ｎ’−ビス（３−メチルフェニル）−１，１’−ビフェニル−４，４’−ジアミンや１，１’−ビス（４−ジ−ｐ−トリルアミノフェニル）シクロヘキサン等の芳香族ジアミン系化合物、特開平２−３１１５９１で示されているヒドラゾン化合物が使用できる。また、ポリ−Ｎ−ビニルカルバゾールやポリシランのような高分子材料も好ましく使用できる（Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．，５９，２７６０（１９９１））。また、前記正極材料で示した、ポリ（３−メチルチオフェン）、ポリ（３，４エチレンジオキシチオフェン）、ポリピロール、ポリアニリン等の有機化合物導電性物質、これらにポリスチレンスルホン酸やパラトルエンスルホン酸、ルイス酸性金属等をドープしたもの等を使用することもできる。さらに、後述正孔注入層に使用される材料を使用することもできる。
【００５７】
正孔輸送層の材料としては、上記有機物質だけではなく無機物質である金属カルコゲン化物、金属ハロゲン化物、金属炭化物、ニッケル酸化物、鉛酸化物、銅のヨウ化物等のｐ型化合物半導体やｐ型水素化非晶質シリコン、ｐ型水素化非晶質炭化シリコン等も使用できる。また、これらの正孔輸送物質を混合して層を形成することもできる。
【００５８】
正孔輸送層の耐熱性や薄膜均一性を向上させるために、正孔のトラップとなりにくいバインダー樹脂を混合して使用することもできる。このようなバインダー樹脂としては、ポリエーテルスルホン、ポリカーボネート、ポリエステル等が挙げられる。バインダー樹脂の含有量は、正孔移動度を低下させない１０〜５０重量％が好ましい。有機物質、無機物質いずれを使用した場合においても正孔輸送層の膜厚は、通常、１０〜２００ｎｍであり、好ましくは、２０〜８０ｎｍである。
【００５９】
正極と正孔輸送層との間には、リーク電流の防止、正孔注入障壁の低減、密着性向上等のために、正孔注入層を設けてもよい。このような材料としては、特開平４−３０８６８８にみられるようなトリフェニルアミンの誘導体である　４，４’，４”−トリス｛Ｎ−（３−メチルフェニル）−Ｎ−フェニルアミノ｝トリフェニルアミン（以下「ＭＴＤＡＴＡ」と略称する）、４，４’，４”−トリス｛Ｎ，Ｎ−ジフェニルアミノ｝トリフェニルアミン（以下「ＴＤＡＴＡ」と略称する）、トリス（４−ブロモフェニル）アミン塩、　トリフェニルアミン−４，４’−ジイル単位を有するポリマーや銅フタロシアニン等が好ましく使用できる。この層を設けるときの膜厚は、５〜１００ｎｍで好ましく使用できる。
電子輸送層の材料としては、電子親和力が大きく、電子の移動度が大きい物質が好ましい。このような材料としては、例えばトリス（８−キノリノラト）アルミニウム（Ａｌｑ_３）等の８−キノリノールなしいその誘導体を配位子とする有機金属錯体などのキノリン誘導体、オキサジアゾール誘導体、ペリレン誘導体、ピリジン誘導体、ピリミジン誘導体、キノキサリン誘導体、ジフェニルキノン誘導体、ニトロ置換フルオレン誘導体、ジスチリルビフェニル誘導体（ＤＰＶＢｉ）、オキサジアゾール誘導体、ビスチリルアントラセン誘導体、ベンゾオキサゾールチオフェン誘導体、チアゾール類等を用いることができる。電子輸送層は後述の有機ＥＬ層を兼ねたものであってもよく、このような場合はトリス（８−キノリノラト）アルミニウム等を使用することが好ましい。
【００６０】
有機ＥＬ層の材料としては、それ自体が発光する発光物質を含有し、該発光物質単独で形成されていてもよい。また、それ自体が発光してもしなくてもよい、電子輸送性および／または正孔輸送性のある材料をホスト材料として用い、これに該発光物質をドーパントとして使用しても良い。このような発光物質としては、テトラフェニルブタジエン、スチリル系色素、スチルベン系色素、オキサゾール系色素、シアニン系色素、キサンテン系色素、オキサジン系色素、クマリン系色素、アクリジン系色素などのレーザー用色素やアントラセン誘導体、ナフタセン誘導体、ペンタセン誘導体、ピレン誘導体、ペリレン誘導体などの芳香族炭化水素系物質、４−ジシアノメチレン−２−メチル−６−ｐ−ジメチルアミノスチリル−４Ｈ−ピラン誘導体、ユーロピウム錯体など幅広く使用できる。このようなドープ有機材料の濃度としては、有機ＥＬ層内において０．０１〜２０モル％とされることが好ましい。また、ポリマー型材料としては、ポリフェニレン誘導体、ポリフルオレン誘導体、ポリチオフェン誘導体、ポリシラン誘導体、ポリアリーレンビニレン誘導体等に挙げられるπおよび／またはσ共役型高分子やこれらのブロックおよび／またはランダム共重合体が挙げられる。また、これらのポリマー型材料にさらに前記の発光物質を所定量添加しても良い。また、前記正孔輸送層および／または電子輸送層自体が発光性がある場合は、これらの層が有機ＥＬ層としての機能を果たすことより有機ＥＬ層とみなすことができる。
【００６１】
また、電子輸送層と負極層が接する場合、この界面にさらに電子注入層が挿入されていても良い。電子注入層を設けることにより、駆動電圧の低減や発光効率の向上、長寿命化を達成できる。この界面層は負極からの電子注入を容易にする効果や負極との密着性を上げる効果がある。
このような材料としては、フッ化リチウム（Ａｐｐｌ．Ｐｈｙｓ．Ｌｅｔｔ．，７０，１５２（１９９７））に代表されるアルカリ金属のフッ化物、アルカリ土類金属のフッ化物、酸化マグネシウム、酸化ストロンチウム、酸化アルミニウム、酸化バリウムなどの酸化物がある。このような界面層材料は絶縁体の場合には、使用する膜厚は、５ｎｍ以下の薄膜であり、好ましくは、２ｎｍ以下とすることにより負極からの電子のトンネル注入が可能となると考えられる。非絶縁体の場合には、１００ｎｍ以下で効果を損しない範囲内とされればよい。
以上にあげた各層は、有機ＥＬ素子として機能する範囲であれば、その層自体が複数の層で形成されていたり、それらの間にさらに他の層を挟んだりしてもよい。これら各層の作製方法としては、真空蒸着法、ディップ法、スピンコート法、インクジェット法、カーテンコート法、グラビア印刷法、ダイコート法、ＬＢ法、ＣＶＤ法等の種々の公知の手法が適用できる。
【００６２】
【実施例】
以下に本発明の実施例を示すが、本発明は下記に限られるものではない。
【００６３】
合成例１
デカフルオロビフェニル５ｍｏｌと２，２−ビス（４−ヒドロキシフェニル）ヘキサフルオロプロパン４ｍｏｌを縮合して末端がデカフルオロビフェニルのオリゴマーを得た。
【００６４】
合成例２
ポリマー１
合成例１で得られたオリゴマーとアウシモント社製「ＦｏｍｂｌｉｎＺｄｏｌ−４０００」（ペルフルオロポリエーテル）の末端トリメチルシリルエーテル化物とヘキサフルオロベンゼンを１：２：１のモル比でＤＭＦ溶媒中ふっ化セシウムを触媒として加熱反応させ、エラストマーを得た。
得られたエラストマーを１，３−（ビストリフルオロメチル）ベンゼン−水系で水洗し、２５０℃２ｈｒ空気下に加熱してエラストマーを精製した。
このエラストマーは−６０℃〜１４０℃の範囲でゴム弾性を保持した。このエラストマーを、１，３−（ビストリフルオロメチル）ベンゼンとペルフルオロトリブチルアミンの１：９混合溶媒に溶解し溶液とした。
【００６５】
ポリマー２
ペルフルオロポリエーテル（分子量約４，０００）の末端を沃素化したものの存在下に、テトラフルオロエチレンとペルフルオロ（２，２−ジメチル−１，３−ジオキソール）を３５：６５のモル比でフィードしながら重合を行い、分子量約１５，０００のＡＢＡ型ブロック共重合体を合成した。得られたエラストマーは−６０℃〜１６０℃でゴム弾性を示した。得られたポリマーを３２０℃２ｈｒ空気下に加熱した後ペルフルオロオクタンに溶解し、水洗、乾燥して精製し、再度ペルフルオロオクタンに溶解してエラストマー溶液を得た。
【００６６】
ポリマー３
１，４−ジヨードオクタフルオロブタン存在下、テトラフルオロエチレンとペルフルオロ（ビニルエーテル）を３：７ｍｏｌ比のランダム共重合体（分子量約１５，０００）になるように重合し、次いで　ペルフルオロ（３−ブテニルビニルエーテル）とＣＦ_２＝ＣＦＯ（ＣＦ_２）_３ＣＯＯＣＨ_３とのモル比９９：１の混合物を分子量約２０，０００になるように重合し、ＡＢＡ型ブロック重合体を合成した。得られたエラストマーは−２０℃〜１１０℃でゴム弾性を示した。得られたポリマーを３２０℃２ｈｒ空気下で加熱した後１Ｈ，１Ｈ，２Ｈ−ペルフルオロ−１−デセンに溶解し、水洗、乾燥することにより精製し、１Ｈ，１Ｈ，２Ｈ−ペルフルオロ−１−デセンに溶解した溶液を得た。
【００６７】
ポリマー４
１，４−ジヨードオクタフルオロブタン存在下、ふっ化ビニリデンとヘキサフルオロプロピレンを７８：２２のモル比でフィードしながら重合を行い、分子量１５万のポリマーを得た。次いでこのポリマー存在下にテトラフルオロエチレンとペルフルオロ（２，２−ジメチル−１，３−ジオキソール）を４０：６０のモル比で連続的にフィードし、分子量約２０，０００のブロック共重合体を合成した。得られたエラストマーは−２０℃〜１５０℃でゴム弾性を示した。得られたポリマーを３００℃２ｈｒ空気下に加熱した後１−メトキシペルフルオロオクタンに分散し、水洗、硫酸マグネシウムにて乾燥し、１−メトキシペルフルオロオクタンの分散液を得た。
【００６８】
ポリマー５
光硬化性エポキシ樹脂（ナガセケムテックス社製ＸＮＲ５５１６）
【００６９】
有機ＥＬ構造体作成例１
ガラス基板上にＩＴＯを膜厚２００ｎｍとなるように蒸着して正極層（シート抵抗７Ω／□）を形成した。この陽極上に、真空蒸着法により正孔注入層として銅フタロシアニンを膜厚２０ｎｍとなるように蒸着し、ついで下図のα−ＮＰＤを膜厚４０ｎｍに蒸着して正孔輸送層を形成した。Ａｌｑを、異なるボートを用いて膜厚６０ｎｍに共着して有機ＥＬ層を形成した。最後に、ＭｇとＡｇを共蒸着して膜厚２００ｎｍのＭｇＡｇ（１０：１）負極合金層を形成して有機ＥＬ構造体を作製した。
【００７０】
【化３】

【００７１】
有機ＥＬ構造体作成例２
ガラス基板上にＩＴＯを膜厚２００ｎｍで蒸着して正極層（シート抵抗７Ω／□）を形成した。この正極層上に、真空蒸着法により前記の銅フタロシアニンを膜厚２０ｎｍ、ついで９ＰＰＤを膜厚４０ｎｍに蒸着して正孔輸送層５を形成した。次いで、前記のＡｌｑとルブレンを、異なるボートを用いて膜厚６０ｎｍに共蒸着して有機ＥＬ層４を形成した。ついでＬｉＦを０．５ｎｍ、最後に、Ａｌを膜厚２００ｎｍの厚さで蒸着して負極を形成して有機ＥＬ構造体を作製した。
【００７２】
実施例１
有機ＥＬ構造体作成例１で得られた有機ＥＬ構造体の負極層の上に、ポリマー１の溶液をスピンコートした後１００℃で１ｈｒ減圧乾燥することにより厚さ５μｍに製膜した。ついでポリマー５を厚さ５０μｍにコートしたガラス板をポリマー５コート面に貼り合わせＵＶを照射することでポリマー５を硬化して封止した。得られた素子を６０℃窒素下５００ｈｒ保管後有機ＥＬ素子の発光面を観察したところ非発光部の面積は５％程度だった。
【００７３】
比較例１
実施例１においてポリマー１を使用することなく有機ＥＬ構造体にポリマー５を厚さ５０μｍにコートしたガラス基板を貼り合わせＵＶを照射することでポリマー５を硬化して封止を行った。得られた素子を６０℃窒素下５００ｈｒ保管後素子の発光面を観察したところ非発光部の面積は３０％に増加した。
【００７４】
実施例２、３、４
有機ＥＬ構造体作成例２で得られた有機ＥＬ構造体の負極層の上にポリマー２、３、４の溶液を各々スピンコートした後１２０℃で１ｈｒ減圧乾燥することにより厚さ１０μｍに製膜した。ついでポリマー５を厚さ５０μｍにコートしたガラス板を各ポリマーコート面に貼り合わせＵＶを照射することでポリマー５を硬化して封止した。得られた素子を１００℃窒素下１日保管後素子の発光面を観察したところ非発光部の面積はいずれも１％程度だった。
【図面の簡単な説明】
【図１】本発明の有機ＥＬ素子の断面を示す概念図である。
【図２】本発明の有機ＥＬ素子の別の例の断面を示す概念図である。
【符号の説明】
１　負極層（背面電極層）
２　正極層（透明電極層）
３　電子注入層
４　有機ＥＬ層
５　正孔輸送層
６　正孔注入層
７　ガラス保護板
８　ガラス基板
９　ＵＶ硬化性樹脂層（封止層外層）
１０　含フッ素エラストマー層（封止層内層）
１１　透明プラスチック基板
１２プラスチック保護板[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescence element (hereinafter abbreviated as “organic EL element”) used for a flat display, a flat light source, and the like, and more particularly to an organic EL element having excellent stability and a method for producing the same.
[0002]
[Prior art]
With the rapid progress of technological development in the information and communication field in recent years, great expectations are placed on a flat display replacing CRT. In particular, organic EL elements are actively studied because they are excellent in high-speed response, visibility, brightness, and the like.
The organic EL device announced by Tang et al. Of Kodak Company in 1987 has a two-layer structure of organic thin films, and uses tris (8-quinolinolato) aluminum (hereinafter abbreviated as “Alq”) for the light emitting layer. 1000 cd / m with low voltage drive of 10V or less ² (Appl. Phys. Lett., 51, 913 (1987)). Since then, research for rapid commercialization has progressed, and a stacked organic EL device in which an organic layer sandwiched between a hole injection electrode and an electron injection electrode is laminated in various layers of about 1 to 10 layers has been developed. Yes. Regarding materials, not only a wide variety of low-molecular compounds can be formed into thin films by vacuum deposition or the like, but organic compounds can be formed by forming thin films of polymer compounds by methods such as spin coating, ink jet, die coating and flexographic printing. A method of creating is proposed.
[0003]
In addition, as a light-emitting element that replaces CRT, in order to emit three colors of RGB, a method of independently forming light-emitting elements of three colors of RGB on one substrate by vapor deposition, an organic EL element that emits white light on a color filter A method of forming, a method of forming a blue light emitting or ultraviolet light emitting organic EL element on a color conversion filter, and the like have been proposed. Further, in order to improve luminance, from a transparent hole injection electrode which has been generally used so far Instead of light extraction, a method of extracting light by making the electron injection side transparent, and a method of forming an organic EL element on a TFT substrate have been proposed for the purpose of high definition and low power consumption.
In general, the organic EL device described above is made of a single metal or aluminum or a low work function metal such as alkali metal, alkaline earth metal, rare earth metal and / or its oxide / halide for efficient electron injection. Use alloyed with metal such as silver. In addition, since organic compounds are used between the electrodes, organic EL devices emit light that is generally called dark spots because the electrodes and / or organic compound layers are easily oxidized or delaminated by atmospheric oxygen and moisture. A portion (defect) that does not emit light is generated in the plane. Therefore, in order to improve the stability and increase the reliability of the organic EL element, a sealing method for protecting the element from active gases such as moisture and oxygen in the atmosphere is indispensable.
[0004]
For this reason, after forming a protective film such as a polymer film or inorganic oxide / nitride on the organic EL element by vacuum deposition or the like, a shield layer such as a resin layer or a glass plate is provided via an adhesive or the like ( JP-A-4-267097, JP-A-5-36475, and JP-A-5-182759 have been proposed. However, in these methods, there is a problem that peeling of the organic EL element, for example, the electron injection layer-organic layer interface, or destruction of the element itself occurs due to the stress of the layer laminated on the organic EL element. There were significant restrictions on the protective layer.
In order to solve this problem, proposals have been made to form a flexible rubber layer on the organic EL element (Japanese Patent Laid-Open Nos. 8-236271 and 9-274990). Organic EL due to the effects of solvents and impurities when forming the rubber layer, by-products during the curing reaction of the rubber layer, and decomposition products that are generated when the rubber layer deteriorates during long-term use (especially when used at high temperatures) The dark spots generated in the device have not been completely suppressed.
[0005]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to provide an organic EL element that protects the organic EL from moisture and oxygen in the atmosphere and suppresses defects such as dark spots over a long period of time.
[0006]
[Means for Solving the Problems]
The above-described problems of the present invention have been solved by the following means.
(1) A thin-film organic EL structure having two electrode layers, at least one of which is transparent, and an organic EL layer sandwiched between the electrode layers, and one or both surfaces of the outer surface of the organic EL structure An organic EL element having a sealing layer, wherein the material of the sealing layer is made of a fluorine-containing elastomer,
(2) The organic EL element is an organic EL element having a substrate, an organic EL structure provided on the substrate, and a sealing layer covering a surface of the organic EL structure that is not in contact with the substrate. ) Organic EL device according to
(3) The sealing layer comprises an inner layer and an outer layer on the organic EL structure side, the inner layer material comprises a fluorine-containing elastomer, and the outer layer material comprises a synthetic resin other than the fluorine-containing elastomer. (1) or (2) An organic EL device according to claim 1,
(4) In the method for producing an organic EL device according to (1), (2) or (3), the surface of the organic EL structure is coated with a solution or dispersion of a fluorine-containing elastomer and dried to form an organic EL structure. A method for producing an organic EL device, wherein a sealing layer comprising a fluorine-containing elastomer is formed on the surface;
(5) The production method according to (4), wherein the solvent in the fluorine-containing elastomer solution or dispersion is a fluorine-containing compound having a fluorine content of 40% by mass or more.
[0007]
The organic EL element of the present invention has a sealing layer made of a fluorine-containing elastomer that is a material that can relieve external physical stress on the organic EL structure. Is suppressed. Further, the productivity of the organic EL element can be improved by forming the sealing layer by a coating method using a solution or dispersion of a fluorine-containing elastomer. By using a fluorine-containing compound having a fluorine content of 40% or more as a solvent in this coating method, an undesirable influence of the solvent on the organic EL structure can be reduced.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
In the present invention, the organic EL structure is a thin film-like structure, and has at least one of two transparent electrode layers and an organic EL layer sandwiched between the electrode layers. One of the two electrode layers is a positive electrode and the other is a negative electrode. In addition to the organic EL layer, a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and the like can be appropriately provided between the electrode layers of the organic EL structure. The sealing layer can be provided on one of the two outer surfaces of the organic EL structure, or can be provided on both outer surfaces. In either case, the very thin side surface of the organic EL structure is usually sealed together with the outer surface.
When both outer surfaces of the organic EL structure are sealed with a sealing layer, one sealing layer can also function as a substrate. For example, an organic EL structure can be formed on a transparent fluorine-containing elastomer film, and the outer surface of the formed organic EL structure can be covered with a fluorine-containing elastomer to form an organic EL element.
The organic EL structure is usually formed on a transparent substrate, and the elastomer layer is usually not provided on the surface of the substrate on which the organic EL structure is not formed. The organic EL device of the present invention preferably has such a structure. Examples of the substrate include a glass substrate and a plastic substrate. On the surface opposite to the substrate of the organic EL structure, a back plate or a plate or film (hereinafter referred to as a protective plate) called a (second) substrate is used for protecting or sealing the organic EL structure. May be provided. The organic EL element of the present invention is also preferably provided with such a protective plate, and the sealing layer in the present invention exists between the protective plate and the organic EL structure. It is also possible to make the protective plate transparent so that light is transmitted from the organic EL structure to the protective plate side.
The sealing layer in this invention may consist of one layer, and may consist of two or more layers inside and outside or three or more layers. Among these, at least one layer of material is made of a fluorine-containing elastomer, and in particular, a material of a layer in contact with the organic EL structure is preferably made of a fluorine-containing elastomer. The other layer may be made of a material other than the fluorine-containing elastomer.
As an embodiment of the present invention, conceptual diagrams of cross sections of organic EL elements are shown in FIGS. 1 includes a glass substrate (8), a transparent positive electrode layer (2), a hole injection layer (6), a hole transport layer (5), an organic EL layer (on the glass substrate (8)). 4) and an organic EL structure formed by laminating the negative electrode layer (1) in this order, an inner layer (10) made of a fluorine-containing elastomer, and an outer layer (9) made of another material. And a protective plate (7) provided on the negative electrode layer (1) side of the organic EL structure. The organic EL element of FIG. 2 includes an organic EL structure having the same configuration as FIG. 1 except that an electron injection layer (3) is provided between the negative electrode layer (1) and the organic EL layer (4), and a transparent It is composed of a plastic substrate (11), a sealing layer composed of the same two outer layers as in FIG. 1, and a plastic protective plate (12). The material of the plastic substrate (11) may be the fluorine-containing elastomer in the present invention. The positive electrode layer (2) is less affected by moisture, oxygen and the like than the other layers such as the negative electrode layer (1) and the organic EL layer. You may have.
[0009]
The fluorine-containing elastomer used in the present invention is an elastic polymer having a fluorine atom, and a temperature range in which the organic EL element is used, specifically 20 ° C. to 70 ° C., preferably 0 ° C. to 90 ° C., more preferably. Means -20 ° C to 120 ° C, particularly preferably -40 ° C to 120 ° C having rubber elasticity. Specifically, for example, what is called a crosslinked fluororubber, a thermoplastic fluororubber, a soft fluororubber resin or the like is meant.
[0010]
Specifically, such a fluorine-containing elastomer is chemically formed from a polymer block having a glass transition temperature of 20 ° C. or lower, preferably 0 ° C. or lower, particularly preferably −20 ° C. or lower, more preferably −40 ° C. or lower. Examples thereof include a crosslinked polymer or a block copolymer of the polymer block and a polymer block having a glass transition temperature of 70 ° C. or higher, preferably 90 ° C. or higher, particularly preferably 120 ° C. or higher.
[0011]
The sealing layer in the present invention is preferably formed using a solution or dispersion of a fluorine-containing elastomer. For this reason, the fluorine-containing elastomer is preferably one that can be dissolved or dispersed in a solvent. The fluorine-containing elastomer can be dissolved or dispersed in a solvent. When the fluorine-containing elastomer is a crosslinked elastomer formed by the reaction of a crosslinkable fluorine-containing polymer (elastomer precursor) and a crosslinking agent, this crosslinking property It also means that the mixture of the fluoropolymer and the crosslinking agent can be dissolved or dispersed in a solvent. By using this fluorine-containing elastomer solution or dispersion, it becomes very easy to form the sealing layer.
The solvent that can dissolve or disperse the fluorine-containing elastomer needs to be a solvent that does not adversely affect the organic EL structure in contact with the solvent. The present inventor has found a solvent comprising a fluorine-containing compound (hereinafter referred to as a fluorine-containing solvent) as a solvent that can dissolve or disperse the fluorine-containing elastomer and does not adversely affect the organic EL structure. As the fluorine-containing solvent, a fluorine-containing solvent having a fluorine content of 40% by mass or more is preferable, and a fluorine-containing solvent having a fluorine content of 60% by mass or more is particularly preferable. The most preferred fluorine-containing solvent is a solvent composed of a compound in which all of hydrogen atoms bonded to carbon atoms are substituted with fluorine atoms, that is, a perfluoro solvent.
[0012]
There are various methods for forming the fluorine-containing elastomer of the present invention as a sealing layer of an organic EL device, but typical forming methods are listed below.
(1) Coating method
For example, when the fluorine-containing elastomer is a thermoplastic elastomer, it is dissolved or dispersed in a fluorine-containing solvent to form a coating agent, and after coating the outer surface of the organic EL structure, the solvent is removed and sealed. It can be a layer. Examples of the method for removing the solvent include a method of drying under normal pressure or reduced pressure while heating as necessary.
(2) Crosslinking method
When a fluorine-containing elastomer is formed by a crosslinking method, an elastomer precursor before crosslinking and, if necessary, a crosslinking agent and a crosslinking catalyst are dissolved or dispersed in a fluorine-containing solvent together to form a coating agent. And the like, and coating the outer surface of the organic EL structure to remove the solvent (dry) and cross-link to form an elastomer. When the elastomer precursor is a liquid oligomer at room temperature, coating may be possible without dissolving or dispersing in a fluorine-containing solvent. In such a case, the solvent may not be used.
(3) Laminating method
Further, there is a method in which a fluorine-containing elastomer layer is formed on a support film in advance, and then this film is laminated on the outer surface of the organic EL structure. In this case, a sealing layer of a fluorine-containing elastomer can be formed on the organic EL structure by heating or pressing under reduced pressure if necessary.
(4) Vapor deposition method
It is also possible to form a sealing layer made of a fluorine-containing elastomer by vapor deposition. However, the elastomer is partially decomposed by heating at the time of vapor deposition, and a low molecular component generated thereby may act as a harmful substance and damage the organic EL structure.
[0013]
Among the above-described sealing layer forming methods, a coating method or a crosslinking method is preferable.
In a coating method or a crosslinking method using a fluorine-containing solvent, by using a fluorine-containing solvent having a fluorine content of 40 wt% or more, the organic EL structure is sealed with a fluorine-containing elastomer in a state in which damage to the organic EL structure is suppressed. A stop layer can be formed. In particular, the thermoplastic fluorine-containing elastomer does not use a low-molecular compound such as a crosslinking agent, so that there is no possibility that the unreacted low-molecular compound after sealing has an adverse effect on the organic EL structure.
[0014]
Examples of the fluorine-containing solvent that can be used in the present invention include aromatic compounds having a fluoroalkyl group or a fluoroalkylene group that may contain oxygen and / or hydrogen partially. Here, the “fluoroalkyl group or fluoroalkylene group which may partially contain oxygen and / or hydrogen” means that 50% or more, particularly 70% or more of the hydrogen atoms are fluorine atoms, and in addition to the fluorine atoms, chlorine atoms or The C1-C12 polyfluoroalkyl group or polyfluoroalkylene group which may have a hydrogen atom and may have an etheric oxygen atom.
In particular, a perfluoroalkyl group or a perfluoroalkylene group which may have 70% or more of hydrogen substituted with fluorine and optionally have an etheric oxygen atom is preferred, and when an etheric oxygen atom is present, it contains 2 to 4 carbon atoms. Those having a ratio of one oxygen atom are preferred. Among them, especially those in which all hydrogen is replaced with fluorine, or only the molecular terminal or side chain is CF ₂ The thing of C1-C12 in which H group is contained is preferable.
[0015]
Specific examples of the aromatic compound having a fluoroalkyl group or a fluoroalkylene group that may partially contain oxygen and / or hydrogen include CF ₃ (CF ₂ ) _n C ₆ H ₅ (Perfluoroalkyl) benzene, 1,3-bis (trifluoromethyl) benzene, 1,4-bis (trifluoromethyl) benzene, 1,4- (bistrifluoromethoxy) represented by (n is an integer of 1 or more) ) Polyfluoroaromatic compounds such as side chain fluorine-substituted benzene such as benzene, perfluorobenzene, and pentafluorobenzene.
[0016]
Examples of other solvents having a fluorine content of 40 wt% or more include the following compounds:
Polyfluorotrialkylamine compounds such as perfluorotributylamine and perfluorotripropylamine;
Perfluorohexane, perfluorooctane, perfluorodecane, perfluorododecane, perfluoro (2,7-dimethyloctane), perfluoro (2,5-dimethylhexane), 2H, 3H-perfluoropentane, 1H-perfluorohexane, 1H-perfluorooctane, 1H -Perfluorodecane, 1H, 4H-perfluorobutane, 1H, 1H, 1H, 2H, 2H-perfluorohexane, 1H, 1H, 1H, 2H, 2H-perfluorooctane, 1H, 1H, 1H, 2H, 2H-perfluorodecane, 3H, 4H-perfluoro (2-methylpentane), 2H, 3H-perfluoro (2-methylpentane), 1,1-dichloro-2,2,3,3,3-pentafluoropropane, 1,3-dichloro- 1,1,2,2,3 Pentafluoropropane, polyfluoroalkanes compounds such as 1,1-dichloro-1-fluoroethane;
[0017]
Polyfluoroolefin compounds such as (perfluoro-n-octyl) ethylene, (perfluoro-n-hexyl) ethylene, (perfluoro-n-butyl) ethylene, hexafluoropropene dimer, hexafluoropropene trimer; Polyfluorocycloalkane compounds such as decalin, perfluorocyclohexane, perfluoro (1,3,5-trimethylcyclohexane), perfluoro (dimethylcyclobutane);
Polyfluoroalicyclic ether compounds such as perfluoro (2-butyltetrahydrofuran);
[0018]
CF ₃ (CF ₂ ) _n OCH ₃ (N = an integer from 3 to 10), CF ₃ (CF ₂ ) _n OCH ₂ CH ₃ (N = an integer from 3 to 10), CF ₃ (CF ₂ ) _n OCH ₂ CF ₃ (N = an integer from 3 to 10), CF ₃ (CF ₂ ) _n OCHFCH ₃ (N = an integer from 3 to 10), CF ₃ (CF ₂ ) _n OCF ₂ CF ₂ H (n = integer of 3 to 10), CH ₃ OCF ₂ CF ₂ H, CF ₃ CFHCF ₂ OCH ₃ , Iso-C ₄ F ₉ OCH ₃ , Iso-C ₄ F ₉ OCH ₂ CF ₃ , Iso-C ₄ F ₉ OCHFCF ₃ , Iso-C ₄ F ₉ OCF ₂ CF ₂ H, iso-C ₄ F ₉ OCH ₂ CH ₃ ,
CH ₃ OCH (CF ₃ ) ₂ , CF ₃ (CF ₂ ) ₂ CH ₂ OCH ₃ , CF ₃ (CF ₂ ) ₂ OCH ₂ CF ₂ CHF ₂ , CF ₃ (CF ₂ ) ₂ OCH ₂ CF ₂ CF ₃ , Cyclo-C ₆ F ₁₁ OCH ₃ Hydrofluoroethers such as;
[0019]
CF ₃ (CF ₂ ) _n (CH ₂ ) _m OH, (CF ₃ ) ₂ CF ₂ (CF ₂ ) _n (CH ₂ ) _m OH, HCF ₂ (CF ₂ ) _n (CH ₂ ) _m OH (n is an integer of 0 or more, m is an integer of 1 or more, provided that the fluorine content is 40 wt% or more),
(CF ₃ ) ₂ CHOH, (CF ₃ ) ₃ Fluorine-containing alcohols such as COH;
Polyfluoro ketones such as perfluoro (diisopropyl ketone) can be mentioned, but are not limited thereto.
[0020]
The fluorine-containing solvent in the present invention is preferably a polyfluoroalkane compound containing no fluorine other than fluorine, hydrofluoroethers, perfluoroalkylbenzene, etc. having a fluorine content of 40 wt% or more, and particularly those having a fluorine content of 60 wt% or more. Fluorine-containing compounds are preferred.
[0021]
The thermoplastic fluorine-containing elastomer in the present invention will be described.
The fluorine-containing elastomer of the present invention is preferably a fluorine-containing elastomer that can be dissolved or dispersed in a fluorine-containing solvent having a fluorine content of 40 wt% or more. The chemical structure is not particularly limited, but a thermoplastic elastomer can be preferably used in the present invention. Thermoplastic elastomers are preferred because they generate less harmful low molecular compounds due to side reactions that can occur during chemical crosslinking. Examples of such a fluorine-containing elastomer include a linear or comb-shaped block copolymer. Furthermore, star-shaped or radial block copolymers can also be used in the present invention.
[0022]
A block copolymer has a block component having a glass transition temperature higher than the operating temperature range (hereinafter simply referred to as “component having a higher glass transition temperature”) and a block component having a glass transition temperature lower than the operating temperature range (hereinafter simply referred to as “ A component having a low glass transition temperature). The linear block copolymer is a copolymer having a structure in which one or more of both block components are alternately arranged. A comb block copolymer is a copolymer having a structure in which one block component is a main chain, the other block component is a side chain, and a number of side chains are bonded to the main chain.
[0023]
Examples of the block component having a high glass transition temperature include the following.
A-1. Polymer with aromatic ring in main chain skeleton
Specifically, for example, aromatic polyester, aromatic polyether such as poly-2,6-dimethylphenylene oxide, polyphenylene ether ketone, polyphenylene ether ether ketone, polyphenylene ether sulfone, polyphenylene sulfide, polyimide, polyether imide, Examples thereof include polyamide and polybenzimidazole.
Among them, a part or all of hydrogen in an aromatic ring as a structural unit is substituted with a fluorine and / or a polyfluoroalkyl group, or a group connected with a polyfluoroalkylene group, specifically, for example, The fluorine-containing aromatic polymer which has a fluorine-containing aromatic ring as a structural unit as shown in above is preferable at the solubility to a fluorine-containing solvent.
[0024]
[Chemical 1]

[0025]
In the above chemical formula, Rf represents a fluoroalkyl group which may partially contain oxygen and / or hydrogen having 1 to 12 carbon atoms, and 50% or more, particularly 70% or more of the hydrogen atoms are substituted with fluorine atoms. The remainder may have a chlorine atom or hydrogen atom other than a fluorine atom and may have an etheric oxygen atom. In particular, a perfluoroalkyl group which may have 70% or more of hydrogen substituted with fluorine and optionally have an etheric oxygen atom is preferable. When an etheric oxygen atom is present, 1 to carbon atom per 4 carbon atoms Those having a ratio of 1 to 2 are preferred. Among them, especially those in which all hydrogen is replaced with fluorine, or only the molecular terminal or side chain is CF. ₂ A group having 1 to 12 carbon atoms to which a fluorine group is bonded and all other groups are preferable.
[0026]
Specific examples of preferred Rf groups include CF ₃ (CF ₂ ) _n ,
HCF ₂ (CF ₂ ) _n CF ₃ O, CF ₃ (CF ₂ ) ₂ (OCF (CF ₃ )) _n OCF (CF ₃ , (Where n is an integer from 0 to 11).
Polymers in which the above aromatic units are 80% or more, particularly preferably 100% of the total aromatics are preferred. As the polymer, a polymer in which aromatic units are directly linked or a polymer in which an ether bond or a carbonyl bond is bonded is particularly preferable because of its stability and ease of synthesis.
[0027]
These preferred polymers can be synthesized by a known method, and the following documents can be exemplified as a method for synthesizing a polymer having a particularly high fluorine content.
1. J. et al. Polym. Sci. Part A: Polym. Chem. Vol30 (1992) p1675
2. JP-A-10-158391 and JP-A-10-158382
[0028]
A block in which a fluorinated aromatic ring is linked with a perfluoroalkylene group, a solvent-soluble fluorinated polyimide, or a fluorinated polybenzimidazole block can also be used as a block having a high glass transition temperature.
[0029]
A-2. Polymer having addition polymerization structure of fluorine-substituted ethylenically unsaturated compound in main chain skeleton
Tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, chlorotrifluoroethylene, perfluorocyclopentene, perfluoro (3-butenyl vinyl ether), perfluoro (allyl vinyl ether), perfluoro (2,2-dimethyl-1,3-dioxole), Perfluoro (1,3-dioxole), perfluoro (2-methylene-4-methyl-1,3-dioxolane), perfluoro (3,5-dioxa-1,6-heptadiene), vinylidene fluoride, vinyl fluoride, 1 , 2 Difluoroethylene, dichlorodifluoroethylene, etc., and / or copolymers.
Among these, amorphous polymers are particularly preferable from the viewpoint of solubility in fluorine-containing solvents. In particular, perfluoro (3-butenyl vinyl ether), perfluoro (allyl vinyl ether), perfluoro (2,2-dimethyl-1,3-dioxole), perfluoro (1,3-dioxole) in that the glass transition temperature can be increased. , At least one selected from cyclic monomers such as perfluoro (2-methylene-4-methyl-1,3-dioxolane) and perfluoro (3,5-dioxa-1,6-heptadiene) and / or cyclopolymerization monomers A homopolymer and / or copolymer having a monomer as an essential component is preferred. Particularly preferred are perfluoro (3-butenyl vinyl ether), homopolymers of perfluoro (2,2-dimethyl-1,3-dioxole) and / or copolymers with tetrafluoroethylene. A functional group may exist at the end of these polymers, and the presence of this functional group is effective in improving the adhesion of the polymer.
[0030]
Examples of the block component having a low glass transition temperature include the following structures. B-1. Reactive sites introduced at the molecular ends of perfluoropolyethers containing as a main component a repeating unit represented by the following general formula
-(CF ₂ -CF (CF ₃ -O) _n −
-(CF ₂ -CF ₂ -O-) _n −
-(CF ₂ -CF ₂ -O-) _n -(CF ₂ O) _m −
-(CF ₂ -CF (CF ₃ -O) _n -(CF (CF ₃ O) _m −
-(CF ₂ -CF ₂ -CH ₂ -O) _n −
-(CF ₂ -CF ₂ -CF ₂ -O) _n −
[0031]
B-2. A reactive site introduced at the molecular terminal of a homopolymer or copolymer of a fluorine-containing monomer represented by the following (formula 1) to (formula 3)
[0032]
[Chemical formula 2]
RfOCF = CF ₂ (Formula 1)
RfCH ₂ OCF = CF ₂ (Formula 2)
RfCF = CH ₂ (Formula 3)
[0033]
In the formula, Rf represents a polyfluoroalkyl group which may have an etheric oxygen atom between carbon atoms. This polyfluoroalkyl group has two or more fluorine atoms, and may have a halogen atom or a hydrogen atom other than the fluorine atom. 1-15 are suitable for carbon number of a polyfluoroalkyl group, and 2-12 are preferable. The polyfluoroalkyl group may have a halogen atom other than a fluorine atom or a hydrogen atom. The etheric oxygen atom can exist between carbon atoms of the polyfluoroalkylene group, and the number of oxygen atoms is preferably 1 to 1 to 4 carbon atoms.
[0034]
As the copolymer, a fluorine-containing monomer represented by (Formula 1) to (Formula 3) is an essential component, and tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, Vinyl fluoride, 1,2-difluoroethylene, dichlorodifluoroethylene, perfluorocyclopentene, perfluoro (3-butenyl vinyl ether), perfluoro (allyl vinyl ether), perfluoro (2,2-dimethyl-1,3-dioxole), perfluoro ( 1,3-dioxole), perfluoro (2-methylene-4-methyl-1,3-dioxolane), perfluoro (3,5-dioxa-1,6-heptadiene), etc. Examples of polymers obtained by polymerization Kill.
[0035]
In this case, the content of the fluorine-containing monomer represented by the above (formula 1) to (formula 3) is 10 mol% or more, preferably 30 mol% or more, particularly preferably 50 mol% or more, so that the elastomer having a low glass transition temperature is contained. Is preferable. In addition, from the viewpoints of solubility in a fluorine-containing solvent, chemical stability, and the like, it is preferable that all of hydrogen bonded to carbon in Rf is substituted with fluorine.
[0036]
B-3. Homopolymer of vinylidene fluoride or copolymer thereof
Vinylidene fluoride as an essential component, tetrafluoroethylene, hexafluoropropylene, trifluoroethylene, chlorotrifluoroethylene, and fluorine-containing monomers represented by (Formula 1) to (Formula 3) listed in B-2 above , Vinyl fluoride, 1,2-difluoroethylene, dichlorodifluoroethylene, perfluorocyclopentene, perfluoro (3-butenyl vinyl ether), perfluoro (allyl vinyl ether), perfluoro (2,2-dimethyl-1,3-dioxole), perfluoro And a fluorine-containing vinyl compound such as (1,3-dioxole), perfluoro (2-methylene-4-methyl-1,3-dioxolane), perfluoro (3,5-dioxa-1,6-heptadiene) Polymer obtained by copolymerization.
In this case, the vinylidene fluoride content is preferably 10 to 90 mol%, preferably 20 to 80 mol%, in order to obtain an elastomer having a low glass transition temperature, and further contains hexafluoropropylene as a copolymerization component. preferable.
[0037]
B-4. A block in which a homopolymer or a copolymer of B-2 and B-3 having a degree of polymerization of 1 to 10 alone is reactive and / or chain-extended with the polymer of A is also included. Can be mentioned.
[0038]
Among these, all of hydrogen bonded to carbon in tetrafluoroethylene and / or chlorotrifluoroethylene in B-1 and B-2 and Rf in (Formula 1) is substituted with fluorine. Copolymers with fluorine monomers, vinylidene fluoride in B-3 and hexafluoropropylene and / or fluorine-containing monomers of the above (formula 1) to (formula 3) copolymerized with tetrafluoroethylene if necessary This is preferable from the viewpoints of solubility in a fluorine-containing solvent and low glass transition temperature.
[0039]
The block copolymer of the polymer having a high glass transition temperature and the polymer having a low glass transition temperature exemplified above can be synthesized by a known method. Specific examples are shown below in (a) to (c).
[0040]
(A) A method in which both block components have a reactive site and a block copolymer is synthesized by the reaction.
Known methods can be used for introduction of reaction sites and reaction methods of reaction sites. Regarding the introduction of the reaction site, for example, in the case of B-1, those synthesized by an oxidation reaction of tetrafluoroethylene or hexafluoropropylene with oxygen can be obtained in which the terminal is a COF group. A method of treating this with a compound having an amino group, a hydroxyl group, a mercapto group, etc., or a method of making a COOH group or a hydroxyl group terminal by utilizing hydrolysis or a reduction reaction, or introducing a reactive site at the terminal or chain extension. A reactive site can be introduced at the terminal while increasing the molecular weight by the reaction.
Specific examples include JP-A-62-120335, JP-B-50-7054, JP-A-60-34924, U.S. Pat. No. 3,845,051, U.S. Pat. No. 3,317,484, JP-A-2-202919, and JP-A-4-85328. JP-A-8-199070 and the like. Specific compounds include perfluoropolyethers such as “Fomblin Zdol” (trade name) and “Fomblin Zdiac” (trade name) manufactured by AUSHIMON Co., Ltd., allyl-terminated perfluoropolyether, triazine chain extended perfluoropolyether, and the like. .
When a polymer is obtained by polymerization of the vinyl compounds A-2, B-2, and B-3, a method of copolymerizing a monomer having a reactive site, an iodine transfer polymerization method (details are described in (b) below) and a reaction A method of treating a molecular terminal by a known method, if necessary, after synthesizing a polymer by a method such as a polymerization initiator having a reactive site and / or a polymer type polymerization initiator (described in detail in (c) below). It can be illustrated as a method for introducing a site.
When utilizing the condensation reaction of the aromatic polymer of A-1, it is possible to introduce a reactive site at the terminal by a known method.
[0041]
A block copolymer synthesis reaction by reaction of each reactive site of two or more polymers can also be performed by a known method. Specific examples are listed below, but are not limited thereto.
(I) A method of synthesizing a block copolymer via an ether bond by condensing a polymer having a site in which an aromatic ring hydrogen bond is substituted with a halogen as a reactive site and a polymer having a hydroxyl group at the terminal.
(Ii) A method of synthesizing a block copolymer by reacting two or more kinds of polymers having a hydroxyl group terminal simultaneously or sequentially with a compound having two or more isocyanates, epoxy groups, alkyl halides, etc. in the molecule. . Alternatively, a method of converting a polymer having a hydroxyl terminal to a block copolymer via an ether bond by a tosylation reaction or a condensation reaction using sulfuric acid.
(Iii) A method in which a polymer having a carbonyl halide and / or a carboxyl group is made into a block copolymer using a compound having two or more amino groups in the molecule is exemplified.
[0042]
(B) A method of sequentially synthesizing a block copolymer using iodine transfer polymerization using a fluorine-containing monomer.
In this case, for example, a method of polymerizing the monomer exemplified in (A-2) after polymerizing the monomer exemplified in (B-2) or (B-3) in the presence of a perfluoroalkylpolyiodine compound, (B-1) It can also be obtained by iodination at the end of the skeleton to form an iodine transfer polymerization initiator and polymerize a vinyl compound having a high glass transition temperature in the presence of this compound. Specific examples thereof include, for example, Polymer Papers Vol. 49, no. 10 (1992) P765.
[0043]
(C) Polymer type peroxide (for example, Japanese Patent Publication No. 55-33446), a method using a vinyl compound having polymerization initiation activity (for example, Japanese Patent Laid-Open No. 5-194625, Japanese Patent Laid-Open No. 8-67717, Japanese Patent Laid-Open No. 8-67720), etc. Is mentioned.
[0044]
In addition, as a method for forming a layer comprising a fluorine-containing elastomer in the present invention, only the fluorine-containing polymer having a reactive site having a low glass transition temperature is included together with a crosslinking agent capable of crosslinking by reacting with the reaction site. It is also possible to form a fluorine-containing elastomer layer having rubber elasticity by dissolving and / or dispersing in a fluorine solvent and crosslinking the fluorine-containing polymer before and / or after coating. The crosslinking agent has two or more functional groups, and known types of functional groups that can react with the reactive site of the fluoropolymer can be used. For example, an isocyanate compound or a polyepoxy compound is used for a fluorine-containing polymer having a hydroxyl group, and a fluorine-containing polymer having an epoxy group is a compound having an amino group, a carboxyl group, a mercapto group, or the like, or light and / or heat. An epoxy curing agent that generates an acid is used. The fluorine-containing polymer having a hydrolyzable silicon group uses a curing catalyst (such as an organic tin compound or an organic acid titanium salt) that can condense and cure the hydrolyzable silicon group, and contains a terminal unsaturated group. For the fluoropolymer, a radical initiator or a silicon hydride compound (and an addition reaction catalyst if necessary) is used, but it is not limited thereto.
[0045]
The fluorine-containing polymer having a reactive site for producing a fluorine-containing elastomer can be obtained by a known method (reprecipitation washing, purification by column chromatography, heat treatment, etc.) during and / or at the end of the polymerization / synthesis process. It is preferable that the component, the polymerization initiator and the like are removed. In particular, heat treatment at a temperature of 200 ° C. or higher, preferably 250 ° C. or higher, more preferably 300 ° C. or higher after polymerization is a preferable processing method because low-molecular unstable components can be decomposed and removed.
[0046]
In addition, fluorination treatment of the fluorine-containing elastomer with fluorine gas means that, for example, perfluoroelastomer finally perfluorinates end groups generated during reaction and / or polymerization, and at the same time, all impurities contained in the elastomer are fluorinated. This is a preferable pretreatment because it can be decomposed and removed by energy. Fluorine-containing elastomers that are not perfluoro have improved fluorine content, improved stability and solubility in fluorine-containing solvents, and can be expected to have the same effects as expected when fluorinating perfluoroelastomers. Therefore, this is a preferred pretreatment method.
[0047]
In addition, the fluorine-containing elastomer solution or dispersion is provided with a known adhesion imparting agent such as a silane coupling agent or an epoxy compound in order to improve adhesion to the substrate, the organic EL structure, the upper resin layer, and the like. A small amount may be added.
[0048]
The method for coating the organic EL structure with a solution of these fluorine-containing elastomers dissolved or dispersed in a fluorine-containing solvent is not particularly limited, but spin coating, die coating, blade coating, screen printing, inkjet, spray coating, curtain coating, etc. These known methods can be used. However, in the case of taking out and mounting the electrode wiring, for example, when further laminating a synthetic resin layer on the fluorine-containing elastomer layer, in the case of securing the adhesion part of the substrate and the synthetic resin layer in order to ensure adhesion, The fluorine-containing elastomer layer is preferably coated only on the upper part of the organic EL structure. In this case, spin coating is used on the entire surface, and after coating, the fluorine-containing elastomer layer is removed mechanically and / or with a laser, etc., excluding a predetermined position, a selective coating method of a specific area by an ink jet method, die coating, etc. A method of processing and coating only a specific area, a method of coating only a specific area using a mask in spray coating, curtain coating and the like are preferable.
[0049]
The thickness of the fluorine-containing elastomer layer is not particularly limited, but if it is too thin, the surface protection effect and / or the stress relaxation effect when a synthetic resin layer or the like is laminated on the upper layer is not preferable. On the other hand, if the thickness is too thick, the total stress of the fluorine-containing elastomer layer itself is increased, which may affect the organic EL structure, or may cause problems such as incomplete drying after coating. Preferably they are 10 nm-2 mm, More preferably, they are 50 nm-500 micrometers, Most preferably, they are 0.1 micrometer-100 micrometers.
[0050]
Further, as the sealing layer in the present invention, the outer surface of the fluorine-containing elastomer layer is further coated with other organic compounds, metals, metal oxides and / or nitrides, inorganic oxides and / or nitridized for the purpose of moisture resistance and device protection. An outer layer made of a product, a synthetic resin layer, or the like can be provided. A glass plate, a plastic film or the like may be further installed outside the sealing layer. Even in such a case, by inserting the fluorine-containing elastomer layer, the linear expansion difference and stress between the outer layer of the sealing layer such as the synthetic resin layer and the glass plate and the lower organic EL structure layer are relieved, and the element Can emit light stably. Specifically, a method of bonding a glass plate, a plastic plate or the like through a sealing layer outer layer made of a synthetic resin is preferable from the viewpoint of mechanical protection and moisture resistance. In addition, a structure in which a synthetic resin layer and an inorganic and / or metal layer are sequentially laminated on a fluorine-containing elastomer layer can be said to be a preferable method from the viewpoint of thinning of the element and moisture resistance.
[0051]
Examples of the synthetic resin layer that is a material of the outer layer of the sealing layer include general photo-curing resins, thermoplastic resins, and thermosetting resins. Among these, in the case of a curable resin, a thermal or photocationic curing epoxy resin and / or an oxetane resin is preferable from the viewpoint of outgassing. A thermoplastic resin is also preferable because it has few problems such as by-products due to the curing reaction. In this case, it is preferable to coat a thermoplastic resin that is soluble in a solvent with a coating because it can be uniformly coated at a low temperature. Moreover, it can be said that a thermoplastic resin soluble in a hydrocarbon solvent or a fluorine-containing solvent having a fluorine content of 40 wt% or more is preferable as a solvent in this case from the viewpoint of the influence of the solvent on the organic EL structure.
[0052]
As the organic EL layer sandwiched between the two electrode layers, a known one can be used. A specific structure is exemplified by an organic EL layer sandwiched between a transparent electrode layer and a back electrode layer. A TFT array is formed on one of the electrodes, a color filter or blue light emission is formed on the transparent electrode. In the case of this element, a blue conversion filter may be installed. These structures are formed on a metal substrate or metal film such as a glass substrate, a plastic substrate, a plastic film, or silicon.
[0053]
One of the two electrodes is a negative electrode (electron injection electrode), the other is a positive electrode (hole injection electrode), and at least one is a transparent electrode.
As a material for the transparent electrode layer usually used as a positive electrode, an indium tin oxide (ITO) thin film, tin oxide doped with antimony or fluorine, zinc oxide doped with a group 3B element, or the like can be used. In addition, metals such as gold having a large work function, inorganic compound conductive materials such as copper iodide, conductive organic compounds such as poly (3-methylthiophene), poly (3,4-ethylenedioxythiophene), polypyrrole, and polyaniline It may be composed of a volatile substance, those doped with polystyrene sulfonic acid, paratoluene sulfonic acid, Lewis acidic metal, or the like.
This electrode is generally prepared by a vacuum deposition method, a sputtering method, etc. In the case of an organic compound conductive material, a solution with an appropriate binder is applied on a substrate, or electropolymerization is performed. By doing so, a thin film can be produced directly on the substrate. The thickness of the anode depends on the required transparency, but is selected so that the visible light transmittance is 60% or more, preferably 80% or more. Usually, this film thickness is about 5 to 1000 nm, preferably 10 to 500 nm.
[0054]
An organic EL layer is laminated on the positive electrode layer, and a second electrode layer is laminated on the organic EL layer. The second electrode layer is usually a negative electrode, and low work function metals such as Li, Na, Cs, Ca, Mg and / or their oxides, hydroxides, fluorides, chlorides, etc. are used as Al, Ag, etc. It consists of materials such as those laminated or alloyed with low resistance metals. The negative electrode is formed in a predetermined shape, orthogonal stripes, or the like so as to face the positive electrode. The above positive electrode, negative electrode, and organic EL layer sandwiched between them form a basic organic EL structure.
[0055]
When using a negative electrode as a transparent electrode, it is common to use the low work function metal. In this case, the negative electrode layer is made thin to the extent that light transmittance can be secured, and an auxiliary electrode or the like is used in combination if necessary. Is preferred.
A hole injection layer or a hole transport layer may be provided between the organic EL layer and the positive electrode layer, and an electron transport layer or an electron injection layer may be provided between the organic EL layer and the negative electrode layer. . In these layers, unnecessary ones may be omitted from the required characteristics of the organic EL layer, and the order of the layer configuration may be changed.
[0056]
As a specific material for the hole transport layer, a material having a low hole injection barrier from the electrode and a high hole mobility can be used. A known hole transport material can be used as such a material. For example, N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine or 1,1′-bis (4-di-p-tolyl) Aromatic diamine compounds such as aminophenyl) cyclohexane, and hydrazone compounds disclosed in JP-A-2-315991 can be used. In addition, polymer materials such as poly-N-vinylcarbazole and polysilane can be preferably used (Appl. Phys. Lett., 59, 2760 (1991)). In addition, organic compound conductive materials such as poly (3-methylthiophene), poly (3,4 ethylenedioxythiophene), polypyrrole, and polyaniline shown in the positive electrode material, polystyrenesulfonic acid and paratoluenesulfonic acid, A material doped with a Lewis acid metal or the like can also be used. Furthermore, the material used for the positive hole injection layer mentioned later can also be used.
[0057]
As a material for the hole transport layer, not only the above organic substances but also inorganic substances such as metal chalcogenides, metal halides, metal carbides, nickel oxides, lead oxides, copper iodides, p-type compound semiconductors, p Type hydrogenated amorphous silicon, p type hydrogenated amorphous silicon carbide, and the like can also be used. In addition, a layer can be formed by mixing these hole transport materials.
[0058]
In order to improve the heat resistance and thin film uniformity of the hole transport layer, a binder resin that is unlikely to trap holes can be mixed and used. Examples of such a binder resin include polyethersulfone, polycarbonate, and polyester. The content of the binder resin is preferably 10 to 50% by weight which does not decrease the hole mobility. In the case of using either an organic substance or an inorganic substance, the thickness of the hole transport layer is usually 10 to 200 nm, preferably 20 to 80 nm.
[0059]
A hole injection layer may be provided between the positive electrode and the hole transport layer in order to prevent leakage current, reduce a hole injection barrier, improve adhesion, and the like. As such a material, 4,4 ′, 4 ″ -tris {N- (3-methylphenyl) -N-phenylamino} triphenyl which is a derivative of triphenylamine as seen in JP-A-4-308688 Amine (hereinafter abbreviated as “MTDATA”), 4,4 ′, 4 ″ -tris {N, N-diphenylamino} triphenylamine (hereinafter abbreviated as “TDATA”), tris (4-bromophenyl) amine salt A polymer having a triphenylamine-4,4′-diyl unit, copper phthalocyanine, or the like can be preferably used. The film thickness when this layer is provided is preferably 5 to 100 nm.
As a material for the electron transport layer, a substance having a high electron affinity and a high electron mobility is preferable. Examples of such a material include tris (8-quinolinolato) aluminum (Alq ₃ ) And other quinoline derivatives such as organometallic complexes having quinolinol or its derivatives as ligands, oxadiazole derivatives, perylene derivatives, pyridine derivatives, pyrimidine derivatives, quinoxaline derivatives, diphenylquinone derivatives, nitro-substituted fluorene derivatives, Distyryl biphenyl derivatives (DPVBi), oxadiazole derivatives, bistyl anthracene derivatives, benzoxazole thiophene derivatives, thiazoles, and the like can be used. The electron transport layer may also serve as an organic EL layer described later. In such a case, it is preferable to use tris (8-quinolinolato) aluminum or the like.
[0060]
The material of the organic EL layer may contain a light emitting substance that itself emits light and may be formed of the light emitting substance alone. In addition, a material having an electron transporting property and / or a hole transporting property, which may or may not emit light, may be used as a host material, and the light emitting material may be used as a dopant. Examples of such luminescent materials include laser dyes such as tetraphenylbutadiene, styryl dyes, stilbene dyes, oxazole dyes, cyanine dyes, xanthene dyes, oxazine dyes, coumarin dyes, acridine dyes, and anthracene dyes. Aromatic hydrocarbon materials such as derivatives, naphthacene derivatives, pentacene derivatives, pyrene derivatives, perylene derivatives, 4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran derivatives, europium complexes, etc. . The concentration of such a doped organic material is preferably 0.01 to 20 mol% in the organic EL layer. Examples of the polymer type material include π and / or σ conjugated polymers such as polyphenylene derivatives, polyfluorene derivatives, polythiophene derivatives, polysilane derivatives, polyarylene vinylene derivatives and the like, and block and / or random copolymers thereof. Can be mentioned. Further, a predetermined amount of the light emitting substance may be added to these polymer type materials. Moreover, when the said hole transport layer and / or electron transport layer itself have luminescent property, these layers can be considered as an organic EL layer from fulfill | performing the function as an organic EL layer.
[0061]
When the electron transport layer and the negative electrode layer are in contact, an electron injection layer may be further inserted at this interface. By providing the electron injecting layer, it is possible to reduce the driving voltage, improve the light emission efficiency, and extend the life. This interface layer has the effect of facilitating electron injection from the negative electrode and the effect of increasing the adhesion to the negative electrode.
Such materials include alkali metal fluorides, alkaline earth metal fluorides represented by lithium fluoride (Appl. Phys. Lett., 70, 152 (1997)), magnesium oxide, strontium oxide, oxidation There are oxides such as aluminum and barium oxide. When such an interface layer material is an insulator, the film thickness to be used is a thin film of 5 nm or less, and it is considered that tunnel injection of electrons from the negative electrode is possible by setting it to 2 nm or less. In the case of a non-insulator, it may be within a range that does not impair the effect at 100 nm or less.
Each of the above-described layers may be formed of a plurality of layers as long as it functions as an organic EL element, or another layer may be sandwiched between them. As a manufacturing method of each of these layers, various known methods such as a vacuum deposition method, a dip method, a spin coating method, an ink jet method, a curtain coating method, a gravure printing method, a die coating method, an LB method, and a CVD method can be applied.
[0062]
【Example】
Examples of the present invention are shown below, but the present invention is not limited to the following.
[0063]
Synthesis example 1
Decafluorobiphenyl 5 mol and 2,2-bis (4-hydroxyphenyl) hexafluoropropane 4 mol were condensed to obtain an oligomer having a terminal decafluorobiphenyl.
[0064]
Synthesis example 2
Polymer 1
The oligomer obtained in Synthesis Example 1 and the terminal trimethylsilyl etherification product of “FomlinZdol-4000” (perfluoropolyether) manufactured by AUSHIMONT and hexafluorobenzene at a molar ratio of 1: 2: 1 using cesium fluoride in a DMF solvent as a catalyst. An elastomer was obtained by heating reaction.
The obtained elastomer was washed with 1,3- (bistrifluoromethyl) benzene-water system and heated at 250 ° C. for 2 hours in air to purify the elastomer.
This elastomer maintained rubber elasticity in the range of -60 ° C to 140 ° C. This elastomer was dissolved in a 1: 9 mixed solvent of 1,3- (bistrifluoromethyl) benzene and perfluorotributylamine to obtain a solution.
[0065]
Polymer 2
While feeding tetrafluoroethylene and perfluoro (2,2-dimethyl-1,3-dioxole) at a molar ratio of 35:65 in the presence of iodinated terminal of perfluoropolyether (molecular weight about 4,000). Polymerization was performed to synthesize an ABA type block copolymer having a molecular weight of about 15,000. The obtained elastomer exhibited rubber elasticity at -60 ° C to 160 ° C. The obtained polymer was heated at 320 ° C. for 2 hours in air and then dissolved in perfluorooctane, washed with water, dried and purified, and again dissolved in perfluorooctane to obtain an elastomer solution.
[0066]
Polymer 3
In the presence of 1,4-diiodooctafluorobutane, tetrafluoroethylene and perfluoro (vinyl ether) are polymerized to a random copolymer (molecular weight of about 15,000) in a 3: 7 mol ratio, and then perfluoro (3-butyl Tenenyl vinyl ether) and CF ₂ = CFO (CF ₂ ) ₃ COOCH ₃ The ABA block polymer was synthesized by polymerizing a mixture with a molar ratio of 99: 1 to a molecular weight of about 20,000. The obtained elastomer exhibited rubber elasticity at -20 ° C to 110 ° C. The obtained polymer was heated at 320 ° C. for 2 hours, dissolved in 1H, 1H, 2H-perfluoro-1-decene, washed with water and dried to be purified to 1H, 1H, 2H-perfluoro-1-decene. A dissolved solution was obtained.
[0067]
Polymer 4
Polymerization was performed while feeding vinylidene fluoride and hexafluoropropylene at a molar ratio of 78:22 in the presence of 1,4-diiodooctafluorobutane to obtain a polymer having a molecular weight of 150,000. Next, tetrafluoroethylene and perfluoro (2,2-dimethyl-1,3-dioxole) are continuously fed at a molar ratio of 40:60 in the presence of this polymer to synthesize a block copolymer having a molecular weight of about 20,000. did. The obtained elastomer exhibited rubber elasticity at -20 ° C to 150 ° C. The obtained polymer was heated at 300 ° C. for 2 hours and then dispersed in 1-methoxyperfluorooctane, washed with water and dried over magnesium sulfate to obtain a dispersion of 1-methoxyperfluorooctane.
[0068]
Polymer 5
Photo-curable epoxy resin (XNR5516 manufactured by Nagase ChemteX Corporation)
[0069]
Organic EL structure creation example 1
ITO was vapor-deposited on a glass substrate so as to have a film thickness of 200 nm to form a positive electrode layer (sheet resistance 7Ω / □). On this anode, copper phthalocyanine was deposited to a thickness of 20 nm as a hole injection layer by a vacuum deposition method, and then α-NPD shown below was deposited to a thickness of 40 nm to form a hole transport layer. Alq was co-attached to a film thickness of 60 nm using a different boat to form an organic EL layer. Finally, Mg and Ag were co-evaporated to form a MgAg (10: 1) negative electrode alloy layer having a thickness of 200 nm to produce an organic EL structure.
[0070]
[Chemical Formula 3]

[0071]
Organic EL structure creation example 2
ITO was vapor-deposited with a film thickness of 200 nm on a glass substrate to form a positive electrode layer (sheet resistance 7Ω / □). On the positive electrode layer, the hole transport layer 5 was formed by vapor-depositing the copper phthalocyanine to a thickness of 20 nm and then depositing 9 PPD to a thickness of 40 nm by vacuum deposition. Subsequently, the above-mentioned Alq and rubrene were co-evaporated to a film thickness of 60 nm using different boats to form the organic EL layer 4. Next, LiF was deposited to a thickness of 0.5 nm, and finally, Al was deposited to a thickness of 200 nm to form a negative electrode to produce an organic EL structure.
[0072]
Example 1
On the negative electrode layer of the organic EL structure obtained in Organic EL structure preparation example 1, a solution of polymer 1 was spin-coated and then dried under reduced pressure at 100 ° C. for 1 hr to form a film having a thickness of 5 μm. Then, a glass plate coated with polymer 5 to a thickness of 50 μm was bonded to the surface of polymer 5 and irradiated with UV to cure and seal polymer 5. The light emitting surface of the organic EL device was observed after storing the obtained device under nitrogen at 60 ° C. for 500 hr. The area of the non-light emitting portion was about 5%.
[0073]
Comparative Example 1
In Example 1, the glass substrate coated with the polymer 5 to a thickness of 50 μm was bonded to the organic EL structure without using the polymer 1, and the polymer 5 was cured by sealing with UV irradiation. When the light emitting surface of the device was observed after storing the obtained device under nitrogen at 60 ° C. for 500 hours, the area of the non-light emitting portion increased to 30%.
[0074]
Examples 2, 3, 4
A solution of polymers 2, 3, and 4 was spin coated on the organic EL structure negative electrode layer obtained in Organic EL structure preparation example 2, and then dried at 120 ° C. for 1 hr under reduced pressure to form a film having a thickness of 10 μm. did. Next, a glass plate coated with a polymer 5 to a thickness of 50 μm was bonded to each polymer-coated surface and irradiated with UV to cure and seal the polymer 5. When the obtained device was stored at 100 ° C. under nitrogen for 1 day and the light emitting surface of the device was observed, the area of the non-light emitting portion was about 1%.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram showing a cross section of an organic EL device of the present invention.
FIG. 2 is a conceptual diagram showing a cross section of another example of the organic EL element of the present invention.
[Explanation of symbols]
1 Negative electrode layer (back electrode layer)
2 Positive electrode layer (transparent electrode layer)
3 Electron injection layer
4 Organic EL layers
5 Hole transport layer
6 Hole injection layer
7 Glass protective plate
8 Glass substrate
9 UV curable resin layer (outer layer of sealing layer)
10 Fluorine-containing elastomer layer (sealing layer inner layer)
11 Transparent plastic substrate
12 plastic protective plate

Claims (5)

A thin-film organic EL structure having two electrode layers transparent at least one and an organic EL layer sandwiched between the electrode layers, and a sealing layer covering one or both surfaces of the outer surface of the organic EL structure An organic EL element having a sealing layer made of a fluorine-containing elastomer. The organic EL element is an organic EL element having a substrate, an organic EL structure provided on the substrate, and a sealing layer that covers a surface of the organic EL structure that is not in contact with the substrate. Organic EL element. The organic EL according to claim 1, wherein the sealing layer comprises an inner layer and an outer layer on the organic EL structure side, the inner layer material comprises a fluorine-containing elastomer, and the outer layer material comprises a synthetic resin other than the fluorine-containing elastomer. element. 4. The method for producing an organic EL device according to claim 1, wherein a solution or dispersion of a fluorine-containing elastomer is coated on the surface of the organic EL structure and dried to comprise the fluorine-containing elastomer on the surface of the organic EL structure. A method for producing an organic EL element, comprising forming a sealing layer. The production method according to claim 4, wherein the solvent in the solution or dispersion of the fluorine-containing elastomer comprises a fluorine-containing compound having a fluorine content of 40% by mass or more.

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