JP2005038661A - Organic electroluminescent element, display device, lighting device and light source - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element which can drastically enhance light extraction efficiency with a long service life while reducing a change in brightness, the breakage and crack of the element when the white the luminant of a flexible film form is deformed by curving, and can attain low cost and resource saving, and to provide the luminant and a light source using the same. <P>SOLUTION: In the organic EL element having a lower electrode, a luminescent layer and an upper electrode on a translucent substrate, the haze value of the translucent substrate is ≥0.5% and ≤50%, and the thickness is ≥30 μm and ≤700 μm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００７８】
用いることのできる測定装置としては、例えば、ＷＹＫＯ社製 ＲＳＴＰＬＵＳ非接触三次元微小表面形状測定システム等を挙げることができる。３０ｃｍ×３０ｃｍとした試料について、３ｃｍ間隔で碁盤目状に１００分割し、各正方形領域の中心について測定を行ない、１００回の測定からその平均値と標準偏差を求めた。
【００７９】
本発明において用いられるシクロオレフィン系ポリマーとしては、
ジシクロペンタジエンなどの多環モノマーの開環重合体の水素化物、ジシクロペンタジエンのような多環モノマーとエチレンとの共重合体の水素化物、また、ノルボルネン系重合体から選ばれるものである。
【００８０】
ジシクロペンタジエンなどの開環重合体の水素化物としては、例えば特公昭５８−４３４１２号、特開昭６３−２１８７２７などでよく知られている。またジシクロペンタジエンなどの多環モノマーとエチレンとの共重合体は、特開昭６３−３１４２２０号、特開昭６１−１２０８１６号などで知られている。もちろんジシクロペンタジエン類は、そのメチルやエチル置換体などのアルキル置換体や、エンド異性体、エキソ異性体またはこれらの混合物なども含むものである。
【００８１】
また、ノルボルネン系重合体はＵＳＰ２８８３３７２号、特公昭４６−１４９１０号、特開平１−１４９７３８号、特開平３−１４８８２号公報や特開平３−１２２１３７号公報などなどに示されたものなどが知られている。
【００８２】
熱可塑性ノルボルネン系重合体は、具体的には、ノルボルネン系単量体の開環重合体、その水素添加物、ノルボルネン系単量体の付加型重合体、ノルボルネン系単量体とオレフィンの付加型重合体などが挙げられる。
【００８３】
ノルボルネン系単量体は、上記公報や特開平２−２２７４２４号、特開平２−２７６８４２号の各公報などで公知の単量体であって、例えば、ノルボルネン、そのアルキル、アルキリデン、芳香族置換誘導体およびこれら置換または非置換のオレフィンのハロゲン、水酸基、エステル基、アルコキシ基、シアノ基、アミド基、イミド基、シリル基等の極性基置換体、例えば、２−ノルボルネン、５−メチル−２−ノルボルネン、５，５−ジメチル−２−ノルボルネン、５−エチル−２−ノルボルネン、５−ブチル−２−ノルボルネン、５−エチリデン−２−ノルボルネン、５−メトキシカルボニル−２−ノルボルネン、５−シアノ−２−ノルボルネン、５−メチル−５−メトキシカルボニル−２−ノルボルネン、５−フェニル−２−ノルボルネン、５−フェニル−５−メチル−２−ノルボルネン等；ノルボルネンに一つ以上のシクロペンタジエンが付加した単量体、その上記と同様の誘導体や置換体、例えば、１，４：５，８−ジメタノ−１，２，３，４，４ａ，５，８，８ａ−２，３−シクロペンタジエノナフタレン、６−メチル−１，４：５，８−ジメタノ−１，４，４ａ，５，６，７，８，８ａ−オクタヒドロナフタレン、１，４：５，１０：６，９−トリメタノ−１，２，３，４，４ａ，５，５ａ，６，９，９ａ，１０，１０ａ−ドデカヒドロ−２，３−シクロペンタジエノアントラセン等；シクロペンタジエンの多量体である多環構造の単量体、その上記と同様の誘導体や置換体、例えば、ジシクロペンタジエン、２，３−ジヒドロジシクロペンタジエン等；シクロペンタジエンとテトラヒドロインデン等との付加物、その上記と同様の誘導体や置換体、例えば、１，４−メタノ−１，４，４ａ，４ｂ，５，８，８ａ，９ａ−オクタヒドロフルオレン、５，８−メタノ−１，２，３，４，４ａ，５，８，８ａ−オクタヒドロ−２，３−シクロペンタジエノナフタレン等；等が挙げられる。
【００８４】
これらのシクロオレフィン系ポリマーとしては、ゼオノア（Ｒ）、ゼオネックス（Ｒ）（日本ゼオン社製）、アートン（Ｒ）（ＪＳＲ社製）等をあげることができる。
【００８５】
本発明で使用する熱可塑性飽和シクロオレフィン系ポリマーの数平均分子量は、トルエン溶媒によるＧＰＣ（ゲル・パーミエーション・クロマトグラフィ）法で測定して、１０，０００〜２００，０００、好ましくは２０，０００〜１５０，０００、より好ましくは２５，０００〜１２０，０００である。特に耐水性、耐湿性がよいものが必要な場合は、極性基を有さない熱可塑性飽和シクロオレフィン系ポリマーが好ましい。
【００８６】
また、ポリエーテルスルホン系ポリマーをシクロオレフィン系ポリマーに代えて用いても、同様に界面での全反射が少なく光の取り出し効率の更に高い透光性の基板が得られる。ポリエーテルスルホン系ポリマーはシクロオレフィン系ポリマーに比べやや透湿性の面では、おちるが、耐熱性が高く、本発明の上記構成を取ることにより前記透光性の基板として、界面での全反射が少なく光の取り出し効率の高い優れた基板を構成する。
【００８７】
ポリエーテルスルホン系ポリマーとしては、ポリエーテルスルホン系フィルムが住友ベークライト（株）製から上市されており、例えば、「スミライト（Ｒ）ＦＳ−１３００」、スミライト（Ｒ） ＦＳＴ−５３００等があり、これらを用いることができる。
【００８８】
このように、コア層となる吸湿性フィラーを含有する層を、他の樹脂層或いはガラス等の基板と積層した積層基板とする場合、樹脂コーティング、ラミネート等の手段を用いることから、表面を粗さを前記の様に調整したり接着性付与のための表面改質を行うことが好ましい。
【００８９】
表面粗さの調整は、前記表面層を構成する層に、共押し出しや、共流延の際に、０．００１〜０．８μｍの平均粒径を有する、シリカ等の不活性な粒子を０．０５から２．０質量％含有させることが好ましい。
【００９０】
表面改質としては、例えば、シランカップリング剤等による処理を用いることができる。前記透湿性フィルムの下部電極側の表面にシランカップリング剤による処理を行って、透明導電膜との密着性（接着性）を向上させることができる。
【００９１】
用いられる好ましいシランカップリング剤としては、下記一般式で表される化合物が好ましい。
【００９２】
【化１】

【００９３】
式中、Ｒは脂肪族或いは芳香族の炭化水素基を表し、不飽和基（例えばビニル基）を介在していてもよいし、Ｒ′ＯＲ″−、Ｒ′ＣＯＯＲ″−、Ｒ′ＮＨＲ″−（Ｒ′はアルキル基、アリール基、Ｒ″はアルキレン基、アリーレン基）その他の置換基で置換されていてもよい。
【００９４】
また、Ｘ_１、Ｘ_２、Ｘ_３は脂肪族或いは芳香族の炭化水素、アシル基、アミド基、アルコキシ基、アルキルカルボニル基、エポキシ基、メルカプト基或いはハロゲン原子を表し、Ｘ_１、Ｘ_２、Ｘ_３は同じであっても互いに異なってもよい。ただし、少なくとも１つは炭化水素基以外の基である。なお、Ｘ_１、Ｘ_２、Ｘ_３は加水分解を受ける基であることが好ましい。
【００９５】
これらシランカップリング剤の具体例としてはメチルトリメトキシシラン、メチルトリエトキシシラン、ビニルトリアセトキシシラン、ビニルトリクロロシラン、ビニルトリエトキシシラン、γ−クロロプロピルトリメトキシシラン、γ−クロロプロピルメチルジクロロシラン、γ−クロロプロピルメチルジメトキシシラン、γ−クロロプロピルメチルジエトキシシラン、γ−アミノプロピルトリエトキシシラン、Ｎ−（β−アミノエチル）−γ−アミノプロピルトリメトキシシラン、Ｎ−（β−アミノエチル）−γ−アミノプロピルメチルジメトキシシラン、γ−メルカプトプロピルトリメトキシシラン、γ−メルカプトプロピルメチルジメトキシシラン、γ−グリシドキシプロピルトリメトキシシラン、γ−グリシドキシプロピルメチルジメトキシシラン、γ−メタクリロキシプロピルトリメトキシシラン、γ−メタクリロキシプロピルメチルジメトキシシラン、γ−（２−アミノエチル）アミノプロピルトリメトキシシラン、γ−イソシアネートプロピルトリエトキシシラン、γ−（２−アミノエチル）アミノプロピルメチルジメトキシシラン、γ−アニリノプロピルトリメトキシシラン、ビニルトリメトキシシラン、Ｎ−β−（Ｎ−（ビニルベンジルアミノエチル）−γ−アミノプロピルトリメトキシシラン・塩酸塩及びアミノシラン配合物などが挙げられる。なかでもビニル系、メルカプト系、グリシド系、メタクリロキシ系が好ましく、特にメルカプト系が好ましい。
【００９６】
特に、γ−アミノプロピルトリエトキシシラン、ｐ−スチリルトリメトキシシランなどのアミノ基、フェニル基、ビニル基を有するシランカップリング剤が好ましい。
【００９７】
シランカップリング剤の処理にあたっては、公知の方法を使用することができる。例えばシランカップリング剤溶液の噴霧や、これを塗布する方法、また、表層となる前記樹脂層組成物中に、シランカップリング剤を含有させる方法等である。また、シランカップリング剤との反応を確実なものにするため６０〜１３０℃で１０分〜２００分程度の乾燥を行うことが望ましい。
【００９８】
また、本発明に係わる透光性の基板、または基板フィルムには、その他、発光の色調を調整するために、染料等を適宜添加して着色してもよい。
【００９９】
《有機ＥＬ素子の構成層》
有機ＥＬ素子の基本的な構成層について説明する。
【０１００】
本発明において、有機ＥＬ素子の層構成の好ましい具体例を以下に示すが、本発明はこれらに限定されない。
（ｉ）陽極／発光層／電子輸送層／陰極
（ｉｉ）陽極／正孔輸送層／発光層／電子輸送層／陰極
（ｉｉｉ）陽極／正孔輸送層／発光層／正孔阻止層／電子輸送層／陰極
（ｉｖ）陽極／正孔輸送層／発光層／正孔阻止層／電子輸送層／陰極バッファー層／陰極
（ｖ）陽極／陽極バッファー層／正孔輸送層／発光層／正孔阻止層／電子輸送層／陰極バッファー層／陰極
《陽極》
有機ＥＬ素子における陽極（本発明においては透光性の基板上に形成される下部電極として記載）としては、仕事関数の大きい（４ｅＶ以上）金属、合金、電気伝導性化合物及びこれらの混合物を電極物質とするものが好ましく用いられる。このような電極物質の具体例としてはＡｕ等の金属、ＣｕＩ、インジウムチンオキシド（ＩＴＯ）、ＳｎＯ_２、ＺｎＯ等の導電性透明材料が挙げられる。また、ＩＤＩＸＯ（Ｉｎ_２Ｏ_３−ＺｎＯ）等非晶質で透明導電膜を作製可能な材料を用いてもよい。陽極は、これらの電極物質を蒸着やスパッタリング等の方法により、薄膜を形成させ、フォトリソグラフィー法で所望の形状のパターンを形成してもよく、あるいはパターン精度をあまり必要としない場合は（１００μｍ以上程度）、上記電極物質の蒸着やスパッタリング時に所望の形状のマスクを介してパターンを形成してもよい。この陽極より発光を取り出す場合には、透過率を１０％より大きくすることが望ましく、また、陽極としてのシート抵抗は数百Ω／□以下が好ましい。さらに膜厚は材料にもよるが、通常１０〜１０００ｎｍ、好ましくは１０〜２００ｎｍの範囲で選ばれる。
【０１０１】
《陰極》
一方、陰極（本発明においては上部電極として記載）としては、仕事関数の小さい（４ｅＶ以下）金属（電子注入性金属と称する）、合金、電気伝導性化合物及びこれらの混合物を電極物質とするものが用いられる。このような電極物質の具体例としては、ナトリウム、ナトリウム−カリウム合金、マグネシウム、リチウム、マグネシウム／銅混合物、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ_２Ｏ_３）混合物、インジウム、リチウム／アルミニウム混合物、希土類金属等が挙げられる。これらの中で、電子注入性及び酸化等に対する耐久性の点から、電子注入性金属とこれより仕事関数の値が大きく安定な金属である第二金属との混合物、例えばマグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ_２Ｏ_３）混合物、リチウム／アルミニウム混合物、アルミニウム等が好適である。陰極は、これらの電極物質を蒸着やスパッタリング等の方法により、薄膜を形成させることにより、作製することができる。また、陰極としてのシート抵抗は数百Ω／□以下が好ましく、膜厚は通常１０ｎｍ〜１０００ｎｍ、好ましくは５０ｎｍ〜２００ｎｍの範囲で選ばれる。なお、発光を透過させるため、有機ＥＬ素子の陽極または陰極のいずれか一方が、透明または半透明であれば発光輝度が向上し好都合である。
【０１０２】
次に、本発明の有機ＥＬ素子の構成層として用いられる、注入層、正孔輸送層、電子輸送層等について説明する。
【０１０３】
《注入層》：電子注入層、正孔注入層
注入層は必要に応じて設け、電子注入層と正孔注入層があり、上記のごとく陽極と発光層または正孔輸送層の間、及び、陰極と発光層または電子輸送層との間に存在させてもよい。
【０１０４】
注入層とは、駆動電圧低下や発光輝度向上のために電極と有機層間に設けられる層のことで、「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日 エヌ・ティー・エス社発行）」の第２編第２章「電極材料」（１２３〜１６６頁）に詳細に記載されており、正孔注入層（陽極バッファー層）と電子注入層（陰極バッファー層）とがある。
【０１０５】
陽極バッファー層（正孔注入層）は、特開平９−４５４７９号公報、同９−２６００６２号公報、同８−２８８０６９号公報等にもその詳細が記載されており、具体例として、銅フタロシアニンに代表されるフタロシアニンバッファー層、酸化バナジウムに代表される酸化物バッファー層、アモルファスカーボンバッファー層、ポリアニリン（エメラルディン）やポリチオフェン等の導電性高分子を用いた高分子バッファー層等が挙げられる。特にポリアニリン（エメラルディン）やポリチオフェン等の導電性高分子を用いた高分子バッファー層が好ましく、これらの陽極バッファー層は厚みとして０．１ｎｍ〜１５０ｎｍ形成することが好ましい。
【０１０６】
陰極バッファー層（電子注入層）は、特開平６−３２５８７１号公報、同９−１７５７４号公報、同１０−７４５８６号公報等にもその詳細が記載されており、具体的にはストロンチウムやアルミニウム等に代表される金属バッファー層、フッ化リチウムに代表されるアルカリ金属化合物バッファー層、フッ化マグネシウムに代表されるアルカリ土類金属化合物バッファー層、酸化アルミニウムに代表される酸化物バッファー層等が挙げられる。
【０１０７】
上記バッファー層（注入層）はごく薄い膜であることが望ましく、素材にもよるが、その膜厚は０．１ｎｍ〜１００ｎｍの範囲が好ましい。
【０１０８】
阻止層は、上記のごとく、有機化合物薄膜の基本構成層の他に必要に応じて設けられるものである。例えば特開平１１−２０４２５８号、同１１−２０４３５９号、及び「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日 エヌ・ティー・エス社発行）」の２３７頁等に記載されている正孔阻止（ホールブロック）層がある。
【０１０９】
正孔阻止層とは広い意味では電子輸送層であり、電子を輸送する機能を有しつつ正孔を輸送する能力が著しく小さい材料からなり、電子を輸送しつつ正孔を阻止することで電子と正孔の再結合確率を向上させることができる。
【０１１０】
一方、電子阻止層とは広い意味では正孔輸送層であり、正孔を輸送する機能を有しつつ電子を輸送する能力が著しく小さい材料からなり、正孔を輸送しつつ電子を阻止することで電子と正孔の再結合確率を向上させることができる。
【０１１１】
正孔輸送層とは正孔を輸送する機能を有する材料からなり、広い意味で正孔注入層、電子阻止層も正孔輸送層に含まれる。
【０１１２】
正孔輸送層、電子輸送層は単層もしくは複数層設けることができる。
本発明の有機ＥＬ素子においては、発光層のホスト、発光層に隣接する正孔輸送層、発光層に隣接する電子輸送層すべての材料の蛍光極大波長が４１５ｎｍ以下であることが好ましい。
【０１１３】
《発光層》
本発明に係る発光層は、電極または電子輸送層、正孔輸送層から注入されてくる電子および正孔が再結合して発光する層であり、発光する部分は発光層の層内であっても発光層と隣接層との界面であっても良い。
【０１１４】
発光層に使用される材料（以下、発光材料という）は、蛍光または燐光を発する有機化合物または錯体であることが好ましく、有機ＥＬ素子の発光層に使用される公知のものの中から適宜選択して用いることができる。このような発光材料は、主に有機化合物であり、所望の色調により、例えば、Ｍａｃｒｏｍｏｌ．Ｓｙｎｔｈ．，１２５巻，１７〜２５頁に記載の化合物等を用いることができるが、本発明においては前記燐光性化合物が好ましい。
【０１１５】
本発明において発光材料として用いられる前記化合物は、発光性能の他に、正孔輸送機能や電子輸送機能を併せ持っていても良く、正孔輸送材料や電子輸送材料の殆どが、発光材料としても使用できる。
【０１１６】
その他の発光材料として、ｐ−ポリフェニレンビニレンやポリフルオレンのような高分子材料でも良く、さらに前記発光材料を高分子鎖に導入した、または前記発光材料を高分子の主鎖とした高分子材料を使用しても良い。
【０１１７】
この発光層は、上記化合物を、例えば真空蒸着法、スピンコート法、キャスト法、ＬＢ法などの公知の薄膜化法により製膜して形成することができる。発光層としての膜厚は、特に制限はないが、通常は５ｎｍ〜５μｍの範囲で選ばれる。この発光層は、これらの発光材料一種又は二種以上からなる一層構造であってもよいし、あるいは、同一組成又は異種組成の複数層からなる積層構造であってもよい。本発明の有機ＥＬ素子の好ましい態様は、発光層が二種以上の材料からなり、その内の一種がリン光性ドーパントであるときである。
【０１１８】
また、この発光層は、特開昭５７−５１７８１号公報に記載されているように、樹脂などの結着材と共に上記発光材料を溶剤に溶かして溶液としたのち、これをスピンコート法などにより薄膜化して形成することができる。このようにして形成された発光層の膜厚については、特に制限はなく、状況に応じて適宜選択することができるが、通常は５ｎｍ〜５μｍの範囲である。
【０１１９】
発光層を構成する材料が２種以上であるとき、主成分をホスト化合物、その他の成分をドーパントといい、本発明においては、前記リン光性ドーパントが用いられることが好ましい。
【０１２０】
その場合、主成分であるホスト化合物に対するドーパントの混合比は好ましくは質量で０．１質量％〜１５質量％未満である。
【０１２１】
（ホスト化合物）
本発明の白色発光有機エレクトロルミネッセンス素子において、ホスト化合物としては、有機化合物または錯体であることが好ましく、本発明においては、好ましくは蛍光極大波長が４１５ｎｍ以下である。ホスト化合物の極大波長を４１５ｎｍ以下にすることにより可視光、前記ドーパントの発光において、特にＢＧＲ発光が可能となる。
【０１２２】
つまり蛍光極大波長を４１５ｎｍ以下にすることにより、通常のπ共役蛍光もしくは燐光材料において、π−π吸収を４２０ｎｍ以下に有するエネルギー移動型のドーパント発光が可能である。また４１５ｎｍ以下の蛍光を有することから非常にワイドエネルギーギャップ（イオン化ポテンシャル−電子親和力、ＨＯＭＯ−ＬＵＭＯ）であるので、キャリアトラップ型にも有利に働く。
【０１２３】
このようなホスト化合物としては、有機ＥＬ素子に使用される公知のものの中から任意のものを選択して用いてもよい。また前記の正孔輸送材料や電子輸送材料の殆どが発光層ホスト化合物としても使用できる。
【０１２４】
ポリビニルカルバゾールやポリフルオレンのような高分子材料でもよく、さらに前記ホスト化合物を高分子鎖に導入した、または前記ホスト化合物を高分子の主鎖とした高分子材料を使用してもよい。
【０１２５】
ホスト化合物としては、正孔輸送能、電子輸送能を有しつつ、かつ、発光の長波長化を防ぎ、なおかつ高Ｔｇ（ガラス転移温度）である化合物が好ましい。
【０１２６】
（ドーパント）
次にドーパントについて述べる。
【０１２７】
原理としては２種挙げられ、一つはキャリアが輸送されるホスト上でキャリアの再結合が起こってホスト化合物の励起状態が生成し、このエネルギーをドーパントに移動させることでドーパントからの発光を得るというエネルギー移動型、もう一つはドーパントがキャリアトラップとなり、ドーパント化合物上でキャリアの再結合が起こりドーパントからの発光が得られるというキャリアトラップ型であるが、いずれの場合においても、ドーパント化合物の励起状態のエネルギーはホスト化合物の励起状態のエネルギーよりも低いことが条件である。
【０１２８】
本発明の白色発光有機エレクトロルミネッセンス素子において、ドーパントとしては、Ｉｒ等の錯体化合物、特に好ましいものは、以下に表される化合物である。
【０１２９】
【化２】

【０１３０】
【化３】

【０１３１】
【化４】

【０１３２】
実質白色の発光を生じる有機エレクトロルミネッセンス素子については、現在のところ単一の発光材料で白色発光を示すものがないため、複数の発光材料により複数の発光色を同時に発光させて混色により白色発光を得る。複数の発光色の組み合わせとしては、青色、緑色、赤色の３原色の３つの発光極大波長を有する発光材料を含有させたものでも良いし、青色と黄色、青緑と橙色等の補色の関係を利用した２つの発光極大波長を有する発光材料を含有したものでも良い。勿論４以上の発光極大波長を有する発光材料を組み合わせてもかまわない。
【０１３３】
例えば、発光材料としてリン光性ドーパントを用いる場合には、発光波長の異なる前記の関係を有する複数のドーパントを用いて混色により白色発光を得る。また蛍光性発光材料の場合にも同様である。
【０１３４】
また、複数の発光色を得るための発光材料の組み合わせは、複数の、燐光または蛍光で発光する材料を、複数組み合わせたもの、これら蛍光または燐光で発光する発光材料と、発光材料からの光を励起光として発光する色素材料と組み合わせたものいずれでも良い。
【０１３５】
発光層の材料としては特に制限はなく、前記、公知の発光材料の中から任意のものを選択して組み合わせて白色化すれば良いが、特に、燐光を利用して発光する素子を形成する場合に用いられる発光ホストとしては、カルバゾール誘導体、ビフェニル誘導体、スチリル誘導体、ベンゾフラン誘導体、チオフェン誘導体、アリールシラン誘導体等の部分構造を単位として含む材料が挙げられる。なかでもカルバゾール誘導体とビフェニル誘導体は高い発光効率を示す好ましい発光材料である。
【０１３６】
正孔輸送層を設ける場合は、材料に特に制限はないが、アノード電極からの正孔を、発光する層に伝達する機能を有していれば良く、前記の、従来光導電材料において、正孔の電荷注入材料として慣用されているものや、ＥＬ素子の正孔輸送層に用いられている公知のものの中から任意のものを選択して用いることができる。
【０１３７】
電子輸送層を設ける場合においても、特に制限はなく、カソード電極からの電子を、発光する層に伝達する機能を有していればよく、前記の公知の材料の中から任意のものを選択して用いることができる。
【０１３８】
《正孔輸送層》
正孔輸送層とは正孔を輸送する機能を有する材料からなり、広い意味で正孔注入層、電子阻止層も正孔輸送層に含まれる。正孔輸送層は単層もしくは複数層設けることができる。
【０１３９】
正孔輸送材料としては、特に制限はなく、従来、光導伝材料において、正孔の電荷注入輸送材料として慣用されているものやＥＬ素子の正孔注入層、正孔輸送層に使用される公知のものの中から任意のものを選択して用いることもできる。
【０１４０】
正孔輸送材料は、正孔の注入もしくは輸送、電子の障壁性のいずれかを有するものであり、有機物、無機物のいずれであってもよい。他に、例えばトリアゾール誘導体、オキサジアゾール誘導体、イミダゾール誘導体、ポリアリールアルカン誘導体、ピラゾリン誘導体及びピラゾロン誘導体、フェニレンジアミン誘導体、アリールアミン誘導体、アミノ置換カルコン誘導体、オキサゾール誘導体、スチリルアントラセン誘導体、フルオレノン誘導体、ヒドラゾン誘導体、スチルベン誘導体、シラザン誘導体、アニリン系共重合体、また、導電性高分子オリゴマー、特にチオフェンオリゴマー等が挙げられる。
【０１４１】
正孔輸送材料としては、上記のものを使用することができるが、ポルフィリン化合物、芳香族第三級アミン化合物及びスチリルアミン化合物、特に芳香族第三級アミン化合物を用いることが好ましい。
【０１４２】
芳香族第三級アミン化合物及びスチリルアミン化合物の代表例としては、Ｎ，Ｎ，Ｎ′，Ｎ′−テトラフェニル−４，４′−ジアミノフェニル；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（ＴＰＤ）；２，２−ビス（４−ジ−ｐ−トリルアミノフェニル）プロパン；１，１−ビス（４−ジ−ｐ−トリルアミノフェニル）シクロヘキサン；Ｎ，Ｎ，Ｎ′，Ｎ′−テトラ−ｐ−トリル−４，４′−ジアミノビフェニル；１，１−ビス（４−ジ−ｐ−トリルアミノフェニル）−４−フェニルシクロヘキサン；ビス（４−ジメチルアミノ−２−メチルフェニル）フェニルメタン；ビス（４−ジ−ｐ−トリルアミノフェニル）フェニルメタン；Ｎ，Ｎ′−ジフェニル−Ｎ，Ｎ′−ジ（４−メトキシフェニル）−４，４′−ジアミノビフェニル；Ｎ，Ｎ，Ｎ′，Ｎ′−テトラフェニル−４，４′−ジアミノジフェニルエーテル；４，４′−ビス（ジフェニルアミノ）クオードリフェニル；Ｎ，Ｎ，Ｎ−トリ（ｐ−トリル）アミン；４−（ジ−ｐ−トリルアミノ）−４′−〔４−（ジ−ｐ−トリルアミノ）スチリル〕スチルベン；４−Ｎ，Ｎ−ジフェニルアミノ−（２−ジフェニルビニル）ベンゼン；３−メトキシ−４′−Ｎ，Ｎ−ジフェニルアミノスチルベンゼン；Ｎ−フェニルカルバゾール、さらには、米国特許第５，０６１，５６９号明細書に記載されている２個の縮合芳香族環を分子内に有するもの、例えば４，４′−ビス〔Ｎ−（１−ナフチル）−Ｎ−フェニルアミノ〕ビフェニル（ＮＰＤ）、特開平４−３０８６８８号公報に記載されているトリフェニルアミンユニットが３つスターバースト型に連結された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（ＭＴＤＡＴＡ）等が挙げられる。
【０１４３】
さらにこれらの材料を高分子鎖に導入した、またはこれらの材料を高分子の主鎖とした高分子材料を用いることもできる。
【０１４４】
また、ｐ型−Ｓｉ，ｐ型−ＳｉＣ等の無機化合物も正孔注入材料、正孔輸送材料として使用することができる。
【０１４５】
また、本発明においては正孔輸送層の正孔輸送材料は４１５ｎｍ以下に蛍光極大波長を有することが好ましい。すなわち、正孔輸送材料は、正孔輸送能を有しつつかつ、発光の長波長化を防ぎ、なおかつ高Ｔｇである化合物が好ましい。
【０１４６】
この正孔輸送層は、上記正孔輸送材料を、例えば真空蒸着法、スピンコート法、キャスト法、インクジェット法、ＬＢ法等の公知の方法により、薄膜化することにより形成することができる。正孔輸送層の膜厚については特に制限はないが、通常は５〜５０００ｎｍ程度である。この正孔輸送層は、上記材料の一種または二種以上からなる一層構造であってもよい。
【０１４７】
《電子輸送層》
電子輸送層とは電子を輸送する機能を有する材料からなり、広い意味で電子注入層、正孔阻止層も電子輸送層に含まれる。電子輸送層は単層もしくは複数層設けることができる。
【０１４８】
従来、単層の電子輸送層、及び複数層とする場合は発光層に対して陰極側に隣接する電子輸送層に用いられる電子輸送材料（正孔阻止材料を兼ねる）としては、下記の材料が知られている。
【０１４９】
さらに、電子輸送層は、陰極より注入された電子を発光層に伝達する機能を有していればよく、その材料としては従来公知の化合物の中から任意のものを選択して用いることができる。
【０１５０】
この電子輸送層に用いられる材料（以下、電子輸送材料という）の例としては、本発明に係わる前記化合物のほか、ニトロ置換フルオレン誘導体、ジフェニルキノン誘導体、チオピランジオキシド誘導体、ナフタレンペリレンなどの複素環テトラカルボン酸無水物、カルボジイミド、フレオレニリデンメタン誘導体、アントラキノジメタン及びアントロン誘導体、オキサジアゾール誘導体などが挙げられる。さらに、上記オキサジアゾール誘導体において、オキサジアゾール環の酸素原子を硫黄原子に置換したチアジアゾール誘導体、電子吸引基として知られているキノキサリン環を有するキノキサリン誘導体も、電子輸送材料として用いることができる。
【０１５１】
さらにこれらの材料を高分子鎖に導入した、またはこれらの材料を高分子の主鎖とした高分子材料を用いることもできる。
【０１５２】
また、８−キノリノール誘導体の金属錯体、例えばトリス（８−キノリノール）アルミニウム（Ａｌｑ）、トリス（５，７−ジクロロ−８−キノリノール）アルミニウム、トリス（５，７−ジブロモ−８−キノリノール）アルミニウム、トリス（２−メチル−８−キノリノール）アルミニウム、トリス（５−メチル−８−キノリノール）アルミニウム、ビス（８−キノリノール）亜鉛（Ｚｎｑ）など、及びこれらの金属錯体の中心金属がＩｎ、Ｍｇ、Ｃｕ、Ｃａ、Ｓｎ、Ｇａ又はＰｂに置き替わった金属錯体も、電子輸送材料として用いることができる。その他、メタルフリー若しくはメタルフタロシアニン、又はそれらの末端がアルキル基やスルホン酸基などで置換されているものも、電子輸送材料として好ましく用いることができる。また、発光層の材料として例示したジスチリルピラジン誘導体も、電子輸送材料として用いることができるし、正孔注入層、正孔輸送層と同様に、ｎ型−Ｓｉ、ｎ型−ＳｉＣなどの無機半導体も電子輸送材料として用いることができる。
【０１５３】
電子輸送層に用いられる好ましい化合物は、４１５ｎｍ以下に蛍光極大波長を有することが好ましい。すなわち、電子輸送層に用いられる化合物は、電子輸送能を有しつつかつ、発光の長波長化を防ぎ、なおかつ高Ｔｇである化合物が好ましい。
【０１５４】
本発明の有機ＥＬ素子に係る基板フィルムとしては、前記のものが好ましく、有機ＥＬ素子にフレキシブル性を与えることが可能な樹脂フィルムが好ましい。用いられる樹脂としては、例えばポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）、ポリエーテルスルホン（ＰＥＳ）、ポリエーテルイミド、ポリエーテルエーテルケトン、ポリフェニレンスルフィド、ポリアリレート、ポリイミド、ポリカーボネート（ＰＣ）、セルローストリアセテート（ＴＡＣ）、セルロースアセテートプロピオネート（ＣＡＰ）等が挙げられ、これらの材料を用いた前記の積層フィルムが好ましい。
【０１５５】
また、透光性の基板の着色のほか、カラーフィルター等の色相改良フィルター等を併用してもよい。
【０１５６】
以下に、有機ＥＬ素子を作製する好適な例を説明する。
《有機ＥＬ素子の作製方法》
本発明の有機ＥＬ素子の作製方法の一例として、陽極／正孔注入層／正孔輸送層／発光層／電子輸送層／電子注入層／陰極からなる有機ＥＬ素子の作製法について説明する。
【０１５７】
まず本発明に係わる透光性の基板上に、所望の電極物質、例えば陽極用物質（例えばＩＴＯ）からなる薄膜を、１μｍ以下、好ましくは１０ｎｍ〜２００ｎｍの膜厚になるように、蒸着やスパッタリング等の方法により形成させ、陽極を作製する。次に、この上に素子材料である正孔注入層、正孔輸送層、発光層、電子輸送層、電子注入層、正孔阻止層の有機化合物薄膜を形成させる。
【０１５８】
この有機化合物薄膜の薄膜化の方法としては、前記の如くスピンコート法、キャスト法、インクジェット法、蒸着法、印刷法等があるが、均質な膜が得られやすく、かつピンホールが生成しにくい等の点から、真空蒸着法またはスピンコート法が特に好ましい。さらに層ごとに異なる製膜法を適用してもよい。製膜に蒸着法を採用する場合、その蒸着条件は、使用する化合物の種類等により異なるが、一般にボート加熱温度５０〜４５０℃、真空度１０^−６Ｐａ〜１０^−２Ｐａ、蒸着速度０．０１ｎｍ〜５０ｎｍ／秒、基板温度−５０℃〜３００℃、膜厚０．１ｎｍ〜５μｍの範囲で適宜選ぶことが望ましい。
【０１５９】
これらの層の形成後、その上に例えばアルミニウム等の陰極用物質からなる薄膜を、１μｍ以下好ましくは５０ｎｍ〜２００ｎｍの範囲の膜厚になるように、例えば蒸着やスパッタリング等の方法により形成させ、陰極を設けることにより、所望の有機ＥＬ素子が得られる。この有機ＥＬ素子の作製は、一回の真空引きで一貫して正孔注入層から陰極まで作製するのが好ましいが、途中で取り出して異なる製膜法を施してもかまわない。その際、作業を乾燥不活性ガス雰囲気下で行う等の配慮が必要となる。
【０１６０】
本発明においては、このようにして透光性の基板上に形成された、前記有機ＥＬ素子を構成する各層の上（上部電極の上）に、別の基板或いはフィルムを封止用の基板として重ねて素子の周囲をスペーサ等をもちいて（或いは、用いずともよいが）封止する。
【０１６１】
封止用基板としては、ガラス、樹脂、セラミック、金属、金属化合物、またはこれらの複合体等で形成してもよく、ＪＩＳ Ｚ−０２０８に準拠した試験において、その厚さが１μｍ以上で水蒸気透過率が１ｇ／ｍ^２・２４ｈｒ（１．０１３×１０^−１ＭＰａ、２５℃）以下であることが望ましい。また、本発明に係わる透光性の基板を用いることも好ましく、両方の基板を透湿性の低い、可撓性の高い基板とすることで、衝撃に強い有機ＥＬ素子が形成出来、また、発光面が曲面である面光源にも適用可能である。
【０１６２】
また、上部電極側（陰極、例えばＡｌ、Ｍｇ電極側）の封止用基板材料（ガラス、フィルム等）においても、電界発光が吸収されたり、背面側に光が拡散するのを抑制するため、封止用基板或いはフィルムの陰極（Ａｌ、Ｍｇなど）側に向き合う表面には白色酸化チタンを充填した顔料層を形成することが好ましい。
【０１６３】
封止は、封止用基板の、例えば、対向陰極（上部電極）側と向き合う面）の周辺部に塗布法や転写法等によって設けられたほぼ枠状のシール材６を介して、対向する前記有機ＥＬ素子各層が形成された透光性の基板とが互いに貼り合わされることで行われる。シール材６は、熱硬化型エポキシ系樹脂、紫外線硬化型エポキシ系樹脂、または反応開始剤をマイクロカプセル化して加圧することにより反応が開始する常温硬化型エポキシ系樹脂等を用いることができる。この場合、シール材６の所定の箇所には空気逃げ用開口部等を設け（図省略）封止を完全にする。空気逃げ用開口部は、真空装置内において減圧雰囲気（真空度１．３３×１０^−２ＭＰａ以下が好ましい）或いは窒素ガスまたは不活性ガス雰囲気中において、上記硬化型エポキシ系樹脂のいずれか、或いは紫外線硬化型樹脂等で封止される。
【０１６４】
エポキシ系樹脂の例としては、ビスフェノールＡ形、ビスフェノールＦ形、ビスフェノールＡＤ形、ビスフェノールＳ形、キシレノール形、フェノールノボラック形、クレゾールノボラック形、多官能形、テトラフェニロールメタン形、ポリエチレングリコール形、ポリプロピレングリコール形、ヘキサンジオール形、トリメチロールプロパン形、プロピレンオキサイドビスフェノールＡ形、水添ビスフェノールＡ形、またはこれらの混合物を主剤としたものである。シール材６を転写法により形成する場合には、フィルム化されたものが好ましい。
【０１６５】
又、本発明において、素子内に水分を吸収する、或いは水分と反応する材料（例えば酸化バリウム等）を上記基板に層形成して封入することもできる。
【０１６６】
以上のように構成された有機ＥＬ素子を図１に示しているが、透明な基板１と対向する基板５とを枠状のシール材６を介して互いに貼り合わせているので、封止用基板５およびシール材６によって透光性の基板１上に設けられた陽極２、有機ＥＬ層３、陰極電極４等を封止することができ、内部が低湿度の状態で素子を封止出来ると同時に、基板を通しての水分の浸透が抑えられ、有機ＥＬ表示装置の耐湿性がより一層向上し、寿命をより一層向上させるすることができる。
【０１６７】
陽極２に正電圧を、陰極４に負電圧を、電圧２〜４０Ｖ程度印加すると、有機ＥＬ層３中で注入されたホールと電子とが、発光層３内で再結合して発光が起こるものである。
【０１６８】
表示素子として単色光を発光させるほか、白色発光素子を最も簡便に構成するには、発光層における、ホスト化合物と共に用いる発光材料に、発光特性が互いに補色の関係にある、例えば青と黄または青緑と橙等補色の関係にある発光色を有する２種のドーパントを組み合わせる、また、青、緑、赤にそれぞれ３色に発光するドーパント（リン光性化合物）を、その発光効率を考慮しながら、適宜、混合してドープすることによって得ることが出来る。勿論、充分な白色光を得るために４種以上の発光材料を組み合わせてもよい。
【０１６９】
白色有機エレクトロルミネッセンス素子においては、基本的にはドーパントを混合するだけで、発光層もしくは正孔輸送層或いは電子輸送層等の形成時のみマスクを設け、マスクにより塗り分けるなど単純に配置するだけでよく、他層は共通であるのでマスク等のパターニングは不要であり、一面に蒸着法、キャスト法、スピンコート法、インクジェット法、印刷法等で例えば電極膜を形成でき、生産性も向上するものである。また、複数色の発光素子をアレー状に並列配置した表示素子とすることも可能である。
【０１７０】
これらの透光性の基板上に形成された有機ＥＬ素子は、可撓性を有しており、ある程度カール変形させた状態においても発光の変化率が小さく充分な発光を維持する。可撓性のない基板上では、基板そのものが、亀裂、また破損を起こすことで発光が維持できない。
【０１７１】
カール値は曲率半径（ｍ）の逆数により求める。＋の数字が大きいほど＋カール（素子面を上にして、上の方に反り上がっている状態）が強い。
【０１７２】
カール＝１／曲率半径（ｍ）
本発明においては、カール値を０（即ち平面状態）〜６０まで変化させた時においても発光の変化率が２０％以下である有機ＥＬ素子が得られる。
【０１７３】
本発明の有機ＥＬ装置は、白色発光光源として、家庭用照明用、車内照明、また露光光源のような一種のランプとして、その他、液晶表示装置、時計等のバックライト、看板広告、信号機、光記憶媒体等の光源、電子写真複写機の光源、光通信処理機の光源、光センサーの光源等各種発光光源、更には表示装置を必要とする一般の家庭用電気器具等広い範囲の用途に用いることができるが、表示デバイス、ディスプレー、またとして表示装置にも有用に用いられる。
【０１７４】
【実施例】
以下に本発明の実施例を説明するが、本発明はこれらの例に限定されるものではない。
【０１７５】
実施例１
（吸湿性フィラーを練りこんだ樹脂チップの作製）
市販のポリエチレンテレフタレートのチップを真空乾燥機を用い、１５０℃で十分乾燥させた後、含有率が５質量％となるように酸化バリウム粉末（平均粒径、０．５μｍ）を、乾燥窒素気流下、２軸押出し混練機を用いて２８０℃で混練し、吸湿性フィラー含有のポリエステルチップ（ポリエステルＡと呼称）を作製した。
【０１７６】
尚、酸化バリウムの平均粒径は、電子顕微鏡で、１００個以上の任意の粒子を観察し粒径を求めて、その単純平均値（個数平均）として求められる。ここで、個々の粒径は、その投影面積に等しい円を仮定した時の直径で表したものである。尚、後述するシリカゲル微粒子、酸化チタン等についても同じ方法により平均粒径を求めた。
【０１７７】
（積層基板の作製）
ポリエステルＡと市販のポリエチレン２，６−ナフタレートのチップを各々１５０℃で８時間真空乾燥した後、乾燥窒素気流中で保温しながら、押出し機上に設置したホッパーから樹脂を３台の押出し機へ各々供給し２９０℃で溶融押出しを行ない、４０メッシュのフィルターを通過させてから、Ｔダイ内で厚み比が１：１：０．５となるように層状に接合して、６０℃の冷却ドラム上に静電印加しながら密着させて急冷冷却固化し、積層未延伸シートを得た。このとき芯（コア）層がポリエステルＡであり、表層がポリエチレン２，６−ナフタレートとなるようにした。この未延伸シートをロール式縦延伸機へ導き、９０℃で予熱し、低速と高速のロール間でＩＲヒーターで加熱しながら、縦方向に３．２倍に延伸した。得られた一軸延伸フィルムをテンター式横延伸機をに供給し、１３０℃で横延伸倍率３．０倍となるように延伸した。得られた二軸配向フィルムを２１０℃で１０秒間熱固定した。次いで横方向に５％弛緩処理しながら室温まで３０秒かけて徐冷して厚さ５０μｍの二軸延伸ポリエステル積層基板（ｂ１）を得た。さらに両端部をトリミングして、各１００ｍずつ、直径２２０ｍｍのコアに巻き取った。
【０１７８】
コアに巻いたまま、第一段目の熱処理（アニール）を１０５℃、２０時間の条件で実施し、第二段目の熱処理（アニール）を９０℃、３０時間行った。
【０１７９】
（有機ＥＬ素子の作製）
有機ＥＬ素子ＯＬＥＤ１−１を以下のようにして作製した。
【０１８０】
１００ｍｍ×１００ｍｍ×５０μｍの上記ｂ１基板のポリエチレンナフタレート層の薄い方の層側の上に、陽極としてＩＴＯ（インジウムチンオキシド）を１００ｎｍの厚みで成膜して基板にパターニングを行った後、このＩＴＯ透明電極を設けた透明支持基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥したのちＩＴＯ透明電極側にＰＥＤＯＴ−ＰＳＳ（ポリエチレンジオキシチオフェン−ポリスチレンスルフォン酸ドープ体；バイエル製ｂａｙｔｒｏｎ）層を乾燥厚み２５ｎｍとなるようにスピンコート塗布により形成した。さらにこの透明支持基板を真空蒸着装置に取付け、透明支持基板の寸法と位置が狂わないように四辺を固定した。次いで、真空槽を４×１０^−４Ｐａまで減圧し、正孔輸送層（α−ＮＰＤ ２５ｎｍ）、発光層（発光ホスト化合物ＣＢＰを蒸着レート５Å／ｓ、リン光性ドーパントとして、Ｉｒ−６を蒸着レート０．０５Å／ｓ、リン光性ドーパントＩｒ−１２を蒸着レート０．２Å／ｓで共蒸着して３０ｎｍの膜厚で成膜した。）、電子輸送層（ＢＣＰ １０ｎｍ）、正孔注入層（Ａｌｑ_３４０ｎｍ）をこの順に記載の厚みと組成に従って、ＰＥＤＯＴ−ＰＳＳ層の上に蒸着積層した。さらに陰極バッファー層としてフッ化リチウム０．５ｎｍ及び陰極としてアルミニウム１５０ｎｍを蒸着して陰極を形成した。
【０１８１】
最後に厚み３００μｍのガラス基板を封止用基板として用いて、周囲にシール材として、エポキシ系光硬化型接着剤（東亞合成社製ラックストラックＬＣ０６２９Ｂ）を適用し、これを上記陰極上に重ねて前記透明支持基板と密着させ、ガラス基板側からＵＶ光を照射して、硬化させて、封止して有機ＥＬ素子ＯＬＥＤ１−１を作製した。
【０１８２】
実施例２
（吸湿フィラーを分散した樹脂塗料の作製）
酸化バリウム（平均粒径３．５μｍ）１５質量部、ポリエーテルスルホン（住友ベークライト製 スミライト ＦＳ−１３００）４５質量部、１，３−ジメチル−２−イミダゾリジノン１００質量部をサンドミルで十分混練し、フィルターでろ過して、吸湿材を分散させた樹脂塗料を作製した。
【０１８３】
（積層基板の作製）
フッ酸でエッチング処理し、水洗後、脱水処理した厚さ３００μｍのガラス基板の、処理した側の面上に前述の樹脂塗料をカーテンコーターで塗布して１００℃、常圧で２時間乾燥後、１３０℃、１．０×１０^−３Ｐａの減圧下で３時間乾燥させた。乾燥後の樹脂層の厚みは２０μｍであった。この上にＵＶ硬化接着層を形成した１００μｍのカバーガラスを貼り合わせて圧着した後、カバーガラス側からＵＶ光を照射して、全体厚みが５８０μｍの積層基板（ｂ３）を作製した。
【０１８４】
（有機ＥＬ素子の作製）
有機ＥＬ素子ＯＬＥＤ３−１を以下のようにして作製した。陽極として、積層基板ｂ３の片面上（１００μｍのカバーガラス層の上）にＩＴＯ（インジウムチンオキシド）を１００ｎｍ成膜して基板にパターニングを行った後、このＩＴＯ透明電極を設けた透明支持基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥したのちＩＴＯ透明電極側にＰＥＤＯＴ−ＰＳＳ（ポリエチレンジオキシチオフェン−ポリスチレンスルフォン酸ドープ体；バイエル製ｂａｙｔｒｏｎ）層を乾燥厚み２５ｎｍとなるようにスピンコート塗布により形成した。さらにこの透明支持基板を真空蒸着装置に取付け、透明支持基板の寸法と位置が狂わないように四辺を固定した。次いで、真空槽を４×１０^−４Ｐａまで減圧し、正孔輸送層（α−ＮＰＤ ２５ｎｍ）、発光層（発光ホスト化合物ＣＢＰを蒸着レート５Å／ｓ、リン光性ドーパント化合物として、Ｉｒ−６を蒸着レート０．０５Å／ｓ、リン光性ドーパントＩｒ−１２を蒸着レート０．２Å／ｓで共蒸着して３０ｎｍの膜厚で成膜した。）、電子輸送層（ＢＣＰ １０ｎｍ）、正孔注入層（Ａｌｑ_３ ４０ｎｍ）をこの順に表１に記載の厚みと組成に従って、ＰＥＤＯＴ−ＰＳＳ層の上に蒸着積層した。さらに陰極バッファー層としてフッ化リチウム０．５ｎｍ及び陰極としてアルミニウム１５０ｎｍを蒸着して陰極を形成した。
【０１８５】
【化５】

【０１８６】
（シクロオレフィン系ポリマーフィルムの製造）
窒素置換した１ｌのオートクレーブに脱水精製したトルエン４００ｍｌとジシクロペンタジエン１００ｍｌを仕込み、これに分子量調節剤としてｌ−ヘキセン０．３７ミリモル、六塩化タングステン０．３７ミリモル、テトラエチルスズ０．７４ミリモルを加え、室温で５時間重合した。反応終了後モノエタノールアミン５ｍｌを加え、安定剤として２，６−ジ−ｔ−ブチルフェノール（ＢＨＴ）１ｇを加えたのち、大量のメタノール中に反応液を投入してポリマーを沈殿させ、真空乾燥することによりトルエン可溶性のポリマーを得た。収率は６２％であった。この重合体のガラス転移点は１２９℃であり、２５℃のトルエン中で測定した極限粘度は０．９５ｄｌ／ｇであった。この可溶ポリマーのシクロヘキサン溶液（濃度５質量％）４００ｇとパラジウムカーボン２ｇとを１ｌのオートクレーブに入れ、水素置換後、攪拌をしながら１４０℃で８時間、水素圧を７０気圧にして反応させた。反応物中の触媒を濾過し多量のアセトン−イソプロピルアルコール（１：１）混合溶媒中に沈殿させ濾過・乾燥した。得られた重合体（Ａ）をプロトンＮＭＲ解析し、オレフィン二重結合プロトンに起因する吸収の値から水添率を計算したところ、９８％であった。該重合体（Ａ）のガラス転移点は１３４℃、吸水率は０．０２％、分子量は約５万であった。
重合体（Ａ）を１２０℃で真空下４時間乾燥させ、低分子揮発物の含有量を５０ｐｐｍ以下にしたのち、９０ｍｍ径の押出機に供給して２９５℃で溶融させる。
【０１８７】
上記９０ｍｍ押出機から吐出される非晶ポリオレフィン溶融を、公知のアダブターを用いて、単層の口金で吐出した。該溶融シートに静電荷を印加させながら、６０℃に保たれたクロムメッキロール上に密着させ、冷却固化させた。シートを１５５℃に加熱されたジャケットロールを用い、長手方向に２．５倍延伸し、つづいて１３０℃および２００℃の２段階で熱固定した。かくして７５μｍの厚みを有する非晶質シクロオレフィン系ポリマーフィルム（構造式１）が得られた。これを所定の幅に裁断して封止用基板（フィルム）として用いた。
【０１８８】
また、口金での吐出量を調整して、膜厚を５０μｍとした非晶質シクロオレフィン系ポリマーフィルムを作製した。
【０１８９】
【化６】

【０１９０】
上記有機ＥＬ素子を、上記シクロオレフィン系ポリマーフィルムを用いて実施例１と同様に封止し、有機ＥＬ素子ＯＬＥＤ３−１を作製した。
【０１９１】
実施例３
（吸湿性フィラー練込みドープの調製）
ステンレスベルト上の、前記作製した５０μｍの厚みを有するシクロオレフィン系ポリマーフィルムの表面に、酸化バリウム（平均粒径１．２μｍ）とシリカゲル微粒子（平均粒径０．７μｍ）を各５質量％分散したポリカーボネート樹脂のメチレンクロライドを溶媒とするドープをキャストすることで、３５μｍの厚みの吸湿性フィラー含有ポリカーボネート層を積層した。さらにこの上にポリカーボネートにγ−アミノプロピルトリメトキシシランを１０％添加したメチレンクロライドを溶媒とする樹脂溶液を乾燥厚み２μｍとなるように塗布して、乾燥し積層基板ｂ６を作製した。
【０１９２】
実施例１と同様にＩＴＯ／ＰＥＤＯＴ−ＰＳＳ／有機層（正孔輸送、発光、電子輸送、電子注入）／陰極バッファー／陰極を蒸着により形成した。
【０１９３】
前記７５μｍの厚みを有するシクロオレフィン系ポリマーフィルムを封止用基板として用いて実施例１と同様に封止し、有機ＥＬ素子ＯＬＥＤ４−１を作製した。
【０１９４】
実施例４
（吸湿性フィラー含有のシクロオレフィンポリマーチップ作製）
前記重合体（Ａ）を真空乾燥機を用い、１５０℃で十分乾燥させた後、酸化バリウム粉末（平均粒径、０．５μｍ）を含有率が５質量％となるように、乾燥窒素気流下２軸押出し混練機を用いて２８０℃で混練し、吸湿性フィラー含有のポリシクロオレフィンポリマーチップ（ポリシクロオレフィンＡと呼称）を作製した。
【０１９５】
（光反射性フィラー含有のポリエステルチップ作製）
ポリ１，４−シクロヘキシレンジメチレンテレフタレート（構造式２）チップを真空乾燥機を用い、１３０℃で十分乾燥させた後、酸化チタン（ＴｉＯ_２）粉末（平均粒径、０．２μｍ）を含有率が１２質量％となるように、乾燥窒素気流下２軸押出し混練機を用いて２９０℃で混練し、光反射性フィラー含有のポリ１，４−シクロヘキシレンジメチレンテレフタレートチップ（ポリエステルＢと呼称）を作製した。
【０１９６】
【化７】

【０１９７】
（積層基板の作製）
ポリシクロオレフィンＡとポリエチレンテレフタレートのチップを各々１５０℃で８時間真空乾燥した後、乾燥窒素気流中で保温しながら、押出し機上に設置したホッパーから樹脂を３台の押出し機へ各々供給し２９０℃で溶融押出しを行ない、４０メッシュのフィルターを通過させてから、Ｔダイ内で厚み比が１：１：１となるように層状に接合して、６０℃の冷却ドラム上に静電印加しながら密着させて急冷冷却固化し、積層未延伸シートを得た。このとき芯（コア）層がポリシクロオレフィンＡであり、表層がポリエチレンテレフタレートとなるようにした。この未延伸シートをロール式縦延伸機へ導き、９０℃で予熱し、低速と高速のロール間でＩＲヒーターで加熱しながら、縦方向に２．８倍に延伸した。得られた一軸延伸フィルムをテンター式横延伸機に供給し、１３０℃で横延伸倍率２．８倍となるように延伸した。得られた二軸配向フィルムを２１０℃で１０秒間熱固定した。次いで横方向に５％弛緩処理しながら室温まで３０秒かけて徐冷して厚さ４５μｍの二軸延伸積層ポリエステル／ポリシクロオレフィン支持体からなる積層基板（ｂ４）を得た。さらに両端部をトリミングして、各１００ｍずつ、直径２２０ｍｍのコアに巻き取った。
【０１９８】
コアに巻いたまま、熱処理（アニール）を７５℃、７０時間、行なった。
（陰極側封止用基板作製）
ポリシクロオレフィンＡとポリエステルＢとポリエチレンテレフタレートのチップを各々１５０℃で８時間真空乾燥した後、乾燥窒素気流中で保温しながら、押出し機上に設置したホッパーから樹脂を３台の押出し機へ各々供給し２９０℃で溶融押出しを行ない、４０メッシュのフィルターを通過させてから、Ｔダイ内で厚み比が１：１：１となるように層状に接合して、６０℃の冷却ドラム上に静電印加しながら密着させて急冷冷却固化し、積層未延伸シートを得た。このとき芯（コア）層がポリシクロオレフィンＡであり、表層がポリエステルＢ、ポリエチレンテレフタレートとなるようにした。この未延伸シートをロール式縦延伸機へ導き、９０℃で予熱し、低速と高速のロール間でＩＲヒーターで加熱しながら、縦方向に２．８倍に延伸した。得られた一軸延伸フィルムをテンター式横延伸機をに供給し、１３０℃で横延伸倍率２．８倍となるように延伸した。得られた二軸配向フィルムを２１０℃で１０秒間熱固定した。次いで横方向に５％弛緩処理しながら室温まで３０秒かけて徐冷して厚さ６０μｍの二軸延伸積層ポリエステル／ポリシクロオレフィン支持体を得た（封止用基板ｂ５）。さらに両端部をトリミングして、各１００ｍずつ、直径２２０ｍｍのコアに巻き取った。
【０１９９】
コアに巻いたまま、熱処理（アニール）を７５℃、７０時間、行なった。
（有機ＥＬ素子の作製）
有機ＥＬ素子ＯＬＥＤ５−１を以下のようにして作製した。
【０２００】
１００ｍｍ×１００ｍｍの積層基板ｂ４の片側に、陽極としてＩＴＯ（インジウムチンオキシド）を１００ｎｍ成膜して基板にパターニングを行った後、このＩＴＯ透明電極を設けた透明支持基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥したのちＩＴＯ透明電極側にＰＥＤＯＴ−ＰＳＳ（ポリエチレンジオキシチオフェン−ポリスチレンスルフォン酸ドープ体；バイエル製ｂａｙｔｒｏｎ）層を乾燥厚み２５ｎｍとなるようにスピンコート塗布により形成した。さらにこの透明支持基板を真空蒸着装置に取付け、透明支持基板の寸法と位置が狂わないように四辺を固定した。次いで、真空槽を４×１０^−４Ｐａまで減圧し、正孔輸送層（α−ＮＰＤ ２５ｎｍ）、発光層（発光ホスト化合物ＣＢＰを蒸着レート５Å／ｓ、リン光性ドーパントとして、Ｉｒ−６を蒸着レート０．０５Å／ｓ、リン光性ドーパントＩｒ−１２を蒸着レート０．２Å／ｓで共蒸着して３０ｎｍの膜厚で成膜した。）、電子輸送層（ＢＣＰ １０ｎｍ）、正孔注入層（Ａｌｑ_３ ４０ｎｍ）をこの順に記載の厚みと組成に従って、ＰＥＤＯＴ−ＰＳＳ層の上に蒸着積層した。さらに陰極バッファー層としてフッ化リチウム０．５ｎｍ及び陰極としてアルミニウム１５０ｎｍを蒸着して陰極を形成した。最後に、アニール処理済の二軸延伸積層ポリエステル／ポリシクロオレフィン支持体（封止用基板ｂ５）を酸化チタンを含有するポリエステル層がアルミニウム陰極と向かい合うように貼り合わせて実施例１と同様にして封止し、有機ＥＬ素子ＯＬＥＤ５−１を作製した。
【０２０１】
比較例１
実施例１において、ポリエステルＡのかわりに市販のポリエチレンテレフタレート、ポリエチレン２，６−ナフタレートの代わりにやはり市販のポリエチレンテレフタレートを用いた他は、まったく同様にして積層基板（ｂ２）を作製した以外は、全く同様にして有機ＥＬ素子ＯＬＥＤ２−１の作製を行なった。
【０２０２】
また、下部電極を設ける基板については、それぞれ下部電極側の表面粗さＲａ、また、下部電極と反対側の光取り出し側の表面粗さＲａを前記ＪＩＳ−Ｂ−０６０１に準じて、測定装置としては、ＷＹＫＯ社製 ＲＳＴＰＬＵＳ非接触三次元微小表面形状測定システムを用いて測定した。
【０２０３】
得られた有機ＥＬ素子ＯＬＥＤ１−１〜ＯＬＥＤ５−１の各々について、下記のような評価を行った。
【０２０４】
《発光輝度、発光効率》
有機ＥＬ素子ＯＬＥＤ１−１〜ＯＬＥＤ５−１について、温度２３℃、乾燥窒素ガス雰囲気下で１０Ｖ直流電圧を印加した時の発光効率（ｌｍ／Ｗ）を測定した。
【０２０５】
尚、有機ＥＬ素子ＯＬＥＤ１−１〜ＯＬＥＤ５−１の発光色は白色であった。有機ＥＬ素子ＯＬＥＤ１−１は初期駆動電圧４Ｖで電流が流れ始めた。
【０２０６】
発光輝度、発光効率の評価は、有機ＥＬ素子ＯＬＥＤ１−１の測定値を１００とした時の相対値（相対発光効率）で行った。また、発光輝度は、ＣＳ−１０００（ミノルタ製）を用いて測定した。
【０２０７】
《耐久性》
有機ＥＬ素子ＯＬＥＤ１−１〜ＯＬＥＤ５−１の各々を２．５ｍＡ／ｃｍ^２の一定電流で駆動したときに初期輝度が元の半分に低下するのに要した時間である半減寿命時間（半減時間ともいう）を指標として表した。また、半減寿命時間は有機ＥＬ素子ＯＬＥＤ１−１の半減時間を１００とした時の相対値で表した。
【０２０８】
《応力負荷時の発光変化》：輝度変化率
各試料素子を５００ｃｄ／ｍ^２となるように電圧を調整したのち、各素子の陰極側をカール値０、５、１０、１５と５きざみに６０までの値となるような各直径を有する円柱上の絶縁性剛体に順に押しあて、輝度変化率と発光状態を観察した。カール値６０まで変形できれば、十分可撓性があるといえる。また輝度変化が２０％以下であれば、実用上支障がない。また、カール値は曲率半径の逆数（１／ｍ）で表した。
【０２０９】
各素子の構成を表１にまた各素子の評価結果を表２に示した。
【０２１０】
【表１】

【０２１１】
【表２】

【０２１２】
【発明の効果】
有機ＥＬ素子における光取り出し効率が飛躍的に向上し、長寿命で、可撓性であり、湾曲変形時の輝度変化と素子の破損、亀裂が低減した、安価で省資源を達成できる有機ＥＬ素子およびこれを用いた発光体、光源が提供できた。
【図面の簡単な説明】
【図１】有機ＥＬ素子の封止方法の一例を示す断面図である。
【符号の説明】
１ 透光性の基板
２ 陽極
３ 有機ＥＬ層
４ 陰極
５ 封止用基板
６ シール材[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a highly durable organic electroluminescence element (also referred to as an organic EL element) formed on a flexible support, a display device using the element, a lighting device, and a light source.
[0002]
[Prior art]
In general, incandescent lamps and fluorescent lamps are widely used for consumer use as white illumination light sources. Incandescent lamps have a light spectrum close to that of sunlight and are close to natural light, but are unsuitable for uniformly brightening the entire wall surface and are difficult to change the emission spectrum. In addition, the efficiency of converting electric energy into light energy is low, and fluorescent lamps are currently widely used because of their efficient use, but fluorescent lamps also have some drawbacks.
[0003]
Since the fluorescent lamp uses the glow discharge of mercury vapor, the lighting time is delayed and the discharge is unstable immediately after the lighting and the light quantity is not stable. In addition, a decrease in the amount of light in a low temperature environment is a problem. Furthermore, since the fluorescent lamp has mercury vapor sealed in a glass tube, it is difficult to reduce the size and environmental pollution due to mercury is also a problem.
[0004]
On the other hand, in recent years, organic EL elements have attracted attention as self-luminous elements. An organic EL device is a device in which a light emitting layer made of a thin organic compound is sandwiched between electrodes and emits light when a current is supplied between the electrodes. Therefore, when an organic EL element that is a thin film is used as a light source, it is easy to reduce the size and weight, and the illuminating device has a faster response speed of light emission than a fluorescent lamp, and the light quantity immediately after lighting is relatively stable.
[0005]
Here, when the organic EL element is used as a light source of a liquid crystal display device or an illumination device for various displays, the emission color is preferably white. However, there is no organic EL element that emits white light with a single light emitting material. For this reason, it is whitened by a combination of a plurality of emission colors other than white. For example, white light emission is obtained by combining a light emitting layer and a fluorescent layer that converts the light of the light emitting layer or a plurality of light emitting layers. Yes.
[0006]
For example, a method of whitening with a fluorescent material is used, and Japanese Patent Application Laid-Open No. 63-19796 discloses a technology for whitening by laminating a fluorescent layer on the opposite side of a transparent electrode. Japanese Patent Laid-Open No. 8-100193 discloses a technique for whitening by providing a phosphor layer that absorbs light emitted from a blue organic EL element and emits visible light fluorescence in the stacking direction of the organic EL element. Has been. Furthermore, Japanese Patent Application Laid-Open No. 2001-250690 describes a technique for whitening by mixing a fluorescent material in a blue light-emitting layer.
[0007]
As a technique for whitening with a light emitting material, Japanese Patent Application Laid-Open No. 7-90260 describes a technique for whitening with a light emitting material and a plurality of dopant materials.
[0008]
Japanese Patent Application Laid-Open No. 7-142169 also describes a technique for stacking a plurality of light emitting layers to whiten.
[0009]
The method using a fluorescent material converts short-wavelength light once emitted into a long wavelength, resulting in energy loss during the exchange of light energy, and the phosphor material itself is expensive, so as long as the fluorescent material is used, It is difficult to improve economy including luminous efficiency.
[0010]
In addition to the white light emitted by organic EL elements, it can be driven at a low voltage, can use a DC power supply, does not use mercury, which is a harmful component, and has a wide brightness setting range, compared to white light from fluorescent lamps. It has many advantages, such as being able to make a light-emitting element and responding to resource savings, and has attracted attention. However, in terms of luminous efficiency and lifetime, nothing superior to fluorescent lamps has been obtained.
[0011]
In particular, in recent years, it has been found that the conversion efficiency of electric energy into light is greatly improved by the organic EL element using a phosphorescent dopant. However, as long as an electrode material, a light emitting layer material, and an element base material having a high refractive index are used, it is difficult to completely extract light emission, and the final light emission efficiency cannot be greatly improved. For example, Japanese Patent Application Laid-Open No. 2003-77680 discloses a technique for providing a base layer between a substrate and an electrode to define each refractive index, but it is still insufficient.
[0012]
In addition, organic EL elements are derived from the principle of bonding electrons and holes in a thin film. Therefore, due to their physical structure, the presence of quenching components such as oxygen and water molecules, components that thermally deactivate excited molecules, In order to extend the lifetime of the organic EL element, it is necessary to reduce the diffusion to the maximum. Conventionally, this technique has also been achieved by a glass cell or a combination of a glass and a metal can in which a highly pure inert gas (for example, nitrogen) atmosphere is sufficiently dried and a desiccant is enclosed together. . For example, Japanese Patent Application Laid-Open No. 10-312882 discloses a technique in which a glass substrate and the entire light emitting element are enclosed in a container with a light extraction window. These methods are clearly unsuitable for thinning, weight reduction, resource saving, and cost reduction.
[0013]
As a method for increasing the light emission extraction efficiency, for example, JP 2003-31374 A discloses that ITO (transparent electrode) on a glass substrate is made of ITO and silica (SiO 2). ₂ ) And a technique such as forming an antireflection layer on the surface opposite to the light emitting layer of the substrate has been disclosed, and attempts have been made to improve the light emission extraction efficiency. There is no big effect. In Japanese Patent Laid-Open No. 2000-260559, a light emitting element is formed on a cross-section of a bundle of optical fibers and a light emitting element is formed to improve the extraction efficiency. It is bad and good flatness cannot be obtained.
[0014]
In JP-A-6-283270, TiO is formed on the ITO production surface side on a glass substrate. ₂ Film, SiO ₂ A technique for suppressing scattered light by laminating films to form a resonant structure is disclosed.
[0015]
Japanese Patent Application Laid-Open No. 2002-184567 describes a method for efficiently extracting light emitted from a pixel by forming a microlens on a substrate by a photolithography method.
[0016]
However, although any of these methods improves the light extraction efficiency, it is difficult to make a thin film and the productivity is low, so that a method for improving the light extraction efficiency and high productivity has not yet been found. Not. In addition, there is no one that simultaneously achieves the difficult problem of increasing the light extraction efficiency, improving the moisture resistance, and achieving a long life. For example, a glass substrate having a moisture absorption layer containing a hygroscopic substance has been studied (Japanese Patent Laid-Open No. 2003-1000044). However, the hygroscopic substance has a reverse current when forming an electrode or patterning an organic EL element. It is not effective because it causes leaks and dark spots during light emission.
[0017]
As another problem, substrates such as glass are usually used in display devices and electro-optical devices provided in portable information terminal equipment such as mobile phones in recent years, and glass is excellent in terms of moisture permeability. However, since it is heavy and does not have flexibility (flexibility), it has a defect such as being easily broken by dropping. With the widespread use of these, a flexible element (for example, using a plastic substrate) that is resistant to bending. There is also a great demand for using an organic EL element as a light-emitting light source on a flexible and flexible support for a light-emitting light source such as illumination instead of the fluorescent lamp.
[0018]
However, plastic generally has higher moisture permeability than glass. In particular, in order for an organic EL element to emit light for a sufficiently long time on a plastic substrate of 150 μm or less, not only the water resistance and high moisture resistance of the plastic itself are required. The important issue is how to add a strong desiccant uniformly into the plastic, which has not yet been achieved.
[0019]
Therefore, as described above, there are currently no known substrates that satisfy all of a plurality of demands such as high light extraction efficiency, low moisture permeability, and flexibility and flexibility. is there.
[0020]
In other words, using organic EL elements, fluorescent lamps surpass in terms of economy (low cost, resource saving), handleability, environmental safety, etc., and further emit white light on a sheet-like flexible carrier. Constructing the light source has never been possible with the prior art.
[0021]
[Patent Document 1]
Japanese Patent Laid-Open No. 2003-77680
[0022]
[Patent Document 2]
JP 2003-31374 A
[0023]
[Patent Document 3]
JP 2000-260559 A
[0024]
[Patent Document 4]
JP-A-6-283270
[0025]
[Patent Document 5]
JP 2002-184567 A
[0026]
[Patent Document 6]
Japanese Patent Laid-Open No. 2003-100448
[0027]
[Problems to be solved by the invention]
Organic EL devices that dramatically improve the light extraction efficiency in organic electroluminescent devices, extend their lifetime, and reduce luminance changes, device damage, and cracks during bending deformation of flexible film-formed white light emitters, and It aims at providing the light-emitting body and light source using this. An object of the present invention is to provide an organic EL element that can achieve resource saving at low cost, and a light emitter and light source using the organic EL element.
[0028]
[Means for Solving the Problems]
The above object of the present invention is achieved by the following means.
[0029]
1. In an organic electroluminescence device having a lower electrode, a light emitting layer, and an upper electrode on a translucent substrate, the haze value of the translucent substrate is 0.5% or more and 50% or less, and the thickness is 30 μm or more. 700 μm or less, an organic electroluminescence element.
[0030]
2. The translucent substrate has a laminated structure, and at least the core layer (one layer) contains a filler having a refractive index of 1.30 or more in an amount of 1% by mass to 40% by mass. 1. The organic EL device according to 1.
[0031]
3. 3. The organic electroluminescence device as described in 1 or 2 above, wherein a hygroscopic substance is dispersed and contained in the translucent substrate with an average particle size of 0.08 μm to 5 μm.
[0032]
4). The translucent substrate has a laminated structure, the surface roughness Ra on the lower electrode side of the translucent substrate is 50 nm or less, and the surface roughness Ra on the side opposite to the lower electrode is 20 nm or more. And at least one layer is a cycloolefin type polymer among the layers which comprise a board | substrate, The organic electroluminescent element of any one of said 1-3 characterized by the above-mentioned.
[0033]
5. The translucent substrate has a laminated structure, the surface roughness Ra on the lower electrode side of the translucent substrate is 50 nm or less, and the surface roughness Ra on the side opposite to the lower electrode is 20 nm or more. 4. At least one layer which comprises a board | substrate is a polyether sulfone type polymer, The organic electroluminescent element of any one of said 1-3 characterized by the above-mentioned.
[0034]
6). 6. The organic electroluminescence device according to any one of 1 to 5, wherein the light emitting layer contains at least one phosphorescent dopant.
[0035]
7. 7. The organic electroluminescence device according to any one of 1 to 6, wherein a conductive polymer layer is formed between the lower electrode and the light emitting layer with a thickness of 1 nm to 150 nm.
[0036]
8.500 cd / m ² The organic electro luminescence device according to any one of the above 1 to 7, wherein a rate of change in luminance is 20% or less when the curl value is changed from 0 to 60 in a state where light is emitted at a luminance of 10%. Luminescence element.
[0037]
9. The display apparatus which has an organic electroluminescent element as described in any one of said 1-8.
[0038]
10. The illuminating device which has an organic electroluminescent element as described in any one of said 1-8.
[0039]
11. The light source which has an organic electroluminescent element as described in any one of said 1-8.
[0040]
Hereinafter, the present invention will be described in detail.
The present invention relates to an organic electroluminescence device having a lower electrode, a light emitting layer, and an upper electrode on a light-transmitting substrate.
[0041]
For organic electroluminescence elements (also referred to as organic EL elements), many approaches have been studied for improving the quantum efficiency of light emission. In the organic EL element, the generation probability of the luminescent excited species in the light emission from the conventional phosphor (light emission from the excited singlet) is 25%, but in recent years, using the phosphorescent dopant, An organic EL device using phosphorescence emission from a term has been proposed, and if the excited triplet is used, the upper limit of the internal quantum efficiency is 100%, so that the emission efficiency is theoretically up to four times that of the conventional method. Attention has been paid. As a result, almost the same performance as a cold cathode tube can be obtained, and it can be applied to illumination. In these electroluminescent devices, by using two or more phosphorescent dopants having different maximum wavelengths of the emission spectrum, for example, in combination of blue-red, blue-green-red, blue-green-red, and the like, White light emission is obtained, and white light for illumination is also obtained.
[0042]
However, since the light extraction efficiency from the light-transmitting substrate is usually about 20%, improvement of the light extraction efficiency from the light-transmitting substrate is important because it further increases the efficiency.
[0043]
The present invention is to improve the light extraction efficiency by reducing the organic EL light emission extraction loss due to reflection inside these translucent substrates.
[0044]
In the present invention, the translucent substrate is selected such that the haze value of the translucent substrate is 0.5% or more and 50% or less. Preferably, it is 3.0% or more. When the haze value is smaller than 0.5%, when used as the substrate film for organic EL of the present invention, light from the light emitting element comes out from the substrate surface when the critical angle is less than the critical angle at the interface between the substrate and the outside. Therefore, the light extraction efficiency is reduced because the light is transmitted in the in-plane direction of the substrate film, and the substrate appears dark when viewed from the surface on the light extraction side (surface where the lower electrode is not formed) even under the same voltage / current load. .
[0045]
In addition, in the case of a laminated substrate using glass, the glass is made as thin as possible to make it flexible, flexible, and lightweight. 30 μm or more and 700 μm or less.
[0046]
The haze value of the substrate can be obtained by measuring one film sample according to ASTM-D1003-52 using T-2600DA manufactured by Tokyo Denshoku Industries Co., Ltd.
[0047]
By making the light-transmitting substrate of the organic EL element a substrate having the haze value, the light from the electroluminescent element is not totally reflected from the interface between the substrate and the outside in the substrate. For the problem of electroluminescence transmitted through the substrate, the interface between the substrate and the outside, the interface between the substrate and the lower electrode (transparent conductive film) that takes out light (observation side), etc. In the case of a laminated substrate, the interface of each laminated film also enters, but the components that are totally reflected at these thin film interfaces and are hardly extracted can be extracted from the translucent substrate by being moderately scattered. It is considered to be.
[0048]
One example of the organic EL element sealing method is shown in a sectional view in FIG.
That is, a transparent conductive film serving as an anode is formed as a lower electrode 2 on a translucent substrate 1, and further, for example, an anode buffer layer, a hole transport layer, and a light emitting layer are formed on the patterned lower electrode 2. An organic EL layer 3 composed of layers such as an electron transport layer and an electron injection layer is formed by vapor deposition or coating (details are omitted here), and an upper electrode 4 serving as a cathode is formed on the organic EL layer. After the formation, the sealing substrate 5 covering the upper electrode is adhered by a sealing material 6 that seals the periphery of each layer of the organic EL element under reduced pressure or an inert gas such as dry nitrogen, The organic EL element is sealed. In the figure, the lead wires from each electrode are omitted, and although not shown, the distance between the translucent substrate and the sealing substrate is adjusted by using a spacer together with a sealing material. Also good. Further, the sealing substrate 5 is not necessarily a substrate, and may be a sealing film such as ceramic or polymer. The configurations of the electrode and the organic EL layer are not limited to those described above, and may be a reverse feed configuration (so-called top emission type). Moreover, you may put a desiccant, a hygroscopic agent, etc. inside as needed.
[0049]
In the above configuration, when the organic EL layer is taken out from the transparent electrode side, for example, the transparent electrode is a lower electrode formed on a light-transmitting substrate, electroluminescence is transmitted through the light-transmitting substrate. It is taken out.
[0050]
In the present invention, the light extraction efficiency of the light-transmitting substrate is improved by adjusting the haze value of the light-transmitting substrate to the above-described range. In order to adjust the haze value of the substrate to the above range, particles of a hygroscopic substance having a specific particle diameter are used as fillers and present in the resin film at a specific content, thereby providing a light scattering function, so The ratio of light diffused and not utilized (not extracted) is suppressed to increase the ratio of light traveling to the extraction surface side, and at the same time, the moisture permeability of the substrate is improved.
[0051]
In order to reduce the weight of the light-transmitting substrate and to make it flexible, since the moisture permeability deteriorates because the glass is made into a resin film, the life of the sealed organic EL element is deteriorated. In the present invention, a hygroscopic material-containing resin layer is formed and supplemented in the substrate film.
[0052]
With respect to the sealing substrate material that seals the organic EL element together with the translucent substrate in contact with the upper electrode, glass or a resin film having excellent moisture permeability may be used. A glass material or a resin film may be selected in accordance with wetness or flexibility (flexibility). Among the resin films, it is preferable to use, for example, a cycloolefin resin substrate having low moisture permeability.
[0053]
However, not only the translucent substrate (the side on which light emission is observed) that forms the lower electrode, but also the substrate material that seals the organic EL element together with the translucent substrate in contact with the upper electrode is flexible. It is preferable to secure the thin film, light weight, long life, economy, and resource saving of the (white) organic EL element by using a resin film in which a layer containing a hygroscopic filler is introduced.
[0054]
In the present invention, as the hygroscopic filler, hygroscopic substances that can be added to the resin layer include ZnO and SnO. ₂ TiO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , GeO ₂ , MgO, BaO, MoO ₃ , ZiO ₂ , V ₂ O ₅ There are oxides such as CaO, SrO, etc., and when they are dried, they are hygroscopic, scatter light, and have a particle size and particle size distribution that can control the surface roughness and add appropriate amounts can do. However, if too much is added, the mechanical strength when the resin layer is formed deteriorates and becomes brittle, and if it is too small, the above functions cannot be expressed, so a ratio of 1% by mass to 40% by mass is preferable. Moreover, in order to give the diffusibility at the time of light extraction, it is preferable that the refractive index of the hygroscopic material itself is 1.30 or more.
[0055]
In addition, a resin is dissolved in a solvent, and a solution of a metal alkoxide compound (for example, tetraethoxysilane, tetramethoxysilane, tetraisopropoxytitanium, etc.) that is a precursor of the above oxide (acid, alkali, water, if necessary) Etc. may be mixed, and the resin layer may be formed by a casting method. By using this so-called sol-gel method, the haze can be easily controlled by the amount of metal alkoxide added to the resin, the type of resin, and the film forming conditions.
[0056]
The hygroscopic substance is used by dispersing in an average particle size of 0.08 μm to 5 μm. A more preferable particle size is 0.1 μm or more and 2 μm or less.
[0057]
The average particle diameter of the inorganic fine particles is obtained as a simple average value (number average) by observing 100 or more arbitrary particles with an electron microscope and determining the particle diameter. Here, each particle size is expressed by a diameter assuming a circle equal to the projected area.
[0058]
Usually, the resin layer containing the hygroscopic filler is kneaded as a dispersion in the casting composition when forming the resin layer, or added to the composition to form a film. (Film) can be obtained.
[0059]
Moreover, the resin film used as these translucent board | substrates may have the laminated structure which uses the resin film which has the said hygroscopic filler as a core layer, and is different especially in thin glass and a resin film. It may be a laminated film composed of a plurality of resin films.
[0060]
If the resin film containing the hygroscopic filler is as it is, the hygroscopic filler protruding on the surface of the resin film is hygroscopic, for example, in the case of barium oxide which is a strong hygroscopic agent, the strong alkali generated by hydrolysis is Since it erodes an electrode etc., it is not preferable. The resin film (layer) containing the hygroscopic filler as described above is used as a core layer, and other resin layers such as polyethylene terephthalate, polyethylene naphthalate, or glass are formed so that the filler is not exposed on the surface. It is preferable that the laminated film is a laminated film laminated by a coextrusion method or a co-casting method described later.
[0061]
The thickness of the layer containing the hygroscopic filler serving as the core layer is preferably 20 to 500 μm, and this is preferably laminated with a resin layer in the range of 20 to 500 μm not containing the hygroscopic filler. It is not always necessary to have a three-layer structure, and another layer may be provided for another purpose, or a filler layer may be laminated by combining different resins or ones having different hygroscopic substances. It is good also as a structure.
[0062]
For example, there are the following configurations.
PET / PET (BaO) / PET
PEN / PET (BaO) / PEN
Glass / PES (BaO) / Glass
Etc. is a typical configuration. In the above, PET: polyethylene terephthalate, PEN: polyethylene 2,6-naphthalate, PES: polyethersulfone. When the electrode of the organic EL element is formed by vapor deposition or sputtering, a heat resistant resin having a higher Tg may be used as the outermost surface on the side on which the electrode is formed.
[0063]
For the purpose described above, when other layers are laminated on a glass substrate to form a laminated substrate, since the means such as resin coating and lamination are used, the surface is adjusted for roughness or bonded as described later. It is necessary to perform surface modification for imparting properties.
[0064]
In the present invention, the core layer containing at least the hygroscopic filler of the laminated film preferably contains at least 1% by mass and 40% by mass of the hygroscopic filler having a refractive index of 1.30 or more as described above.
[0065]
For the formation of a resin film or a resin layer, for example, a polyester film, the raw material polyester is usually formed into pellets, dried with hot air or vacuum, melt-extruded, extruded into a sheet from a T-die, and electrostatic The sheet is brought into close contact with a cooling drum by an application method or the like, and cooled and solidified to obtain an unstretched sheet.
[0066]
When laminating these polyester films, a conventionally known method may be used. For example, a plurality of extruders and a co-extrusion method using a feed block die or a multi-manifold die, or a single layer film constituting a laminate or another resin constituting a laminate on the laminated film is melt extruded from the extruder. Examples thereof include an extrusion laminating method for cooling and solidifying on a cooling drum, and a dry laminating method in which a single layer film or a laminated film constituting a laminate is laminated via an anchor agent or an adhesive as necessary. Among them, a coextrusion method that requires few manufacturing steps and good adhesion between the layers is preferable.
[0067]
Using a multi-manifold die, by laminating layers that do not contain the filler on both sides of the core layer as a resin layer containing at least 1% by mass of a hygroscopic filler by the coextrusion method, A laminated substrate (film) according to the present invention can be obtained.
[0068]
The obtained unstretched sheet is heated in a range of Tg + 100 ° C. from the glass transition temperature (Tg) of the polyester through a plurality of roll groups and / or a heating device such as an infrared heater, and stretched in one or more stages. The draw ratio is usually in the range of 2.5 to 6 times, and it is necessary to make it a range in which subsequent transverse drawing is possible. When the sheet has a multilayer structure, the stretching temperature is preferably set based on the highest Tg among the Tg of the polyester of each constituent layer.
[0069]
The polyester film uniaxially stretched in the longitudinal direction thus obtained is further transversely stretched within a temperature range of Tg to Tm-20 ° C. and then heat-set. The transverse draw ratio is usually 3 to 6 times, and the ratio between the longitudinal and transverse draw ratios is appropriately adjusted so as to measure the physical properties of the obtained biaxially stretched film and to have preferable characteristics.
[0070]
In terms of dimensional stability, the cooling is preferably performed by gradually cooling from the final heat setting temperature to room temperature at a cooling rate of 1 ° C. to 100 ° C. per second. What is necessary is just to determine a cooling rate by measuring the physical property of the obtained biaxially stretched film, and adjusting suitably so that it may have a preferable characteristic.
[0071]
For example, when manufacturing a chip of a resin such as polyester that is crystallized, the molten polymer after polymerization is gradually cooled from the melting point to crystallize and become cloudy and brittle. Although it is generally performed to be introduced into the chip cutter and then introduced into the chip cutter, in the present invention, water cannot be used in the resin kneaded with a moisture absorbent using a kneader. It is preferable to use a nonaqueous, low-reactivity, and easy-to-dry cooling solvent such as normal heptane and normal octane under an air flow.
[0072]
In addition, when formed by a solvent casting method, the hygroscopic filler may be added to the dope in a dispersed state and then formed into a film. Moreover, the film which has a laminated structure can be similarly obtained by the co-casting method.
[0073]
In the present invention, in order to reduce the thickness of the substrate, even when glass is used, it is made as thin as possible, and a flexible and lightweight substrate is obtained by using a resin film. Therefore, the thickness of the substrate is 30 μm or more, 700 μm or less.
[0074]
In order to make a flexible substrate, it is preferable to use a resin film. Among the resins, cycloolefin polymers are excellent in water absorption (moisture permeability) and transparency, but are expensive and have a refractive index of 1. There is a drawback that it is inferior in uniformity of the film thickness at the time of stretch film formation. By co-extrusion with a polyester (polyethylene terephthalate or the like) that can obtain a uniform film with a stretchable film at a low cost, a substrate for organic EL and a sealing film can be manufactured with low productivity and low cost.
[0075]
In the light-transmitting substrate having the laminated structure, at least one layer (core layer) of the layers constituting the substrate is the cycloolefin-based polymer, and a hygroscopic filler is contained, so that the substrate is further excellent in moisture permeability. Can be obtained. At that time, in order to further improve light scattering, the surface roughness Ra of the translucent substrate having the cycloolefin polymer as a core layer on the lower electrode side is set to 50 nm or less, and the surface opposite to the lower electrode is used. The roughness Ra is adjusted to 20 nm or more. Thereby, not only the moisture permeability and the adhesion with the transparent conductive film such as ITO which is the lower electrode are improved, but also a light transmissive substrate with less total reflection at the interface and higher light extraction efficiency. As a result, the overall light emission efficiency of the organic EL device using this is greatly improved.
[0076]
The surface roughness Ra of the surface of the produced substrate is a center line average roughness, and is defined by JIS-B-0601 of JIS surface roughness. That is, the centerline average roughness (Ra) is a portion of the measured length L (preferably 2.5 mm in the present invention) in the direction of the centerline from the roughness curve, and the cut-off value of 0. When the center line of this extracted part is represented by X axis, the direction of the vertical magnification is represented by Y axis, and the roughness curve is represented by Y = f (X), the value obtained by the following equation is represented by micrometers (μm). What you did.
[0077]
[Expression 1]

[0078]
Examples of the measuring apparatus that can be used include a RSTPLUS non-contact three-dimensional micro surface shape measuring system manufactured by WYKO. A sample having a size of 30 cm × 30 cm was divided into 100 in a grid pattern at intervals of 3 cm, the center of each square region was measured, and the average value and standard deviation were obtained from 100 measurements.
[0079]
As the cycloolefin polymer used in the present invention,
A hydride of a ring-opening polymer of a polycyclic monomer such as dicyclopentadiene, a hydride of a copolymer of a polycyclic monomer such as dicyclopentadiene and ethylene, or a norbornene-based polymer.
[0080]
As hydrides of ring-opening polymers such as dicyclopentadiene, for example, Japanese Patent Publication No. 58-43412 and Japanese Patent Laid-Open No. 63-218727 are well known. Copolymers of polycyclic monomers such as dicyclopentadiene and ethylene are known from JP-A-63-314220 and JP-A-612020816. Of course, the dicyclopentadiene includes alkyl substituents such as methyl and ethyl substituents, endo isomers, exo isomers, and mixtures thereof.
[0081]
Further, norbornene-based polymers include those shown in US Pat. No. 2,883,372, JP-B-46-14910, JP-A-1-14997, JP-A-3-14882, JP-A-3-122137 and the like. ing.
[0082]
The thermoplastic norbornene polymer specifically includes a ring-opening polymer of a norbornene monomer, a hydrogenated product thereof, an addition polymer of a norbornene monomer, and an addition type of a norbornene monomer and an olefin. A polymer etc. are mentioned.
[0083]
The norbornene-based monomer is a known monomer in the above-mentioned publications, JP-A-2-227424, JP-A-2-276842, etc., and examples thereof include norbornene, its alkyl, alkylidene, and aromatic substituted derivatives. And polar group substitution products such as halogen, hydroxyl group, ester group, alkoxy group, cyano group, amide group, imide group and silyl group of these substituted or unsubstituted olefins, for example, 2-norbornene, 5-methyl-2-norbornene 5,5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, 5-methoxycarbonyl-2-norbornene, 5-cyano-2- Norbornene, 5-methyl-5-methoxycarbonyl-2-norbornene, 5-phenyl-2-norborn , 5-phenyl-5-methyl-2-norbornene and the like; monomers obtained by adding one or more cyclopentadiene to norbornene, derivatives and substitutes thereof similar to the above, for example, 1,4: 5,8- Dimethano-1,2,3,4,4a, 5,8,8a-2,3-cyclopentadienonaphthalene, 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5 6,7,8,8a-octahydronaphthalene, 1,4: 5,10: 6,9-trimethano-1,2,3,4,4a, 5,5a, 6,9,9a, 10,10a- Dodecahydro-2,3-cyclopentadienoanthracene and the like; a monomer having a polycyclic structure which is a multimer of cyclopentadiene, and derivatives and substitutes thereof similar to the above, for example, dicyclopentadiene, 2,3-dihydrodiene Cyclopentadiene, etc .; cyclopen Adducts of dienes with tetrahydroindene and the like, derivatives and substitutes similar to those mentioned above, for example, 1,4-methano-1,4,4a, 4b, 5,8,8a, 9a-octahydrofluorene, 5, 8-methano-1,2,3,4,4a, 5,8,8a-octahydro-2,3-cyclopentadienonaphthalene and the like.
[0084]
Examples of these cycloolefin-based polymers include ZEONOR (R), ZEONEX (R) (manufactured by ZEON Corporation), ARTON (R) (manufactured by JSR Corporation), and the like.
[0085]
The number average molecular weight of the thermoplastic saturated cycloolefin polymer used in the present invention is measured by GPC (gel permeation chromatography) method using a toluene solvent, and is 10,000 to 200,000, preferably 20,000 to 150,000, more preferably 25,000 to 120,000. In particular, a thermoplastic saturated cycloolefin-based polymer having no polar group is preferable when water resistance and moisture resistance are required.
[0086]
Further, even when a polyethersulfone-based polymer is used instead of a cycloolefin-based polymer, a light-transmitting substrate having a low total reflection at the interface and a higher light extraction efficiency can be obtained. The polyethersulfone-based polymer is slightly moisture-permeable compared to the cycloolefin-based polymer, but has high heat resistance. By taking the above configuration of the present invention, the translucent substrate has total reflection at the interface. An excellent substrate with little light extraction efficiency is formed.
[0087]
As the polyethersulfone-based polymer, polyethersulfone-based films are marketed by Sumitomo Bakelite Co., Ltd., for example, "Sumilite (R) FS-1300", Sumilite (R) FST-5300, etc. Can be used.
[0088]
Thus, when the layer containing the hygroscopic filler serving as the core layer is a laminated substrate laminated with another resin layer or a substrate such as glass, the surface is roughened by using means such as resin coating and lamination. It is preferable to adjust the thickness as described above or to modify the surface for imparting adhesion.
[0089]
The adjustment of the surface roughness is carried out by adding inactive particles such as silica having an average particle diameter of 0.001 to 0.8 μm to the layer constituting the surface layer at the time of co-extrusion or co-casting. 0.05 to 2.0% by mass is preferable.
[0090]
As the surface modification, for example, treatment with a silane coupling agent or the like can be used. The surface of the moisture permeable film on the lower electrode side can be treated with a silane coupling agent to improve the adhesion (adhesiveness) with the transparent conductive film.
[0091]
As a preferable silane coupling agent to be used, a compound represented by the following general formula is preferable.
[0092]
[Chemical 1]

[0093]
In the formula, R represents an aliphatic or aromatic hydrocarbon group, which may contain an unsaturated group (for example, a vinyl group), R'OR "-, R'COOR"-, R'NHR ". -(R 'is an alkyl group, an aryl group, R "is an alkylene group, an arylene group) and may be substituted with other substituents.
[0094]
X ₁ , X ₂ , X ₃ Represents an aliphatic or aromatic hydrocarbon, acyl group, amide group, alkoxy group, alkylcarbonyl group, epoxy group, mercapto group or halogen atom; ₁ , X ₂ , X ₃ May be the same or different. However, at least one is a group other than a hydrocarbon group. X ₁ , X ₂ , X ₃ Is preferably a group that undergoes hydrolysis.
[0095]
Specific examples of these silane coupling agents include methyltrimethoxysilane, methyltriethoxysilane, vinyltriacetoxysilane, vinyltrichlorosilane, vinyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldichlorosilane, γ-chloropropylmethyldimethoxysilane, γ-chloropropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -Γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxy Silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, γ-isocyanatopropyltriethoxysilane, γ- (2-aminoethyl) Aminopropylmethyldimethoxysilane, γ-anilinopropyltrimethoxysilane, vinyltrimethoxysilane, N-β- (N- (vinylbenzylaminoethyl) -γ-aminopropyltrimethoxysilane, hydrochloride, aminosilane compound, etc. Of these, vinyl type, mercapto type, glycid type, and methacryloxy type are preferable, and mercapto type is particularly preferable.
[0096]
In particular, a silane coupling agent having an amino group, a phenyl group, or a vinyl group such as γ-aminopropyltriethoxysilane or p-styryltrimethoxysilane is preferable.
[0097]
A known method can be used for the treatment of the silane coupling agent. For example, spraying of a silane coupling agent solution, a method of applying the solution, a method of containing a silane coupling agent in the resin layer composition as a surface layer, and the like. Moreover, in order to ensure reaction with a silane coupling agent, it is desirable to perform drying at 60-130 degreeC for about 10 minutes-200 minutes.
[0098]
In addition, the light-transmitting substrate or substrate film according to the present invention may be colored by appropriately adding a dye or the like in order to adjust the color tone of light emission.
[0099]
<< Constituent layers of organic EL elements >>
A basic constituent layer of the organic EL element will be described.
[0100]
In this invention, although the preferable specific example of the layer structure of an organic EL element is shown below, this invention is not limited to these.
(I) Anode / light emitting layer / electron transport layer / cathode
(Ii) Anode / hole transport layer / light emitting layer / electron transport layer / cathode
(Iii) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode
(Iv) Anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode
(V) Anode / anode buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode
"anode"
As an anode in an organic EL element (described as a lower electrode formed on a light-transmitting substrate in the present invention), a metal, an alloy, an electrically conductive compound, and a mixture thereof having a large work function (4 eV or more) are used. What is used as a substance is preferably used. Specific examples of such electrode materials include metals such as Au, CuI, indium tin oxide (ITO), SnO. ₂ And conductive transparent materials such as ZnO. IDIXO (In ₂ O ₃ -ZnO) or other amorphous material capable of producing a transparent conductive film may be used. For the anode, a thin film may be formed by depositing these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when the pattern accuracy is not required (100 μm or more) Degree), a pattern may be formed through a mask having a desired shape when the electrode material is deposited or sputtered. When light emission is extracted from the anode, it is desirable that the transmittance is greater than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 to 1000 nm, preferably 10 to 200 nm.
[0101]
"cathode"
On the other hand, as a cathode (described as an upper electrode in the present invention), a metal having a small work function (4 eV or less) (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof are used as electrode materials. Is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value than this, such as a magnesium / silver mixture, magnesium, from the viewpoint of electron injectability and durability against oxidation, etc. / Aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 1000 nm, preferably 50 nm to 200 nm. In order to transmit light, if either one of the anode or the cathode of the organic EL element is transparent or translucent, the light emission luminance is improved, which is convenient.
[0102]
Next, an injection layer, a hole transport layer, an electron transport layer, etc. used as a constituent layer of the organic EL element of the present invention will be described.
[0103]
<< Injection layer >>: Electron injection layer, hole injection layer
The injection layer is provided as necessary, and there are an electron injection layer and a hole injection layer, and as described above, exists between the anode and the light emitting layer or the hole transport layer, and between the cathode and the light emitting layer or the electron transport layer. You may let them.
[0104]
An injection layer is a layer provided between an electrode and an organic layer in order to reduce driving voltage and improve light emission luminance. “Organic EL element and its forefront of industrialization (November 30, 1998, issued by NTS Corporation) 2), Chapter 2, “Electrode Materials” (pages 123 to 166) in detail, and includes a hole injection layer (anode buffer layer) and an electron injection layer (cathode buffer layer).
[0105]
The details of the anode buffer layer (hole injection layer) are also described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. As a specific example, copper phthalocyanine is used. Examples thereof include a phthalocyanine buffer layer represented by an oxide, an oxide buffer layer represented by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene. In particular, a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene is preferable, and the anode buffer layer is preferably formed to a thickness of 0.1 nm to 150 nm.
[0106]
The details of the cathode buffer layer (electron injection layer) are described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like. Specifically, strontium, aluminum, etc. Metal buffer layer represented by lithium, alkali metal compound buffer layer represented by lithium fluoride, alkaline earth metal compound buffer layer represented by magnesium fluoride, oxide buffer layer represented by aluminum oxide, etc. .
[0107]
The buffer layer (injection layer) is preferably a very thin film, and although it depends on the material, the film thickness is preferably in the range of 0.1 nm to 100 nm.
[0108]
As described above, the blocking layer is provided as necessary in addition to the basic constituent layer of the organic compound thin film. For example, JP-A-11-204258, JP-A-11-204359, and “Organic EL devices and their forefront of industrialization” (issued on November 30, 1998 by NTS, Inc.), page 237, etc. There is a hole blocking layer.
[0109]
The hole blocking layer is an electron transport layer in a broad sense, and is made of a material that has a function of transporting electrons and has a very small ability to transport holes. By blocking holes while transporting electrons, And the recombination probability of holes can be improved.
[0110]
On the other hand, the electron blocking layer is a hole transport layer in a broad sense, made of a material that has a function of transporting holes and has a very small ability to transport electrons, and blocks electrons while transporting holes. Thus, the probability of recombination of electrons and holes can be improved.
[0111]
The hole transport layer is made of a material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer.
[0112]
The hole transport layer and the electron transport layer can be provided as a single layer or a plurality of layers.
In the organic EL device of the present invention, it is preferable that the fluorescence maximum wavelength of all the materials of the host of the light emitting layer, the hole transport layer adjacent to the light emitting layer, and the electron transport layer adjacent to the light emitting layer is 415 nm or less.
[0113]
<Light emitting layer>
The light emitting layer according to the present invention is a layer that emits light by recombination of electrons and holes injected from the electrode, the electron transport layer, or the hole transport layer, and the light emitting portion is in the layer of the light emitting layer. May also be the interface between the light emitting layer and the adjacent layer.
[0114]
The material used for the light emitting layer (hereinafter referred to as the light emitting material) is preferably an organic compound or complex that emits fluorescence or phosphorescence, and is appropriately selected from known materials used for the light emitting layer of the organic EL device. Can be used. Such a light-emitting material is mainly an organic compound, and has a desired color tone, for example, Macromol. Synth. 125, pages 17 to 25, and the like. In the present invention, the phosphorescent compound is preferable.
[0115]
The compound used as the light emitting material in the present invention may have a hole transport function and an electron transport function in addition to the light emitting performance, and most of the hole transport materials and electron transport materials are also used as the light emitting material. it can.
[0116]
As other light-emitting materials, polymer materials such as p-polyphenylene vinylene and polyfluorene may be used. Further, a polymer material in which the light-emitting material is introduced into a polymer chain or the light-emitting material is a polymer main chain. May be used.
[0117]
This light emitting layer can be formed by forming the above compound by a known thinning method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method. Although the film thickness as a light emitting layer does not have a restriction | limiting in particular, Usually, it selects in the range of 5 nm-5 micrometers. This light emitting layer may have a single layer structure composed of one or two or more of these light emitting materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions. A preferred embodiment of the organic EL device of the present invention is when the light emitting layer is composed of two or more materials, and one of them is a phosphorescent dopant.
[0118]
Further, as described in JP-A-57-51781, this light emitting layer is prepared by dissolving the above light emitting material in a solvent together with a binder such as a resin, and then using a spin coating method or the like. It can be formed as a thin film. There is no restriction | limiting in particular about the film thickness of the light emitting layer formed in this way, Although it can select suitably according to a condition, Usually, it is the range of 5 nm-5 micrometers.
[0119]
When there are two or more materials constituting the light emitting layer, the main component is called a host compound and the other components are called dopants. In the present invention, the phosphorescent dopant is preferably used.
[0120]
In that case, the mixing ratio of the dopant to the host compound as the main component is preferably 0.1% by mass to less than 15% by mass.
[0121]
(Host compound)
In the white light emitting organic electroluminescence device of the present invention, the host compound is preferably an organic compound or a complex. In the present invention, the fluorescence maximum wavelength is preferably 415 nm or less. By setting the maximum wavelength of the host compound to 415 nm or less, BGR light emission can be realized particularly in the light emission of visible light and the dopant.
[0122]
That is, by setting the fluorescence maximum wavelength to 415 nm or less, energy transfer type dopant emission having a π-π absorption at 420 nm or less is possible in a normal π-conjugated fluorescence or phosphorescent material. In addition, since it has a fluorescence of 415 nm or less, it has a very wide energy gap (ionization potential-electron affinity, HOMO-LUMO), and therefore works advantageously for a carrier trap type.
[0123]
As such a host compound, you may select and use arbitrary things from the well-known thing used for an organic EL element. Most of the above hole transport materials and electron transport materials can also be used as the light emitting layer host compound.
[0124]
A polymer material such as polyvinyl carbazole or polyfluorene may be used, and a polymer material in which the host compound is introduced into a polymer chain or the host compound as a polymer main chain may be used.
[0125]
As the host compound, a compound that has a hole transporting ability and an electron transporting ability, prevents the emission of light from being increased in wavelength, and has a high Tg (glass transition temperature) is preferable.
[0126]
(Dopant)
Next, the dopant will be described.
[0127]
There are two types of principles. One is the recombination of carriers on the host to which the carriers are transported to generate an excited state of the host compound, and this energy is transferred to the dopant to obtain light emission from the dopant. The other is the carrier trap type in which the dopant becomes a carrier trap and carrier recombination occurs on the dopant compound, and light emission from the dopant is obtained. In either case, the dopant compound is excited. The condition is that the energy of the state is lower than the energy of the excited state of the host compound.
[0128]
In the white light-emitting organic electroluminescence device of the present invention, the dopant is a complex compound such as Ir, and particularly preferred are the compounds represented below.
[0129]
[Chemical 2]

[0130]
[Chemical 3]

[0131]
[Formula 4]

[0132]
As for organic electroluminescence devices that emit substantially white light, there is currently no single light-emitting material that emits white light. Therefore, multiple light-emitting materials emit light at the same time to emit white light by mixing colors. obtain. As a combination of a plurality of light emission colors, a light emission material having three light emission maximum wavelengths of three primary colors of blue, green, and red may be included, or a complementary color relationship such as blue and yellow, blue green and orange may be used. It may be one containing a light emitting material having two light emission maximum wavelengths utilized. Of course, a light emitting material having a light emission maximum wavelength of 4 or more may be combined.
[0133]
For example, in the case where a phosphorescent dopant is used as the light emitting material, white light emission is obtained by color mixing using a plurality of dopants having the above-described relationship with different emission wavelengths. The same applies to fluorescent light-emitting materials.
[0134]
In addition, a combination of light-emitting materials for obtaining a plurality of emission colors is a combination of a plurality of materials that emit phosphorescence or fluorescence, a light-emitting material that emits fluorescence or phosphorescence, and light from the light-emitting material. Any combination with a dye material that emits light as excitation light may be used.
[0135]
The material of the light emitting layer is not particularly limited, and any of the above known light emitting materials may be selected and combined to be whitened. In particular, when an element that emits light using phosphorescence is formed. Examples of the light-emitting host used in the above include materials containing a partial structure such as a carbazole derivative, a biphenyl derivative, a styryl derivative, a benzofuran derivative, a thiophene derivative, and an arylsilane derivative as a unit. Of these, a carbazole derivative and a biphenyl derivative are preferable light emitting materials exhibiting high light emission efficiency.
[0136]
In the case of providing the hole transport layer, the material is not particularly limited, but may have a function of transmitting holes from the anode electrode to the light emitting layer. Any material commonly used as a hole charge injection material or a known material used for a hole transport layer of an EL element can be selected and used.
[0137]
Even when the electron transport layer is provided, there is no particular limitation as long as it has a function of transmitting electrons from the cathode electrode to the light emitting layer, and any one of the known materials can be selected. Can be used.
[0138]
《Hole transport layer》
The hole transport layer is made of a material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer are also included in the hole transport layer. The hole transport layer can be provided as a single layer or a plurality of layers.
[0139]
The hole transport material is not particularly limited, and is conventionally used as a hole charge injection / transport material in an optical transmission material or a well-known material used for a hole injection layer or a hole transport layer of an EL element. Any one can be selected and used.
[0140]
The hole transport material has one of hole injection or transport and electron barrier properties, and may be either organic or inorganic. Other examples include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazones. Derivatives, stilbene derivatives, silazane derivatives, aniline copolymers, conductive polymer oligomers, particularly thiophene oligomers, and the like can be given.
[0141]
As the hole transport material, those described above can be used, and it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound.
[0142]
Representative examples of aromatic tertiary amine compounds and styrylamine compounds include N, N, N ′, N′-tetraphenyl-4,4′-diaminophenyl; N, N′-diphenyl-N, N′— Bis (3-methylphenyl)-[1,1′-biphenyl] -4,4′-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′, N′-tetra-p-tolyl-4,4′-diaminobiphenyl; 1,1-bis (4-di-p-tolyl) Aminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N ' − (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4′-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two more described in US Pat. No. 5,061,569 Having a condensed aromatic ring of, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-308 4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units described in Japanese Patent No. 88 are linked in a starburst type ( MTDATA) and the like.
[0143]
Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.
[0144]
In addition, inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injection material and the hole transport material.
[0145]
In the present invention, the hole transport material of the hole transport layer preferably has a fluorescence maximum wavelength at 415 nm or less. That is, the hole transport material is preferably a compound that has a hole transport ability, prevents the emission of light from becoming longer, and has a high Tg.
[0146]
The hole transport layer can be formed by thinning the hole transport material by a known method such as a vacuum deposition method, a spin coating method, a casting method, an ink jet method, or an LB method. Although there is no restriction | limiting in particular about the film thickness of a positive hole transport layer, Usually, it is about 5-5000 nm. The hole transport layer may have a single layer structure composed of one or more of the above materials.
[0147]
《Electron transport layer》
The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, an electron injection layer and a hole blocking layer are also included in the electron transport layer. The electron transport layer can be provided as a single layer or a plurality of layers.
[0148]
Conventionally, in the case of a single-layer electron transport layer and a plurality of layers, the following materials are used as the electron transport material (also serving as a hole blocking material) used for the electron transport layer adjacent to the cathode side with respect to the light emitting layer. Are known.
[0149]
Further, the electron transport layer only needs to have a function of transmitting electrons injected from the cathode to the light emitting layer, and any material can be selected from conventionally known compounds. .
[0150]
Examples of materials used for the electron transport layer (hereinafter referred to as electron transport materials) include the above-described compounds according to the present invention, as well as complex compounds such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, naphthalene perylene, and the like. Examples thereof include cyclic tetracarboxylic acid anhydrides, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, and oxadiazole derivatives. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material.
[0151]
Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.
[0152]
In addition, metal complexes of 8-quinolinol derivatives such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metals of these metal complexes are In, Mg, Cu Metal complexes replaced with Ca, Sn, Ga, or Pb can also be used as electron transport materials. In addition, metal-free or metal phthalocyanine, or those having terminal ends substituted with an alkyl group or a sulfonic acid group can be preferably used as the electron transport material. In addition, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as an electron transport material, and similarly to the hole injection layer and the hole transport layer, inorganic such as n-type-Si and n-type-SiC. A semiconductor can also be used as an electron transport material.
[0153]
It is preferable that the preferable compound used for an electron carrying layer has a fluorescence maximum wavelength in 415 nm or less. That is, the compound used for the electron transport layer is preferably a compound that has an electron transport ability, prevents emission of longer wavelengths, and has a high Tg.
[0154]
As a board | substrate film concerning the organic EL element of this invention, the said thing is preferable and the resin film which can give a flexibility to an organic EL element is preferable. Examples of the resin used include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), and cellulose. Examples include triacetate (TAC), cellulose acetate propionate (CAP), and the like, and the laminated film using these materials is preferable.
[0155]
In addition to coloring of the light-transmitting substrate, a hue improving filter such as a color filter may be used in combination.
[0156]
Below, the suitable example which produces an organic EL element is demonstrated.
<< Method for producing organic EL element >>
As an example of the method for producing the organic EL device of the present invention, a method for producing an organic EL device comprising an anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.
[0157]
First, on a translucent substrate according to the present invention, a thin film made of a desired electrode material, for example, an anode material (for example, ITO) is deposited or sputtered to a thickness of 1 μm or less, preferably 10 nm to 200 nm. Thus, the anode is formed. Next, an organic compound thin film of a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a hole blocking layer, which are element materials, is formed thereon.
[0158]
As described above, there are spin coating methods, casting methods, ink jet methods, vapor deposition methods, printing methods, and the like as methods for thinning the organic compound thin films, but it is easy to obtain a uniform film and pinholes are not easily generated. In view of the above, the vacuum deposition method or the spin coating method is particularly preferable. Further, different film forming methods may be applied for each layer. When a vapor deposition method is employed for film formation, the vapor deposition conditions vary depending on the type of compound used, but generally a boat heating temperature of 50 to 450 ° C. and a degree of vacuum of 10 ^-6 Pa-10 ^-2 It is desirable to select appropriately within the ranges of Pa, vapor deposition rate of 0.01 nm to 50 nm / second, substrate temperature of −50 ° C. to 300 ° C., and film thickness of 0.1 nm to 5 μm.
[0159]
After the formation of these layers, a thin film made of a cathode material such as aluminum is formed thereon by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 50 nm to 200 nm, By providing the cathode, a desired organic EL element can be obtained. The organic EL element is preferably produced from the hole injection layer to the cathode consistently by a single evacuation, but may be taken out halfway and subjected to different film forming methods. At that time, it is necessary to consider that the work is performed in a dry inert gas atmosphere.
[0160]
In the present invention, another substrate or film is used as a sealing substrate on each layer (on the upper electrode) constituting the organic EL element thus formed on the light-transmitting substrate. The elements are stacked and sealed using a spacer or the like (or not used).
[0161]
The sealing substrate may be formed of glass, resin, ceramic, metal, metal compound, or a composite thereof. In a test according to JIS Z-0208, the thickness is 1 μm or more and water vapor is transmitted. Rate is 1 g / m ² ・ 24 hr (1.013 × 10 ^-1 (MPa, 25 ° C.) or less. In addition, it is also preferable to use a light-transmitting substrate according to the present invention. By using both substrates as a substrate having low moisture permeability and high flexibility, an organic EL element resistant to impact can be formed, and light emission The present invention can also be applied to a surface light source whose surface is a curved surface.
[0162]
Moreover, in order to suppress the electroluminescence absorption or the diffusion of light to the back side also in the sealing substrate material (glass, film, etc.) on the upper electrode side (cathode, eg, Al, Mg electrode side) A pigment layer filled with white titanium oxide is preferably formed on the surface facing the cathode (Al, Mg, etc.) side of the sealing substrate or film.
[0163]
The sealing is performed through a substantially frame-shaped sealing material 6 provided by a coating method, a transfer method, or the like on the peripheral portion of the sealing substrate, for example, the surface facing the counter cathode (upper electrode) side. This is performed by pasting together a light-transmitting substrate on which each layer of the organic EL element is formed. As the sealing material 6, a thermosetting epoxy resin, an ultraviolet curable epoxy resin, a room temperature curable epoxy resin whose reaction starts by microencapsulating and pressurizing a reaction initiator, or the like can be used. In this case, an air escape opening or the like is provided at a predetermined location of the sealing material 6 (not shown) to complete the sealing. The air escape opening has a reduced-pressure atmosphere (vacuum degree 1.33 × 10 6 in the vacuum apparatus). ^-2 Or less) or in an atmosphere of nitrogen gas or inert gas, it is sealed with any of the above curable epoxy resins or ultraviolet curable resins.
[0164]
Examples of epoxy resins include bisphenol A, bisphenol F, bisphenol AD, bisphenol S, xylenol, phenol novolac, cresol novolac, polyfunctional, tetraphenylolmethane, polyethylene glycol, polypropylene A glycol type, hexanediol type, trimethylolpropane type, propylene oxide bisphenol A type, hydrogenated bisphenol A type, or a mixture thereof is mainly used. When the sealing material 6 is formed by a transfer method, a film is preferable.
[0165]
In the present invention, a material that absorbs moisture or reacts with moisture (for example, barium oxide) can be formed in a layer on the substrate and sealed.
[0166]
Although the organic EL element configured as described above is shown in FIG. 1, since the transparent substrate 1 and the opposite substrate 5 are bonded to each other via a frame-shaped sealing material 6, a sealing substrate is provided. 5 and the sealing material 6 can seal the anode 2, the organic EL layer 3, the cathode electrode 4, and the like provided on the light-transmitting substrate 1, and the device can be sealed in a state of low humidity inside. At the same time, the penetration of moisture through the substrate can be suppressed, the moisture resistance of the organic EL display device can be further improved, and the lifetime can be further improved.
[0167]
When positive voltage is applied to the anode 2 and negative voltage is applied to the cathode 4 at a voltage of about 2 to 40 V, holes and electrons injected in the organic EL layer 3 are recombined in the light emitting layer 3 to emit light. It is.
[0168]
In addition to emitting monochromatic light as a display element, the most simple configuration of a white light-emitting element is that the light-emitting material used together with the host compound in the light-emitting layer has a complementary color relationship with each other, such as blue and yellow or blue Combining two types of dopants that have complementary colors such as green and orange, and dopants (phosphorescent compounds) that emit light in three colors, blue, green, and red, while considering their luminous efficiency It can be obtained by mixing and doping as appropriate. Of course, in order to obtain sufficient white light, four or more kinds of light emitting materials may be combined.
[0169]
In a white organic electroluminescence device, basically only by mixing a dopant, a mask is provided only at the time of formation of a light emitting layer, a hole transport layer, an electron transport layer, etc. Well, since other layers are common, patterning such as a mask is unnecessary, and for example, an electrode film can be formed on one side by vapor deposition, casting, spin coating, ink jet, printing, etc., and productivity is also improved. It is. It is also possible to provide a display element in which light emitting elements of a plurality of colors are arranged in parallel in an array.
[0170]
The organic EL elements formed on these light-transmitting substrates are flexible and maintain a sufficient light emission even with a small change rate of light emission even in a state where they are curled to some extent. On a non-flexible substrate, light emission cannot be maintained by causing the substrate itself to crack or break.
[0171]
The curl value is obtained by the reciprocal of the radius of curvature (m). The larger the + number, the stronger the + curl (the element surface is up and warps upward).
[0172]
Curl = 1 radius of curvature (m)
In the present invention, an organic EL device having a light emission change rate of 20% or less even when the curl value is changed from 0 (that is, in a planar state) to 60 can be obtained.
[0173]
The organic EL device of the present invention is used as a white light source, as a kind of lamp for home lighting, interior lighting, and exposure light source, as well as a backlight for liquid crystal display devices, clocks, signboard advertisements, traffic lights, light, etc. Used in a wide range of applications, such as light sources for storage media, light sources for electrophotographic copying machines, light sources for optical communication processors, light sources for optical sensors, and general household appliances that require display devices Although it can be used, it is also useful for display devices, displays, and also display devices.
[0174]
【Example】
Examples of the present invention will be described below, but the present invention is not limited to these examples.
[0175]
Example 1
(Preparation of resin chip with hygroscopic filler)
A commercially available polyethylene terephthalate chip was sufficiently dried at 150 ° C. using a vacuum dryer, and then barium oxide powder (average particle size, 0.5 μm) was placed under a dry nitrogen stream so that the content was 5% by mass. A polyester chip (referred to as polyester A) containing a hygroscopic filler was prepared by kneading at 280 ° C. using a biaxial extrusion kneader.
[0176]
The average particle diameter of barium oxide is obtained as a simple average value (number average) by observing 100 or more arbitrary particles with an electron microscope and determining the particle diameter. Here, each particle size is expressed by a diameter assuming a circle equal to the projected area. In addition, the average particle diameter was calculated | required by the same method also about the silica gel fine particle, titanium oxide, etc. which are mentioned later.
[0177]
(Production of laminated substrate)
Polyester A and commercially available polyethylene 2,6-naphthalate chips were each vacuum dried at 150 ° C. for 8 hours, and then the resin was transferred from the hopper installed on the extruder to the three extruders while keeping the temperature in a dry nitrogen stream. Each is supplied and melt-extruded at 290 ° C., passed through a 40-mesh filter, joined in layers in a T-die with a thickness ratio of 1: 1: 0.5, and cooled at 60 ° C. The sheet was brought into close contact with electrostatic application and rapidly cooled and solidified to obtain a laminated unstretched sheet. At this time, the core layer was made of polyester A, and the surface layer was made of polyethylene 2,6-naphthalate. The unstretched sheet was guided to a roll type longitudinal stretching machine, preheated at 90 ° C., and stretched 3.2 times in the longitudinal direction while being heated with an IR heater between low-speed and high-speed rolls. The obtained uniaxially stretched film was supplied to a tenter-type transverse stretching machine and stretched at 130 ° C. so that the transverse stretching ratio was 3.0 times. The obtained biaxially oriented film was heat-fixed at 210 ° C. for 10 seconds. Subsequently, it was gradually cooled to room temperature over 30 seconds while being subjected to a 5% relaxation treatment in the transverse direction to obtain a biaxially stretched polyester laminated substrate (b1) having a thickness of 50 μm. Further, both end portions were trimmed, and each 100 m was wound around a core having a diameter of 220 mm.
[0178]
The first stage heat treatment (annealing) was performed at 105 ° C. for 20 hours while being wound on the core, and the second stage heat treatment (annealing) was performed at 90 ° C. for 30 hours.
[0179]
(Production of organic EL element)
Organic EL element OLED1-1 was produced as follows.
[0180]
On the thin layer side of the polyethylene naphthalate layer of the above-mentioned b1 substrate of 100 mm × 100 mm × 50 μm, ITO (indium tin oxide) was formed as an anode with a thickness of 100 nm and patterned on the substrate. The transparent support substrate provided with the ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol and dried with dry nitrogen gas, and then the PEDOT-PSS (polyethylenedioxythiophene-polystyrene sulfonic acid dope; Bayer Baytron) layer on the ITO transparent electrode side Was formed by spin coating to a dry thickness of 25 nm. Furthermore, this transparent support substrate was attached to a vacuum deposition apparatus, and the four sides were fixed so that the dimensions and positions of the transparent support substrate were not changed. The vacuum chamber is then 4 × 10 ^-4 The pressure is reduced to Pa, the hole transport layer (α-NPD 25 nm), the light emitting layer (light emitting host compound CBP is used as a deposition rate of 5 Å / s, phosphorescent dopant is used, Ir-6 is used as the deposition rate of 0.05 Å / s, phosphorescence) The dopant Ir-12 was co-deposited at a deposition rate of 0.2 Å / s to form a film with a film thickness of 30 nm.), An electron transport layer (BCP 10 nm), a hole injection layer (Alq ₃ 40 nm) was deposited on the PEDOT-PSS layer according to the thickness and composition described in this order. Further, lithium cathode 0.5 nm was deposited as a cathode buffer layer and aluminum 150 nm was deposited as a cathode to form a cathode.
[0181]
Finally, using a glass substrate having a thickness of 300 μm as a sealing substrate, an epoxy photo-curing adhesive (Lux Track LC0629B manufactured by Toagosei Co., Ltd.) is applied as a sealing material around the glass substrate, and this is overlaid on the cathode. The organic EL element OLED1-1 was made to adhere to the transparent support substrate, irradiated with UV light from the glass substrate side, cured and sealed.
[0182]
Example 2
(Preparation of resin paint in which hygroscopic filler is dispersed)
15 parts by mass of barium oxide (average particle size 3.5 μm), 45 parts by mass of polyethersulfone (Sumilite FS-1300, manufactured by Sumitomo Bakelite) and 100 parts by mass of 1,3-dimethyl-2-imidazolidinone were sufficiently kneaded in a sand mill. The resin paint in which the hygroscopic material was dispersed was prepared by filtering with a filter.
[0183]
(Production of laminated substrate)
Etching treatment with hydrofluoric acid, washing with water, dewatering treatment of 300 μm thick glass substrate, the above-mentioned resin paint was applied on the treated side surface with a curtain coater and dried at 100 ° C. and normal pressure for 2 hours. 130 ° C, 1.0 x 10 ^-3 It was dried for 3 hours under reduced pressure of Pa. The thickness of the resin layer after drying was 20 μm. A 100 μm cover glass having a UV cured adhesive layer formed thereon was bonded and pressure-bonded, and then irradiated with UV light from the cover glass side to produce a multilayer substrate (b3) having an overall thickness of 580 μm.
[0184]
(Production of organic EL element)
Organic EL element OLED3-1 was produced as follows. As an anode, after depositing 100 nm of ITO (indium tin oxide) on one side of the laminated substrate b3 (on a cover glass layer of 100 μm) and patterning the substrate, a transparent support substrate provided with this ITO transparent electrode was formed. After ultrasonic cleaning with isopropyl alcohol and drying with dry nitrogen gas, a PEDOT-PSS (polyethylenedioxythiophene-polystyrene sulfonic acid dope; Bayer Baytron) layer is spin-coated on the ITO transparent electrode side to a dry thickness of 25 nm. It was formed by coating. Furthermore, this transparent support substrate was attached to a vacuum deposition apparatus, and the four sides were fixed so that the dimensions and positions of the transparent support substrate were not changed. The vacuum chamber is then 4 × 10 ^-4 The pressure is reduced to Pa, the hole transport layer (α-NPD 25 nm), the light emitting layer (the light emitting host compound CBP is used as a deposition rate of 5 Å / s, the phosphorescent dopant compound is used, Ir-6 is used as the deposition rate of 0.05 Å / s, phosphorus The optical dopant Ir-12 was co-deposited at a deposition rate of 0.2 Å / s to form a film with a film thickness of 30 nm.), An electron transport layer (BCP 10 nm), a hole injection layer (Alq ₃ 40 nm) was deposited on the PEDOT-PSS layer according to the thickness and composition shown in Table 1 in this order. Further, lithium cathode 0.5 nm was deposited as a cathode buffer layer and aluminum 150 nm was deposited as a cathode to form a cathode.
[0185]
[Chemical formula 5]

[0186]
(Manufacture of cycloolefin polymer film)
A 1-liter autoclave purged with nitrogen was charged with 400 ml of dehydrated and purified toluene and 100 ml of dicyclopentadiene. To this, 0.37 mmol of l-hexene, 0.37 mmol of tungsten hexachloride, and 0.74 mmol of tetraethyltin were added as molecular weight regulators. And polymerized at room temperature for 5 hours. After completion of the reaction, 5 ml of monoethanolamine is added, and 1 g of 2,6-di-t-butylphenol (BHT) is added as a stabilizer, and then the reaction solution is poured into a large amount of methanol to precipitate the polymer, followed by vacuum drying. As a result, a toluene-soluble polymer was obtained. The yield was 62%. The glass transition point of this polymer was 129 ° C., and the intrinsic viscosity measured in toluene at 25 ° C. was 0.95 dl / g. 400 g of this soluble polymer cyclohexane solution (concentration 5 mass%) and 2 g of palladium carbon were placed in a 1 l autoclave, and after hydrogen substitution, the reaction was carried out with stirring at 140 ° C. for 8 hours and a hydrogen pressure of 70 atm. . The catalyst in the reaction product was filtered, precipitated in a large amount of acetone-isopropyl alcohol (1: 1) mixed solvent, filtered and dried. The obtained polymer (A) was analyzed by proton NMR, and the hydrogenation rate was calculated from the value of absorption due to olefin double bond protons. As a result, it was 98%. The polymer (A) had a glass transition point of 134 ° C., a water absorption of 0.02%, and a molecular weight of about 50,000.
The polymer (A) is dried at 120 ° C. under vacuum for 4 hours, and after the content of low molecular volatiles is reduced to 50 ppm or less, it is supplied to a 90 mm diameter extruder and melted at 295 ° C.
[0187]
The amorphous polyolefin melt discharged from the 90 mm extruder was discharged with a single-layer die using a known adapter. While applying an electrostatic charge to the molten sheet, it was brought into close contact with a chromium plating roll maintained at 60 ° C. and cooled and solidified. The sheet was stretched 2.5 times in the longitudinal direction using a jacket roll heated to 155 ° C., and then heat-set in two stages of 130 ° C. and 200 ° C. Thus, an amorphous cycloolefin polymer film (Structural Formula 1) having a thickness of 75 μm was obtained. This was cut into a predetermined width and used as a sealing substrate (film).
[0188]
Moreover, the amorphous cycloolefin type polymer film which adjusted the discharge amount with a nozzle | cap | die and made the film thickness into 50 micrometers was produced.
[0189]
[Chemical 6]

[0190]
The organic EL element was sealed using the cycloolefin polymer film in the same manner as in Example 1 to produce an organic EL element OLED3-1.
[0191]
Example 3
(Preparation of hygroscopic filler kneaded dope)
Barium oxide (average particle size: 1.2 μm) and silica gel fine particles (average particle size: 0.7 μm) were dispersed in an amount of 5% by mass on the surface of the cycloolefin polymer film having a thickness of 50 μm prepared on a stainless steel belt. A polycarbonate layer containing a hygroscopic filler having a thickness of 35 μm was laminated by casting a dope using methylene chloride of a polycarbonate resin as a solvent. Further thereon, a resin solution using methylene chloride in which 10% of γ-aminopropyltrimethoxysilane was added to polycarbonate as a solvent was applied so as to have a dry thickness of 2 μm, and dried to produce a multilayer substrate b6.
[0192]
In the same manner as in Example 1, ITO / PEDOT-PSS / organic layer (hole transport, light emission, electron transport, electron injection) / cathode buffer / cathode was formed by vapor deposition.
[0193]
Using the cycloolefin polymer film having a thickness of 75 μm as a sealing substrate, sealing was performed in the same manner as in Example 1 to fabricate an organic EL element OLED4-1.
[0194]
Example 4
(Production of hygroscopic filler-containing cycloolefin polymer chip)
The polymer (A) is sufficiently dried at 150 ° C. using a vacuum dryer, and then the barium oxide powder (average particle size, 0.5 μm) is contained in a dry nitrogen stream so that the content is 5% by mass. Using a biaxial extrusion kneader, kneading was performed at 280 ° C. to prepare a hygroscopic filler-containing polycycloolefin polymer chip (referred to as polycycloolefin A).
[0195]
(Production of light-reflective filler-containing polyester chip)
A poly 1,4-cyclohexylene dimethylene terephthalate (structural formula 2) chip was sufficiently dried at 130 ° C. using a vacuum dryer, and then titanium oxide (TiO 2). ₂ ) Powder (average particle size, 0.2 μm) was kneaded at 290 ° C. using a twin-screw extrusion kneader in a dry nitrogen stream so that the content rate was 12% by mass, and the light-reflective filler-containing poly 1, A 4-cyclohexylenedimethylene terephthalate chip (referred to as polyester B) was produced.
[0196]
[Chemical 7]

[0197]
(Production of laminated substrate)
The polycycloolefin A and polyethylene terephthalate chips were each vacuum dried at 150 ° C. for 8 hours, and then the resin was supplied to each of the three extruders from the hopper installed on the extruder while keeping the temperature in a dry nitrogen stream. Perform melt extrusion at ℃, pass through a 40-mesh filter, bond in layers so that the thickness ratio is 1: 1: 1 in a T-die, and apply static electricity on a cooling drum at 60 ℃ Then, it was brought into close contact and rapidly cooled and solidified to obtain a laminated unstretched sheet. At this time, the core layer was made of polycycloolefin A and the surface layer was made of polyethylene terephthalate. This unstretched sheet was guided to a roll-type longitudinal stretching machine, preheated at 90 ° C., and stretched 2.8 times in the longitudinal direction while being heated with an IR heater between low-speed and high-speed rolls. The obtained uniaxially stretched film was supplied to a tenter-type transverse stretching machine and stretched at 130 ° C. so that the transverse stretching ratio was 2.8 times. The obtained biaxially oriented film was heat-fixed at 210 ° C. for 10 seconds. Next, the laminate was slowly cooled to room temperature over 30 seconds while being subjected to a 5% relaxation treatment in the transverse direction to obtain a laminate substrate (b4) composed of a biaxially stretched laminated polyester / polycycloolefin support having a thickness of 45 μm. Further, both end portions were trimmed, and each 100 m was wound around a core having a diameter of 220 mm.
[0198]
While being wound around the core, heat treatment (annealing) was performed at 75 ° C. for 70 hours.
(Preparation of cathode side sealing substrate)
The chips of polycycloolefin A, polyester B and polyethylene terephthalate were each vacuum dried at 150 ° C for 8 hours, and then the resin was transferred from the hopper installed on the extruder to the three extruders while keeping the temperature in a dry nitrogen stream. After being fed and melt-extruded at 290 ° C., passed through a 40 mesh filter, it was joined in layers so that the thickness ratio was 1: 1: 1 in a T-die, and statically placed on a 60 ° C. cooling drum. It was made to adhere, applying electricity, rapidly cooling and solidifying, and the lamination unstretched sheet was obtained. At this time, the core layer was made of polycycloolefin A, and the surface layer was made of polyester B and polyethylene terephthalate. This unstretched sheet was guided to a roll-type longitudinal stretching machine, preheated at 90 ° C., and stretched 2.8 times in the longitudinal direction while being heated with an IR heater between low-speed and high-speed rolls. The obtained uniaxially stretched film was supplied to a tenter-type transverse stretching machine and stretched at 130 ° C. so that the transverse stretching ratio was 2.8 times. The obtained biaxially oriented film was heat-fixed at 210 ° C. for 10 seconds. Subsequently, the film was slowly cooled to room temperature over 30 seconds while being subjected to a 5% relaxation treatment in the transverse direction to obtain a biaxially stretched laminated polyester / polycycloolefin support having a thickness of 60 μm (sealing substrate b5). Further, both end portions were trimmed, and each 100 m was wound around a core having a diameter of 220 mm.
[0199]
While being wound around the core, heat treatment (annealing) was performed at 75 ° C. for 70 hours.
(Production of organic EL element)
Organic EL element OLED5-1 was produced as follows.
[0200]
After 100 nm of ITO (indium tin oxide) is deposited on one side of a 100 mm × 100 mm laminated substrate b4 and patterned on the substrate, the transparent support substrate provided with the ITO transparent electrode is ultrasonically cleaned with isopropyl alcohol. After drying with dry nitrogen gas, a PEDOT-PSS (polyethylenedioxythiophene-polystyrene sulfonic acid dope; Baytron Baytron) layer was formed on the ITO transparent electrode side by spin coating so as to have a dry thickness of 25 nm. Furthermore, this transparent support substrate was attached to a vacuum deposition apparatus, and the four sides were fixed so that the dimensions and positions of the transparent support substrate were not changed. The vacuum chamber is then 4 × 10 ^-4 The pressure is reduced to Pa, the hole transport layer (α-NPD 25 nm), the light emitting layer (light emitting host compound CBP is used as a deposition rate of 5 Å / s, phosphorescent dopant is used, Ir-6 is used as the deposition rate of 0.05 Å / s, phosphorescence) The dopant Ir-12 was co-deposited at a deposition rate of 0.2 Å / s to form a film with a film thickness of 30 nm.), An electron transport layer (BCP 10 nm), a hole injection layer (Alq ₃ 40 nm) was deposited on the PEDOT-PSS layer according to the thickness and composition described in this order. Further, lithium cathode 0.5 nm was deposited as a cathode buffer layer and aluminum 150 nm was deposited as a cathode to form a cathode. Finally, the annealed biaxially stretched laminated polyester / polycycloolefin support (sealing substrate b5) is bonded so that the polyester layer containing titanium oxide faces the aluminum cathode, and the same as in Example 1. The organic EL element OLED5-1 was produced by sealing.
[0201]
Comparative Example 1
In Example 1, a laminated substrate (b2) was prepared in exactly the same manner except that a commercially available polyethylene terephthalate was used instead of the polyester A, and a commercially available polyethylene terephthalate was used instead of the polyethylene 2,6-naphthalate. The organic EL element OLED2-1 was produced in exactly the same manner.
[0202]
Further, for the substrate on which the lower electrode is provided, the surface roughness Ra on the lower electrode side and the surface roughness Ra on the light extraction side opposite to the lower electrode are measured according to JIS-B-0601. Was measured using a RSTPLUS non-contact three-dimensional micro surface shape measurement system manufactured by WYKO.
[0203]
The following evaluation was performed about each of obtained organic EL element OLED1-1-OLED5-1.
[0204]
<Emission brightness, luminous efficiency>
With respect to the organic EL elements OLED1-1 to OLED5-1, luminous efficiency (lm / W) was measured when a 10 V DC voltage was applied at a temperature of 23 ° C. in a dry nitrogen gas atmosphere.
[0205]
The emission color of the organic EL elements OLED1-1 to OLED5-1 was white. The organic EL element OLED1-1 began to flow at an initial drive voltage of 4V.
[0206]
The evaluation of the light emission luminance and the light emission efficiency was carried out by relative values (relative light emission efficiency) when the measured value of the organic EL element OLED1-1 was 100. Moreover, the light emission luminance was measured using CS-1000 (manufactured by Minolta).
[0207]
"durability"
Each of the organic EL elements OLED1-1 to OLED5-1 is 2.5 mA / cm. ² The half-life time (also referred to as half-life), which is the time required for the initial luminance to drop to half of the original brightness when driven at a constant current, was expressed as an index. The half-life time was expressed as a relative value when the half-life time of the organic EL element OLED1-1 was 100.
[0208]
<< Luminescence change under stress load >>: Brightness change rate
Each sample element is 500 cd / m ² After the voltage is adjusted, the cathode side of each element is pushed in turn against an insulating rigid body on a cylinder having each diameter such that the curl values are 0, 5, 10, 15, and 5 in increments of 60. The luminance change rate and the light emission state were observed. If it can be deformed to a curl value of 60, it can be said to be sufficiently flexible. If the luminance change is 20% or less, there is no practical problem. The curl value was expressed as the reciprocal of the radius of curvature (1 / m).
[0209]
The configuration of each element is shown in Table 1, and the evaluation results of each element are shown in Table 2.
[0210]
[Table 1]

[0211]
[Table 2]

[0212]
【The invention's effect】
Light extraction efficiency in organic EL elements is dramatically improved, long life is flexible, luminance change at the time of bending deformation, damage to elements and cracks are reduced, and organic EL elements that can achieve resource saving at low cost In addition, a light emitter and a light source using the same can be provided.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a sealing method of an organic EL element.
[Explanation of symbols]
1 Translucent substrate
2 Anode
3 Organic EL layer
4 Cathode
5 Sealing substrate
6 Sealing material

Claims (11)

In an organic electroluminescence device having a lower electrode, a light emitting layer, and an upper electrode on a translucent substrate, the haze value of the translucent substrate is 0.5% or more and 50% or less, and the thickness is 30 μm or more. 700 μm or less, an organic electroluminescence element. The translucent substrate has a laminated structure, and at least a core layer (one layer) contains a filler having a refractive index of 1.30 or more in an amount of 1% by mass to 40% by mass. Item 2. The organic electroluminescence device according to Item 1. 3. The organic electroluminescence device according to claim 1, wherein a hygroscopic substance is dispersed and contained in the light-transmitting substrate with an average particle size of 0.08 μm to 5 μm. The translucent substrate has a laminated structure, the surface roughness Ra on the lower electrode side of the translucent substrate is 50 nm or less, and the surface roughness Ra on the side opposite to the lower electrode is 20 nm or more. And at least one layer is a cycloolefin type polymer among the layers which comprise a board | substrate, The organic electroluminescent element of any one of Claims 1-3 characterized by the above-mentioned. The translucent substrate has a laminated structure, the surface roughness Ra on the lower electrode side of the translucent substrate is 50 nm or less, and the surface roughness Ra on the side opposite to the lower electrode is 20 nm or more. And at least one layer is a polyether sulfone type polymer among the layers which comprise a board | substrate, The organic electroluminescent element of any one of Claims 1-3 characterized by the above-mentioned. The light emitting layer contains at least 1 or more types of phosphorescent dopants, The organic electroluminescent element of any one of Claims 1-5 characterized by the above-mentioned. The organic electroluminescent element according to claim 1, wherein a conductive polymer layer is formed between the lower electrode and the light emitting layer with a thickness of 1 nm or more and 150 nm or less. The luminance change rate when the curl value is changed from 0 to 60 in a state where light is emitted at a luminance of 500 cd / m ² is 20% or less. The organic electroluminescent element of description. The display apparatus which has an organic electroluminescent element as described in any one of Claims 1-8. The illuminating device which has an organic electroluminescent element as described in any one of Claims 1-8. The light source which has an organic electroluminescent element as described in any one of Claims 1-8.

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