JP3545981B2 - Material for organic electroluminescence element and method for producing the same - Google Patents

Description

【００２１】
ナイルレッドの発光波長は、５８０nm（赤色発光）、クマリン６の発光波長は４９０nm（緑色発光）である。
【００２２】
これらの発光中心形成化合物は、単独又は２種以上組み合わせて使用してもよい。
【００２３】
［バインダー］
バインダーとしては、通常、皮膜形成能を有する樹脂（熱可塑性樹脂、熱硬化性樹脂）が使用できる。
【００２４】
熱可塑性樹脂としては、例えば、ポリエチレン、ポリプロピレン、エチレン−プロピレン共重合体、ポリブテンなどのオレフィン系樹脂；ポリスチレン、ゴム変性ポリスチレン（ＨＩＰＳ)、アクリロニトリル−スチレン共重合体、アクリロニトリル−ブタジエン−スチレン共重合体などのスチレン系樹脂；ポリメチル（メタ）アクリレート、ポリエチル（メタ）アクリレート、ポリブチル（メタ）アクリレートなどの（メタ）アクリレート系単量体の単独または共重合体、メチルメタクリレート−スチレン共重合体などの（メタ）アクリレート系単量体と共重合性単量体との共重合体、ポリアクリロニトリルなどのアクリル系樹脂；ポリビニルアルコール、エチレン−ビニルアルコール共重合体などのビニルアルコール系重合体、ポリ塩化ビニル、塩化ビニル−酢酸ビニル共重合体、ポリ塩化ビニリデン、ポリ酢酸ビニル、エチレン−酢酸ビニル共重合体などのビニル系樹脂；６−ナイロン、６，６−ナイロン、６，１０−ナイロン、６，１２−ナイロンなどのポリアミド系樹脂；ポリアルキレンテレフタレート（ポリエチレンテレフタレート、ポリブチレンテレフタレートなど）、ポリアルキレンナフタレートなどのポリエステル系樹脂；フッ素系樹脂；ポリカーボネート；ポリアセタール；ポリフェニレンエーテル；ポリフェニレンスルフィド；ポリエーテルスルホン；ポリエーテルケトン；熱可塑性ポリイミド；熱可塑性ポリウレタン；ノルボルネン系ポリマーなどが挙げられる。
【００２５】
熱硬化性樹脂としては、フェノール樹脂、尿素樹脂、メラミン樹脂、熱硬化性アクリル樹脂、不飽和ポリエステル樹脂、アルキド樹脂、ジアリルフタレート樹脂、エポキシ樹脂、シリコーン樹脂などが挙げられる。
【００２６】
これらのバインダーは、単独または二種以上組合わせて使用してもよい。
【００２７】
ソースを、発光中心形成化合物とバインダーとで構成する場合、発光中心形成化合物の含有量は、特に制限されないが、例えば、バインダー１００重量部に対して、０．１〜３０重量部、好ましくは１〜２５重量部、さらに好ましくは３〜２０重量部程度である。
【００２８】
ソース(A)は、皮膜形成能を有する発光中心形成化合物単独で形成してもよく、非成膜性又は皮膜形成性の発光中心形成化合物と前記バインダーとを組み合わせて形成してもよい。ソースは、それ自身が所定のパターンに形成されていてもよい。例えば、発光中心形成化合物を含むフィルム又はシートを打ち抜きなどの方法によりパターン形成し、ソースを得てもよい。また、基板（基材）上に所定のパターンの被膜を形成し、ソースを得てもよい。基板としては、レーザー光を透過可能な程度に透明であればよく、例えば、ソーダガラス、無アルカリガラス、石英ガラスなどのガラス板、あるいはポリエステル、ポリスチレン、アクリル系樹脂、ビニル系樹脂（ポリビニルアセタールなど）、ポリスルホン、ポリエーテルスルホンなどの高分子シートまたはフィルムなどが挙げられる。ソースの被膜（塗膜）を形成するためのコーティング剤（塗布液）には、必要により、溶媒（例えば、水；メタノール、エタノールなどのアルコール類；酢酸エチル、酢酸イソブチルなどのエステル類；アセトン、メチルエチルケトンなどのケトン類；トルエンなどの芳香族炭化水素類；シクロヘキサンなどの脂環式炭化水素類；クロロホルム、クロロベンゼンなどのハロゲン化炭化水素類；エーテル類；セロソルブ類；カルビトール類など）などを使用してもよい。被膜の膜厚は、特に制限されないが、０．１〜５０μｍ、好ましくは０．５〜３０μｍ、さらに好ましくは１〜２０μｍ程度であってもよい。基板上に所定のパターンを形成する方法としては、例えば、スクリーン印刷などの印刷、インクジェット法、溶融転写又は熱転写法、マスキングと組み合わせて行われる蒸着法（昇華印刷）により基板上に所定のパターンを形成できる。
【００２９】
ソースのパターンとしては、所望の用途に応じて選択され、例えば、ドット状（点状）、線状（例えば、平行線、ランダム、格子状など）、平面状（例えば、円状、楕円状、三角形、四角形などの多角形状、星型など）のいずれであってもよい。
【００３０】
[ターゲット(B)]
ターゲットは、レーザー光が透過可能であり、かつ電子輸送機能およびホール輸送機能から選択された少なくとも１つの機能を有していれば、特に制限されず、(I)電子輸送機能およびホール輸送機能から選択された少なくとも１つの機能を有する樹脂、又は（II)電子輸送機能およびホール輸送機能を備えていない樹脂に、電子輸送機能およびホール輸送機能から選択された少なくとも１つの機能を付与した樹脂組成物であってもよい。(I)及び(II)に使用される樹脂としては、皮膜形成能を有する樹脂（有機高分子）が好ましい。なお、ターゲットの形態は、特に制限されないが、通常、フィルムの形態で使用される。
【００３１】
前記電子輸送機能及びホール輸送機能から選択された少なくとも１つの機能を有する樹脂(I)としては、例えば、ポリフェニレンビニレン、ポリ２，５−ジメトキシフェニレンビニレン、ポリナフタレンビニレンなどのポリフェニレンビニレン類；ポリパラフェニレン、ポリ２，５−ジメトキシパラフェニレンなどのポリフェニレン類（特に、ポリパラフェニレン類）；ポリ（３−アルキルチオフェン）などのポリアルキルチオフェン類、ポリ（３−シクロヘキシルチオフェン）などのポリシクロアルキルチオフェン類、ポリ（３−（４−ｎ−ヘキシルフェニル）チオフェン）などのポリアリールチオフェン類；ポリアルキルフルオレンなどのポリフルオレン類；ポリ−Ｎ−ビニルカルバゾール(ＰＶＫ)、ポリ−４−Ｎ，Ｎ−ジフェニルアミノスチレン、ポリ（Ｎ−（ｐ−ジフェニルアミノ）フェニルメタクリルアミド）、ポリ（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’−ジアミノメタクリルアミド）(ＰＴＰＤＭＡ)、ポリ−４−(５−ナフチル−１，３，４−オキサジアゾール)スチレンなどの主鎖又は側鎖にホール輸送機能基及び電子輸送機能基から選択された少なくとも１種の機能基を有するビニル系重合体；ポリメチルフェニルシラン；芳香族アミン誘導体を側鎖または主鎖に有する重合体；またはこれらの共重合体などが挙げられる。これらの樹脂は、単独で又は二種以上組み合わせて使用してもよい。好ましいターゲットとしては、ホール輸送機能を有するポリ−Ｎ−ビニルカルバゾール又はＮ−ビニルカルバゾールを主成分として含む共重合体、芳香族アミン誘導体などが挙げられる。
【００３２】
ＰＶＫは、非晶質で、耐熱性に優れている（ガラス転移温度Ｔｇ：２２４℃）。上記ＰＶＫの重合度は、特に制限されないが、例えば、２００〜２０００００（例えば、３００〜１０００００）、好ましくは５００〜５００００程度である。
【００３３】
さらに、必要に応じて、上記樹脂（I)に電子輸送機能又はホール輸送機能を付与してもよい。
【００３４】
電子輸送機能を有する化合物としては、例えば、２−(４−ビフェニル)−５−(４−tert−ブチルフェニル)−１，３，４−オキサジアゾール（ＰＢＤ）、２，５−ビス(１−ナフチル)−１，３，４−オキサジアゾール（ＢＮＤ）、１，３−ビス[５−(４−tert−ブチルフェニル)−１，３，４−オキサジアゾール]ベンゼン（ＢＰＯＢ）、１，３，５−トリス[５−(４−tert−ブチルフェニル)−１，３，４−オキサジアオール]ベンゼン（ＴＰＯＢ）、１，３，５−トリス[５−(１−ナフチル)−１，３，４−オキサジアゾール]ベンゼン（ＴＮＯＢ）などのオキサジアゾール誘導体；３，５，３’，５’−テトラキス−tert−ブチルジフェノキノンなどのジフェノキノン類；１，２，３，４，５−ペンタフェニル−１，３−シクロペンタジエン（ＰＰＣＰ）；トリス(８−キノリノラト)アルミニウム(III)錯体、ビス（ベンゾキノリノラト）ベリリウム錯体、トリス(１０−ヒドロキシベンゾ[h]キノリラート)ベリリウム錯体などのキノリン酸錯体が挙げられる。特に、ＰＢＤが好ましい。
【００３５】
ホール輸送機能を有する化合物としては、例えば、Ｎ，Ｎ’−ジフェニル−Ｎ，Ｎ’−ビス(３−メチルフェニル）−１，１’−ビフェニル−４，４’−ジアミン（ＴＰＤ）、Ｎ，Ｎ’−ジフェニル−Ｎ，Ｎ’−ビス(１−ナフチル)−１，１’−ビフェニル−４，４’−ジアミン（ＮＰＤ）、１，１−ビス[(ジ−４−トリルアミノ)フェニル]シクロヘキサン、Ｎ，Ｎ，Ｎ’，Ｎ’−テトラ（３−メチルフェニル）−１，３−ジアミノベンゼン（ＰＤＡ）、４，４’、４”−トリス（３−メチルフェニルフェニルアミノ）トリフェニルアミン（ｍ−ＭＴＤＡＴＡ）、４，４’、４”−トリス（１−ナフチルフェニルアミノ）トリフェニルアミン（１−ＴＮＡＴＡ）、４，４’、４”−トリス（２−ナフチルフェニルアミノ）トリフェニルアミン（２−ＴＮＡＴＡ）、４，４’、４”−トリ（Ｎ−カルバゾリル）トリフェニルアミン（ＴＣＴＡ）、１，３，５−トリス［４−（３−メチルフェニルフェニルアミノ）フェニル］ベンゼン（ｍ−ＭＴＤＡＰＢ）、トリフェニルアミンなどの芳香族第３級アミン類；フタロシアニン類などが挙げられる。
【００３６】
前記化合物は、単独で又は二種以上組み合わせて使用してもよい。なお、これらの化合物は、発光中心形成化合物として使用してもよい。
【００３７】
樹脂(I)（例えば、ＰＶＫ)中に含まれる上記成分の割合は、有機ＥＬ素子用材料としての機能を損なわない範囲で選択でき、例えば、樹脂(I)１００重量部に対して、１０〜３００重量部、好ましくは２０〜２００重量部程度である。
【００３８】
ターゲットが、樹脂(I)と前記化合物とで構成されている場合、後述する有機ＥＬ素子において、単層構造が可能となり、発光効率が向上するばかりか、経済的にも有利である。
【００３９】
樹脂組成物（II)で使用される樹脂としては、特に制限されないが、例えば、前記ソースの項で例示した種々のバインダー（熱可塑性樹脂や熱硬化性樹脂など）が使用できる。これらの樹脂に、電子輸送機能およびホール輸送機能のうち少なくとも１つの機能を付与してもよい。電子輸送機能及び／又はホール輸送機能を付与するために使用される化合物としては、上記と同様の化合物が挙げられる。なお、通常、皮膜形成能を有する樹脂（有機高分子）が使用できる。
【００４０】
電子輸送機能またはホール輸送機能を有する化合物の添加量は、バインダー樹脂１００重量部に対して、１０〜３００重量部（例えば、１０〜２００重量部）、好ましくは２０〜１００重量部（例えば、２０〜８０重量部）程度である。
【００４１】
また、上記樹脂(I)および樹脂組成物(II)を組み合わせて使用してもよく、さらに、電子輸送機能およびホール輸送機能のうち少なくとも１つの機能を付与してもよい。
【００４２】
[有機ＥＬ素子用材料の製造方法（分子注入法）]
本発明の有機ＥＬ素子用材料の製造方法は、レーザー光を吸収可能な発光中心形成化合物を少なくとも含み、かつ所定のパターンに形成されたソース(A)と、ターゲット(B)とを接触させ、レーザー光をソース(A)側又はターゲット(B)側から照射し、ソース(A)中の発光中心形成化合物をターゲット(B)内に注入して、ソース(A)のパターンに対応する領域に発光中心を有する有機エレクトロルミネッセンス素子用材料を製造する。ターゲットとしては、通常、フィルムを用い、有機ＥＬ素子用フィルムを製造する。
【００４３】
本発明に使用されるレーザー光としては、使用する発光中心形成化合物の種類によって異なるが、例えば、波長として１９０〜１１００ｎｍの範囲の発振波長を有するレーザー光が挙げられる。パルスレーザー光を使用した場合、周波数は、０．５〜５０Ｈｚ、好ましくは０．５〜３０Ｈｚ程度である。また、パルス幅は、レーザー光の波長などによって異なるが、１０ｐｓ〜１０μｓ（例えば、１０ｐｓ〜１μｓ）、好ましくは５０ｐｓ〜１００ｎｓ（例えば、１００ｐｓ〜５０ｎｓ）程度である。パルス幅が短いほど、発光中心形成化合物の分解などを抑制でき、損傷を受け難い。
【００４４】
レーザー光源としては、例えば、ＡｒＦエキシマーレーザー（１９３ｎｍ）、ＫｒＦエキシマーレーザー（２４８ｎｍ）、ＸｅＣｌエキシマーレーザー（３０８ｎｍ）、ＸｅＦエキシマーレーザー（３５１ｎｍ）、窒素レーザー（３３７ｎｍ）、色素レーザー（窒素レーザー、エキシマーレーザー、あるいはＹＡＧレーザー励起、３００〜１０００ｎｍ）、固体レーザー（Ｎｄ：ＹＡＧ励起、半導体レーザー励起など）、ルビーレーザー（６９４ｎｍ）、半導体レーザー（６５０〜９８０ｎｍ）、チューナブルダイオードレーザー（６３０〜１５５０ｎｍ）、チタンサファイアレーザー（Ｎｄ：ＹＡＧ励起、３４５〜５００ｎｍ、６９０〜１０００ｎｍ）、Ｎｄ：ＹＡＧレーザー（ＦＨＧ：２６６ｎｍ、ＴＨＧ：３５４ｎｍ、ＳＨＧ：５３２ｎｍ、基本波：１０６４ｎｍ）などが挙げられる。
【００４５】
本発明の製造方法において、ターゲット(B)の表面が損傷を受けない強度でレーザー光を照射するのが重要である。また、ソース(A)を発光中心形成化合物とバインダーとで構成する場合、バインダーのアブレーション閾値以下の強度、又はソース(A)が発光中心形成化合物単独で構成されている場合には、発光中心形成化合物の被膜のアブレーション閾値以下の強度で、レーザー光を照射することにより、ソース中の発光中心形成化合物を効率よく、ターゲットに注入できる。なお、レーザーの強度、波長、照射回数などを調整することにより、注入量をコントロールできる。
【００４６】
ソース(A)のアブレーション閾値は、フィルムを構成する化合物又はバインダー樹脂、発光中心形成化合物の種類によって異なる。また、レーザー光の波長、パルス幅にも依存する。従って、本発明においては、アブレーション閾値を以下のように定義する。
【００４７】
本発明で使用するソースおよびレーザーと同一のものを使用して、ソースにレーザー光を１ショット照射し、そのソースを接触型の表面形状測定装置（例えば、SLOAN社製、DEKTAK3030ST)で観察したとき、レーザー光照射表面に、５０ｎｍ以上の形状変化が起こり得る照射表面での最小のレーザー光強度（ｍJ/ｃｍ²）を、本発明におけるアブレーション閾値と定義する。
【００４８】
以下、図面を用いて本発明の有機ＥＬ素子用材料（特に、有機ＥＬ素子用フィルム）の製造方法を説明する。図１は、本発明の１つの実施態様を示す図である。ソース（１)、ターゲットフィルム(２ａ，２ｂ)、発光中心形成化合物(３)、ターゲットフィルム側の基板(４)、ソース側の基板（５）を示す。ソースのパターンは、発光中心形成化合物（３）を注入したい領域（所望の発光パターン）に対応するように形成できる。
【００４９】
まず、ソース（１)と基板(４)との間に、ソース（１）と接触又は密着したターゲットフィルム（２ａ，２ｂ）を介在させ、ターゲットフィルム（２ａ，２ｂ）側から、ソース(１)のアブレーション閾値以下の強度のレーザー光を照射する。照射回数は、通常、１〜５０回（好ましくは１〜２５回）程度である。レーザー光を吸収したソース中の発光中心形成化合物が、高い並進エネルギーを有し、ソースからターゲットフィルム（２ａ）へ未分解のまま注入され、有機ＥＬ素子用フィルムが得られる。また、レーザー光を、ソース側から照射してもよい。
【００５０】
使用する基板としては、レーザー光を透過可能な程度に透明であればよく、例えば、ソーダガラス、無アルカリガラス、石英ガラスなどのガラス板、あるいはポリエステル、ポリスチレン、アクリル系樹脂、ビニル系樹脂（例えば、ポリビニルアセタールなど）、ポリスルホン、ポリエーテルスルホンなどの高分子シートまたはフィルムなどが挙げられる。フレキシブルな有機ＥＬ素子を作製する場合には、高分子フィルムが好ましい。
【００５１】
本発明の有機ＥＬ素子用材料を製造する方法において、所定のパターンに形成されたソースから発光中心形成化合物を効率よく、ターゲットに注入するために、レーザーの平均ビーム径は大きいのが好ましく、例えば、円換算で、１０μｍ〜１００ｍｍ（例えば、５０μｍ〜９０ｍｍ）、好ましくは１００μｍ〜８０ｍｍ、さらに好ましくは１５０μｍ〜６０ｍｍ程度である。また、レーザービームの断面形状は、特に制限されず、円状、楕円状、多角形状（三角形、四角形など）などであってもよい。レーザービームの断面形状が非円状の場合、平均ビーム径とは、内接円の平均径を表す。また、異なる発光中心形成化合物を有する複数のソースを使用してもよい。例えば、赤、緑又は青の発光中心形成化合物を含有する各ソースを使用すれば、色選択が容易に行える。従って、本発明によれば、多色で多彩な形状のパターンを有する有機ＥＬ素子用材料を得ることができる。
【００５２】
なお、レーザー光のビーム径を所望の大きさに絞り、所定のパターンを走査すること、又はフォトマスクを介在させてレーザー光を照射することにより、所定の領域に発光中心形成化合物をターゲット内に注入してもよいが、前者の方法は、工業的に不利であり、後者の方法では、フォトマスクを介在させることにより、レーザー光の干渉が生じるおそれがあり、干渉を防ぐためには、マスクを緊密にターゲットに密着させる必要がある。
【００５３】
本発明の製造方法によれば、注入された発光中心形成化合物は、ターゲット中に、分散又は拡散した形態ではなく、ステップ型（すなわち、ターゲット内に注入された深さが均一な矩形の形態）で注入できる。その深さは、発光中心形成化合物やターゲットの種類、またはレーザー強度などにより異なるが、例えば、１０ｎｍ〜３００ｎｍ、好ましくは１５ｎｍ〜２００ｎｍ、さらに好ましくは２０ｎｍ〜１００ｎｍ程度である。また、アブレーション閾値以下の照射であるため、有機ＥＬ素子用材料表面の平滑性を低下させることなく、発光中心形成化合物だけを注入できる。
【００５４】
[有機エレクトロルミネッセンス素子]
本発明の有機エレクトロルミネッセンス素子は、上記方法により得られた有機ＥＬ素子用材料（特に、発光中心形成化合物が注入されたターゲットフィルムで構成された発光層）と、一対の電極から構成されている。
【００５５】
陽極としては、真空蒸着法などにより形成された透明電極（例えば、インジウム−すず−酸化物（ＩＴＯ）電極）などが使用され、陰極としては、仕事関数の小さい高導電性金属（例えば、マグネシウム、リチウム、アルミニウム又は銀など）が使用される。陰極としてマグネシウムを使用する場合には、有機ＥＬ素子用フィルムとの接着性を向上させるために、少量（例えば、１〜１０重量％）の銀と共蒸着させてもよい。
【００５６】
発光層が、電子輸送機能およびホール輸送機能を有する場合、本発明の有機ＥＬ素子は、単層構造が可能である。また、電子輸送機能およびホール輸送機能のうち、いずれかの機能を具備していない場合や、各機能を向上させる場合には、その機能を有する層を、従来の蒸着法や溶液塗布法などにより積層させてもよい。これらの層は、低分子化合物であっても、高分子化合物であってもよい。有機ＥＬ素子の構造は、例えば、図２〜５に示される単層または多層構造が可能である。
【００５７】
すなわち、図２に示すように、基板(10)上に陽極(11)が形成され、その上に発光層(12)、陰極(13)が順に積層した有機ＥＬ素子、図３に示すように、基板(20)上に陽極(21)が形成され、その上にホール輸送層(24)、発光層(22)、陰極(23)が順に積層した有機ＥＬ素子であってもよい。さらに、図４に示すように、基板(30)上に陽極(31)が形成され、その上に発光層(32)、電子輸送層(35)、陰極(33)が順に積層した有機ＥＬ素子、図５に示すように、基板(40)上に陽極(41)が形成され、その上にホール輸送層(44)、発光層(42)、電子輸送層(45)、陰極(43)が順に積層した有機ＥＬ素子であってもよい。
【００５８】
有機ＥＬ素子を構成する各層の膜厚は、特に制限されないが、１０ｎｍ〜１μｍ（例えば、１０〜５００ｎｍ）、好ましくは３０〜３００ｎｍ、さらに好ましくは３０〜２００ｎｍ、特に０．１〜１μｍ程度である。フィルムを用いた場合、フィルムの膜厚は、上記と同様の範囲から選択できる。
【００５９】
なお、基板としては、前記例示の基板、例えば、レーザー光を透過可能な程度に透明な基板（例えば、ソーダガラス、無アルカリガラス、石英ガラスなどのガラス板など、あるいはポリエステル、ポリスルホン、ポリエーテルスルホンなどの高分子シートまたはフィルムなど）が挙げられる。フレキシブルな有機ＥＬ素子を作製する場合には、高分子フィルムが好ましい。
【００６０】
本発明の方法によれば、有機ＥＬ素子において、従来、高分子化合物を使用した有機ＥＬ素子で困難であった微細な多色パターニングが可能である。さらに、本発明の有機ＥＬ素子用材料（特に、有機ＥＬ素子用フィルム）は、表面平滑性に優れているため、電極との接着性が良く、さらに、発光中心形成化合物がステップ型に注入されているため、電圧を印加したときに電圧ムラなどが生じない。
【００６１】
【発明の効果】
本発明では、所定のパターンに形成されたソースを用いる分子注入法により、有機ＥＬ素子材料として高分子化合物を使用する場合であっても、微細な多色パターニングが可能である。さらに、ターゲットを損傷させない程度又はソースのアブレーション閾値以下の強度でレーザー光の照射を行うため、有機ＥＬ素子用材料の平滑性を低下させることなく、発光中心形成化合物を均一に注入できる。従って、本発明の有機ＥＬ素子用材料を使用すれば、電極との密着性に優れ、均一に電圧を印加できる。
【００６２】
【実施例】
実施例１
（ソースの調製）
５重量％のクマリン６（日本感光色素（株）製）を含むポリブチルメタクリレート（アルドリッチ社製、分子量３．４×１０⁵）をクロロベンゼンに溶解し、スクリーン印刷法により、石英基板上にパターン（１ｍｍ×１ｍｍの四角形）を印刷し、１０μｍのソース被膜を作製した。
（ターゲットフィルムの調製）
ホール輸送機能を有するポリ−Ｎ−ビニルカルバゾール（ＰＶＫ：関東化学社製）５００ｍｇと、電子輸送機能を有する２−(４−ビフェニル)−５−(４-tert-ブチルフェニル)−１，３，４−オキサジアゾール（ＰＢＤ：アルドリッチ社製）５００ｍｇを、１，２−ジクロロエタン１０ｍＬに溶解した。一方、ガラス基板上にインジウム−すず−酸化物（ＩＴＯ）皮膜を形成させた。上記の１，２−ジクロロエタン溶液を用いてディップコーティング法により、ＩＴＯ皮膜上に膜厚１００ｎｍの電子・ホール輸送機能を有するターゲットフィルムを作製した。
（分子注入）
上記のようにして得られたソースとターゲットフィルムとを接触させた試料を作製し、ターゲットフィルムの基板側から、ＸｅＦエキシマーレーザー（ビーム形状３ｍｍ×５ｍｍの四角形、波長３５１ｎｍ、パルス幅１０ｎｓ、単位面積あたりの照射エネルギー２０ｍＪ／ｃｍ²）を、１Ｈｚで１０回照射した。
（有機ＥＬ素子）
分子注入したターゲットフィルムに、厚み２００ｎｍのＡｌ／Ｌｉ電極（高純度化学（株）製、Ｌｉ含有量０．７８重量％）を真空蒸着法により作製し、有機ＥＬ素子を得た。
【００６３】
上記有機ＥＬ素子のＩＴＯ電極を陽極、Ａｌ／Ｌｉ電極層を陰極として、大気中で両電極間に直流電場を印加して発光させた。電圧約１８Ｖより発光が確認できた。ソースのパターンに対応する領域（１ｍｍ×１ｍｍの四角形）では、クマリン６の緑色発光が確認された。前記領域以外の部分ではＰＶＫの青色発光が確認できた。
【００６４】
実施例２
（ソースの調製）
実施例１と同様にしてソースを得た。
（ターゲットフィルムの調製）
ホール輸送機能を有する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：東京化成（株）製）１５０ｍｇと、電子輸送機能を有する２−(４−ビフェニル)−５−(４-tert-ブチルフェニル)−１，３，４−オキサジアゾール（ＰＢＤ：アルドリッチ社製）３００ｍｇと、さらにキャリア輸送機能を有していないバインダーポリマーとしてポリメチルメタクリレート（アルドリッチ社製、ＰＭＭＡ）４５０ｍｇとを、１，２−ジクロロエタン３０ｍＬ溶解した。一方、ガラス基板上にインジウム−すず−酸化物（ＩＴＯ）皮膜を形成させた。上記の１，２−ジクロロエタン溶液を用いてディップコーティング法により、ＩＴＯ皮膜上に膜厚１００ｎｍの電子・ホール輸送機能を有するターゲットフィルムを作製した。
（分子注入）
上記のようにして得られたソースとターゲットフィルムとを接触させた試料を作製し、ターゲットフィルムの基板側から、ＸｅＦエキシマーレーザー（ビーム形状３ｍｍ×５ｍｍの四角形、波長３５１ｎｍ、パルス幅１０ｎｓ、単位面積あたりの照射エネルギー２０ｍＪ／ｃｍ²）を、１Ｈｚで１０回照射した。
（有機ＥＬ素子）
分子注入したターゲットフィルムに、厚み２００ｎｍのＡｌ／Ｌｉ電極（高純度化学（株）製、Ｌｉ含有量０．７８重量％）を真空蒸着法により作製し、有機ＥＬ素子を得た。
【００６５】
上記有機ＥＬ素子のＩＴＯ電極を陽極、Ａｌ／Ｌｉ電極層を陰極として、大気中で両電極間に直流電場を印加して発光させた。電圧約１８Ｖより発光が確認できた。ソースのパターンに対応する領域（１ｍｍ×１ｍｍの四角形）では、クマリン６の緑色発光が確認できた。前記領域以外の部分ではＴＰＤの青色発光が確認できた。
【図面の簡単な説明】
【図１】図１は、発光中心形成化合物を注入する方法を説明するための概略図である。
【図２】図２は、本発明の有機エレクトロルミネッセンス素子の１例（単層構造）を示す概略断面図である。
【図３】図３は、本発明の有機エレクトロルミネッセンス素子の他の例（多層構造）を示す概略断面図である。
【図４】図４は、本発明の有機エレクトロルミネッセンス素子のさらに他の例（多層構造）を示す概略断面図である。
【図５】図５は、本発明の有機エレクトロルミネッセンス素子の別の例（多層構造）を示す概略断面図である。
【符号の説明】
１…ソース
２ａ，２ｂ…ターゲットフィルム
３…発光中心形成化合物
４，５…基板
１０，２０，３０，４０…基板
１１，２１，３１，４１…陽極
１２，２２，３２，４２…発光層
１３，２３，３３，４３…陰極
２４，４４…ホール輸送層
３５，４５…電子輸送層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a method for producing a material for an organic electroluminescent device by injecting a compound for forming an emission center into a predetermined region by molecular injection using a laser, and a material for an organic electroluminescent device obtained by the method, and The present invention relates to an organic electroluminescence device using the material for an organic electroluminescence device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, electroluminescent elements (hereinafter, sometimes referred to as EL elements) are classified into inorganic EL elements and organic EL elements according to materials used. Some inorganic EL devices using inorganic phosphor molecules have been put to practical use, and are used for backlights of watches and the like. On the other hand, organic EL elements are superior to inorganic EL elements in terms of high luminance, high efficiency, and high-speed response, and are expected to be put to practical use.
[0003]
The electroluminescent element is composed of a compound having an electron transport function, a hole transport function, and a luminescent center forming function. As the structure, a single layer type in which one layer has all the above functions, a multilayer type in which different layers have each function, and the like are reported. The light emitting principle is thought to be based on the fact that electrons or holes injected from a pair of electrodes recombine in the light emitting layer to generate excitons, which excite light emitting material molecules constituting the light emitting layer. I have.
[0004]
As a compound constituting each layer, a low molecular weight compound having high luminous efficiency, a high molecular compound having high physical strength, or the like is used. However, when a low molecular weight compound is used, the film is formed by a vapor deposition method with low productivity, whereas in the case of a high molecular compound, the film is formed by applying a solution, so that the area can be increased.
[0005]
JP-A-8-96959 and JP-A-9-63770 each provide a single-layer light-emitting layer in which a plurality of types of fluorescent dyes are dispersed in a polymer binder having an electron transport function and a hole transport function. An organic EL device has been disclosed. It has been reported that in these organic EL devices, each light emitting compound emits light alone and exhibits white light as a whole. In addition, the emission intensity is less likely to decrease as compared with an organic EL element having a multilayer structure.
[0006]
These organic EL elements form a film by a solution coating method in which a polymer binder and a fluorescent dye are dispersed in a specific solvent and applied to a substrate, so that fine patterning, particularly, multicolor patterning (full colorization) is performed. Is difficult.
[0007]
As the multicolor patterning method, a color filter method, a color conversion method, an ink jet method by TR Hebner et al. (Appl. Phys. Lett. 72, 5 (1998) p. 519), a photo bleaching method by Kido et al. I have.
[0008]
However, the color filter method and the color conversion method have an advantage that the patterning of the light emitting layer is not required, but the conversion efficiency is lowered because the light passes through the filter. In the ink-jet method, the pattern formed by the ink-jet method has a conical shape with a high center, and has poor surface smoothness, so that it is difficult to form electrodes uniformly. The cross-sectional pattern is ideally a quadrangle, but is circular in the ink jet method. Further, the size of the pattern greatly depends on the drying conditions and the concentration of the solution. In the photobleaching method, only a special luminescent center compound that loses fluorescence due to UV oxidation can be used, and the colors that can be expressed are limited.
[0009]
As described above, in the conventional film forming method by solution coating, a polymer compound having high physical strength can be used, but fine patterning is difficult. Also, in the above-mentioned patterning method, not only compounds that can be used are limited, but also a film having surface smoothness suitable for an organic EL device cannot be obtained.
[0010]
As a molecular injection method, JP-A-6-297457 discloses that a solid material (A) containing a functional material or a functional material is opposed to a solid material (B) into which a functional component is injected. A method of injecting a functional component into a solid material (B) by irradiating the solid material (B) with a pulsed laser. JP-A-8-106006 discloses a source film in which a dye capable of absorbing pulsed laser light is dispersed in an organic polymer compound, and a target film made of an organic polymer compound that can transmit a pulsed laser. A method is disclosed in which a dye is injected into a target film by irradiating the target film side with a pulsed laser beam at an intensity equal to or lower than the ablation threshold of the source film in close contact. This document describes that the molecular injection method can be used for producing a display color filter and the like.
[0011]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a material for an organic EL device (particularly, a film for an organic EL device) capable of fine patterning even when a polymer compound is used as the material for the EL device, and a method for producing the same. It is in.
[0012]
Another object of the present invention is to provide a material for an organic EL device having excellent surface smoothness and good contact with an electrode, and an organic EL device using the same.
[0013]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to achieve the above object, and as a result, according to the molecular injection method using a source formed in a predetermined pattern, an organic EL capable of fine patterning even in a polymer compound. The inventors have found that a device material can be obtained, and have completed the present invention.
[0014]
That is, the method for producing a material for an organic EL device of the present invention includes at least a luminescence center forming compound capable of absorbing laser light, and a source (A) formed in a predetermined pattern, and laser light can be transmitted, And contact with a target (B) having at least one function selected from an electron transport function and a hole transport function, and irradiate a laser beam from the source (A) side or the target (B) side, the source (A) The luminescent center forming compound therein is injected into the target (B) to produce a material for an organic electroluminescent element having a luminescent center in a region corresponding to the pattern of the source (A). The source may be a coating formed on the substrate in a predetermined pattern (for example, a coating made of a compound forming a luminescent center). Further, the source may be composed of a luminescent center forming compound and a binder. The target may be an organic polymer having at least one function selected from an electron transport function and a hole transport function (for example, poly-N-vinyl carbazole or the like), and may be selected from the electron transport function and the hole transport function. And a compound having at least one function and an organic polymer having a film-forming ability.
[0015]
The organic EL element material may be in the form of a film. The laser light is a pulsed laser light, and its pulse width may be 10 ps to 10 μs. Further, the laser beam diameter may be 10 μm to 100 mm.
[0016]
The present invention also includes an organic EL device material obtained by the above manufacturing method, and an organic EL device using the organic EL device material.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
[Source (A)]
The source only needs to contain at least a compound that forms a luminescence center capable of absorbing laser light, and may be composed of a compound that forms a luminescence center alone or a compound that forms a luminescence center and a binder.
[0018]
[Emission center forming compound]
The luminescent center forming compound may be any compound having a function as a luminescent center compound for an organic EL device and capable of absorbing laser light. For example, 2,5-bis (5-tert-butyl-2- Coumarins such as benzoxazoyl) -thiophene, Nile red, coumarin 6, coumarin 7, and oxygen atoms such as 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran and quinacridone , A heterocyclic compound containing at least one hetero atom selected from a nitrogen atom and a sulfur atom; condensed polycyclic hydrocarbons such as rubrene and perylene; 1,1,4,4-tetraphenyl-1,3-butadiene (TPB), 1,4-bis (2- (4-ethylphenyl) ethynyl) benzene, 4.4′-bis (2,2′-diphenylvinyl) biphenyl and the like. I can do it. Particularly, Nile Red and Coumarin 6 are preferable among them.
[0019]
The structures of Nile Red and Coumarin 6 are shown below.
[0020]
Embedded image

[0021]
The emission wavelength of Nile Red is 580 nm (red emission), and the emission wavelength of Coumarin 6 is 490 nm (green emission).
[0022]
These luminescent center forming compounds may be used alone or in combination of two or more.
[0023]
[binder]
As the binder, a resin having a film-forming ability (a thermoplastic resin or a thermosetting resin) can be generally used.
[0024]
Examples of the thermoplastic resin include olefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, and polybutene; polystyrene, rubber-modified polystyrene (HIPS), acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer. Styrene-based resins such as polymethyl (meth) acrylate, polyethyl (meth) acrylate, polybutyl (meth) acrylate and the like, homo- or copolymers of (meth) acrylate-based monomers, such as methyl methacrylate-styrene copolymer ( Copolymers of meth) acrylate monomers and copolymerizable monomers; acrylic resins such as polyacrylonitrile; vinyl alcohol polymers such as polyvinyl alcohol and ethylene-vinyl alcohol copolymer; Vinyl resins such as vinyl chloride, vinyl acetate-vinyl acetate copolymer, polyvinylidene chloride, polyvinyl acetate, and ethylene-vinyl acetate copolymer; 6-nylon, 6,6-nylon, 6,10-nylon, 6, Polyamide resins such as 12-nylon; polyester resins such as polyalkylene terephthalate (polyethylene terephthalate, polybutylene terephthalate, etc.) and polyalkylene naphthalate; fluororesins; polycarbonate; polyacetal; polyphenylene ether; polyphenylene sulfide; Polyether ketone; thermoplastic polyimide; thermoplastic polyurethane; norbornene-based polymer and the like.
[0025]
Examples of the thermosetting resin include a phenol resin, a urea resin, a melamine resin, a thermosetting acrylic resin, an unsaturated polyester resin, an alkyd resin, a diallyl phthalate resin, an epoxy resin, and a silicone resin.
[0026]
These binders may be used alone or in combination of two or more.
[0027]
When the source is composed of the luminescent center-forming compound and the binder, the content of the luminescent center-forming compound is not particularly limited, but for example, 0.1 to 30 parts by weight, preferably 1 to 100 parts by weight of the binder. To 25 parts by weight, more preferably about 3 to 20 parts by weight.
[0028]
The source (A) may be formed of a luminescent center-forming compound having film-forming ability alone, or may be formed by combining a non-film-forming or film-forming luminescent center-forming compound with the binder. The source itself may be formed in a predetermined pattern. For example, a source may be obtained by patterning a film or sheet containing a luminescent center forming compound by a method such as punching. Alternatively, a source may be obtained by forming a coating of a predetermined pattern on a substrate (base material). The substrate may be transparent enough to transmit laser light. For example, a glass plate such as soda glass, non-alkali glass, and quartz glass, or polyester, polystyrene, an acrylic resin, and a vinyl resin (such as polyvinyl acetal) ), Polysulfone, polyethersulfone, and other polymer sheets or films. The coating agent (coating solution) for forming the source film (coating film) may optionally include a solvent (eg, water; alcohols such as methanol and ethanol; esters such as ethyl acetate and isobutyl acetate); Ketones such as methyl ethyl ketone; aromatic hydrocarbons such as toluene; alicyclic hydrocarbons such as cyclohexane; halogenated hydrocarbons such as chloroform and chlorobenzene; ethers; cellosolves; May be. The thickness of the coating is not particularly limited, but may be about 0.1 to 50 μm, preferably about 0.5 to 30 μm, and more preferably about 1 to 20 μm. As a method of forming a predetermined pattern on the substrate, for example, printing such as screen printing, inkjet method, melt transfer or thermal transfer method, by vapor deposition method (sublimation printing) performed in combination with masking, the predetermined pattern on the substrate Can be formed.
[0029]
The source pattern is selected according to a desired application, and is, for example, a dot shape (dot shape), a linear shape (for example, a parallel line, a random shape, a lattice shape, or the like), a flat shape (for example, a circular shape, an elliptical shape, Polygon, such as a triangle or a quadrangle, or a star).
[0030]
[Target (B)]
The target is not particularly limited as long as it can transmit laser light and has at least one function selected from an electron transport function and a hole transport function. A resin composition in which a resin having at least one selected function or (II) a resin not having an electron transport function and a hole transport function is provided with at least one function selected from an electron transport function and a hole transport function. It may be. As the resin used in (I) and (II), a resin (organic polymer) having a film forming ability is preferable. The form of the target is not particularly limited, but is usually used in the form of a film.
[0031]
Examples of the resin (I) having at least one function selected from the electron transport function and the hole transport function include polyphenylenevinylenes such as polyphenylenevinylene, poly2,5-dimethoxyphenylenevinylene, and polynaphthalenevinylene; Polyphenylenes (especially polyparaphenylenes) such as phenylene and poly 2,5-dimethoxyparaphenylene; polyalkylthiophenes such as poly (3-alkylthiophene), and polycycloalkylthiophenes such as poly (3-cyclohexylthiophene) , Polyarylthiophenes such as poly (3- (4-n-hexylphenyl) thiophene); polyfluorenes such as polyalkylfluorene; poly-N-vinylcarbazole (PVK), poly-4-N, N- Diphenylamino Tylene, poly (N- (p-diphenylamino) phenyl methacrylamide), poly (N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4 ′ -Diaminomethacrylamide) (PTPDMA), poly-4- (5-naphthyl-1,3,4-oxadiazole) styrene, etc., selected from a hole transporting functional group and an electron transporting functional group in the main chain or side chain. A vinyl polymer having at least one functional group; polymethylphenylsilane; a polymer having an aromatic amine derivative in a side chain or a main chain; or a copolymer thereof. These resins may be used alone or in combination of two or more. Preferable examples of the target include poly-N-vinylcarbazole or a copolymer containing N-vinylcarbazole as a main component and an aromatic amine derivative having a hole transporting function.
[0032]
PVK is amorphous and has excellent heat resistance (glass transition temperature Tg: 224 ° C.). Although the polymerization degree of the PVK is not particularly limited, it is, for example, about 200 to 200,000 (for example, 300 to 100,000), and preferably about 500 to 50,000.
[0033]
Further, if necessary, the resin (I) may have an electron transporting function or a hole transporting function.
[0034]
Examples of the compound having an electron transport function include 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (PBD) and 2,5-bis (1 -Naphthyl) -1,3,4-oxadiazole (BND), 1,3-bis [5- (4-tert-butylphenyl) -1,3,4-oxadiazole] benzene (BPOB), , 3,5-Tris [5- (4-tert-butylphenyl) -1,3,4-oxadiaol] benzene (TPOB), 1,3,5-tris [5- (1-naphthyl) -1 1,3,4-oxadiazole] benzene (TNOB); diphenoquinones such as 3,5,3 ', 5'-tetrakis-tert-butyldiphenoquinone; 1,2,3,4 , 5-pentaphenyl-1,3-cyclopentadiene (PPCP); Squirrel (8-quinolinolato) aluminum (III) complex, bis (benzoquinolinolato) beryllium complex, tris (10-hydroxybenzo [h] Kinorirato) include quinolinic acid complexes such as beryllium complex. In particular, PBD is preferred.
[0035]
Examples of the compound having a hole transport function include N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-biphenyl-4,4′-diamine (TPD), N, N'-diphenyl-N, N'-bis (1-naphthyl) -1,1'-biphenyl-4,4'-diamine (NPD), 1,1-bis [(di-4-tolylamino) phenyl] cyclohexane , N, N, N ', N'-tetra (3-methylphenyl) -1,3-diaminobenzene (PDA), 4,4', 4 "-tris (3-methylphenylphenylamino) triphenylamine ( m-MTDATA), 4,4 ', 4 "-tris (1-naphthylphenylamino) triphenylamine (1-TNATA), 4,4', 4" -tris (2-naphthylphenylamino) triphenylamine ( 2-TNATA), , 4 ', 4 "-tri (N-carbazolyl) triphenylamine (TCTA), 1,3,5-tris [4- (3-methylphenylphenylamino) phenyl] benzene (m-MTDAPB), triphenylamine Aromatic tertiary amines; phthalocyanines;
[0036]
The compounds may be used alone or in combination of two or more. In addition, these compounds may be used as a luminescent center forming compound.
[0037]
The proportion of the above components contained in the resin (I) (for example, PVK) can be selected within a range that does not impair the function as a material for an organic EL element. It is 300 parts by weight, preferably about 20 to 200 parts by weight.
[0038]
When the target is composed of the resin (I) and the compound, a single-layer structure is possible in the organic EL device described later, which not only improves the luminous efficiency but is economically advantageous.
[0039]
The resin used in the resin composition (II) is not particularly limited, and for example, various binders (thermoplastic resins, thermosetting resins, and the like) exemplified in the section of the source can be used. These resins may have at least one of an electron transport function and a hole transport function. Examples of the compound used for imparting the electron transport function and / or the hole transport function include the same compounds as described above. Usually, a resin (organic polymer) having a film forming ability can be used.
[0040]
The amount of the compound having an electron transport function or a hole transport function is 10 to 300 parts by weight (for example, 10 to 200 parts by weight), preferably 20 to 100 parts by weight (for example, 20 parts by weight) based on 100 parts by weight of the binder resin. ８０80 parts by weight).
[0041]
Further, the resin (I) and the resin composition (II) may be used in combination, and may have at least one of an electron transport function and a hole transport function.
[0042]
[Production method of organic EL device material (molecular injection method)]
The method for producing a material for an organic EL device of the present invention includes at least a luminescent center forming compound capable of absorbing laser light, and a source (A) formed in a predetermined pattern and a target (B) are brought into contact with each other, Laser light is irradiated from the source (A) side or the target (B) side, the luminescent center forming compound in the source (A) is injected into the target (B), and the region corresponding to the pattern of the source (A) is A material for an organic electroluminescence element having a light emission center is manufactured. As a target, a film is usually used to produce a film for an organic EL device.
[0043]
The laser light used in the present invention varies depending on the kind of the luminescent center forming compound used, and examples thereof include a laser light having an oscillation wavelength in the range of 190 to 1100 nm. When pulsed laser light is used, the frequency is 0.5 to 50 Hz, preferably about 0.5 to 30 Hz. The pulse width varies depending on the wavelength of the laser light and the like, but is about 10 ps to 10 μs (for example, 10 ps to 1 μs), and preferably about 50 ps to 100 ns (for example, 100 ps to 50 ns). The shorter the pulse width is, the more the decomposition of the luminescent center forming compound can be suppressed, and the less the damage is.
[0044]
Examples of the laser light source include ArF excimer laser (193 nm), KrF excimer laser (248 nm), XeCl excimer laser (308 nm), XeF excimer laser (351 nm), nitrogen laser (337 nm), dye laser (nitrogen laser, excimer laser, Alternatively, YAG laser excitation, 300 to 1000 nm, solid-state laser (Nd: YAG excitation, semiconductor laser excitation, etc.), ruby laser (694 nm), semiconductor laser (650 to 980 nm), tunable diode laser (630 to 1550 nm), titanium sapphire Laser (Nd: YAG excitation, 345 to 500 nm, 690 to 1000 nm), Nd: YAG laser (FHG: 266 nm, THG: 354 nm, SHG: 532) m, the fundamental wave: 1064nm) and the like.
[0045]
In the production method of the present invention, it is important that the surface of the target (B) is irradiated with laser light at such an intensity that the surface is not damaged. When the source (A) is composed of the luminescent center-forming compound and the binder, the intensity is not more than the ablation threshold of the binder, or when the source (A) is composed of the luminescent center-forming compound alone, the luminescent center is formed. By irradiating a laser beam with an intensity equal to or lower than the ablation threshold of the compound film, the luminescent center forming compound in the source can be efficiently injected into the target. The injection amount can be controlled by adjusting the laser intensity, wavelength, irradiation frequency, and the like.
[0046]
The ablation threshold value of the source (A) differs depending on the type of the compound or binder resin constituting the film and the luminescent center forming compound. It also depends on the wavelength and pulse width of the laser light. Therefore, in the present invention, the ablation threshold is defined as follows.
[0047]
When the same source and laser as used in the present invention are used and the source is irradiated with a laser beam for one shot, and the source is observed with a contact-type surface shape measuring device (for example, DEKTAK3030ST manufactured by SLOAN). , The minimum laser light intensity (mJ / cm) at the irradiation surface where a shape change of 50 nm or more may occur on the laser irradiation surface. ^Two ) Is defined as the ablation threshold in the present invention.
[0048]
Hereinafter, a method for producing a material for an organic EL device (particularly, a film for an organic EL device) of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing one embodiment of the present invention. A source (1), a target film (2a, 2b), a luminescent center forming compound (3), a substrate (4) on the target film side, and a substrate (5) on the source side are shown. The source pattern can be formed so as to correspond to a region (a desired light emission pattern) into which the light emission center forming compound (3) is to be injected.
[0049]
First, a target film (2a, 2b) in contact with or in close contact with the source (1) is interposed between the source (1) and the substrate (4), and the source (1) is placed from the target film (2a, 2b) side. Is irradiated with a laser beam having an intensity equal to or lower than the ablation threshold. The number of irradiations is usually about 1 to 50 times (preferably 1 to 25 times). The luminescent center forming compound in the source that has absorbed the laser light has a high translational energy and is injected from the source into the target film (2a) without decomposition, thereby obtaining a film for an organic EL device. Further, laser light may be emitted from the source side.
[0050]
The substrate to be used only needs to be transparent enough to transmit laser light. For example, soda glass, non-alkali glass, a glass plate such as quartz glass, or polyester, polystyrene, acrylic resin, vinyl resin (for example, , Polyvinyl acetal, etc.), polymer sheets or films of polysulfone, polyethersulfone and the like. When fabricating a flexible organic EL element, a polymer film is preferable.
[0051]
In the method for producing a material for an organic EL device of the present invention, the average beam diameter of a laser is preferably large in order to efficiently and efficiently inject a luminescent center forming compound from a source formed in a predetermined pattern into a target. In terms of circle, it is about 10 μm to 100 mm (for example, 50 μm to 90 mm), preferably about 100 μm to 80 mm, and more preferably about 150 μm to 60 mm. The cross-sectional shape of the laser beam is not particularly limited, and may be a circular shape, an elliptical shape, a polygonal shape (a triangle, a quadrangle, or the like). When the cross-sectional shape of the laser beam is non-circular, the average beam diameter represents the average diameter of an inscribed circle. Further, a plurality of sources having different luminescent center forming compounds may be used. For example, if each source containing a red, green or blue emission center forming compound is used, color selection can be easily performed. Therefore, according to the present invention, it is possible to obtain a material for an organic EL device having a pattern of various colors and various shapes.
[0052]
In addition, the beam diameter of the laser beam is reduced to a desired size, and a predetermined pattern is scanned, or the laser beam is irradiated with a photomask interposed therebetween, so that the luminescent center forming compound is in a predetermined region in the target. Although the injection may be performed, the former method is industrially disadvantageous, and in the latter method, laser light interference may occur due to the interposition of a photomask. It is necessary to closely adhere to the target.
[0053]
According to the manufacturing method of the present invention, the injected luminescent center forming compound is not dispersed or diffused in the target, but is a step type (that is, a rectangular shape having a uniform depth injected into the target). Can be injected. The depth varies depending on the type of the luminescent center forming compound and the target, or the laser intensity, but is, for example, about 10 nm to 300 nm, preferably about 15 nm to 200 nm, and more preferably about 20 nm to 100 nm. In addition, since the irradiation is performed at the ablation threshold or less, only the luminescent center forming compound can be injected without lowering the smoothness of the surface of the organic EL element material.
[0054]
[Organic electroluminescence device]
The organic electroluminescence device of the present invention is composed of the material for an organic EL device obtained by the above method (particularly, a light emitting layer formed of a target film into which a compound for forming a light emission center is injected) and a pair of electrodes. .
[0055]
As the anode, a transparent electrode (eg, indium-tin-oxide (ITO) electrode) formed by a vacuum evaporation method or the like is used, and as the cathode, a highly conductive metal (for example, magnesium, Lithium, aluminum or silver). When magnesium is used as the cathode, it may be co-evaporated with a small amount (for example, 1 to 10% by weight) of silver in order to improve the adhesion to the film for an organic EL device.
[0056]
When the light emitting layer has an electron transport function and a hole transport function, the organic EL device of the present invention can have a single layer structure. In addition, when any of the electron transport function and the hole transport function is not provided, or when each function is improved, a layer having the function is formed by a conventional vapor deposition method or a solution coating method. They may be stacked. These layers may be low molecular compounds or high molecular compounds. The structure of the organic EL element can be, for example, a single layer or a multilayer structure shown in FIGS.
[0057]
That is, as shown in FIG. 2, an anode (11) is formed on a substrate (10), and a light emitting layer (12) and a cathode (13) are sequentially stacked thereon, as shown in FIG. Alternatively, an organic EL device in which an anode (21) is formed on a substrate (20), and a hole transport layer (24), a light emitting layer (22), and a cathode (23) are sequentially stacked thereon may be used. Further, as shown in FIG. 4, an organic EL device in which an anode (31) is formed on a substrate (30), and a light emitting layer (32), an electron transport layer (35), and a cathode (33) are sequentially stacked thereon. As shown in FIG. 5, an anode (41) is formed on a substrate (40), on which a hole transport layer (44), a light emitting layer (42), an electron transport layer (45), and a cathode (43) are formed. Organic EL elements stacked in order may be used.
[0058]
The thickness of each layer constituting the organic EL element is not particularly limited, but is 10 nm to 1 μm (for example, 10 to 500 nm), preferably 30 to 300 nm, more preferably 30 to 200 nm, and particularly about 0.1 to 1 μm. . When a film is used, the thickness of the film can be selected from the same range as described above.
[0059]
As the substrate, the above-described substrate, for example, a substrate transparent to the extent that laser light can be transmitted (for example, a glass plate of soda glass, non-alkali glass, quartz glass, or the like, or polyester, polysulfone, polyether sulfone, or the like) Polymer sheet or film). When fabricating a flexible organic EL element, a polymer film is preferable.
[0060]
According to the method of the present invention, fine multicolor patterning, which has conventionally been difficult with an organic EL device using a polymer compound, is possible in an organic EL device. Furthermore, since the material for an organic EL device (especially, a film for an organic EL device) of the present invention has excellent surface smoothness, it has good adhesion to an electrode, and further, a luminescent center forming compound is injected in a step type. Therefore, when voltage is applied, voltage unevenness does not occur.
[0061]
【The invention's effect】
According to the present invention, fine multicolor patterning is possible by a molecular injection method using a source formed in a predetermined pattern, even when a polymer compound is used as an organic EL device material. Furthermore, since the laser beam is irradiated at an intensity that does not damage the target or is equal to or lower than the ablation threshold of the source, the compound for forming the luminescent center can be uniformly injected without reducing the smoothness of the material for the organic EL device. Therefore, when the material for an organic EL device of the present invention is used, the adhesion to the electrode is excellent, and the voltage can be applied uniformly.
[0062]
【Example】
Example 1
(Preparation of sauce)
Polybutyl methacrylate (manufactured by Aldrich, molecular weight 3.4 × 10 5) containing 5% by weight of coumarin 6 (manufactured by Nippon Kogaku Dye Co., Ltd.) ^Five Was dissolved in chlorobenzene, and a pattern (1 mm × 1 mm square) was printed on a quartz substrate by screen printing to form a 10 μm source film.
(Preparation of target film)
500 mg of poly-N-vinylcarbazole having a hole transport function (PVK: manufactured by Kanto Chemical Co., Ltd.) and 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3 having an electron transport function 500 mg of 4-oxadiazole (PBD: manufactured by Aldrich) was dissolved in 10 mL of 1,2-dichloroethane. On the other hand, an indium-tin-oxide (ITO) film was formed on a glass substrate. A target film having a 100 nm-thick electron / hole transport function was formed on the ITO film by dip coating using the above 1,2-dichloroethane solution.
(Molecular injection)
A sample in which the source and the target film obtained as described above were brought into contact with each other was prepared, and a XeF excimer laser (a square having a beam shape of 3 mm × 5 mm, a wavelength of 351 nm, a pulse width of 10 ns, a unit area) was formed from the substrate side of the target film. Irradiation energy per unit 20mJ / cm ^Two ) Was irradiated 10 times at 1 Hz.
(Organic EL device)
An Al / Li electrode (manufactured by Kojundo Chemical Co., Ltd., Li content 0.78% by weight) having a thickness of 200 nm was formed on the target film into which the molecules had been injected by a vacuum evaporation method to obtain an organic EL device.
[0063]
Using the ITO electrode of the organic EL element as an anode and the Al / Li electrode layer as a cathode, a DC electric field was applied between the two electrodes in the air to emit light. Light emission was confirmed from a voltage of about 18 V. In an area (1 mm × 1 mm square) corresponding to the source pattern, green light emission of coumarin 6 was confirmed. Blue light emission of PVK was confirmed in portions other than the above region.
[0064]
Example 2
(Preparation of sauce)
A sauce was obtained in the same manner as in Example 1.
(Preparation of target film)
150 mg of N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine (TPD: manufactured by Tokyo Chemical Industry Co., Ltd.) having a hole transport function And 300 mg of 2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (PBD: manufactured by Aldrich) having an electron transport function, and further having a carrier transport function. 450 mL of polymethyl methacrylate (manufactured by Aldrich Co., Ltd., PMMA) as an unbound binder polymer was dissolved in 30 mL of 1,2-dichloroethane. On the other hand, an indium-tin-oxide (ITO) film was formed on a glass substrate. A target film having a 100 nm-thick electron / hole transport function was formed on the ITO film by dip coating using the above 1,2-dichloroethane solution.
(Molecular injection)
A sample in which the source and the target film obtained as described above were brought into contact with each other was prepared, and a XeF excimer laser (a square having a beam shape of 3 mm × 5 mm, a wavelength of 351 nm, a pulse width of 10 ns, a unit area) was formed from the substrate side of the target film. Irradiation energy per unit 20mJ / cm ^Two ) Was irradiated 10 times at 1 Hz.
(Organic EL device)
An Al / Li electrode (manufactured by Kojundo Chemical Co., Ltd., Li content 0.78% by weight) having a thickness of 200 nm was formed on the target film into which the molecules had been injected by a vacuum evaporation method to obtain an organic EL device.
[0065]
Using the ITO electrode of the organic EL element as an anode and the Al / Li electrode layer as a cathode, a DC electric field was applied between the two electrodes in the air to emit light. Light emission was confirmed from a voltage of about 18 V. In a region (1 mm × 1 mm square) corresponding to the source pattern, green light emission of coumarin 6 was confirmed. Blue light emission of the TPD was confirmed in portions other than the above-mentioned region.
[Brief description of the drawings]
FIG. 1 is a schematic diagram for explaining a method of injecting a luminescent center forming compound.
FIG. 2 is a schematic cross-sectional view showing one example (single-layer structure) of an organic electroluminescence device of the present invention.
FIG. 3 is a schematic cross-sectional view illustrating another example (multilayer structure) of the organic electroluminescence element of the present invention.
FIG. 4 is a schematic cross-sectional view showing still another example (multilayer structure) of the organic electroluminescence device of the present invention.
FIG. 5 is a schematic cross-sectional view showing another example (multilayer structure) of the organic electroluminescence element of the present invention.
[Explanation of symbols]
1 ... Source
2a, 2b: Target film
3 ... Emission center forming compound
4,5 ... substrate
10, 20, 30, 40 ... substrate
11, 21, 31, 41 ... anode
12, 22, 32, 42 ... light emitting layer
13, 23, 33, 43 ... cathode
24,44… Hole transport layer
35, 45 ... electron transport layer

Claims (16)

A source (A) containing at least a luminescence center forming compound capable of absorbing laser light, and formed in a predetermined pattern, and at least one selected from an electron transport function and a hole transport function, which is capable of transmitting laser light and The target (B) having two functions is brought into contact with each other, laser light is irradiated from the source (A) side or the target (B) side, and the luminescent center forming compound in the source (A) is injected into the target (B). And producing a material for an organic electroluminescence element having a light emission center in a region corresponding to the pattern of the source (A). The method according to claim 1, wherein the source (A) is a coating formed on the substrate in a predetermined pattern. 2. The method according to claim 1, wherein the source (A) comprises a luminescent center forming compound and a binder. 4. The method according to claim 3, wherein the laser beam is irradiated at an intensity equal to or lower than the ablation threshold of the binder of the source (A). The method according to claim 1, wherein the material for an organic electroluminescence element is a film. The method according to claim 1, wherein the laser light is a pulsed laser light. 7. The method according to claim 6, wherein the pulse width of the pulse laser beam is 10 ps to 10 [mu] s. The method according to claim 1, wherein the laser beam diameter is 10 μm to 100 mm. The method according to claim 1, wherein the target is an organic polymer having at least one function selected from an electron transport function and a hole transport function. The method according to claim 9, wherein the organic polymer is poly-N-vinylcarbazole or a copolymer containing N-vinylcarbazole as a main component. 2. The method according to claim 1, wherein the target comprises a compound having at least one function selected from an electron transport function and a hole transport function, and an organic polymer having a film forming ability. The method according to claim 11, wherein the compound is at least one compound selected from an oxadiazole derivative having an electron transport function and an aromatic tertiary amine having a hole transport function. A material for an organic electroluminescence device obtained by the method according to claim 1. 14. The material for an organic electroluminescence device according to claim 13, wherein the target is an organic polymer having at least one function selected from an electron transport function and a hole transport function. An organic electroluminescence device comprising a pair of electrodes and the material for an organic electroluminescence device according to claim 13 interposed between the pair of electrodes. The organic electroluminescence device according to claim 15, wherein a single layer made of the material for an organic electroluminescence device according to claim 14 is interposed between the pair of electrodes.

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