JP4527935B2 - Organic electroluminescent image display device - Google Patents

Description

【００２６】
次いで、低酸素（酸素濃度１ｐｐｍ以下）、低湿度（水蒸気濃度１ｐｐｍ以下）状態のグローブボックス中にて、正孔注入輸送層上に下記構造式（２）で示されるポリ（ジオクチルジビニレンフルオレン−ｃｏ−アントラセン）（ＰＦ）であるＡＤＳ（株）製ＡＤＳ１０６ＧＥ）をスピンコート法により塗布、乾燥して発光層（厚み８０ｎｍ）を形成した。
【００２７】
【化２】

【００２８】
更に、上記の発光層上にＣａを５ｎｍの厚みで蒸着して電子注入層を形成した。蒸着条件は、真空度５×１０^-5Ｐａ、成膜速度１Å／秒とした。この電子注入層の形成では、マスクを使用して、陽極と直交するように幅２ｍｍのライン状の電子注入層を２本形成した。
次に、対向ターゲット式マグネトロンスパッタリング装置を用いてＴｉＮ薄膜（厚み５０ｎｍ）を成膜してバリア性導電層とした。このバリア性導電層の形成では、マスクを使用して、幅２ｍｍのライン状のバリア性導電層を電子注入層上に形成した。ＴｉＮ薄膜の成膜は、スパッタガスとしてＡｒ、Ｎ₂を使用し、圧力２×１０^-2Ｐａ、ＲＦ出力１００Ｗ、ＤＣ出力１５０Ｗとした。
【００２９】
次いで、マグネトロンスパッタリング法によりＩＴＯ薄膜（厚み１５０ｎｍ）を成膜して陰極とした。この陰極の形成では、マスクを使用して、幅２ｍｍのライン状の陰極をバリア性導電層上に形成した。上記のＩＴＯ薄膜の成膜は、スパッタガスとしてＡｒとＯ₂の混合ガス（体積比Ａｒ：Ｏ₂＝１００：１）を使用し、圧力５．５×１０^-2Ｐａ、ＲＦ出力１００Ｗ、ＤＣ出力１５０Ｗ、成膜速度４Å／秒とした。
尚、透明ガラス基板上に、上記と同条件で別途ＴｉＮ薄膜とＩＴＯ薄膜を形成し、ＴｉＮ薄膜を含むＩＴＯ薄膜の表面抵抗値を三菱化学（株）製Ｌｏｒｅｓｔａ−ＧＰを用いて四探針法により測定した結果、１９Ω／□であった。
また、透明ガラス基板上に、上記と同条件で別途ＴｉＮ薄膜を形成し、これについて、下記の条件で水蒸気透過率、酸素透過率、固有抵抗および可視領域３８０〜７８０ｎｍにおける光透過率を測定した。その結果、水蒸気透過率は０．２ｇ／ｍ²／ｄａｙ、酸素透過率は０．２ｃｃ／ｍ^２／ｄａｙ・ａｔｍ、固有抵抗は３．０×１０^-4Ω・ｃｍ、可視領域平均透過率は約７０％であった。
【００３０】
（水蒸気透過率の測定）
水蒸気透過率測定装置（ＭＯＣＯＮ社製 ＰＥＲＭＡＴＲＡＮ−Ｗ ３／３１）を用い、３７．８℃、１００％ＲＨの条件で測定する。
（酸素透過率の測定）
酸素ガス透過率測定装置（ＭＯＣＯＮ社製 ＯＸ−ＴＲＡＮ ２／２０）を用い、２３℃、９０％ＲＨの条件で測定する。
（固有抵抗の測定）
測定した表面抵抗値（Ω／□）に膜厚（ｃｍ）を乗じて固有抵抗値（Ω・ｃｍ）を算出する。膜厚はセイコーインスツルメンツ（株）製 Ｎａｎｏｐｉｃｓ１０００を用い、膜断面を計測する。
（光透過率の測定）
紫外可視分光光度計（（株）島津製作所製 ＵＶ−２２００Ａ）を用い、室温、大気中で測定する。
【００３１】
次に、マグネトロンスパッタリング法によりＳｉＯ₂膜（厚み５μｍ）を封止膜として形成した。成膜は、ターゲットとしてＳｉＯ_x（ｘ＝１〜２）を使用し、スパッタガスとしてＡｒとＯ₂の混合ガス（体積比Ａｒ：Ｏ₂＝２００：１）を使用し、圧力０．５Ｐａ、ＲＦ出力１５０Ｗ、ＤＣ出力２００Ｗとした。
以上により、幅２ｍｍのライン状にパターニングされた陽極と、この陽極に直交するように幅２ｍｍのライン状で形成された電子注入層、バリア性導電層、陰極を備え、４ヶ所の発光エリア（面積４ｍｍ²）を有する有機ＥＬ表示装置を作製した。
この有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は２８０ｍＡ／ｃｍ²で、上面（陰極）側から測定した発光エリアの輝度は２２０００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、ダークスポットは存在しなかった。この結果より、上記発光エリアでは、ＴｉＮ薄膜からなるバリア性導電層が存在することにより、陰極形成時の酸素導入による発光層や電子注入層の酸化が防止されていることが確認された。
【００３２】
［実施例２］
バリア性導電層として、ＴｉＮ薄膜の代わりにＺｒＮ薄膜（厚み５０ｎｍ）を同条件で成膜した他は、実施例１と同様にして、有機ＥＬ表示装置を作製した。
尚、実施例１と同様にして、ＺｒＮ薄膜を含むＩＴＯ薄膜の表面抵抗値を測定した結果、２０Ω／□であった。また、実施例１と同様にして、ＺｒＮ薄膜の水蒸気透過率、酸素透過率、固有抵抗および可視領域３８０〜７８０ｎｍにおける光透過率を測定した結果、水蒸気透過率は０．３ｇ／ｍ²／ｄａｙ、酸素透過率は０．２ｃｃ／ｍ^２／ｄａｙ・ａｔｍ、固有抵抗は３．４×１０^-4Ω・ｃｍ、可視領域平均透過率は約７０％であった。
【００３３】
上記の有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は２６０ｍＡ／ｃｍ²であり、上面（陰極）側から測定した発光エリアの輝度は２００００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、ダークスポットは存在しなかった。この結果より、上記発光エリアでは、ＺｒＮ薄膜からなるバリア性導電層が存在することにより、陰極形成時の酸素導入による発光層や電子注入層の酸化が防止されていることが確認された。
【００３４】
［実施例３］
バリア性導電層として、ＴｉＮ薄膜の代わりにＡｕ薄膜（厚み３０ｎｍ）を真空蒸着法（真空度５×１０^-5Ｐａ、成膜速度０．５Å／秒）で形成した他は、実施例１と同様にして、有機ＥＬ表示装置を作製した。
尚、実施例１と同様にして、Ａｕ薄膜を含むＩＴＯ薄膜の表面抵抗値を測定した結果、１５Ω／□であった。また、実施例１と同様にして、Ａｕ薄膜の水蒸気透過率、酸素透過率、固有抵抗および可視領域３８０〜７８０ｎｍにおける光透過率を測定した結果、水蒸気透過率は０．１ｇ／ｍ²／ｄａｙ、酸素透過率は０．１ｃｃ／ｍ^２／ｄａｙ・ａｔｍ、固有抵抗は１．６×１０^-4Ω・ｃｍ、可視領域平均透過率は約４０％であった。
【００３５】
上記の有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は３３０ｍＡ／ｃｍ²であり、上面（陰極）側から測定した発光エリアの輝度は１５０００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、ダークスポットは存在しなかった。この結果より、上記発光エリアでは、Ａｕ薄膜からなるバリア性導電層が存在することにより、陰極形成時の酸素導入による発光層や電子注入層の酸化が防止されていることが確認された。
【００３６】
［実施例４］
バリア性導電層として、Ａｕ薄膜の代わりにＡｌ薄膜（厚み３０ｎｍ）を形成した他は、実施例３と同様にして、有機ＥＬ表示装置を作製した。
尚、実施例１と同様にして、Ａｌ薄膜を含むＩＴＯ薄膜の表面抵抗値を測定した結果、１４Ω／□であった。また、実施例１と同様にして、Ａｌ薄膜の水蒸気透過率、酸素透過率、固有抵抗および可視領域３８０〜７８０ｎｍにおける光透過率を測定した結果、水蒸気透過率は０．１ｇ／ｍ²／ｄａｙ、酸素透過率は０．１ｃｃ／ｍ^２／ｄａｙ・ａｔｍ、固有抵抗は１．５×１０^-4Ω・ｃｍ、可視領域平均透過率は約４０％であった。
【００３７】
上記の有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は３２０ｍＡ／ｃｍ²で、上面（陰極）側から測定した発光エリアの輝度は１５０００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、ダークスポットは存在しなかった。この結果より、上記発光エリアでは、Ａｌ薄膜からなるバリア性導電層が存在することにより、陰極形成時の酸素導入による発光層や電子注入層の酸化が防止されていることが確認された。
【００３８】
［実施例５］
バリア性導電層として、ＴｉＮ薄膜の代わりに無機酸化物であるＩＴＯ薄膜（厚み５０ｎｍ）を成膜した他は、実施例１と同様にして、有機ＥＬ表示装置を作製した。ＩＴＯ薄膜の成膜は、スパッタガスとしてＡｒを使用し、圧力３×１０^-2Ｐａ、ＲＦ出力５００Ｗ、ＤＣ出力１００Ｗ、成膜速度１Å／秒とした。
尚、実施例１と同様にして、バリア性導電層としてのＩＴＯ薄膜を含む陰極ＩＴＯ薄膜の表面抵抗値を測定した結果、２０Ω／□であった。また、実施例１と同様にして、ＩＴＯ薄膜の水蒸気透過率、酸素透過率、固有抵抗および可視領域３８０〜７８０ｎｍにおける光透過率を測定した結果、水蒸気透過率は０．２ｇ／ｍ²／ｄａｙ、酸素透過率は０．２ｃｃ／ｍ^２／ｄａｙ・ａｔｍ、固有抵抗は２．５×１０^-4Ω・ｃｍ、可視領域平均透過率は約７０％であった。
【００３９】
上記の有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は２８０ｍＡ／ｃｍ²であり、上面（陰極）側から測定した発光エリアの輝度は２７０００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、ダークスポットは存在しなかった。この結果より、上記発光エリアでは、ＩＴＯ薄膜からなるバリア性導電層が存在することにより、陰極形成時の酸素導入による発光層や電子注入層の酸化が防止されていることが確認された。
【００４０】
［実施例６］
バリア性導電層として、ＩＴＯ薄膜の代わりに、同じく無機酸化物である酸化インジウム亜鉛（ＩＺＯ）薄膜を形成した他は、実施例５と同様にして、有機ＥＬ表示装置を作製した。
尚、実施例１と同様にして、ＩＺＯ薄膜を含むＩＴＯ薄膜の表面抵抗値を測定した結果、２０Ω／□であった。また、実施例１と同様にして、ＩＺＯ薄膜の水蒸気透過率、酸素透過率、固有抵抗および可視領域３８０〜７８０ｎｍにおける光透過率を測定した結果、水蒸気透過率は０．２ｇ／ｍ²／ｄａｙ、酸素透過率は０．２ｃｃ／ｍ^２／ｄａｙ・ａｔｍ、固有抵抗は２．４×１０^-4Ω・ｃｍ、可視領域平均透過率は約７０％であった。
【００４１】
上記の有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は２８０ｍＡ／ｃｍ²であり、上面（陰極）側から測定した発光エリアの輝度は２６０００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、ダークスポットは存在しなかった。この結果より、上記発光エリアでは、ＩＺＯ薄膜からなるバリア性導電層が存在することにより、陰極形成時の酸素導入による発光層や電子注入層の酸化が防止されていることが確認された。
【００４２】
［比較例１］
バリア性導電層を形成しない他は、実施例１と同様にして、有機ＥＬ表示装置を作製した。
この有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は１１０ｍＡ／ｃｍ²で、上面（陰極）側から測定した発光エリアの輝度は８０００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、直径約０．１ｍｍのダークスポットが１ｍｍ²の範囲に数個の割合で確認された。この結果より、上記発光エリアでは、陰極形成時の酸素導入により発光層や電子注入層が酸化されていることが確認された。
【００４３】
［比較例２］
ＴｉＮ薄膜からなるバリア性導電層の代わりに、酸素導入を行うスパッタリング法により、ＩＴＯ薄膜（厚み５０ｎｍ）を成膜した他は、実施例１と同様にして、有機ＥＬ表示装置を作製した。このＩＴＯ薄膜の成膜条件は、スパッタガスとしてＡｒとＯ₂の混合ガス（体積比Ａｒ：Ｏ₂＝１００：１）を使用し、圧力５．５×１０^-2Ｐａ、ＲＦ出力１００Ｗ、ＤＣ出力１５０Ｗ、成膜速度４Å／秒とした。
尚、実施例１と同様にして、ＩＴＯ薄膜の表面抵抗値を測定した結果、１９Ω／□であった。また、実施例１と同様にして、ＩＴＯ薄膜の水蒸気透過率、酸素透過率、固有抵抗および可視領域３８０〜７８０ｎｍにおける光透過率を測定した結果、水蒸気透過率は０．２ｇ／ｍ²／ｄａｙ、酸素透過率は０．３ｃｃ／ｍ^２／ｄａｙ・ａｔｍ、固有抵抗は２．１×１０^-4Ω・ｃｍ、可視領域平均透過率は約８０％であった。
【００４４】
上記の有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は１１０ｍＡ／ｃｍ²で、上面（陰極）側から測定した発光エリアの輝度は８０００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、直径約０．１ｍｍのダークスポットが１ｍｍ²の範囲に数個の割合で確認された。この結果より、上記発光エリアでは、酸素導入を行うＩＴＯ薄膜や陰極形成時に、発光層や電子注入層が酸化されていることが確認された。
【００４５】
［実施例７］
まず、実施例１と同様にして、透明ガラス基板上に幅２ｍｍのライン状の陽極を２本形成した。
次に、陽極を備えた透明ガラス基板を酸素プラズマ下に曝し、その後、真空加熱蒸着法により、陽極を覆うように透明ガラス基板上に下記構造式（３）で示されるビス（Ｎ−ナフチル）−Ｎ−フェニルベンジジン（α−ＮＰＤ）からなる正孔輸送層（厚み５０ｎｍ）を形成した。この正孔輸送層の成膜条件は、真空度５×１０^-5Ｐａ、成膜速度３Å／秒、加熱温度３５０℃とした。
【００４６】
【化３】

【００４７】
次いで、真空蒸着法により、正孔輸送層上に下記構造式（４）で示されるトリス（８−キノリノラト）アルミニウム錯体（Ａｌｑ３）を成膜して発光層（厚み６０ｎｍ）を形成した。この発光層の成膜条件は、真空度５×１０^-5Ｐａ、成膜速度３Å／秒とした。
【００４８】
【化４】

【００４９】
更に、真空蒸着法により、上記の発光層上に下記構造式（５）で示されるバソキュプロイン（ＢＣＰ）とＬｉの共蒸着層を成膜して電子注入層（厚み２０ｎｍ）を形成した。この蒸着条件は、真空度５×１０^-5Ｐａ、各材料による成膜速度３Å／秒とした。
【００５０】
【化５】

【００５１】
次いで、実施例１と同様にして、バリア性導電層と陰極を形成し、更に、封止膜を形成した。
以上により、幅２ｍｍのライン状にパターニングされた陽極と、この陽極に直交するように幅２ｍｍのライン状で形成されたバリア性導電層、陰極を備え、４ヶ所の発光エリア（面積４ｍｍ²）を有する有機ＥＬ表示装置を作製した。
この有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は３．６ｍＡ／ｃｍ²であり、上面（陰極）側から測定した発光エリアの輝度は２００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、ダークスポットは存在しなかった。この結果より、上記発光エリアでは、ＴｉＮ薄膜からなるバリア性導電層が存在することにより、陰極形成時の酸素導入による発光層や電子注入層の酸化が防止されていることが確認された。
【００５２】
［実施例８］
バリア性導電層として、ＴｉＮ薄膜の代わりにＺｒＮ薄膜（厚み５０ｎｍ）を同条件で成膜した他は、実施例７と同様にして、有機ＥＬ表示装置を作製した。
この有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は３．６ｍＡ／ｃｍ²で、上面（陰極）側から測定した発光エリアの輝度は２１０ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、ダークスポットは存在しなかった。この結果より、上記発光エリアでは、ＺｒＮ薄膜からなるバリア性導電層が存在することにより、陰極形成時の酸素導入による発光層や電子注入層の酸化が防止されていることが確認された。
【００５３】
［比較例３］
バリア性導電層を形成しない他は、実施例７と同様にして、有機ＥＬ表示装置を作製した。
この有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は３．０ｍＡ／ｃｍ²で、上面（陰極）側から測定した発光エリアの輝度は１５０ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、直径約０．１ｍｍのダークスポットが１ｍｍ²の範囲に数個の割合で確認された。この結果より、上記発光エリアでは、陰極形成時の酸素導入により発光層や電子注入層が酸化されていることが確認された。
【００５４】
［実施例９］
まず、実施例１と同様にして、透明ガラス基板上に幅２ｍｍのライン状の陽極を２本形成した。
次に、実施例７と同様にして、正孔輸送層（厚み５０ｎｍ）、発光層（厚み６０ｎｍ）、電子注入層（厚み２０ｎｍ）を形成した。
次いで、実施例１と同様にして、バリア性導電層と陰極を形成し、更に、封止膜を形成した。但し、バリア性導電層として、ＴｉＮ薄膜の代わりにＡｌ薄膜（厚み３０ｎｍ）を真空蒸着法（真空度５×１０^-5Ｐａ、成膜速度０．５Å／秒）で形成した。
【００５５】
以上により、幅２ｍｍのライン状にパターニングされた陽極と、この陽極に直交するように幅２ｍｍのライン状で形成されたバリア性導電層、陰極を備え、４ヶ所の発光エリア（面積４ｍｍ²）を有する有機ＥＬ表示装置を作製した。
この有機ＥＬ表示装置の陽極と陰極に電圧６Ｖを印加した時の電流密度は４．０ｍＡ／ｃｍ²であり、上面（陰極）側から測定した発光エリアの輝度は１００ｃｄ／ｍ²であった。また、上記の有機ＥＬ表示装置を２０ｍＡで２４０時間連続駆動させた後の発光エリア面を光学顕微鏡で観察（３０倍）したところ、ダークスポットは存在しなかった。この結果より、上記発光エリアでは、ＴｉＮ薄膜からなるバリア性導電層が存在することにより、陰極形成時の酸素導入による発光層や電子注入層の酸化が防止されていることが確認された。
【００５６】
【発明の効果】
以上詳述したように、本発明によれば有機層と陰極との間にバリア性導電層を介在させた構造とし、かつ、このバリア性導電層を成膜工程において酸素導入を行わない真空成膜法により形成された金属、無機窒化物、無機酸化物の少なくとも１種からなる薄膜としたので、有機層は、バリア性導電層の成膜時は勿論のこと、光透過性を有する陰極の成膜時においても、酸素導入による酸化が防止され、これにより、有機層は特性劣化のない信頼性の高いものとなり、上面側の陰極から高効率で光を取り出して高品質の画像表示が可能な有機エレクトロルミネッセント画像表示装置が得られる。
【図面の簡単な説明】
【図１】本発明の有機エレクトロルミネッセント（ＥＬ）画像表示装置の一実施形態を示す基本構成概念図である。
【符号の説明】
１…有機エレクトロルミネッセント画像表示装置
２…基材
３…陽極
４…有機層
５…バリア性導電層
６…陰極[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescent image display device, and more particularly to an organic electroluminescent image display device capable of extracting light from a cathode on the upper surface side.
[0002]
[Prior art]
[Patent Document 1]
Japanese Patent Laid-Open No. 10-162959
[Patent Document 2]
Japanese Patent Laid-Open No. 10-144957
[Patent Document 3]
JP-A-10-125469
[Patent Document 4]
JP 2002-15859 A
[Patent Document 5]
Japanese Patent Laid-Open No. 2002-15860
Organic electroluminescence (EL) elements have high visibility due to self-coloring, are all solid-state displays unlike liquid crystal displays, have excellent impact resistance, have fast response speeds, and are not significantly affected by temperature changes. In addition, it has advantages such as a large viewing angle, and in recent years, its use as a light emitting element in an image display device has been attracting attention.
[0003]
The structure of an image display device using an organic EL element is based on a laminated structure of an anode / light emitting layer / cathode, and a structure in which a transparent anode is formed on a base material using a glass substrate or the like is usually employed. In this case, light emission is taken out from the substrate side (anode side).
In recent years, attempts have been made to make the cathode transparent and take out light emission from the cathode side (top emission). By realizing the top emission, first, when the anode is made transparent together with the cathode, a transparent light emitting element as a whole becomes possible. An arbitrary color can be adopted as the background color of such a transparent light emitting element, and it becomes possible to make a colorful display other than during light emission, and the decorativeness is improved. On the other hand, by adopting black as the background color, the contrast during light emission is improved. In addition, when a color filter or a color conversion layer is used due to the realization of top emission, the above layers can be arranged on the light emitting layer. Further, since light emission is not blocked by the TFT (Thin Film Transistor) of the active drive display device, a display device with a high aperture ratio is possible.
[0004]
As an example of the organic EL image display device that can emit light from the upper surface by making the cathode transparent, an organic layer including an organic EL light emitting layer is interposed between the anode and the cathode, and the cathode is an electron injection metal layer. And an amorphous transparent conductive layer, and a configuration in which this electron injection metal layer is in contact with an organic layer is disclosed (Patent Document 1). Also disclosed is a configuration in which a Ca diffusion barrier layer is provided between the cathode and the organic layer in order to prevent the cathode material from diffusing into the organic layer, thereby preventing a short circuit of the organic EL element and deterioration of characteristics. (Patent Document 2). Further, as an example of double-sided light emission, a configuration is disclosed in which a conductive layer such as Ag, Mg, or TiN is interposed between the transparent cathode and the light emitting layer in order to reduce the resistance of the transparent cathode (Patent Document). 3). Furthermore, for the purpose of preventing the penetration and diffusion of oxygen and indium into the organic layer, a configuration using TiN for the anode is disclosed (Patent Documents 4 and 5).
[0005]
[Problems to be solved by the invention]
However, in the conventional organic EL image display device capable of emitting light from the top surface, oxidation of the organic layer and the electron injection layer is unavoidable due to the introduction of oxygen in the process of forming the transparent cathode. However, there is a problem that a dark spot occurs and a high-quality image display cannot be obtained.
The present invention has been made in view of such circumstances, and provides an organic electroluminescent image display device capable of extracting light from a cathode on the upper surface side with high efficiency and capable of displaying a high-quality image. Objective.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, an organic electroluminescent image display device of the present invention includes a base material, an anode, an organic layer, and a light-transmitting barrier conductive layer sequentially provided on the base material. And has light transparency Made of conductive oxide And the barrier conductive layer is formed by a vacuum film formation method in which oxygen is not introduced in the film formation process. Zirconium nitride A water vapor permeability of 1 g / m ² / Day or less, oxygen permeability is 1 cc / m ² / Day · atm or less, specific resistance is 1.0 × 10 ^-2 Ω · cm or less, light transmittance in visible region 380 to 780 nm is 30% or more , Thickness The configuration is such that the thickness is in the range of 20 to 100 nm.
[0008]
In another embodiment of the present invention, the cathode is , Thickness The light transmittance in the visible region of 380 to 780 nm is 60% or more.
As another embodiment of the present invention, the anode is made of at least one metal selected from the group consisting of at least one metal having a work function of 4.7 eV or more, an alloy of these metals, and a conductive inorganic oxide. The configuration is as follows.
As another aspect of the present invention, the anode has a structure in which a layer made of the metal or alloy and a layer made of the conductive inorganic oxide are laminated in order from the base material side and has light reflectivity. The configuration.
As another aspect of the present invention, the anode is made of the metal or alloy and has light reflectivity.
[0009]
As another aspect of the present invention, the cathode including the barrier conductive layer has a sheet resistance of 20Ω / □ or less.
As another aspect of the present invention, the anode has a sheet resistance of 1Ω / □ or less.
As another aspect of the present invention, the base material is configured to be one of a glass substrate, a silicon substrate, and a polymer film.
In the present invention as described above, the barrier conductive layer interposed between the organic layer and the cathode functions to prevent oxidation of the organic layer due to oxygen introduction during the formation of the cathode.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
FIG. 1 is a conceptual diagram of a basic configuration showing an embodiment of an organic electroluminescent (EL) image display device of the present invention. In FIG. 1, an organic EL image display device 1 has a base material 2, an anode 3 sequentially provided on the base material 2, an organic layer 4, a light-transmitting barrier conductive layer 5, and a light-transmitting property. And a cathode 6.
[0011]
The base material 2 constituting the organic EL image display device 1 serves as a support for the organic EL image display device 1, and is a process for manufacturing TFTs (thin film transistors) of active drive display elements (for example, a polycrystalline silicon film forming step). In view of the process temperature in (2), those having a heat resistance of 200 ° C. or higher are preferred, and quartz, glass, and silicon wafers are preferably used. In addition, when the TFT uses amorphous silicon, the process temperature becomes relatively low, and therefore a polymer material can be used in addition to the above materials. However, in the case of using a polymer material, a gas barrier layer made of silicon oxide, silicon nitride, or the like is provided on at least the anode forming surface of the base material in order to prevent deterioration of the organic layer 4 due to the gas generated from the base material. There is a need.
The thickness of such a base material 2 can be set in consideration of the material, the usage status of the image display device, and the like, and can be set to about 0.05 to 5 mm, for example.
[0012]
The anode 3 constituting the organic EL image display device 1 is not particularly limited as long as it is made of a conductive material. For example, metal such as Au, Ta, W, Pt, Ni, Pd, Cr, Al alloy, Ni Alloys, alloys such as Cr alloys, conductive inorganic oxides such as In-Sn-O, In-Zn-O, Zn-O, Zn-O-Al, Zn-Sn-O, metal-doped polythiophene, etc. Examples thereof include conductive polymers, amorphous semiconductors such as α-Si, α-SiC, and α-C, and microcrystals such as μ-C-Si and μ-C—O—Si. In particular, it is preferable that the anode 3 is formed of at least one kind of metal having a work function of 4.7 eV or more, an alloy of these metals, and a substance included in the group consisting of conductive inorganic oxides. The thickness of the anode 3 is preferably in the range of 40 to 500 nm, although it depends on the material, and the sheet resistance of the anode 3 is preferably 1Ω / □ or less. When the thickness of the anode 3 is less than 40 nm, the resistance may be increased. When the thickness exceeds 500 nm, the upper layer (the organic layer 4, the barrier conductive layer) is formed due to a step existing at the end of the patterned anode 3. The layer 5 and the cathode 6) may be cut or disconnected, or the anode 3 and the cathode 6 may be short-circuited.
[0013]
The organic layer 4 constituting the organic EL image display device 1 has a structure composed of a light emitting layer alone, a structure in which a hole injection layer or a hole injection transport layer is provided on the anode 3 side of the light emitting layer, a barrier conductive layer of the light emitting layer 5 has an electron injection layer or electron injection transport layer, a light emitting layer on the anode 3 side with a hole injection layer or hole injection transport layer, and a barrier conductive layer 5 side with an electron injection layer or electron injection transport. A structure in which a layer is provided can be employed. In particular, when a conductive material made of a metal, inorganic nitride, or inorganic oxide as described later is used as the barrier conductive layer 5 as in the present invention, the work function is large (4.2 eV or more), and the barrier conductive layer 5 The energy barrier at the interface between the layer 5 and the light emitting layer becomes high, and it is difficult to inject electrons directly from the barrier conductive layer 5 to the light emitting layer under a low voltage. Therefore, it is preferable to have a structure in which an electron injection layer or an electron injection transport layer is provided on the barrier conductive layer 5 side. The electron injection layer or the electron injection transport layer needs to have sufficient light transmittance in order to extract light from the cathode 6 on the upper surface side with high efficiency.
The hole injecting and transporting layer and the electron injecting and transporting layer may have a laminated structure in which an injection function layer and a transport layer are separately provided.
[0014]
The light emitting layer constituting the organic layer 4 has the following functions.
・ Injection function: A function capable of injecting holes from the anode or the hole injection layer and applying electrons from the cathode or the electron injection layer when an electric field is applied.
・ Transport function: Function to move injected electric charges (electrons and holes) by the force of electric field
・ Light emission function: A function to provide a field for recombination of electrons and holes, and to connect this to light emission.
As the material for the light emitting layer having such a function, conventionally known materials can be used as the light emitting layer material for the organic layer, and there is no particular limitation. For example, tris (8-quinolinolato) aluminum complex (Alq3 And high molecular weight materials such as polydialkylfluorene derivatives are preferably used. There is no restriction | limiting in particular in the thickness of a light emitting layer, For example, it can be about 10-200 nm.
[0015]
The hole injecting and transporting layer is a layer made of a hole transporting compound and has a function of transporting holes injected by the anode to the light emitting layer, and the hole injecting and transporting layer is interposed between the anode and the light emitting layer. By interposing, in the light emitting layer, many holes are injected with a lower electric field. As the hole transport compound, an arbitrary one can be selected and used from known compounds conventionally used for the hole injection transport layer of the organic EL device. Specific examples include bis (N-naphthyl) -N-phenylbenzidine (α-NPD), 4,4,4-tris (3-methylphenylphenylamino) triphenylamine (MTDATA), and the like. High molecular weight materials include polyvinylcarbazole ( PVCz ), Polyethylenedioxythiophene (PEDOT), polyphenylene vinylene derivatives and the like are preferably used. The thickness of the hole injection layer is not particularly limited, and can be, for example, about 10 to 300 nm.
[0016]
In addition, as the material of the electron injection layer, oxides or fluorides of alkali metals or alkaline earth metals (for example, LiF, NaF, LiO) ₂ , MgF ₂ , CaF ₂ , BaF ₂ ) And the like. Among these, alkaline earth metal fluorides (MgF ₂ , CaF ₂ , BaF ₂ ) Is preferably used in that the stability and life of the organic layer 4 can be improved. This is because the alkaline earth metal fluoride is less reactive with water than the alkali metal compound or alkaline earth metal oxide, and absorbs less water during or after film formation. It is. Further, the alkaline earth metal fluoride has a higher melting point and better heat resistance stability than the alkali metal compound. The thickness of the electron injection layer is preferably in the range of about 0.2 to 10 nm because the oxides and fluorides of the above alkali metals and alkaline earth metals are insulative.
[0017]
In addition, the electron injection layer can be formed by thinning a material having a work function of 4.0 eV or less to a sufficient light transmittance. Examples of the material having a work function of 4.0 eV or less include Ba, Ca, Li, Cs, Mg, and the like. The thickness of the electron injection layer needs to be reduced in order to obtain sufficient light transmittance. .2 to 50 nm, preferably about 0.2 to 20 nm.
As the electron injecting and transporting layer, a metal doped layer in which an electron transporting organic material is doped with an alkali metal or an alkaline earth metal can be formed. Examples of the electron transporting organic material include bathocuproin (BCP) and bathophenanthroline (Bphen). Examples of the doped metal material include Li, Cs, Ba, and Sr. The molar ratio of the electron transporting organic material to the metal in the metal doped layer is about 1: 1 to 1: 3, preferably about 1: 1 to 1: 2. The thickness of the electron injecting and transporting layer composed of such a metal doped layer is set to about 5 to 1000 nm, preferably about 10 to 100 nm, because the electron mobility is large and the light transmittance is higher than that of a single metal.
[0018]
The barrier conductive layer 5 constituting the organic EL image display device 1 is a thin film made of at least one of metal, inorganic nitride, and inorganic oxide formed by a vacuum film forming method in which oxygen is not introduced in the film forming process. is there. As said metal, the metal whose work function is 4.2 eV or more is preferable, for example, Au, Ag, Al, Cu etc. can be mentioned. Examples of the inorganic nitride include nitrides of elements such as Ti, Zr, and Hf belonging to Group 4 of the periodic table. Examples of the inorganic oxide include oxides such as In—Sn—O, In—Zn—O, Zn—O, Zn—O—Al, and Zn—Sn—O. Examples of the vacuum film forming method without introducing oxygen for forming the barrier conductive layer 5 include a resistance heating vapor deposition method, an ion beam vapor deposition method, a sputtering method, an ion plating method, and a CVD method.
[0019]
Such a barrier conductive layer 5 has a water vapor transmission rate of 1 g / m. ² / Day or less, oxygen permeability is 1 cc / m ² / Day · atm or less, specific resistance is 1.0 × 10 ^-2 It is preferable that the light transmittance in the visible region of 380 to 780 nm is 30% or more. The thickness of the barrier conductive layer 5 having such characteristics is 10 to 50 nm, preferably about 15 to 30 nm when the thin film is made of metal, and 10 to 10 when the thin film is made of inorganic nitride. The thickness is about 500 nm, preferably about 20 to 100 nm, and in the case of a thin film made of an inorganic oxide, it is about 10 to 500 nm, preferably about 20 to 200 nm.
[0020]
The cathode 6 constituting the organic EL image display device 1 is not particularly limited as long as it is made of a transparent conductive material. For example, In—Sn—O, In—Zn—O, Zn—O, Zn Examples thereof include conductive oxides such as —O—Al and Zn—Sn—O. The thickness of the cathode 6 is preferably in the range of 10 to 500 nm, and the light transmittance in the visible region of 380 to 780 nm is preferably 60% or more. When the thickness of the cathode 6 is less than 10 nm, the conductivity becomes insufficient, and when it exceeds 500 nm, the light transmittance becomes insufficient, and when the organic EL image display device is deformed after the manufacturing process or after manufacturing, Defects such as cracks are likely to occur in the cathode 6, which is not preferable. Furthermore, the sheet resistance of the cathode 6 including the barrier conductive layer 5 is preferably 20Ω / □ or less.
Such a cathode 6 can be formed by a vacuum film forming method such as a sputtering method, an ion plating method, or an electron beam method. In the formation of such a cathode 6, oxidation of the organic layer 4 due to oxygen introduction is blocked by the barrier conductive layer 5, thereby preventing deterioration of the characteristics of the organic layer 4.
[0021]
In the present invention, a color filter layer and / or a color conversion phosphor layer may be provided on the cathode 6, and the color purity of the light of each color may be improved by increasing the color purity. As the color filter layer, for example, a resin prepared by dispersing one or a plurality of pigments such as azo, phthalocyanine, and anthraquinone in a photosensitive resin in each of a blue colored layer, a red colored layer, and a green colored layer It can be formed using a composition. The color conversion phosphor layer is formed by applying a coating solution in which a desired fluorescent dye and resin are dispersed or solubilized by spin coating, roll coating, cast coating, or the like. The red conversion phosphor layer, the green conversion phosphor layer, and the blue conversion phosphor layer may be formed by a patterning method using a photolithography method.
[0022]
【Example】
Next, an Example is shown and this invention is demonstrated further in detail.
[Example 1]
As a base material, a transparent glass substrate (non-alkali glass NA35 manufactured by NH Techno Glass Co., Ltd.) having a thickness of 25 mm × 25 mm and a thickness of 0.7 mm was prepared. A thin film (thickness 100 nm) was formed. In the above Al thin film formation, Ar was used as the sputtering gas, the pressure was 0.15 Pa, and the DC output was 200 W. Next, a thin film (thickness 20 nm) of indium tin oxide (ITO) was formed on the Al thin film by a magnetron sputtering method in order to have a role of promoting hole injection. In the above ITO thin film formation, Ar and O are used as sputtering gases. ₂ Gas mixture (volume ratio Ar: O ₂ = 100: 1), the pressure was 0.1 Pa, and the DC output was 150 W.
[0023]
Next, with respect to the anode composed of the Al thin film and the ITO thin film, a four-probe method using a low resistivity meter Loresta-GP (MCP-T600) manufactured by Dia Instruments Co., Ltd. and a probe PSP type (electrode spacing 1.5 mm). As a result of measuring the surface resistance value by, it was 0.5Ω / □.
[0024]
Next, a photosensitive resist (OFPR-800 manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied on the anode, mask exposure, development (using NMD3 manufactured by Tokyo Ohka Kogyo Co., Ltd.), etching, and width of 2 mm. Two line-shaped anodes were formed. The anode patterning could be performed by dry etching.
Next, the transparent glass substrate provided with the anode is exposed to oxygen plasma, and then the polyethylenedioxythiophene (PEDOT) represented by the following structural formula (1) is formed on the transparent glass substrate so as to cover the anode in the air. Baytron P CH8000 made by Bayer, which is a mixture of styrene and polystyrene sulfonate (PSS), was applied by a spin coat method and dried to form a hole injection transport layer (thickness 80 nm).
[0025]
[Chemical 1]

[0026]
Subsequently, poly (dioctyl divinylene fluorene represented by the following structural formula (2) is formed on the hole injecting and transporting layer in a low oxygen (oxygen concentration 1 ppm or less) and low humidity (water vapor concentration 1 ppm or less) state glove box. ADS106GE manufactured by ADS Co., which is co-anthracene) (PF) was applied by a spin coating method and dried to form a light emitting layer (thickness 80 nm).
[0027]
[Chemical 2]

[0028]
Furthermore, Ca was vapor-deposited with a thickness of 5 nm on the light emitting layer to form an electron injection layer. Deposition conditions are: vacuum degree 5 × 10 ^-Five Pa and the film formation rate were 1 liter / second. In the formation of the electron injection layer, two linear electron injection layers having a width of 2 mm were formed using a mask so as to be orthogonal to the anode.
Next, a TiN thin film (thickness 50 nm) was formed into a barrier conductive layer using an opposed target type magnetron sputtering apparatus. In the formation of this barrier conductive layer, a 2 mm wide line-shaped barrier conductive layer was formed on the electron injection layer using a mask. The TiN thin film is formed using Ar, N as the sputtering gas. ₂ And pressure 2 × 10 ^-2 Pa, RF output 100W, DC output 150W.
[0029]
Next, an ITO thin film (thickness 150 nm) was formed by magnetron sputtering to form a cathode. In forming the cathode, a line-like cathode having a width of 2 mm was formed on the barrier conductive layer using a mask. The above ITO thin film is formed using Ar and O as sputtering gases. ₂ Gas mixture (volume ratio Ar: O ₂ = 100: 1), pressure 5.5 x 10 ^-2 Pa, RF output 100 W, DC output 150 W, and deposition rate of 4 速度 / sec.
In addition, a TiN thin film and an ITO thin film are separately formed on the transparent glass substrate under the same conditions as described above, and the surface resistance value of the ITO thin film including the TiN thin film is measured using a four-probe method using Loresta-GP manufactured by Mitsubishi Chemical Corporation. As a result of measurement, it was 19Ω / □.
In addition, a TiN thin film was separately formed on the transparent glass substrate under the same conditions as above, and the water vapor transmission rate, oxygen transmission rate, specific resistance, and light transmission rate in the visible region of 380 to 780 nm were measured with respect to this. . As a result, the water vapor transmission rate is 0.2 g / m. ² / Day, oxygen permeability is 0.2 cc / m ² / Day · atm, specific resistance is 3.0 × 10 ^-Four The average transmittance in Ω · cm and visible region was about 70%.
[0030]
(Measurement of water vapor transmission rate)
Using a water vapor transmission rate measuring device (PERMATRAN-W 3/31 manufactured by MOCON), measurement is performed under conditions of 37.8 ° C. and 100% RH.
(Measurement of oxygen permeability)
Using an oxygen gas permeability measuring device (OX-TRAN 2/20 manufactured by MOCON), the measurement is performed at 23 ° C. and 90% RH.
(Specific resistance measurement)
The specific resistance value (Ω · cm) is calculated by multiplying the measured surface resistance value (Ω / □) by the film thickness (cm). The film thickness is measured using Nanopics 1000 manufactured by Seiko Instruments Inc.
(Measurement of light transmittance)
Using a UV-visible spectrophotometer (UV-2200A, manufactured by Shimadzu Corporation), measurement is performed at room temperature in the air.
[0031]
Next, SiO2 is formed by magnetron sputtering. ₂ A film (thickness 5 μm) was formed as a sealing film. For film formation, target SiO _x (X = 1 to 2) and Ar and O as sputtering gases ₂ Gas mixture (volume ratio Ar: O ₂ = 200: 1), the pressure was 0.5 Pa, the RF output was 150 W, and the DC output was 200 W.
As described above, an anode patterned in a line shape having a width of 2 mm, and an electron injection layer, a barrier conductive layer, and a cathode formed in a line shape having a width of 2 mm so as to be orthogonal to the anode have four light emitting areas ( Area 4mm ² An organic EL display device having) was produced.
The current density when a voltage of 6 V is applied to the anode and cathode of this organic EL display device is 280 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 22000 cd / m. ² Met. Moreover, when the organic EL display device was continuously driven at 20 mA for 240 hours, the light emitting area surface was observed with an optical microscope (30 times), and no dark spot was present. From this result, it was confirmed that in the light emitting area, the presence of the barrier conductive layer made of the TiN thin film prevents the light emitting layer and the electron injection layer from being oxidized due to the introduction of oxygen during the cathode formation.
[0032]
[Example 2]
An organic EL display device was produced in the same manner as in Example 1 except that a ZrN thin film (thickness 50 nm) was formed under the same conditions as the barrier conductive layer instead of the TiN thin film.
In addition, it was 20 ohms / square as a result of measuring the surface resistance value of the ITO thin film containing a ZrN thin film like Example 1. FIG. Moreover, as in Example 1, the water vapor transmission rate, oxygen transmission rate, specific resistance, and light transmission rate in the visible region of 380 to 780 nm of the ZrN thin film were measured. As a result, the water vapor transmission rate was 0.3 g / m. ² / Day, oxygen permeability is 0.2 cc / m ² / Day · atm, specific resistance is 3.4 × 10 ^-Four The average transmittance in Ω · cm and visible region was about 70%.
[0033]
The current density when a voltage of 6 V is applied to the anode and cathode of the organic EL display device is 260 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 20000 cd / m. ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours, the light emitting area surface was observed with an optical microscope (30 times), and no dark spot was present. From this result, it was confirmed that in the light emitting area, the presence of the barrier conductive layer made of the ZrN thin film prevents oxidation of the light emitting layer and the electron injection layer due to oxygen introduction during the cathode formation.
[0034]
[Example 3]
As the barrier conductive layer, an Au thin film (thickness 30 nm) was used instead of the TiN thin film by vacuum deposition (vacuum degree 5 × 10 ^-Five An organic EL display device was fabricated in the same manner as in Example 1 except that the film was formed at Pa and a film formation rate of 0.5 Å / sec.
As a result of measuring the surface resistance value of the ITO thin film including the Au thin film in the same manner as in Example 1, it was 15Ω / □. Further, in the same manner as in Example 1, as a result of measuring the water vapor transmission rate, the oxygen transmission rate, the specific resistance, and the light transmission rate in the visible region of 380 to 780 nm of the Au thin film, the water vapor transmission rate was 0.1 g / m. ² / Day, oxygen permeability is 0.1 cc / m ² / Day · atm, specific resistance is 1.6 × 10 ^-Four The average transmittance in Ω · cm and visible region was about 40%.
[0035]
The current density when a voltage of 6 V is applied to the anode and cathode of the organic EL display device is 330 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 15000 cd / m. ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours, the light emitting area surface was observed with an optical microscope (30 times), and no dark spot was present. From this result, it was confirmed that in the light emitting area, the presence of the barrier conductive layer made of the Au thin film prevents the light emitting layer and the electron injection layer from being oxidized due to the introduction of oxygen during the cathode formation.
[0036]
[Example 4]
An organic EL display device was produced in the same manner as in Example 3 except that an Al thin film (thickness 30 nm) was formed instead of the Au thin film as the barrier conductive layer.
In addition, it was 14 ohms / square as a result of measuring the surface resistance value of the ITO thin film containing Al thin film similarly to Example 1. FIG. Moreover, as in Example 1, the water vapor transmission rate, the oxygen transmission rate, the specific resistance, and the light transmission rate in the visible region of 380 to 780 nm were measured for the Al thin film. As a result, the water vapor transmission rate was 0.1 g / m. ² / Day, oxygen permeability is 0.1 cc / m ² / Day · atm, specific resistance is 1.5 × 10 ^-Four The average transmittance in Ω · cm and visible region was about 40%.
[0037]
The current density when a voltage of 6 V is applied to the anode and cathode of the organic EL display device is 320 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 15000 cd / m. ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours, the light emitting area surface was observed with an optical microscope (30 times), and no dark spot was present. From this result, it was confirmed that in the light emitting area, the presence of the barrier conductive layer made of an Al thin film prevents the light emitting layer and the electron injection layer from being oxidized due to the introduction of oxygen during the cathode formation.
[0038]
[Example 5]
An organic EL display device was produced in the same manner as in Example 1 except that an ITO thin film (thickness 50 nm), which was an inorganic oxide, was formed as the barrier conductive layer instead of the TiN thin film. The ITO thin film is formed using Ar as a sputtering gas and a pressure of 3 × 10. ^-2 Pa, RF output 500 W, DC output 100 W, and deposition rate of 1 kg / sec.
In addition, it was 20 ohms / square as a result of measuring the surface resistance value of the cathode ITO thin film containing the ITO thin film as a barrier conductive layer like Example 1. FIG. Further, in the same manner as in Example 1, the water vapor transmission rate, the oxygen transmission rate, the specific resistance, and the light transmission rate in the visible region of 380 to 780 nm of the ITO thin film were measured. As a result, the water vapor transmission rate was 0.2 g / m. ² / Day, oxygen permeability is 0.2 cc / m ² / Day · atm, specific resistance is 2.5 × 10 ^-Four The average transmittance in Ω · cm and visible region was about 70%.
[0039]
The current density when a voltage of 6 V is applied to the anode and cathode of the organic EL display device is 280 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 27000 cd / m. ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours, the light emitting area surface was observed with an optical microscope (30 times), and no dark spot was present. From this result, it was confirmed that in the light emitting area, the presence of a barrier conductive layer made of an ITO thin film prevents the light emitting layer and the electron injection layer from being oxidized due to the introduction of oxygen during the formation of the cathode.
[0040]
[Example 6]
An organic EL display device was produced in the same manner as in Example 5, except that an indium zinc oxide (IZO) thin film, which was also an inorganic oxide, was formed as the barrier conductive layer instead of the ITO thin film.
In addition, as a result of measuring the surface resistance value of the ITO thin film including the IZO thin film in the same manner as in Example 1, it was 20Ω / □. Moreover, as in Example 1, the water vapor transmission rate, oxygen transmission rate, specific resistance and light transmission rate in the visible region of 380 to 780 nm of the IZO thin film were measured. As a result, the water vapor transmission rate was 0.2 g / m. ² / Day, oxygen permeability is 0.2 cc / m ² / Day · atm, specific resistance is 2.4 × 10 ^-Four The average transmittance in Ω · cm and visible region was about 70%.
[0041]
The current density when a voltage of 6 V is applied to the anode and cathode of the organic EL display device is 280 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 26000 cd / m. ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours, the light emitting area surface was observed with an optical microscope (30 times), and no dark spot was present. From this result, it was confirmed that in the light emitting area, the presence of the barrier conductive layer made of the IZO thin film prevents the light emitting layer and the electron injection layer from being oxidized due to the introduction of oxygen during the cathode formation.
[0042]
[Comparative Example 1]
An organic EL display device was produced in the same manner as in Example 1 except that the barrier conductive layer was not formed.
The current density when a voltage of 6 V is applied to the anode and cathode of this organic EL display device is 110 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 8000 cd / m. ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours and the light emitting area surface was observed with an optical microscope (30 times), a dark spot having a diameter of about 0.1 mm was 1 mm. ² It was confirmed at a rate of several in the range. From this result, it was confirmed that in the light emitting area, the light emitting layer and the electron injection layer were oxidized by the introduction of oxygen at the time of cathode formation.
[0043]
[Comparative Example 2]
An organic EL display device was produced in the same manner as in Example 1 except that an ITO thin film (thickness 50 nm) was formed by sputtering using oxygen introduction instead of the barrier conductive layer made of a TiN thin film. The film forming conditions for this ITO thin film are Ar and O as sputtering gases. ₂ Gas mixture (volume ratio Ar: O ₂ = 100: 1), pressure 5.5 x 10 ^-2 Pa, RF output 100 W, DC output 150 W, and deposition rate of 4 速度 / sec.
In addition, as a result of measuring the surface resistance value of the ITO thin film in the same manner as in Example 1, it was 19Ω / □. Further, in the same manner as in Example 1, the water vapor transmission rate, the oxygen transmission rate, the specific resistance, and the light transmission rate in the visible region of 380 to 780 nm of the ITO thin film were measured. As a result, the water vapor transmission rate was 0.2 g / m. ² / Day, oxygen permeability is 0.3 cc / m ² / Day · atm, specific resistance is 2.1 × 10 ^-Four The average transmittance of Ω · cm and visible region was about 80%.
[0044]
The current density when a voltage of 6 V is applied to the anode and cathode of the organic EL display device is 110 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 8000 cd / m. ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours and the light emitting area surface was observed with an optical microscope (30 times), a dark spot having a diameter of about 0.1 mm was 1 mm. ² It was confirmed at a rate of several in the range. From this result, it was confirmed that in the light emitting area, the light emitting layer and the electron injection layer were oxidized during the formation of the ITO thin film into which oxygen was introduced and the cathode.
[0045]
[Example 7]
First, in the same manner as in Example 1, two line-shaped anodes having a width of 2 mm were formed on a transparent glass substrate.
Next, the transparent glass substrate provided with the anode is exposed to oxygen plasma, and then bis (N-naphthyl) represented by the following structural formula (3) is formed on the transparent glass substrate so as to cover the anode by vacuum heating deposition. A hole transport layer (thickness 50 nm) made of -N-phenylbenzidine (α-NPD) was formed. The film formation condition of this hole transport layer is that the degree of vacuum is 5 × 10. ^-Five Pa, a film forming rate of 3 Å / sec, and a heating temperature of 350 ° C. were used.
[0046]
[Chemical 3]

[0047]
Next, a tris (8-quinolinolato) aluminum complex (Alq3) represented by the following structural formula (4) was formed on the hole transport layer by vacuum deposition to form a light emitting layer (thickness 60 nm). The film forming conditions for the light emitting layer are as follows: degree of vacuum: 5 × 10 ^-Five The film was formed at a Pa of 3 Pa / second.
[0048]
[Formula 4]

[0049]
Further, a vapor deposition layer of bathocuproin (BCP) and Li represented by the following structural formula (5) was formed on the light emitting layer by vacuum deposition to form an electron injection layer (thickness 20 nm). This vapor deposition condition is that the degree of vacuum is 5 × 10. ^-Five Pa and the film formation rate of each material were 3 liters / second.
[0050]
[Chemical formula 5]

[0051]
Next, in the same manner as in Example 1, a barrier conductive layer and a cathode were formed, and a sealing film was further formed.
As described above, an anode patterned in a line shape having a width of 2 mm, a barrier conductive layer formed in a line shape having a width of 2 mm so as to be orthogonal to the anode, and a cathode are provided. ² An organic EL display device having) was produced.
The current density when a voltage of 6 V is applied to the anode and cathode of this organic EL display device is 3.6 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 200 cd / m. ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours, the light emitting area surface was observed with an optical microscope (30 times), and no dark spot was present. From this result, it was confirmed that in the light emitting area, the presence of the barrier conductive layer made of the TiN thin film prevents the light emitting layer and the electron injection layer from being oxidized due to the introduction of oxygen during the cathode formation.
[0052]
[Example 8]
An organic EL display device was produced in the same manner as in Example 7 except that a ZrN thin film (thickness 50 nm) was formed under the same conditions as the barrier conductive layer instead of the TiN thin film.
The current density when a voltage of 6 V is applied to the anode and cathode of this organic EL display device is 3.6 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 210 cd / m ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours, the light emitting area surface was observed with an optical microscope (30 times), and no dark spot was present. From this result, it was confirmed that in the light emitting area, the presence of the barrier conductive layer made of the ZrN thin film prevents oxidation of the light emitting layer and the electron injection layer due to oxygen introduction during the cathode formation.
[0053]
[Comparative Example 3]
An organic EL display device was produced in the same manner as in Example 7 except that the barrier conductive layer was not formed.
The current density when a voltage of 6 V is applied to the anode and cathode of this organic EL display device is 3.0 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 150 cd / m. ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours and the light emitting area surface was observed with an optical microscope (30 times), a dark spot having a diameter of about 0.1 mm was 1 mm. ² It was confirmed at a rate of several in the range. From this result, it was confirmed that in the light emitting area, the light emitting layer and the electron injection layer were oxidized by the introduction of oxygen at the time of cathode formation.
[0054]
[Example 9]
First, in the same manner as in Example 1, two line-shaped anodes having a width of 2 mm were formed on a transparent glass substrate.
Next, in the same manner as in Example 7, a hole transport layer (thickness 50 nm), a light emitting layer (thickness 60 nm), and an electron injection layer (thickness 20 nm) were formed.
Next, in the same manner as in Example 1, a barrier conductive layer and a cathode were formed, and a sealing film was further formed. However, as the barrier conductive layer, an Al thin film (thickness 30 nm) is used instead of the TiN thin film by vacuum evaporation (vacuum degree 5 × 10 ^-Five Pa, film formation rate 0.5 Å / sec).
[0055]
As described above, an anode patterned in a line shape having a width of 2 mm, a barrier conductive layer formed in a line shape having a width of 2 mm so as to be orthogonal to the anode, and a cathode are provided. ² An organic EL display device having) was produced.
The current density when a voltage of 6 V is applied to the anode and cathode of this organic EL display device is 4.0 mA / cm. ² The luminance of the light emitting area measured from the upper surface (cathode) side is 100 cd / m ² Met. Further, when the above-mentioned organic EL display device was continuously driven at 20 mA for 240 hours, the light emitting area surface was observed with an optical microscope (30 times), and no dark spot was present. From this result, it was confirmed that in the light emitting area, the presence of the barrier conductive layer made of the TiN thin film prevents the light emitting layer and the electron injection layer from being oxidized due to the introduction of oxygen during the cathode formation.
[0056]
【The invention's effect】
As described above in detail, according to the present invention, a barrier conductive layer is interposed between the organic layer and the cathode, and the barrier conductive layer is vacuum-formed without introducing oxygen in the film forming process. Since the thin film made of at least one of metal, inorganic nitride, and inorganic oxide formed by the film method is used, the organic layer is not only a barrier conductive layer but also a light-transmitting cathode. Oxidation due to the introduction of oxygen is prevented even during film formation, which makes the organic layer highly reliable with no characteristic deterioration, and enables high-quality image display by extracting light from the cathode on the top side with high efficiency. An organic electroluminescent image display device can be obtained.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram of a basic configuration showing an embodiment of an organic electroluminescent (EL) image display device of the present invention.
[Explanation of symbols]
1 ... Organic electroluminescent image display device
2 ... Base material
3 ... Anode
4 ... Organic layer
5 ... Barrier conductive layer
6 ... Cathode

Claims (8)

A barrier material comprising at least a base material, an anode sequentially provided on the base material, an organic layer, a light-transmitting barrier conductive layer, and a light-transmitting conductive oxide ; The conductive layer is a thin film made of zirconium nitride formed by a vacuum film forming method in which oxygen is not introduced in the film forming process, and has a water vapor transmission rate of 1 g / m ² / day or less and an oxygen transmission rate of 1 cc / m ² / day · atm or less, resistivity 1.0 × 10 ^-2 Ω · cm or less and a light transmittance in the visible region 380~780nm 30% or more, and characterized by a range of thickness Hiroyoshi 20~100nm Organic electroluminescent image display device. The cathode is in the range Thickness of 10 to 500 nm, an organic electroluminescent image display device according to claim 1, wherein the light transmittance in the visible region 380~780nm is 60% or more.   The anode is made of at least one metal selected from the group consisting of at least one metal having a work function of 4.7 eV or more, an alloy of these metals, and a conductive inorganic oxide. The organic electroluminescent image display apparatus according to claim 1 or 2.   4. The anode according to claim 3, wherein the anode has a structure in which a layer made of the metal or alloy and a layer made of the conductive inorganic oxide are laminated in order from the base material side, and has light reflectivity. Organic electroluminescent image display device.   4. The organic electroluminescent image display device according to claim 3, wherein the anode is made of the metal or alloy and has light reflectivity.   The organic electroluminescent image display device according to any one of claims 1 to 5, wherein a sheet resistance of the cathode including the barrier conductive layer is 20Ω / □ or less.   The organic electroluminescent image display device according to claim 1, wherein the anode has a sheet resistance of 1Ω / □ or less.   The organic electroluminescent image display device according to any one of claims 1 to 7, wherein the base material is any one of a glass substrate, a silicon substrate, and a polymer film.

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