JP2004119272A - Organic EL element and substrate used therein - Google Patents

Abstract

An object of the present invention is to provide an organic EL device that uses an electrode layer containing a specific inorganic compound, is excellent in transparency and durability, has low driving voltage, and has high emission luminance.
In an organic electroluminescent device in which an anode layer, an organic light emitting layer, and a cathode layer are sequentially laminated, at least one of the anode layer and the cathode layer is selected from Group A-1. It contains at least one inorganic compound and at least one compound selected from the following group B-1. Here, the A-1 group is a chalcogenide, oxynitride, or nitride of Si, Ge, Sn, Pb, Ga, In, Zn, Cd, or Mg. Group B-1 is a lanthanoid-based chalcogenide, oxynitride, or nitride. By providing the anode layer 10 and the like made of a specific organic compound in this way, it is possible to provide an organic EL element that is excellent in transparency and durability and that can obtain high emission luminance even at a low driving voltage.
[Selection diagram] Fig. 1

Description

ここで、一般式（化学式１）中、Ａｒ^１は、炭素数が６〜４０の芳香族基であり、Ａｒ^２、Ａｒ^３、及びＡｒ^４は、それぞれ水素原子又は炭素数が６〜４０の芳香族基であり、Ａｒ^１、Ａｒ^２、Ａｒ^３、及びＡｒ^４の少なくとも一つは芳香族基であり、縮合数ｎは、１〜６の整数である。
【００５２】
【化５】

ここで、一般式（化学式２）中、Ａｒ^５は、炭素数が６〜４０の芳香族基であり、Ａｒ^６及びＡｒ^７は、それぞれ水素原子又は炭素数が６〜４０の芳香族基であり、Ａｒ^５、Ａｒ^６及びＡｒ^７の少なくとも一つはスチリル基で置換されており、縮合数ｍは、１〜６の整数である。
【００５３】
【化６】

ここで、一般式（化学式３）中、Ａｒ^８及びＡｒ^１４は、炭素数が６〜４０の芳香族基であり、Ａｒ^９〜ｒ^１３は、それぞれ水素原子又は炭素数が６〜４０の芳香族基であり、Ａｒ^８〜Ａｒ^１４の少なくとも一つはスチリル基で置換されており、縮合数ｐ、ｑ、ｒ、ｓは、それぞれ０又は１である。
【００５４】
また、本発明は、これまで述べた有機エレクトロルミネッセンス素子の製造方法において、前記電極層をスパッタリング法により形成し、前記有機発光層を真空蒸着法により形成することを特徴とする有機エレクトロルミネッセンス素子の製造方法である。このように形成すると、緻密で、均一な膜厚を有する正孔注入層や有機発光層を形成することができる。したがって、より均一な発光輝度を有する有機ＥＬ素子を提供することができる。
【００５５】
【発明の実施の形態】
以下、図面を参照して、本発明の実施の形態について具体的に説明する。なお、参照する図面は、この発明が理解できる程度に各構成成分の大きさ、形状及び配置関係を概略的に示してあり、実際の素子等とは各部の比率は異なる。したがって、この発明は図示例にのみ限定されるものではない。また、図面では、断面を表すハッチングを省略する場合がある。
【００５６】
［第１の実施形態］
まず、図１を参照して、本発明の有機ＥＬ素子における第１の実施形態について説明する。図１は、有機ＥＬ素子１００の断面図である。この図に示すように、有機ＥＬ素子１００は、陽極層１０、有機発光層１４及び陰極層１６を、基板（図示せず）上に順次に積層した構造である。
【００５７】
以下、第１の実施形態における特徴的な部分である陽極層１０及び有機発光層１４を中心に説明する。その他の構成部分、例えば、陰極層１６等の構成や製法についてはごく簡単に説明するものとし、言及していない部分については、有機ＥＬ素子の分野において一般的に知られている各種の構成や製法を採ることができる。
【００５８】
なお、第１の実施形態においては、陽極層１０を、以下に述べるＡ−１群又はＡ−２群（以下、これをＡ群と総称する）及びＢ−１群又はＢ−２群（以下、これをＢ群と総称する）からなる化合物から構成している。しかしながら、上記無機化合物の仕事関数を４．０ｅＶ未満の値とした上で、陰極層１６を、上記無機化合物から構成しても良い。
【００５９】
（１）陽極層１０の構成材料
第１の本実施の形態の陽極層１０は、下記Ａ−１群の無機化合物及びＢ−１群の化合物を組み合わせて含有する構成、又は、下記Ａ−２群の無機化合物及びＢ−２群の化合物を組み合わせて含有する構成、のいずれかを採用している。ただし、Ａ−１群の無機化合物及びＢ−１群の化合物の組み合わせと、Ａ−２群の無機化合物及びＢ−２群の化合物の組み合わせと、の間にはその一部において重複している化合物がある。
【００６０】
Ａ−１群：Ｓｉ，Ｇｅ，Ｓｎ，Ｐｂ，Ｇａ，Ｉｎ，Ｚｎ，Ｃｄ，Ｍｇのカルコゲナイド、酸窒化物、又は窒化物
Ａ−２群：Ｇｅ，Ｓｎ，Ｐｂ，Ｇａ，Ｉｎ，Ｚｎ，Ｃｄ，Ｍｇのカルコゲナイド、酸窒化物、又は窒化物
Ｂ−１群：ランタノイド系元素のカルコゲナイド、酸窒化物、又は窒化物
Ｂ−２群：ランタノイド系元素のカルコゲナイド
このように、Ａ群とＢ群の２種の化合物を組み合わせる理由は、上述したように、いずれか一方（Ａ群又はＢ群）のみの化合物（有機化合物又は無機化合物）では、イオン化ポテンシャルの値を効率的に上昇させることが困難なためである。具体的には、イオン化ポテンシャルを５．８ｅＶを超える値まで上昇させることが困難となるためである。
【００６１】
したがって、Ａ−１群の無機化合物及びＢ−１群の化合物を組み合わせ、又はＡ−２群の無機化合物及びＢ−２群の化合物を組み合わせて、陽極層１０を構成することにより、イオン化ポテンシャルを極めて大きな値である５．８ｅＶ以上とすることができる。その結果、耐久性や透明性に優れるとともに、駆動電圧が低く（比抵抗が低い）、しかも発光輝度が高い有機ＥＬ素子を得ることができる。
【００６２】
また、Ａ−１群の無機化合物及びＢ−１群の化合物を組み合わせた化合物、あるいはＡ−２群の無機化合物及びＢ−２群の化合物を組み合わせた化合物、は、酸、例えば、塩酸や蓚酸によるエッチング特性が優れているという特徴を有する。具体的には、酸処理部と、非処理部との境界における断面が平滑であり、当該酸処理部と、非処理部との領域を明確に区別することができる。よって、このような無機化合物で構成した電極層は、電極パターンのエッチング精度に優れており、微小電極や複雑な形状の電極であっても、断線や変形、あるいは抵抗値増加等が少なくなるという効果が得られる。
【００６３】
Ａ群無機化合物
なお、より具体的なＡ−１群の無機化合物としては、ＳｉＯｘ　（１≦ｘ≦２），ＧｅＯｘ　（１≦ｘ≦２），ＳｎＯ_２　，ＰｂＯ，Ｉｎ_２Ｏ_３　，ＺｎＯ，ＧａＯ，ＣｄＯ，ＺｎＳ，ＺｎＣｅ，ＣｄＳｅ，Ｉｎｘ　Ｚｎｙ　Ｏ（０．２≦ｘ／（ｘ＋ｙ）≦０．９５），ＺｎＯＳ，ＣｄＺｎＯ，ＣｄＺｎＳ，ＭｇＩｎＯ，ＣｄＩｎＯ，ＭｇＺｎＯ，ＧａＮ，ＩｎＧａＮ，ＭｇＺｎＳＳｅ等が挙げられる。
【００６４】
また、具体的なＡ−２群の無機化合物としては、上記Ａ−１群の無機化合物からＳｉＯｘ　（１≦ｘ≦２）等を除いた化合物が挙げられる。ここで、もちろん、ＺｎＯはＺｎの酸化物であり、ＺｎＳはＺｎの硫化物をそれぞれ意味しているが、特に、本実施の形態では、ＺｎとＯ、ＺｎとＳはそれぞれ１：１の比率で正規組成しているばかりでなく、それからはずれた比率の化合物も含む。
【００６５】
また、Ａ−１群及びＡ−２群の無機化合物では、特に、Ｓｎ，Ｉｎ及びＺｎのカルコゲナイド又はこれらの窒化物が好ましい材料である。この理由も、一部上述したように、これらの化合物は、Ａ−１群及びＡ−２群の無機化合物の中でも吸収係数が小さく、特に消光性が低く、透明性に優れているため、外部に取り出すことができる光量を多くすることができるためである。また、上述したＧｅ，Ｓｎ，Ｚｎ及びＣｄのカルコゲナイドにおいては、特に、これらの酸化物であることがより好ましい。
【００６６】
Ｂ群化合物
また、具体的なＢ−１群の化合物としては、Ｃｅ_２Ｏ_３、ＣｅＯ_２、Ｐｒ_６Ｏ_１１、Ｎｄ_２Ｏ_３、Ｓｍ_２Ｏ_３、Ｅｕ_２Ｏ_３、Ｇｄ_２Ｏ_３、Ｔｂ_４Ｏ_７、Ｄｙ_２Ｏ_３、Ｈｏ_２Ｏ_３、Ｅｒ_２Ｏ_３、Ｔｍ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｌｕ_２Ｏ_３、ＣｅＮ、ＰｒＮ、ＮｄＮ、ＳｍＮ、ＥｕＮ、ＧｄＮ、ＴｂＮ、ＤｙＮ、ＨｏＮ、ＥｒＮ、ＴｍＮ、ＹｂＮ、ＬｕＮ等の一種単独又は二種以上の組み合わせが挙げられる。
【００６７】
また、具体的なＢ−２群の化合物としては、Ｃｅ_２Ｏ_３、ＣｅＯ_２、Ｐｒ_６Ｏ_１１、Ｎｄ_２Ｏ_３、Ｓｍ_２Ｏ_３、Ｅｕ_２Ｏ_３、Ｇｄ_２Ｏ_３、Ｔｂ_４Ｏ_７、Ｄｙ_２Ｏ_３、Ｈｏ_２Ｏ_３、Ｅｒ_２Ｏ_３、Ｔｍ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｌｕ_２Ｏ_３からなる群から選択した一種単独又は二種以上の組み合わせが挙げられる。
【００６８】
これらのＢ−１群及びＢ−２群の化合物のうち、Ｃｅ、Ｎｄ、Ｓｍ、Ｅｕ、Ｔｂ及びＨｏの酸化物、すなわち、ＣｅＯｘ　，Ｎｄ_２Ｏ_３，Ｓｍ_２Ｏ_３，Ｅｕ_２Ｏ_３　，Ｔｂ_４Ｏ_７　，及びＨｏ_２Ｏ_３　であることがより好ましい。この理由も、一部上述したように、これらの無機化合物を使用することにより、陽極層１０におけるイオン化ポテンシャルの値をより効率的に上昇させることができるためである。
【００６９】
Ｂ群（Ｂ−１群又はＢ−２群）化合物の含有量
次に、Ｂ群（Ｂ−１群又はＢ−２群を単にＢ群と称する）の化合物の含有量について説明する。かかるＢ群の化合物の含有量を、陽極層１０の全体量を１００ａｔ．％としたときに、０．５〜３０ａｔ．％の範囲内の値とすることが好ましい。この理由は、Ｂ群の化合物の含有量が０．５ａｔ．％未満となると、陽極層１０のイオン化ポテンシャルの調整性が悪化するためである。具体的には、イオン化ポテンシャルを５．６５〜６．４０ｅＶの範囲内に調整することが困難となる場合があるためである。一方、Ｂ群の化合物の含有量が３０ａｔ．％を超えると、導電性が低下したり、着色したり、あるいは透明性（光透過率）が低下する場合があるためである。
【００７０】
したがって、陽極層１０におけるイオン化ポテンシャルの値の調整性と、透明性等とのバランスがより良好となることから、Ｂ群の化合物の含有量を、陽極層の全体量を１００ａｔ．％としたときに、０．８〜２０ａｔ．％の範囲内の値とすることがより好ましく、１〜１０ａｔ．％の範囲内の値とすることがよりさらに好ましい。
【００７１】
Ａ群（Ａ−１群又はＡ−２群）化合物の含有量
なお、Ａ群（Ａ−１群又はＡ−２群を単に、Ａ群と称する）の無機化合物の含有量は、陽極層１０をＡ群（Ａ−１群又はＡ−２群）及びＢ群（Ｂ−１群又はＢ−２群）の化合物から構成する場合には、全体量である１００ａｔ．％から、かかるＢ群の化合物の含有量を差し引いた値となる。したがって、Ｂ群の化合物の含有量が陽極層１０の中で０．５〜３０ａｔ．％の範囲内の値の場合は、Ａ群の無機化合物の陽極層１０中の含有量は、７０〜９９．５ａｔ．％の範囲内の値となる。
【００７２】
ただし、陽極層１０内に、Ａ群及びＢ群以外の化合物（第三成分）を含む場合には、当該第三成分の含有量を考慮して、Ａ群の無機化合物の含有量を定めることが好ましい。
【００７３】
陽極層の膜厚及び構造
また、陽極層１０の膜厚は、特に制限されるものではないが、具体的に、０．５〜１０００ｎｍの範囲内の値とするのが好ましい。この理由は、陽極層１０の膜厚が０．５ｎｍ未満となると、長期間使用した場合に、ピンホールが生じて、リーク電流が観察される場合があるためであり、一方、陽極層１０の膜厚が１０００ｎｍを超えると、電極の透明性が低くなり、発光輝度が低下する場合があるためである。したがって、耐久性と駆動電圧の値等のバランスがより良好となるため、陽極層１０の膜厚を１．０〜８００ｎｍの範囲内の値とするのがより一層好ましく、２．０〜３００ｎｍの範囲内の値とするのがさらにより一層好ましい。また、陽極層１０の構造についても、特に制限されるものでなく、単層構造であっても、二層以上の複層構造であっても良い。したがって、より高い透明性（光透過率）やより高い導電性を得たい場合には、より透明性の高い導電電極層やより導電性の高い導電電極層、例えばＩＴＯやＩｎ２　Ｏ３　−ＺｎＯ上に積層し、二層構造とすることもできる。
【００７４】
陽極層の比抵抗
次に、陽極層１０の比抵抗について説明する。かかる比抵抗の値は特に制限されるものではないが、例えば、１Ω・ｃｍ未満の値とすることが好ましい。この理由は、比抵抗の値が１Ω・ｃｍ以上となると、画素内の発光の不均一性が生じるほか、製造する有機ＥＬ素子の駆動電圧が高くなる場合があるためである。したがって、より低い駆動電圧を達成するために、陽極層１０の比抵抗を４０ｍΩ・ｃｍ以下の値とするのがより好ましく、１ｍΩ・ｃｍ以下の値とするのがさらにより好ましい。なお、陽極層１０の比抵抗の値は、四探針法抵抗測定機を用いて、表面抵抗を測定した上、別途膜厚を測定することにより、算出することができる。
【００７５】
陽極層の形成方法
次に、陽極層１０を形成する方法について説明する。かかる形成方法は特に特定の方法に制限されるものではない。例えば、スパッタリング法、蒸着法、スピンコート法、キャスト法を用いたゾルゲル法、スプレイパイロリシス法、イオンプレーティング法等の方法を採ることができる。特に、高周波マグネトロンスパッタリング法を採ることが好ましい。具体的には、真空度１×１０^−７〜１×１０^−３Ｐａ、成膜速度０．０１〜５０ｎｍ／秒、基板温度−５０〜３００℃の条件でスパッタリングすることが好ましい。
【００７６】
（２）有機発光層
次に、有機発光層の説明を行う。
【００７７】
有機発光層の構成材料
有機発光層１４の構成材料として使用する有機発光材料は、以下の３つの機能を併せ持つことが好ましい。
【００７８】
（ａ）電荷の注入機能：電界印加時に陽極あるいは正孔注入層から正孔を注入することができるとともに、陰極層あるいは電子注入層から電子を注入することができる機能。
【００７９】
（ｂ）輸送機能：注入された正孔及び電子を電界の力で移動させる機能。
【００８０】
（ｃ）発光機能：電子と正孔の再結合の場を提供し、これらを発光につなげる機能。
【００８１】
ただし、上記（ａ）〜（ｃ）の各機能全てを併せ持つことは、必ずしも必要ではなく、例えば正孔の注入輸送性が電子の注入輸送性より大きく優れているものの中にも有機発光材料として好適なものがある。したがって、有機発光層１４における電子の移動が促進されて、有機発光層１４の内部の中央付近で正孔と電子が再結合可能な材料であれば好適に使用することができる。
【００８２】
ここで、有機発光層１４における再結合性を向上させるために、有機発光材料の電子移動度を、１×１０^−７ｃｍ^２　／Ｖ・ｓ以上の値とするのが好ましい。この理由は、１×１０^−７ｃｍ^２　／Ｖ・ｓ未満の値となると、有機ＥＬ素子における高速応答が困難となったり、発光輝度が低下する場合があるためである。したがって、有機発光材料の電子移動度を、１．１×１０^−７〜２×１０^−３ｃｍ^２　／Ｖ・ｓの範囲内の値とするのがより好ましく、１．２×１０^−７−７〜１．０×１０^−３ｃｍ^２　／Ｖ・ｓの範囲内の値とするのがさらに好ましい。
【００８３】
また、有機発光層１４における有機発光材料の正孔移動度よりも、電子移動度の値を小さくするのが好ましい。この関係が逆の場合には、有機発光層１４に使用可能な有機発光材料が過度に制限される場合があり、また、発光輝度が低下する場合があるためである。一方、有機発光材料の電子移動度を、正孔移動度の値の１／１０００よりも大きくすることが好ましい。電子移動度が過度に小さくなると、有機発光層１４の内部の中央近傍で正孔と電子が再結合することが困難となり、やはり発光輝度が低下する場合があるためである。したがって、有機発光層１４における有機発光材料の正孔移動度（μｈ　）と電子移動度（μｅ　）とが、μｈ　／２＞μｅ　＞μｈ　／５００の関係を満足するのがより好ましく、μｈ　／３＞μｅ　＞μｈ　／１００の関係を満足するのがさらに好ましい。
【００８４】
また、本第１の実施形態において、有機発光層１４には、上述した一般式（１）〜（３）で表されるスチリル基を有する芳香族環化合物を使用することが好ましい。このようなスチリル基を有する芳香族環化合物を使用することにより、上述した有機発光層１４における有機発光材料の電子移動度及び正孔移動度の条件を容易に満足することができる。一般式（１）〜（３）における炭素数が６〜４０の芳香族基のうち、好ましい核原子数５〜４０のアリール基としては、フェニル、ナフチル、アントラニル、フェナンスリル、ピレニル、コロニル、ビフェニル、ターフェニル、ピローリル、フラニル、チオフェニル、ベンゾチオフェニル、オキサジアゾリル、ジフェニルアントラニル、インドリル、カルバゾリル、ピリジル、ベンゾキノリル等が挙げられる。
【００８５】
また、好ましい核原子数５〜４０のアリーレン基としては、フェニレン、ナフチレン、アントラニレン、フェナンスリレン、ピレニレン、コロニレン、ビフェニレン、ターフェニレン、ピローリレン、フラニレン、チオフェニレン、ベンゾチオフェニレン、オキサジアゾリレン、ジフェニルアントラニレン、インドリレン、カルバゾリレン、ピリジレン、ベンゾキノリレン等が挙げられる。なお、炭素数が６〜４０の芳香族基は、さらに置換基により置換されていても良く、好ましい置換基としては、炭素数１〜６のアルキル基（エチル基、メチル基、ｉ−プロピル基、ｎ−プロピル基、ｓ−ブチル基、ｔ−ブチル基、ペンチル基、ヘキシル基、シクロペンチル基、シクロヘキシル基等）、炭素数１〜６のアルコキシ基（エトキシ基、メトキシ基、ｉ−プロポキシ基、ｎ−プロポキシ基、ｓ−ブトキシ基、ｔ−ブトキシ基、ペントキシ基、ヘキシルオキシ基、シクロペントキシ基、シクロヘキシルオキシ基等）、核原子数５〜４０のアリール基、核原子数５〜４０のアリール基で置換されたアミノ基、核原子数５〜４０のアリール基を有するエステル基、炭素数１〜６のアルキル基を有するエステル基、シアノ基、ニトロ基、ハロゲン原子が挙げられる。
【００８６】
また、有機発光層１４に、ベンゾチアゾール系、ベンゾイミダゾール系、ベンゾオキサゾール系等の蛍光増白剤や、スチリルベンゼン系化合物、８−キノリノール誘導体を配位子とする金属錯体を併用することも好ましい。また、ジスチリルアリーレン骨格の有機発光材料、例えば４，４’一ビス（２，２−ジフェニルビニル）ビフェニル等をホストとし、当該ホストに青色から赤色までの強い蛍光色素、例えばクマリン系あるいはホストと同様の蛍光色素をドープしたものを併用することも好適である。
【００８７】
有機発光層の形成方法
次に、有機発光層１４を形成する方法について説明する。かかる形成方法は特定の方法に限定されるものではない。例えば、真空蒸着法、スピンコート法、キャスト法、ＬＢ法、スパッタリング法等の方法を採用することができる。例えば、真空蒸着法により形成する場合は、蒸着温度５０〜４５０℃、真空度１×１０^−７〜１×１０^−３Ｐａ、成膜速度０．０１〜５０ｎｍ／秒、基板温度−５０〜３００℃の条件を採ることが好ましい。
【００８８】
また、結着剤と有機発光材料とを所定の溶剤に溶かして溶液状態とした後、これをスピンコート法等により薄膜化することによっても、有機発光層１４を形成することができる。なお、有機発光層１４は、形成方法や形成条件を適宜選択し、気相状態の材料化合物から沈着されて形成された薄膜や、溶液状態又は液相状態の材料化合物から固体化されて形成された膜である分子堆積膜とすることが好ましい。通常、この分子堆積膜は、ＬＢ法により形成された薄膜（分子累積膜）とは、凝集構造や高次構造の相違や、それに起因する機能的な相違により十分に区別することができる。
【００８９】
有機発光層の膜厚
有機発光層１４の膜厚については特に制限はなく、状況に応じて適宜適切な膜厚を選択することができるが、現実には５ｎｍ〜５μｍの範囲内の値が好ましい場合が多い。この理由は、有機発光層の膜厚が５ｎｍ未満となると、発光輝度や耐久性が低下する場合があり、一方、有機発光層１４の膜厚が５μｍを超えると、印加電圧の値が高くなる場合が多いためである。したがって、発光輝度や印加電圧の値等とのバランスがより良好となることから、有機発光層１４の膜厚を１０ｎｍ〜３μｍの範囲内の値とすることがより好ましく、２０ｎｍ〜１μｍの範囲内の値とすることがさらに好ましい。
【００９０】
（３）陰極層
陰極層１６には、仕事関数の小さい（例えば、４．０ｅＶ未満の）金属、合金、電気電導性化合物又はこれらの混合物を使用することが好ましい。具体的には、マグネシウム、アルミニウム、インジウム、リチウム、ナトリウム、セシウム、銀等の一種を単独で、又は二種以上を組み合わせて使用することができる。また陰極層１６の厚さも特に制限されるものではないが、１０〜１０００ｎｍの範囲内の値とするのが好ましく、１０〜２００ｎｍの範囲内の値とするのがより好ましい。
【００９１】
（４）その他
また、図１には示さないが、有機ＥＬ素子１００への水分や酸素の侵入を防止するための封止層を、有機ＥＬ素子１００全体を覆うように設けることも好ましい。好ましい封止層の材料としては、テトラフルオロエチレンと、少なくとも一種のコモノマーとを含むモノマー混合物を共重合させて得られる共重合体；共重合主鎖中に環状構造を有する合フッ素共重合体；ポリエチレン、ポリプロピレン、ポリメチルメタクリレート、ポリイミド、ポリユリア、ポリテトラフルオロエチレン、ポリクロロトリフルオロエチレン、ポリジクロロジフルオロエチレン又はクロロトリフルオロエチレンとジクロロジフルオロエチレンとの共重合体等が挙げられる。
【００９２】
さらに、好ましい封止層の材料としては、吸収率１％以上の吸水性物質；吸水率０．１％以下の防湿性物質；Ｉｎ，Ｓｎ，Ｐｂ，Ａｕ，Ｃｕ，Ａｇ，Ａｌ，Ｔｉ，Ｎｉ等の金属；ＭｇＯ，ＳｉＯ，ＳｉＯ_２２，ＧｅＯ，ＮｉＯ，ＣａＯ，ＢａＯ，Ｆｅ_２Ｏ，Ｙ_２Ｏ_３　，ＴｉＯ_２　等の金属酸化物；ＭｇＦ_２　，ＬｉＦ，ＡｌＦ_３　，ＣａＦ_２　等の金属フッ化物；パーフルオロアルカン，パーフルオロアミン，パーフルオロポリエーテル等の液状フッ素化炭素；及び当該液状フッ素化炭素に水分や酸素を吸着する吸着剤を分散させた組成物等が挙げられる。
【００９３】
また、封止層の形成にあたっては、真空蒸着法、スピンコート法、スパッタリング法、キャスト法、ＭＢＥ（分子線エピタキシー）法、クラスターイオンビーム蒸着法、イオンプレーティング法、プラズマ重合法（高周波励超イオンプレーティング法）、反応性スパッタリング法、プラズマＣＶＤ法、レーザーＣＶＤ法、熱ＣＶＤ法、ガスソースＣＶＤ法等を適宜採用することができる。
【００９４】
［第２の実施形態］
次に、図２を参照して、この発明の第２の実施形態について説明する。図２は、第２の実施形態における有機ＥＬ素子１０２の断面図であり、陽極層１０、無機薄膜層１２、有機発光層１４及び陰極層１６を、基板上（図示せず。）に順次に積層した構造を有していることを表している。このように無機薄膜層１２を設けることにより、注入された正孔を効率的に輸送することができる。したがって、無機薄膜層１２を設けることにより、有機ＥＬ素子１０２の低電圧駆動が可能となるとともに、耐久性も向上する。
【００９５】
なお、第２の実施形態の有機ＥＬ素子１０２における特徴的な事項は、陽極層１０と、有機発光層１４との間に、無機薄膜層１２を挿入してあることである。
【００９６】
この点以外は、第１の実施形態の有機ＥＬ素子１００と同一の構造を有している。
【００９７】
したがって、以下の説明は、主に、第２の実施形態における特徴的な部分である無機薄膜層１２についてのものであり、その他の構成部分、例えば陰極層１６等については、第１の実施形態と同様の構成であるので第１の実施の形態の説明を参照されたい。
【００９８】
まず、無機薄膜層１２を構成する無機化合物としては、上述した陽極層１０を構成するＡ群（Ａ−１群又はＡ−２群）及びＢ群（Ｂ−１群又はＢ−２群）の化合物の組み合わせが挙げられる。したがって、かかるＢ群の化合物の含有量を、陽極層１０と同様に、無機薄膜層の全体量を１００ａｔ．％としたときに、０．５〜５０ａｔ．％の範囲内の値とすることが好ましく、１．０〜４０ａｔ．％の範囲内の値とすることがより好ましく、５．０〜３０ａｔ．％の範囲内の値とすることがさらに好ましい。また、その膜厚や形成方法についても、陽極層１０と同様の構成とすることが好ましい。
【００９９】
ただし、陽極層１０と有機発光層１４との間に無機薄膜層１２を設ける場合には、陽極層１０と無機薄膜層１４との組成を異ならせる必要がある。具体的に、陽極層１０には、Ａ群（Ａ−１群又はＡ−２群）／Ｂ群（Ｂ−１群又はＢ−２群）＝７０〜９０ａｔ．％／０．５〜１０ａｔ．％からなる化合物を使用し、一方、無機薄膜層１２には、Ａ群（Ａ−１群又はＡ−２群）／Ｂ群（Ｂ−１群又はＢ−２群）＝５０〜９０ａｔ．％未満／１０ａｔ．％超〜５０ａｔ．％からなる無機化合物を使用することが好ましい。この理由は、Ｂ群（Ｂ−１群又はＢ−２群）の化合物量がこの範囲外となると、透明性が低下したり、比抵抗が大きくなり、電極として好ましくないためである。
【０１００】
［第３の実施形態］
次に、図３を参照して、この発明の第３の実施形態について説明する。図３は、第３の実施形態における有機ＥＬ素子１０４の断面図であり、陽極層１０、無機薄膜層１２、正孔輸送層１３、有機発光層１４及び陰極層１６を、基板上（図示せず。）に順次に積層した構造を有していることを表している。
【０１０１】
本第３の実施の形態においては、第１や第２の実施の形態に加え、正孔輸送層１３をさらに設けることにより、注入された正孔を効率的に輸送することができる。したがって、正孔輸送層１３を設けることにより、有機ＥＬ素子１０４の低電圧駆動が可能となるとともに、耐久性も向上する。
【０１０２】
なお、本第３の実施形態の有機ＥＬ素子１０４は、無機薄膜層１２と、有機発光層１４との間に、正孔輸送層１３を挿入してある点を除いては、第２の実施形態の有機ＥＬ素子１０２と同一の構造を有している。したがって、以下の説明は、第３の実施形態における特徴的な部分である正孔輸送層１３を中心に行う。その他の構成部分、例えば陰極層１６等については、第１及び第２の実施形態と同様の構成とすることができるので、上記第１及び第２の実施の形態の説明を参照されたい。
【０１０３】
（１）正孔輸送層１３の構成材料
正孔輸送層１３は、有機化合物又は無機化合物で構成することが好ましい。このような有機材料としては、例えば、フタロシアニン化合物、ジアミン化合物、含ジアミンオリゴマー及び含チオフェンオリゴマー等を挙げることができる。また、好ましい無機化合物の材料としては、例えば、アモルファスシリコン（α−Ｓｉ）、α−ＳｉＣ、マイクロクリスタルシリコン（μＣ−Ｓｉ）、μＣ−ＳｉＣ、ＩＩ−ＶＩ族化合物、ＩＩＩ　−Ｖ族化合物、非晶質炭素、結晶質炭素及びダイヤモンド等を挙げることができる。また、別種の無機材料として、酸化物、フッ化物及びチッ化物が挙げられ、より具体的には、Ａｌ_２Ｏ_３、ＳｉＯ、ＳｉＯｘ　（１≦ｘ≦２）、ＧａＮ、ＩｎＮ、ＧａＩｎＮ、ＧｅＯｘ　（１≦ｘ≦２）、ＬｉＦ、ＳｒＯ、ＣａＯ、ＢａＯ、ＭｇＦ_２、ＣａＦ_２、ＵｇＦ_２、ＳｉＮｘ　（１≦ｘ≦４／３）等の一種単独又は二種以上の組み合わせが挙げられる。また、正孔移動度が１×１０^６ｃｍ^２／Ｖ・秒以上の値（印加電圧１×１０^４〜１×１０^６　Ｖ／ｃｍ）であり、かつ、イオン化ポテンシャルの値が５．５ｅＶ以下の値となるように構成材料を選択することが好ましい。
【０１０４】
（２）正孔輸送層１３の構造及び形成方法
また、正孔輸送層１３は、一層構造に限らず、例えば、二層構造又は三層構造であっても良い。さらに、正孔輸送層１３の膜厚についても特に制限されるものではないが、例えば０．５ｎｍ〜５μｍの範囲内の値とするのが好ましい。また、正孔輸送層１３の形成方法についても特に制限はなく種々の方法を採用可能である。しかし現実的には、正孔注入層の形成方法と同様の方法を採ることが好ましい。
【０１０５】
［第４の実施形態］
次に、図４を参照して、この発明の第４の実施形態について説明する。図４は、第４の実施形態における有機ＥＬ素子１０６の断面図であり、陽極層１０、無機薄膜層１２、正孔輸送層１３、有機発光層１４、電子注入層１５及び陰極層１６を、基板上（図示せず。）に順次に積層した構造を有していることを表している。このように、本題４の実施の形態においては、電子注入層１５を設けることにより、電子を効率的に注入する機能を発揮することができる。したがって、電子注入層１５を設けることにより、電子の有機発光層１４への移動が容易となり、有機ＥＬ素子１０６の応答性能が改善される。
【０１０６】
なお、第４の実施形態における有機ＥＬ素子１０６の特徴的な点は、有機発光層１４と陰極層１６との間に、電子注入層１５を挿入してある点である。この点除けば、第４の実施の形態の有機ＥＬ素子１０６は、第３の実施形態の有機ＥＬ素子１０４と同一の構造を有している。したがって、以下の説明は、第４の実施形態における特徴的な部分である電子注入層１５を中心に行い、その他の構成部分については、上で述べた第１〜第３の実施の形態と同様の構成、もしくは有機ＥＬ素子の分野において一般的に公知な構成、を採用することができる。
【０１０７】
（１）電子注入層の構成材料
電子注入層１５は、有機化合物あるいは無機化合物から構成することが好ましい。特に、有機化合物から構成することにより、陰極からの電子の注入性や耐久性により優れた有機ＥＬ素子とすることができる。ここで、好ましい有機化合物としては、８―ヒドロキシキノリンやオキサジアゾール、あるいはこれらの誘導体、例えば、８―ヒドロキシキノリンを含む金属キレートオキシノイド化合物等が挙げられる。
【０１０８】
また、電子注入層１５を無機化合物で構成する場合、この無機化合物として、絶縁体又は半導体を使用することが好ましい。電子注入層１５が絶縁体や半導体で構成されていれば、電流のリークを有効に防止して、電子注入性を向上させることができるのである。このような絶縁体としては、アルカリ金属カルコゲナイド（酸化物、硫化物、セレン化物、テルル化物）、アルカリ土類金属カルコゲナイド、アルカリ金属のハロゲン化物及びアルカリ土類金属のハロゲン化物からなる群から選択される少なくとも一つの金属化合物を使用するのが好ましい。電子注入層１５がこれらのアルカリ金属カルコゲナイド等で構成されていれば、電子注入性をさらに向上させることができる点で好ましい。
【０１０９】
具体的に、好ましいアルカリ金属カルコゲナイドとしては、例えば、Ｌｉ_２Ｏ、ＬｉＯ、Ｎａ_２Ｓ、Ｎａ_２Ｓｅ及びＮａＯが挙げられる。好ましいアルカリ土類金属カルコゲナイドとしては、例えば、ＣａＯ、ＢａＯ、ＳｒＯ、ＢｅＯ、ＢａＳ、及びＣａＳｅが挙げられる。また、好ましいアルカリ金属のハロゲン化物としては、例えば、ＬｉＦ、ＮａＦ、ＫＦ、ＬｉＣｌ、ＫＣｌ及びＮａＣｌ等が挙げられる。また、好ましいアルカリ土類金属のハロゲン化物としては、例えば、ＣａＦ_２、ＢａＦ_２、ＳｒＦ_２、ＭｇＦ_２及びＢｅＦ_２といったフッ化物や、フッ化物以外のハロゲン化物が挙げられる。
【０１１０】
また、電子注入層１５を半導体で構成する場合、好ましい半導体としては、Ｂａ、Ｃａ、Ｓｒ、Ｙｂ、Ａｌ、Ｇａ、Ｉｎ、Ｌｉ、Ｎａ、Ｃｄ、Ｍｇ、Ｓｉ、Ｔａ、Ｓｂ及びＺｎの少なくとも一つの元素を含む酸化物、窒化物又は酸化窒化物等の一種単独又は二種以上の組み合わせが挙げられる。また、電子注入層１５を構成する無機化合物は、微結晶又は非晶質の絶縁性薄膜であることが好ましい。電子注入層１５がこれらの絶縁性薄膜で構成されていれば、より均質な薄膜が形成されるために、ダークスポット等の画素欠陥を減少させることができる。なお、このような無機化合物としては、上述したアルカリ金属カルコゲナイド、アルカリ土類金属カルコゲナイド、アルカリ金属のハロゲン化物及びアルカリ土類金属のハロゲン化物等が挙げられる。
【０１１１】
（２）電子親和力
また、第４の実施形態における電子注入層１５の電子親和力は、１．８〜３．６ｅＶの範囲内の値とすることが好ましい。電子親和力の値が１．８ｅＶ未満となると、電子注入性が低下し、駆動電圧の上昇，発光効率の低下をまねく傾向があり、一方で、電子親和力の値が３．６ｅＶを超えると、発光効率の低い錯体が発生しやすくなったり、ブロッキング接合の発生を効率的に抑制することができる。したがって、電子注入層の電子親和力を、１．９〜３．０ｅＶの範囲内の値とすることがより好ましく、さらに２．０〜２．５ｅＶの範囲内の値とすることがより一層好ましい。また、電子注入層１５と有機発光層１４との電子親和力の差を１．２ｅＶ以下の値とすることが好ましく、０．５ｅＶ以下の値とすることがより好ましい。この電子親和力の差が小さいほど、電子注入層１５から有機発光層１４への電子注入が容易となり、応答性能が改善された有機ＥＬ素子１０６を構成することができる。
【０１１２】
（３）エネルギーギャップ
また、第４の実施形態における電子注入層１５のエネルギーギャップ（バンドギャップエネルギー）を２．７ｅＶ以上の値とすることが好ましく、３．０ｅＶ以上の値とすることがより好ましい。このように、エネルギーギャップの値を所定値以上、例えば２．７ｅＶ以上と大きな値とすることによって、正孔が有機発光層１４を超えて電子注入層１５に移動してしまうことを少なくすることができる。したがって、正孔と電子との再結合の効率が向上し、有機ＥＬ素子１０６の発光輝度が高まるとともに、電子注入層１５自体が発光することを回避することができる。
【０１１３】
（４）構造
次に、無機化合物からなる電子注入層１５の構造について説明する。かかる電子注入層１５の構造は特に制限されるものではなく、例えば、一層構造であっても良く、あるいは、二層構造又は三層構造であっても良い。また、電子注入層１５の厚さについても特に制限はなく、状況により種々の厚みを採用することができる。現実的には、例えば０．１ｎｍ〜１０００ｎｍの範囲内の値とするのが好ましい。この理由は、無機化合物からなる電子注入層１５の厚さが０．１ｎｍ未満となると、電子注入性が低下したり、あるいは機械的強度が低下する場合があるためである。その一方、無機化合物からなる電子注入層１５の厚さが１０００ｎｍを超えると、高抵抗となるため、有機ＥＬ素子１０６の応答性能が劣化、すなわち高速応答が困難となったり、あるいは成膜に長時間を要する場合があるためである。したがって、無機化合物からなる電子注入層１５の厚さは０．５〜１００ｎｍの範囲内の値とするのがより好ましく、１〜５０ｎｍの範囲内の値とするのがより一層好ましい。
【０１１４】
（５）形成方法
次に、電子注入層１５を形成する方法について説明する。電子注入層１５の形成方法については、均一な厚さを有する薄膜層として形成できれば特に制限があるものではない。例えば、真空蒸着法、スピンコート法、キャスト法、ＬＢ法、スッパリング法等、各種の方法を適用することができる。
【０１１５】
［第５の実施形態］
次に、本発明の第５の実施形態について説明する。第５の実施形態は、複数の無機化合物を用いた場合であっても、構成材料の組成比が均一である、エッチング特性や透明性に優れた陽極層１６が得られる。結果として、駆動電圧が小さく、しかも発光輝度や耐久性に優れた有機ＥＬ素子が効率的に得られる製造方法を提供するものである。すなわち、第５の実施形態においては、特定のターゲット及びスパッタリング法を用いて、陽極層１６を形成することを第１の特徴としている。また、第５の実施形態は、例えば、複数の有機発光材料を用いた場合であっても、構成材料の組成比が均一な有機発光層１４が得られる。結果として、駆動電圧が小さく、高い発光輝度が得られ、しかも耐久性に優れた有機ＥＬ素子が効率的に得られる製造方法を提供するものである。すなわち、第５の実施形態においては、特定の真空蒸着法を用いて、複数の有機化合物から有機発光層１４を形成することを第２の特徴としている。
【０１１６】
構成材料の組成比が均一であるという特性を有する有機ＥＬ素子を得るために、少なくとも陽極層１０と有機発光層１４とを、大気に露出せず、一貫した同一真空条件で形成することが好ましい。第５の実施形態においては、スパッタリング法を実施する真空槽と真空蒸着法を実施する真空槽とを共用していることを第３の特徴としている。その理由は、構成材料の組成比が均一な特性を有する有機ＥＬ素子を得るためである。そこで、第５の実施形態においては、一つの真空槽内に、スパッタリング法を実施するために必要な加熱装置及び、基板保持手段のみならず、真空蒸着法を実施するするために必要な加熱装置、蒸着源等を備えることにより、スパッタリング法を実施する真空管と真空蒸着法を実施する真空槽とを共有することができる。なお、第５の実施形態の変形例として、スパッタリング用の真空槽と真空蒸着用の真空槽とをそれぞれ別途に設け、それらを予め連結しておく構成も採用可能である。このような変形よれば、真空蒸着法を実施した後所定の搬送装置により基板をスパッタリング法用の真空槽内に移動させることによって、真空槽を共有する場合と同様の結果が得られる。また、本第５の実施の形態で説明する有機ＥＬ素子の構成は、理解の容易のため、第４の実施形態と同様としてある。
【０１１７】
第５の実施形態において採用した製造方法によれば、下記に示す各層を、それぞれに対応する製法により形成した。
【０１１８】
陽極層１０：　高周波マグネトロンスパッタリング法
無機薄膜層１２：高周波マグネトロンスパッタリング法
正孔輸送層１３：真空蒸着法
有機発光層１４：真空蒸着法
電子注入層１５：真空蒸着法
陰極層１６：　真空蒸着法
（１）陽極層及び無機薄膜層の形成
陽極層１０及び無機薄膜層１２を高周波マグネトロンスパッタリング法で形成するにあたり、Ａ群（Ａ−１群又はＡ−２群）及びＢ群（Ｂ−１群又はＢ−２群）の化合物からなるターゲットを用いることが好ましい。具体的には、ターゲットは、少なくともＡ群（Ａ−１群又はＡ−２群）及びＢ群（Ｂ−１群又はＢ−２群）を所定割合で含んでいなければならない。また、原材料であるターゲット（平均粒子径１μｍ以下）は、溶液法（共沈法）（濃度：０．０１〜１０ｍｏｌ／リットル、溶媒：多価アルコール等、沈殿形成剤：水酸化カリウム等）、物理混合法（撹拌機：ボールミル、ビーズミル等、混合時間：１〜２００時間）を用いることにより均一に混合された後、焼結（温度１２００〜１５００℃、時間１０〜７２時間、より好ましくは、２４〜４８時間）し、さらに成型（プレス成型やＨＩＰ成型等）して得られたものが好ましい。このときに、成型する際の昇温速度を１〜５０℃／分の範囲内の値とするのがより好ましい。これらの方法により得られたターゲットは、構成材料の組成比が均一あるという特性を有しているという特徴がある。なお、スパッタリング条件だけで組成比等を調節することができることから、Ａ群（Ａ−１群又はＡ−２群）及びＢ群（Ｂ−１群又はＢ−２群）の化合物を、それ別個に、スパッタリングすることも好ましい。
【０１１９】
また、スパッタリングの条件は、特に制限されるものでないが、アルゴン等の不活性ガス中、プラズマ出力をターゲットの表面積１ｃｍ^２　あたり０．３〜４Ｗ、真空度１×１０^−７〜１×１０^−３Ｐａ、成膜速度０．０１〜５０ｎｍ／秒、成膜時間５〜１２０分、基板温度−５０〜３００℃の条件を採ることが好ましい。このようなスパッタリング条件であれば経済的であり、また、均一な膜厚を有する緻密な陽極層１６及び無機薄膜層１２を形成することができるからである。
【０１２０】
（２）有機発光層１４の形成
図５及び図６を参照して、異なる蒸着材料を同時に蒸発させて有機発光層１４を形成する方法を説明する。まず、真空蒸着装置２０１を用い、基板２０３に当該基板２０３を自転させるための回転軸線２１３Ａを設定する。次に、蒸着源２１２Ａ〜２１２Ｆをそれぞれ基板２０３の回転軸線２１３Ａから離れた位置に配設し、基板２０３を自転させる。それと同時に、当該基板２０３に対向して配置した複数の蒸着源２１２Ａ〜２１２Ｆから異なる蒸着材料を同時に蒸発させて蒸着を行う。このようにして、有機発光層１４を得ることができる。
【０１２１】
ここで、図５及び図６に示す真空蒸着装置２０１は、真空槽２１０と、この真空槽２１０内の上部に設置された基板２０３を固定するための基板ホルダ２１１と、この基板ホルダ２１１の下方に対向配置された蒸着材料を充填するための複数（６個）の蒸着源２１２Ａ〜２１２Ｆとを含んで構成されている。この真空槽２１０は、排気手段（図示せず）により、内部を所定の減圧状態に維持できるようになっている。なお、蒸着源の数は、図面上６つ示されているが、これに限定されるものではなく、５つ以下であっても良く、あるいは７つ以上であっても良い。
【０１２２】
また、基板ホルダ２１１は、基板２０３の周縁部を支持する保持部２１２を備え、真空槽２１０内で、基板２０３を水平に保持するように構成されている。この基板ホルダ２１１の上面の中央部分には、基板２０３を回転（自転）させるための回転軸部２１３が垂直方向に立設されている。この回転軸部２１３には、回転騒動手段であるモータ２１４が接続され、モータ２１４の回転動作により、基板ホルダ２１１に保持された基板２０３が、当該基板ホルダ２１１とともに回転軸部２１３を回転中心として自転するようになっている。すなわち、基板２０３の中心には、回転軸部２１３による回転軸線２１３Ａが垂直方向に設定されている。
【０１２３】
次に、このように構成された真空蒸着装置２０１を用いて、二種類の有機発光材料（ホスト材料とドーパント材料）から、有機発光層１２を基板２０３上に成膜する方法について、具体的に説明する。まず、図５に示すような平面正方形状の基板２０３を用意し、この基板２０３を基板ホルダ２１１の保持部２１２に係止して水平な状態とする。この点、図５に示す基板２０３が水平状態に保持されているということは、基板２０３が基板ホルダ２１１の保持部２１２に係止して水平な状態であることを示している。
【０１２４】
ここで、有機発光層１２を成膜するにあたり、仮想円２２１上で、隣接する二つの蒸着源２１２Ｂ及び２１２Ｃに、ホスト材料とドーパント材料とをそれぞれ充填する。充墳の後、排気手段により真空槽２１０内を所定の真空度、例えば１．０×１０−４Ｔｏｒｒになるまで減圧する。次いで、蒸着源２１２Ｂ及び２１２Ｃを加熱して、各蒸着源２１２Ｂ及び２１２Ｃからそれぞれホスト材料とドーパント材料とを同時に蒸発させる。それと同時に、モータ２１４を回転騒動させて、基板２０３を回転軸線２１３Ａに沿って所定速度、例えば１〜１００ｒｐｍで回転させる。このようにして、基板２０３を自転させながらホスト材料とドーパント材料とを共蒸着して有機発光層１２を成膜する。このとき、図６に示すように、蒸着源２１２Ｂ及び２１２Ｃは、基板２０３の回転軸線２１３Ａから、水平方向に所定距離Ｍだけずれた位置に設けられているので、基板２０３の回転により、ホスト材料やドーパント材料等の蒸着材料における基板２０３への入射角度を規則的に変化させることができる。したがって、蒸着材料を基板２０３に対して一様に付着させることができ、電子注入層１５の膜面内で、蒸着材料の組成比が均一である薄膜層を確実に成膜することができる。例えば、濃度ムラが±１０％（モル換算）である薄膜層を成膜することができることである。また、このように蒸着を実施することにより、基板２０３を公転させなくても良いので、そのスペースや設備が不要になり、最小限のスペースで経済的に成膜を行うことができる。ここで、基板２０３を公転させるとは、基板以外に存在する回転軸の周りを回転させることをいい、自転させる場合よりも広い空間が必要となる。
【０１２５】
また、同時蒸着を実施するにあたり、基板２０３の形状は特に限定されることはない。一例として、図５に示すように、基板２０３が短形平板状であり、基板２０３の辺の長さがそれぞれ同一である場合には、この基板２０３の回転軸線２１３Ａを中心とする仮想円２２１の円周上に沿って複数の蒸着源２１２Ａ〜２１２Ｆを配設し、仮想円２２１の半径をＭ、基板２０３の一辺の長さをＬとしたときに、Ｍ＞（１／２）×Ｌを満足ような短形平板状であることが望ましい。これに対し、基板２０３の辺の長さがそれぞれ同一でなく、異なる場合には、最も長い辺の長さをＬとする。このように構成することにより、複数の蒸着源２１２Ａ〜２１２Ｆから、基板２０３に対する蒸着材料の入射角度を互いに同一にできるので、蒸着材料の組成比をより容易に制御することができる。また、このように構成することにより、蒸着材料が、基板２０３に対して一定の入射角度を以て蒸発されるため、垂直に入射することがなくなり、膜面内における組成比の均一性を一層向上させることができる。
【０１２６】
また、第５の実施形態の製造方法を実施するにあたり、図５に示すように、複数の蒸着源２１２Ａ〜２１２Ｆを、基板２０３の回転軸線２１３Ａを中心とする仮想円２２１の円周上に配設し、複数の蒸着源２１２Ａ〜２１２Ｆの配設数（個数）をｎとしたときに、各蒸着源２１２Ａ〜２１２Ｆを、仮想円２２１の中心から３６０°／ｎの角度で配設することが好ましい。例えば、蒸着源２１２を６個配設する場合には、仮想円２２１の中心から６０°の角度で配設することが好適である。このように配置すると、基板２０３の各部分に対して、複数の蒸着材料を順次重ねるように成膜できるので、膜の厚さ方向において、組成比が規則的に異なる薄膜層を容易に成膜することができる。
【０１２７】
次に、上述した同時蒸着方法により成膜した有機発光層１４における組成の均一性についてより詳細に説明する。一例として、ホスト材料としてＡｌｑを用い、ドーパント材料としてＣｓを用い、図７に示す基板２０３を５ｒｐｍで回転させながら、厚さ約１０００オングストローム（設定値）の薄膜層を以下の条件で同時蒸着した。
【０１２８】
Ａｌｑの蒸着速度：　０．１〜０．３ｎｍ／ｓ
Ｃｓの蒸着速度：　０．１〜０．３ｎｍ／ｓ
Ａｌｑ／Ｃｓの膜厚：１０００オングストローム（設定値）
なお、Ａｌｑの化学構造式は図８に示されている。
【０１２９】
次いで、図７に示すガラス基板２０３上の測定点（４Ａ〜４Ｍ）における得られた薄膜層の膜厚を、触針式膜厚計を用いて測定するとともに、Ｃｓ／Ａｌ（Ａｌｑ中のＡｌ）組成比（原子比）をＸ線光電子分光装置（ＸＰＳ）を用いて測定した。なお、図７に示すガラス基板２０３上の測定点（４Ａ〜４Ｍ）は、基板２０３の表面を、予め１６等分して、一辺の長さＰが５０ｍｍの正方形の区画を設定し、これらの区画における任意の角部（１３箇所）としたものである。得られた結果を表１に示す。
【０１３０】
【表１】

一方、ガラス基板２０３を回転させないほかは、上記同時蒸着方法と同様の蒸着条件において、厚さ約１０００オングストローム（設定値）の薄膜層を形成した。得られた薄膜層の測定点（４Ａ〜４Ｍ）におけるの膜厚及びＣｓ／Ａｌの組成比（原子比）を測定し、結果を表２に示す。
【０１３１】
【表２】

これらの結果から明らかなように、上述した同時蒸着方法によれば、基板２０３上の測定点（４Ａ〜４Ｍ）にて、膜厚が１００８〜１０９３オングストロームの範囲内という極めて均一な厚さで、かつ、Ｃｓ／Ａｌの組成比（原子比）が１．０〜１．１０の範囲内という極めて均一な組成比である薄膜層が得られることが確認された。一方、上述した同時蒸着方法と異なる製造方法を用いた場合、基板２０３上の測定点（４Ａ〜４Ｍ）にて、膜厚が８８４〜１０６７オングストロームの範囲内の値であり、Ｃｓ／Ａｌの組成比が０．６〜１．３の範囲内の値であることが確認された。
【０１３２】
【実施例】
［実施例１］
（１）有機ＥＬ素子の製造準備（ターゲットの作成）
酸化インジウムと酸化セリウムとの粉末（平均粒子径１μｍ以下）を、Ｃｅ／（Ｉｎ＋Ｃｅ）のモル比が０．０５になるように、湿式ボールミル容器内に収容し、７２時間にわたって混合粉砕した。次いで、得られた粉砕物を造粒してから、直径４インチ、厚さ５ｍｍの寸法にプレス成形した。これを焼成炉に収容した後、１４００℃の温度で、３６時間加熱焼成し、陽極層１０用のターゲット１を製造した。
【０１３３】
（２）陽極層１０の形成
次いで、高周波スパッタリング装置と真空蒸着装置における共用の真空槽内に厚さ１．１ｍｍ、縦２５ｍｍ、横７５ｍｍの透明なガラス基板及び、得られたターゲット１を配置し、高周波スパッタリング装置を稼働して、厚さ７５ｎｍの透明電極膜を陽極層１０として形成し基板を得た。なお、真空度を３×１０^−１Ｐａまで減圧した状態で、アルゴンガスに酸素ガスを混入したガスを封入し、当該雰囲気中において、到達真空度５×１０^−４Ｐａ、基板温度２５℃、投入電力１００Ｗ、成膜時間１４分の条件で、スパッタリングした。以下、このガラス基板と陽極層１０とを併せて基板とする。続いて、この基板をイソプロピルアルコールで超音波洗浄し、さらに、Ｎ_２（窒素ガス）雰囲気中で乾燥させた後、ＵＶ（紫外線）及びオゾンを用いて１０分間洗浄した。この状態で、基板における陽極層１０のイオン化ポテンシャルの値をＡＣ−１（理研計器社製）を用いて測定したところ、６．２０ｅＶであった。また、陽極層１０を形成した基板の光透過率（波長５５０ｎｍ）を測定したところ、８９％であった。
【０１３４】
（３）真空蒸着装置における処理
真空槽の基板ホルダに基板を装着し、次いで、真空槽内を、１×１０^−６Ｔｏｒｒ以下の真空度になるまで減圧した後、基板の陽極層１０及び無機薄膜層１２上に、正孔輸送層１３、有機発光層１４、電子注入層１５及び陰極層１６を順次積層して有機ＥＬ素子を得た。なお、このとき、有機発光層１４の形成から陰極層１６の形成までの間は、一度も真空状態を破ることなく、同一真空条件であった。
【０１３５】
まず、正孔輸送材料としてＴＢＤＢを６０ｎｍ真空蒸着した。次に発光層としてＤＰＶＤＰＡＮとＤ１を真空下で４０ｎｍ共蒸着した。このときのＤＰＶＤＰＡＮの蒸着速度：は４０ｎｍ／ｓであり、Ｄ１の蒸着速度は　１ｎｍ／ｓであった。
【０１３６】
なお、ＴＢＤＢの化学構造式は、図８に示されている。また、ＤＰＶＤＰＡＮの化学構造式も、図８に示されている。また、Ｄ１の化学構造式も、図８に示されている。
【０１３７】
次いで、電子注入層としてＡｌｑを２０ｎｍ真空蒸着した。
【０１３８】
最後に、Ａｌ及びＬｉを真空蒸着し、電子注入層１５上に陰極層１６を形成し、有機ＥＬ素子とした。このときのＡｌの蒸着速度は　１ｎｍ／ｓであり、Ｌｉの蒸着速度は　０．０１ｎｍ／ｓであり、Ａｌ／Ｌｉの膜厚は２００ｎｍであった。
【０１３９】
（４）有機ＥＬ素子の評価得られた有機ＥＬ素子における陰極層１６をマイナス（−）電極、陽極層１０をプラス（＋）電極として、両電極間に４．８Ｖの直流電圧を印加した。このときの電流密度は２．０ｍＡ／ｃｍ^２であり、発光輝度は１６４ｎｉｔ（ｃｄ／ｍ^２）であった。また、発光色は青色であることを確認した。さらに、耐久性評価として、１０ｍＡ／ｃｍ^２で定電流駆動したところ、１０００時間以上経過後にも、特にリーク電流の発生は見られなかった。
【０１４０】
【表３】

【表４】

［実施例２］
実施例１におけるターゲット１のかわりに、酸化インジウムと、酸化スズと、酸化亜鉛と、酸化ネオジウムとからなる、インジウムのモル比（Ｉｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．８であり、スズのモル比（Ｓｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．１であり、亜鉛（Ｚｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））のモル比が０．１であるターゲット３を用いた。その他の製造条件は実施例１と同様にして有機ＥＬ素子を作成した。なお、陽極層１０のイオン化ポテンシャルの値は、５．８５ｅＶであった。得られた有機ＥＬ素子に実施例１と同様に、電極間に５．３Ｖの直流電圧を印加したところ、電流密度の値は２．０ｍＡ／ｃｍ^２であり、発光輝度は１５８ｎｉｔであった。また、発光色は青色であることを確認した。
【０１４１】
［実施例３］
実施例１におけるターゲット１のかわりに、酸化インジウムと、酸化スズと、酸化亜鉛と、酸化サマリウムとからなる、インジウムのモル比（Ｉｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．８であり、スズのモル比（Ｓｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．１であり、亜鉛（Ｚｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））のモル比が０．１であり、かつ、金属全体におけるサマリウムのモル比（Ｓｍ／（Ｉｎ＋Ｓｎ＋Ｚｎ＋Ｓｍ））が０．０４であるターゲット４を用いた。その他の製造条件は実施例１と同様にして有機ＥＬ素子を作成した。なお、陽極層１０のイオン化ポテンシャルの値は、５．９５ｅＶであった。得られた有機ＥＬ素子に実施例１と同様に、電極間に５．０Ｖの直流電圧を印加したところ、電流密度の値は２．０ｍＡ／ｃｍ^２であり、発光輝度は１６８ｎｉｔであった。また、発光色は青色であることを確認した。
【０１４２】
［実施例４］
実施例１におけるターゲット１のかわりに、酸化インジウムと、酸化スズと、酸化亜鉛と、酸化ユウロピウムとからなる、インジウムのモル比（Ｉｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．８であり、スズのモル比（Ｓｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．１であり、亜鉛（Ｚｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））のモル比が０．１であり、かつ、金属全体におけるユウロピウムのモル比（Ｅｕ／（Ｉｎ＋Ｓｎ＋Ｚｎ＋Ｅｕ））が０．０４であるターゲット５を用いた。その他の製造条件は実施例１と同様にして有機ＥＬ素子を作成した。なお、陽極層１０のイオン化ポテンシャルの値は、５．８０ｅＶであった。得られた有機ＥＬ素子に実施例１と同様に、電極間に５．１Ｖの直流電圧を印加したところ、電流密度の値は２．０ｍＡ／ｃｍ^２であり、発光輝度は１６５ｎｉｔであった。また、発光色は青色であることを確認した。
【０１４３】
［実施例５］
実施例１におけるターゲット１のかわりに、酸化インジウムと、酸化スズと、酸化亜鉛と、酸化テルビウムとからなる、インジウムのモル比（Ｉｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．８であり、スズのモル比（Ｓｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．１であり、亜鉛（Ｚｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））のモル比が０．１であり、かつ、金属全体におけるテルビウムのモル比（Ｔｂ／（Ｉｎ＋Ｓｎ＋Ｚｎ＋Ｔｂ））が０．０６であるターゲット６を用いた。その他の製造条件は実施例１と同様にして有機ＥＬ素子を作成した。なお、陽極層１０のイオン化ポテンシャルの値は、５．８４ｅＶであった。得られた有機ＥＬ素子に実施例１と同様に、電極間に５．１Ｖの直流電圧を印加したところ、電流密度の値は１６５ｍＡ／ｃｍ^２であり、発光輝度は９５ｎｉｔであった。また、発光色は青色であることを確認した。
【０１４４】
［実施例６］
実施例１におけるターゲット１のかわりに、酸化インジウムと、酸化スズと、酸化亜鉛と、酸化ホルニウムとからなる、インジウムのモル比（Ｉｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．８であり、スズのモル比（Ｓｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．１であり、亜鉛（Ｚｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））のモル比が０．１であり、かつ、金属全体におけるホルニウムのモル比（Ｈｏ／（Ｉｎ＋Ｓｎ＋Ｚｎ＋Ｈｏ））が０．１２であるターゲット７を用いた。その他の製造条件は実施例１と同様にして有機ＥＬ素子を作成した。なお、陽極層１０のイオン化ポテンシャルの値は、５．８２ｅＶであった。得られた有機ＥＬ素子に実施例１と同様に、電極間に５．１Ｖの直流電圧を印加したところ、電流密度の値は２．０ｍＡ／ｃｍ^２であり、発光輝度は１６６ｎｉｔであった。また、発光色は青色であることを確認した。
【０１４５】
［実施例７］
実施例１におけるターゲット１のかわりに、酸化インジウムと、酸化スズと、酸化亜鉛と、酸化セリウムとからなる、インジウムのモル比（Ｉｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．８であり、スズのモル比（Ｓｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．１であり、亜鉛（Ｚｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））のモル比が０．１であり、かつ、金属全体におけるセリウムのモル比（Ｃｅ／（Ｉｎ＋Ｓｎ＋Ｚｎ＋Ｃｅ））が０．０６であるターゲット８を用いた。その他の製造条件は実施例１と同様にして有機ＥＬ素子を作成した。なお、陽極層１０のイオン化ポテンシャルの値は、５．９８ｅＶであった。得られた有機ＥＬ素子に実施例１と同様に、電極間に４．９Ｖの直流電圧を印加したところ、電流密度の値は２．０ｍＡ／ｃｍ^２であり、発光輝度は１６４ｎｉｔであった。また、発光色は青色であることを確認した。
【０１４６】
［実施例８］
実施例１におけるターゲット１のかわりに、酸化インジウムと、酸化スズと、酸化セリウムとからなる、インジウムのモル比（Ｉｎ／（Ｉｎ＋Ｓｎ））が０．９であり、スズのモル比（Ｓｎ／（Ｉｎ＋Ｓｎ））が０．１であるターゲット８を用いて７５ｎｍの膜厚に成膜した基板に、酸化亜鉛を主体とし、金属全体におけるセリウムのモル比（Ｃｅ／（Ｚｎ＋Ｃｅ））が０．０５であるターゲットを用いて２０ｎｍの膜厚を成膜した基板を用いた。その他の製造条件は実施例１と同様にして有機ＥＬ素子を作成した。なお、陽極層１０のイオン化ポテンシャルの値は、６．１８ｅＶであり、透過率は７９％であった。また、得られた有機ＥＬ素子に実施例１と同様に、電極間に４．８Ｖの直流電圧を印加した。このときの電流密度は２．０ｍＡ／ｃｍ^２であり、発光輝度は１６２ｎｉｔ（ｃｄ／ｍ^２）であった。また、発光色は青色であることを確認した。さらに、耐久性評価として、１０ｍＡ／ｃｍ^２で定電流駆動したところ、１０００時間以上経過後にも、特にリーク電流の発生は見られなかった。
【０１４７】
［比較例１］
実施例１におけるターゲット１のかわりに、酸化インジウムと、酸化スズと、酸化亜鉛とからなる、インジウムのモル比（Ｉｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．６であり、スズのモル比（Ｓｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））が０．３であり、亜鉛（Ｚｎ／（Ｉｎ＋Ｓｎ＋Ｚｎ））のモル比が０．１であるターゲット９を用いた。その他は、実施例１と同様に有機ＥＬ素子を作成した。なお、陽極層１０のイオン化ポテンシャルの値は、５．２３ｅＶであった。得られた有機ＥＬ素子に実施例１と同様に、電極間に６．０Ｖの直流電圧を印加したところ、電流密度の値は２．０ｍＡ／ｃｍ^２であり、発光輝度は１６６ｎｉｔであった。また、発光色は青色であることを確認した。
【０１４８】
【発明の効果】
以上、詳細に説明したように、本発明の有機エレクトロルミネッセンス素子によれば、特定の有機化合物からなる陽極層等を備えることにより、透明性や耐久性に優れ、駆動電圧が低くとも、高い発光輝度が得られる有機ＥＬ素子を提供することができるようになった。また、特定の無機化合物からなる陽極層等は、優れたエッチング特性を有していることも確認された。
【０１４９】
また、本発明の有機エレクトロルミネッセンス素子用基板によれば、このような良好な性能を示す有機エレクトロルミネッセンス素子を容易に製造することができる。
【０１５０】
また、本発明の有機ＥＬ素子の製造方法によれば、上述した透明性や耐久性に優れ、駆動電圧が低くとも、高い発光輝度が得られる有機ＥＬ素子を効率的に提供することができるようになった。
【図面の簡単な説明】
【図１】第１の実施形態における有機ＥＬ素子の断面図である。
【図２】第２の実施形態における有機ＥＬ素子の断面図である。
【図３】第３の実施形態における有機ＥＬ素子の断面図である。
【図４】第４の実施形態における有機ＥＬ素子の断面図である。
【図５】第５の実施形態における真空蒸着装置の斜視図である。
【図６】第５の実施形態における真空蒸着装置の断面図である。
【図７】基板における測定点の説明に供する図である。
【図８】各化学物質を表す化学構造式の図である。
【符号の説明】
１０　陽極層
１２　無機薄膜層
１３　正孔輸送層
１４　有機発光層
１５　電子注入層
１６　陰極層
３０　基板
１００，１０２，１０４，１０６　有機ＥＬ素子
２０１　真空蒸着装置
２０３　基板
２１０　真空槽
２１１　基板ホルダ
２１２　保持部
２１２Ａ、２１２Ｂ、２１２Ｃ、２１２Ｄ、２１２Ｅ、２１２Ｆ　蒸着源
２１３　回転軸部
２１３Ａ　回転軸線
２１４　モータ
２２１　仮想円[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an organic electroluminescence device (hereinafter, sometimes referred to as an organic EL device), a substrate used for the organic EL device, and a method of manufacturing the same. More specifically, the present invention relates to an organic EL element suitable for use as a consumer or industrial display device (display) or a light source of a printer head, a substrate used for the organic EL element, and a method of manufacturing the same.
[0002]
[Prior art]
BACKGROUND ART Conventionally, an organic EL device having a structure in which an organic light emitting layer is sandwiched between electrodes has been intensively studied for the following reasons and the like, and has been a target of development.
[0003]
(1) Since it is a completely solid element, it is easy to handle and manufacture.
[0004]
(2) Since self light emission is possible, no light emitting member is required.
[0005]
(3) Since it is excellent in visibility, it is suitable for a display.
[0006]
(4) Easy full color printing.
[0007]
However, the organic light-emitting layer is an organic substance, and generally has a problem that it is difficult to transport electrons and holes and thus easily deteriorated.
[0008]
Various measures have been conventionally devised for such a problem.
[0009]
For example, Patent Document 1 described below discloses an organic EL device in which the energy difference between the work function of the anode and the ionization energy of the hole transport layer is reduced to extend the life. Patent Document 1 describes that in order to achieve such an object, a metal oxide material having a work function larger than that of indium tin oxide (ITO) and being conductive is used for the anode. ing. Such conductive metal oxides include, for example, RuOx, MoO₃, V₂O₅Patent Document 1 discloses an organic EL device using these metal oxides.
[0010]
In addition, Patent Document 1 proposes a two-layer anode in which a thin film made of such a conductive metal oxide material and ITO are stacked in order to improve the light transmittance (%).
[0011]
Further, Patent Document 2 below discloses an organic EL device including an insulating thin film layer between an electrode and an organic light emitting layer so as to enable long-term use. The organic EL device disclosed in Patent Document 2 specifically has an insulating property made of aluminum nitride, tantalum nitride, or the like between an anode layer and an organic light emitting layer or between a cathode layer and an organic light emitting layer. A configuration having a thin film layer is adopted.
[0012]
In addition, Patent Document 3 below discloses a method of providing a low-cost organic EL device without using m-MTDATA or a tetraaryldiamine derivative, etc., by using NiO between an electrode and an organic light emitting layer. In₂O₃, ZnO, SnO₂Or an inorganic material layer to which at least one of B, P, C, N, and O is added;_1-xAn organic EL device having an inorganic material layer formed of O (0.05 ≦ x ≦ 0.5) is disclosed.
[0013]
[Patent Document 1]
Japanese Patent No. 2842411 (JP-A-9-63771)
[Patent Document 2]
JP-A-8-288069
[Patent Document 3]
JP-A-9-260063
[Problems to be solved by the invention]
However, the organic EL devices disclosed in Patent Document 1 are RuOx, MoO₃, V₂O₅It is considered that even if a metal oxide material such as the above is used, hole mobility and durability are still insufficient. Also, RuOx, MoO₃, V₂O₅Has a light absorption coefficient of 27000 cm^-1This is a large value. This means that the degree of coloring is strong. Therefore, the anode layer made of these metal oxide materials has an extremely low light transmittance (%) in the visible light range, for example, about 1/9 to 1/5 of ITO. Therefore, the organic EL element has a problem that the luminous efficiency is low and the amount of light that can be extracted outside is small. Even when an anode having a two-layer structure in which a thin film made of such a metal oxide material and ITO are laminated, the light transmittance (%) is about 1/2 of that of ITO, and the value is still low. It was confirmed that there was a problem that the value was not practical. Further, in the case of forming the anode layer having the two-layer structure, the thickness of the ITO or metal oxide thin film must be limited to a value within a predetermined range, and there is a problem that manufacturing restrictions are large.
[0014]
In the organic EL device disclosed in Patent Document 2, since aluminum nitride, tantalum nitride, or the like is used for the insulating thin film layer, a voltage loss (voltage drop) occurs in this portion (insulating thin film layer). As a result, there has been a problem that the driving voltage tends to be high.
[0015]
Therefore, the inventors of the present application have diligently studied the above problem, and have found that by using a specific inorganic compound in combination with the electrode layer of the organic EL element, transparency and durability are excellent, and a low voltage (for example, It has been found that excellent emission luminance can be obtained even when a driving voltage of 10 V or less is applied.
[0016]
That is, an object of the present invention is to provide an organic EL device which is excellent in transparency and durability, has a low driving voltage, and has high emission luminance by providing an electrode layer containing a specific inorganic compound. I do. Still another object of the present invention is to provide a method for manufacturing an organic EL device capable of efficiently manufacturing such an organic EL device.
[0017]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems.
[0018]
First, the substrate for an organic EL device of the present invention is a substrate for an organic electroluminescence device comprising at least an electrode layer and a base material, wherein the electrode layer is at least one compound selected from the following A-1 group, and A substrate for an organic electroluminescence device, comprising at least one compound selected from the group B-1.
[0019]
Here, the A-1 group is a chalcogenide, oxynitride, or nitride of Si, Ge, Sn, Pb, Ga, In, Zn, Cd, or Mg, and the B-1 group is It is a lanthanoid-based chalcogenide, oxynitride or nitride.
[0020]
Another configuration of the substrate for an organic EL element of the present invention is a substrate for an organic electroluminescence element including at least an electrode layer and a base material, wherein the electrode layer is at least one selected from Group A-2. A substrate for an organic electroluminescence device, comprising a compound and at least one compound selected from the group B-2.
[0021]
Here, the A-2 group is a chalcogenide, oxynitride or nitride of Ge, Sn, Pb, Ga, In, Zn, Cd, and Mg, and the B-2 group is a lanthanoid-based chalcogenide. It is.
[0022]
The substrate for an organic EL device of the present invention is a substrate for an organic electroluminescence device, wherein the electrode layer is an anode layer.
[0023]
The substrate for an organic EL device of the present invention is a substrate for an organic electroluminescence device, wherein the electrode layer is a cathode layer.
[0024]
According to the constitutions of these inventions, a compound of Group A-1 and a compound of Group B-1 are used in combination, or a compound of Group A-2 and a compound of Group B-2 are used in combination. By using, the ionization potential of the electrode layer can be efficiently increased. Therefore, when the organic EL device is formed using the substrate for an organic EL device of the present invention, an organic EL device having excellent durability, low driving voltage, and high light emission luminance can be obtained.
[0025]
Further, the electrode layer thus configured has a feature that it has excellent etching characteristics. Furthermore, the electrode layer is formed by including Si chalcogenide or its nitride in at least one of the groups A-1, A-2, B-1 and B-2. In this case, the adhesion between the substrate and the substrate can be further improved, and the electrode layer can be formed more uniformly. When the anode layer is composed of these inorganic compounds, it is preferable to set the ionization potential to a value of 5.6 eV or more in consideration of hole injection properties. On the other hand, when the cathode layer is formed, the ionization potential is preferably set to a value of less than 4.0 eV in consideration of the electron injection property.
[0026]
The material shown in the present invention can have an ionization potential of 5.8 eV or more, and is extremely suitable as a material for an anode.
[0027]
The substrate for an organic EL device of the present invention is a substrate for an organic electroluminescence device, wherein the electrode layer has a specific resistance of less than 1 Ω · cm.
[0028]
By employing such a means, it is possible to prevent a phenomenon that light emission unevenness occurs in a display screen due to a high resistance of the electrode layer.
[0029]
Therefore, by limiting the specific resistance value of the electrode layer in this way, the injection properties of electrons and holes can be improved, and the driving voltage of the organic EL element can be further reduced. Conversely, when the specific resistance of the constituent material of the electrode layer exceeds 1 Ω · cm, it is preferable to have a two-layer structure with the electrode layer made of the constituent material having a specific resistance of less than 1 Ω · cm.
[0030]
Further, the substrate for an organic EL device of the present invention is a substrate for an organic electroluminescence device in which the compound of Group A-1 or A-2 is any of chalcogenides or nitrides of Sn, In and Zn. These compounds can constitute an organic EL device having low quenching property and high light emission luminance, particularly among the compounds of the group A-1 or the group A-2.
[0031]
Further, the substrate for an organic EL device of the present invention is a substrate for an organic electroluminescence device, wherein the compound of the group B-1 or B-2 is any of oxides of Ce, Nd, Sm, Eu, Tb and Ho. It is a substrate. By using these compounds in combination, it is easy to adjust the values of the ionization potential and the band gap energy in the electrode layer.
[0032]
Further, in the substrate for an organic EL device of the present invention, the total amount of the electrode layer is 100 at. %, The content of the compound of Group B-1 or Group B-2 is 0.5 to 30 at. %, Which is a value within the range of%. By setting the value within such a range, it is possible to more easily adjust the value of the ionization potential in the electrode layer while maintaining high transparency (light transmittance). Further, the electrode layer thus configured is characterized by having excellent etching characteristics with an acid or the like.
[0033]
Further, the substrate for an organic EL element of the present invention is a substrate for an organic electroluminescence element in which the thickness of the electrode layer is set to a value within a range of 1 to 100 nm. With such a configuration, it is possible to manufacture an organic EL element which is more excellent in durability, has a low driving voltage, and has high light emission luminance. Further, if the thickness of the electrode layer is in such a range, the thickness of the organic EL element does not become excessively large.
[0034]
Next, the configuration of the present invention relating to the organic EL element will be described.
[0035]
First, the organic EL device of the present invention is an organic electroluminescent device having a structure in which at least an anode layer, an organic light emitting layer, and a cathode layer are sequentially laminated, wherein the anode layer and the cathode layer, or any one of the above. An organic electroluminescent device in which the electrode layer contains at least one compound selected from the following group A-1 and at least one compound selected from the following group B-1.
[0036]
Here, the group A-1 is a chalcogenide, an oxynitride or a nitride of Si, Ge, Sn, Pb, Ga, In, Zn, Cd, and Mg, and the group B-1 is a lanthanoid element Chalcogenide, oxynitride or nitride.
[0037]
Further, another organic EL element of the present invention is an organic electroluminescence element having a structure in which at least an anode layer, an organic light emitting layer, and a cathode layer are sequentially laminated, wherein the anode layer and the cathode layer, or One of the electrode layers is an organic electroluminescence device including at least one inorganic compound selected from the following group A-2 and at least one compound selected from the following group B-2.
[0038]
Here, the A-2 group is a chalcogenide, oxynitride or nitride of Ge, Sn, Pb, Ga, In, Zn, Cd, and Mg, and the B-2 group is a lanthanoid-based chalcogenide. It is.
[0039]
As described above, by using the compound of Group A-1 and the compound of Group B-1 in combination, or by using the compound of Group A-2 and the compound of Group B-2 in combination, The ionization potential of the layer can be increased efficiently. Therefore, it is possible to obtain an organic EL element which is excellent in durability, has low driving voltage, and has high light emission luminance. Further, the electrode layer thus configured has a feature that it has excellent etching characteristics. Furthermore, the electrode layer is formed by including Si chalcogenide or its nitride in at least one of the groups A-1, A-2, B-1 and B-2. In this case, the adhesion between the substrate and the substrate can be further improved, and the electrode layer can be formed more uniformly.
[0040]
When the anode layer is composed of these compounds, it is preferable to set the ionization potential to a value of 5.6 eV or more in consideration of hole injection properties. On the other hand, when the cathode layer is formed, the ionization potential is preferably set to a value of less than 4.0 eV in consideration of the electron injection property. The material shown in the present invention can have an ionization potential of 5.8 eV or more, and is extremely suitable as an anode material.
[0041]
Further, the organic EL device of the present invention is an organic electroluminescence device in which the specific resistance of the anode layer and the cathode layer or any one of the electrode layers is less than 1 Ω · cm. With such a configuration, it is possible to prevent the occurrence of uneven light emission in the display screen due to the high resistance of the electrode layer.
[0042]
Therefore, by limiting the specific resistance value of the electrode layer in this way, the injection properties of electrons and holes can be improved. Further, the driving voltage of the organic EL element can be made lower. Conversely, when the specific resistance of the constituent material of the electrode layer exceeds 1 Ω · cm, it is preferable to have a two-layer structure with the electrode layer made of the constituent material having a specific resistance of less than 1 Ω · cm.
[0043]
Further, the present invention is the organic electroluminescent device, wherein the compound of the A-1 group or the A-2 group is any of chalcogenides or nitrides of Sn, In and Zn. Since these compounds have particularly low quenching properties among the compounds in the group A-1 or group A-2, an organic electroluminescent device having higher emission luminance can be realized.
[0044]
Further, the present invention is the organic electroluminescent device, wherein the compound of the group B-1 or B-2 is an oxide of any substance of Ce, Nd, Sm, Eu, Tb and Ho. By using these compounds in combination, it is easy to adjust the values of the ionization potential and the band gap energy in the electrode layer.
[0045]
Further, the present invention provides that the total amount of the electrode layer is 100 at. %, The content of the compound of Group B-1 or Group B-2 is 0.5 to 30 at. % Of the organic electroluminescent element. By setting the value within such a range, the value of the ionization potential in the electrode layer can be more easily adjusted while maintaining high transparency (light transmittance). Further, the electrode layer thus configured is characterized by having excellent etching characteristics with an acid or the like.
[0046]
Further, the present invention is the organic electroluminescence device wherein the thickness of the electrode layer is set to a value within a range of 1 to 100 nm. With such a configuration, it is possible to obtain an organic EL element that is more excellent in durability, has low driving voltage, and has high emission luminance. Further, if the thickness of the electrode layer is in such a range, the thickness of the organic EL element does not become excessively large.
[0047]
Further, the present invention provides at least one selected from the group A-1 between the anode layer and the organic light emitting layer, and between the cathode layer and the organic light emitting layer, or any one thereof. An inorganic thin film layer containing an inorganic compound and at least one compound selected from Group B-1, or at least one compound selected from Group A-2 and at least one compound selected from Group B-2 Is an organic electroluminescent element provided with an inorganic thin film layer containing
[0048]
By further providing the inorganic thin film layer in this manner, a leak current can be efficiently suppressed, the efficiency of the organic EL element can be improved, and the durability can be improved.
[0049]
In the case where an inorganic thin film layer is provided between the anode layer and the organic light emitting layer, it is highly preferable that the compositions of the anode layer and the inorganic thin film layer be different. Specifically, the A-1 group compound / B-1 group compound = 70 to 90 at. % / 0.5 to 10 at. % Of the compound, the compound A-1 / compound B-1 = 50-90 at. % / 10 at. % To 50 at. % Of the compound is preferably used. The same applies to the case where the compounds of the groups A-2 and B-2 are used.
[0050]
Further, in the present invention, the organic light-emitting layer may include at least one aromatic compound having a styryl group represented by any one of the following general formulas (Chemical Formula 1) to (Chemical Formula 3). It is an electroluminescent element.
[0051]
Embedded image

Here, in the general formula (chemical formula 1), Ar¹Is an aromatic group having 6 to 40 carbon atoms, and Ar is², Ar³, And Ar⁴Is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, and Ar is¹, Ar², Ar³, And Ar⁴Is an aromatic group, and the condensation number n is an integer of 1 to 6.
[0052]
Embedded image

Here, in the general formula (chemical formula 2), Ar⁵Is an aromatic group having 6 to 40 carbon atoms, and Ar is⁶And Ar⁷Is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, and Ar is⁵, Ar⁶And Ar⁷Is substituted with a styryl group, and the condensation number m is an integer of 1 to 6.
[0053]
Embedded image

Here, in the general formula (chemical formula 3), Ar⁸And Ar¹⁴Is an aromatic group having 6 to 40 carbon atoms, and Ar is⁹~ R^ThirteenIs a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, and Ar is⁸~ Ar¹⁴Is substituted with a styryl group, and the condensed numbers p, q, r, and s are each 0 or 1.
[0054]
Further, the present invention provides the method of manufacturing an organic electroluminescence device described above, wherein the electrode layer is formed by a sputtering method, and the organic light emitting layer is formed by a vacuum deposition method. It is a manufacturing method. When formed in this manner, a hole injection layer or an organic light emitting layer having a dense and uniform film thickness can be formed. Therefore, it is possible to provide an organic EL device having more uniform light emission luminance.
[0055]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In the drawings referred to, the size, shape and arrangement of each component are schematically shown to the extent that the present invention can be understood, and the ratio of each component is different from that of an actual element or the like. Therefore, the present invention is not limited only to the illustrated example. In the drawings, hatching representing a cross section may be omitted in some cases.
[0056]
[First Embodiment]
First, a first embodiment of the organic EL device of the present invention will be described with reference to FIG. FIG. 1 is a sectional view of the organic EL element 100. As shown in this figure, the organic EL element 100 has a structure in which an anode layer 10, an organic light emitting layer 14, and a cathode layer 16 are sequentially laminated on a substrate (not shown).
[0057]
Hereinafter, the description will focus on the anode layer 10 and the organic light emitting layer 14 which are characteristic portions in the first embodiment. Other components, for example, the configuration and manufacturing method of the cathode layer 16 and the like will be described in a very simple manner, and the components not mentioned above will be described in various configurations generally known in the field of organic EL devices. A manufacturing method can be adopted.
[0058]
Note that, in the first embodiment, the anode layer 10 is formed of a group A-1 or a group A-2 (hereinafter, collectively referred to as a group A) and a group B-1 or a group B-2 (hereinafter, referred to as a group A). , Which are collectively referred to as Group B). However, after setting the work function of the inorganic compound to a value less than 4.0 eV, the cathode layer 16 may be made of the inorganic compound.
[0059]
(1) Constituent material of anode layer 10
The anode layer 10 according to the first embodiment has a configuration containing a combination of the following inorganic compound of group A-1 and the compound of group B-1 or the following inorganic compound of group A-2 and group B-2. Or any combination of the above compounds. However, the combination of the inorganic compound of Group A-1 and the compound of Group B-1 and the combination of the inorganic compound of Group A-2 and the compound of Group B-2 partially overlap. There are compounds.
[0060]
Group A-1: chalcogenide, oxynitride or nitride of Si, Ge, Sn, Pb, Ga, In, Zn, Cd, Mg
Group A-2: chalcogenide, oxynitride or nitride of Ge, Sn, Pb, Ga, In, Zn, Cd, Mg
Group B-1: lanthanoid-based chalcogenides, oxynitrides or nitrides
Group B-2: chalcogenides of lanthanoid elements
As described above, the reason why the two types of compounds of Group A and Group B are combined is that, as described above, the compound (organic compound or inorganic compound) of only one of them (Group A or Group B) has the value of the ionization potential. This is because it is difficult to raise the efficiency efficiently. Specifically, it is difficult to increase the ionization potential to a value exceeding 5.8 eV.
[0061]
Therefore, by combining the inorganic compound of Group A-1 and the compound of Group B-1 or combining the inorganic compound of Group A-2 and the compound of Group B-2 to form the anode layer 10, the ionization potential is reduced. It can be 5.8 eV or more, which is an extremely large value. As a result, it is possible to obtain an organic EL element which is excellent in durability and transparency, has a low driving voltage (low specific resistance), and has high light emission luminance.
[0062]
Further, a compound obtained by combining an inorganic compound of Group A-1 and a compound of Group B-1 or a compound obtained by combining an inorganic compound of Group A-2 and a compound of Group B-2 is an acid such as hydrochloric acid or oxalic acid. It is characterized by having excellent etching characteristics. Specifically, the cross section at the boundary between the acid-treated portion and the non-treated portion is smooth, and the region between the acid-treated portion and the non-treated portion can be clearly distinguished. Therefore, an electrode layer made of such an inorganic compound has excellent etching accuracy of an electrode pattern, and even if it is a micro electrode or an electrode having a complicated shape, disconnection, deformation, or increase in resistance value is reduced. The effect is obtained.
[0063]
Group A inorganic compounds
In addition, more specific inorganic compounds of the A-1 group include SiOx (1 ≦ x ≦ 2), GeOx (1 ≦ x ≦ 2), SnO₂, PbO, In₂O₃, ZnO, GaO, CdO, ZnS, ZnCe, CdSe, Inx Zny O (0.2 ≦ x / (x + y) ≦ 0.95), ZnOS, CdZnO, CdZnS, MgInO, CdInO, MgZnO, GaN, InGaN, MgZnSSe, etc. Is mentioned.
[0064]
Specific examples of the inorganic compound of Group A-2 include compounds obtained by removing SiOxＳｉＯ (1 ≦ x ≦ 2) from the inorganic compound of Group A-1. Here, of course, ZnO is an oxide of Zn, and ZnS is a sulfide of Zn. Particularly, in the present embodiment, Zn and O, and Zn and S have a ratio of 1: 1. In addition to the compound having the normal composition, the ratio includes a compound having a ratio deviating therefrom.
[0065]
Further, among the inorganic compounds of the groups A-1 and A-2, the chalcogenides of Sn, In and Zn or nitrides thereof are particularly preferable materials. For this reason, as described above in part, these compounds have a small absorption coefficient among inorganic compounds of Group A-1 and Group A-2, particularly have low quenching properties, and are excellent in transparency. This is because it is possible to increase the amount of light that can be taken out at a time. Further, among the above-described chalcogenides of Ge, Sn, Zn and Cd, it is particularly preferable to use these oxides.
[0066]
Group B compounds
Further, specific compounds of the B-1 group include Ce.₂O₃, CeO₂, Pr₆O₁₁, Nd₂O₃, Sm₂O₃, Eu₂O₃, Gd₂O₃, Tb₄O₇, Dy₂O₃, Ho₂O₃, Er₂O₃, Tm₂O₃, Yb₂O₃, Lu₂O₃, CeN, PrN, NdN, SmN, EuN, GdN, TbN, DyN, HoN, ErN, TmN, YbN, LuN, etc., alone or in combination of two or more.
[0067]
Further, specific compounds in the B-2 group include Ce.₂O₃, CeO₂, Pr₆O₁₁, Nd₂O₃, Sm₂O₃, Eu₂O₃, Gd₂O₃, Tb₄O₇, Dy₂O₃, Ho₂O₃, Er₂O₃, Tm₂O₃, Yb₂O₃, Lu₂O₃Or a combination of two or more selected from the group consisting of:
[0068]
Among these compounds of Group B-1 and Group B-2, oxides of Ce, Nd, Sm, Eu, Tb and Ho, that is, CeOx, Nd₂O₃, Sm₂O₃, Eu₂O₃, Tb₄O₇And Ho₂O₃Is more preferable. This is also because, as described above in part, by using these inorganic compounds, the value of the ionization potential in the anode layer 10 can be more efficiently increased.
[0069]
Group B (Group B-1 or Group B-2) Compound Content
Next, the content of the compound of Group B (the Group B-1 or B-2 is simply referred to as Group B) will be described. The content of the compound of Group B is set to 100 at. %, 0.5 to 30 at. %. The reason is that the content of the group B compound is 0.5 at. %, The adjustability of the ionization potential of the anode layer 10 deteriorates. Specifically, it is sometimes difficult to adjust the ionization potential within the range of 5.65 to 6.40 eV. On the other hand, when the content of the compound of Group B is 30 at. %, The conductivity may be reduced, the color may be reduced, or the transparency (light transmittance) may be reduced.
[0070]
Accordingly, the balance between the adjustability of the value of the ionization potential in the anode layer 10 and the transparency becomes better, so that the content of the compound of Group B is set to 100 at. %, 0.8 to 20 at. %, More preferably in the range of 1 to 10 at. It is even more preferred that the value be in the range of%.
[0071]
Group A (Group A-1 or Group A-2) Compound Content
The content of the inorganic compound in Group A (the Group A-1 or Group A-2 is simply referred to as Group A) is determined based on the content of the anode layer 10 in Group A (Group A-1 or Group A-2) and Group B. (Group B-1 or Group B-2), the total amount of 100 at. % Is the value obtained by subtracting the content of the compound of Group B from%. Therefore, the content of the compound of Group B is 0.5 to 30 at. %, The content of the inorganic compound of Group A in the anode layer 10 is 70 to 99.5 at. %.
[0072]
However, when the anode layer 10 contains a compound (third component) other than the group A and the group B, the content of the inorganic compound of the group A is determined in consideration of the content of the third component. Is preferred.
[0073]
Anode layer thickness and structure
Further, the thickness of the anode layer 10 is not particularly limited, but specifically, is preferably set to a value within a range of 0.5 to 1000 nm. The reason for this is that if the thickness of the anode layer 10 is less than 0.5 nm, pinholes may occur and a leakage current may be observed when used for a long period of time. If the film thickness exceeds 1000 nm, the transparency of the electrode becomes low, and the light emission luminance may decrease. Therefore, since the balance between the durability and the value of the driving voltage and the like becomes better, the thickness of the anode layer 10 is more preferably set to a value within the range of 1.0 to 800 nm, and more preferably 2.0 to 300 nm. It is even more preferred that the value be in the range. Also, the structure of the anode layer 10 is not particularly limited, and may be a single-layer structure or a multi-layer structure of two or more layers. Therefore, in order to obtain higher transparency (light transmittance) or higher conductivity, a conductive electrode layer having higher transparency or a conductive electrode layer having higher conductivity, for example, ITO or In2 {O3} -ZnO is required. They may be laminated to form a two-layer structure.
[0074]
Anode layer specific resistance
Next, the specific resistance of the anode layer 10 will be described. The value of the specific resistance is not particularly limited, but is preferably, for example, less than 1 Ω · cm. The reason for this is that if the value of the specific resistance is 1 Ω · cm or more, non-uniformity of light emission in the pixel occurs, and the driving voltage of the organic EL element to be manufactured may increase. Therefore, in order to achieve a lower driving voltage, the specific resistance of the anode layer 10 is more preferably set to a value of 40 mΩ · cm or less, and still more preferably set to a value of 1 mΩ · cm or less. The value of the specific resistance of the anode layer 10 can be calculated by measuring the surface resistance using a four-probe resistance measuring instrument and then measuring the film thickness separately.
[0075]
Method of forming anode layer
Next, a method for forming the anode layer 10 will be described. Such a forming method is not particularly limited to a specific method. For example, a sol-gel method using a sputtering method, an evaporation method, a spin coating method, a casting method, a spray pyrolysis method, an ion plating method, or the like can be employed. In particular, it is preferable to employ a high frequency magnetron sputtering method. Specifically, the degree of vacuum is 1 × 10^-7~ 1 × 10^-3It is preferable to perform sputtering under the conditions of Pa, a deposition rate of 0.01 to 50 nm / sec, and a substrate temperature of -50 to 300 ° C.
[0076]
(2) Organic light emitting layer
Next, the organic light emitting layer will be described.
[0077]
Constituent material of organic light emitting layer
The organic light emitting material used as a constituent material of the organic light emitting layer 14 preferably has the following three functions.
[0078]
(A) Charge injection function: a function that can inject holes from an anode or a hole injection layer when an electric field is applied, and can also inject electrons from a cathode layer or an electron injection layer.
[0079]
(B) Transport function: a function of moving injected holes and electrons by the force of an electric field.
[0080]
(C) Light-emitting function: a function of providing a field for recombination of electrons and holes and connecting them to light emission.
[0081]
However, it is not always necessary to have all of the above functions (a) to (c). For example, even those having a hole injection / transport property larger than an electron injection / transport property as an organic light emitting material are included. Some are suitable. Therefore, any material can be suitably used as long as the movement of electrons in the organic light emitting layer 14 is promoted and holes and electrons can recombine near the center inside the organic light emitting layer 14.
[0082]
Here, in order to improve the recombination property in the organic light emitting layer 14, the electron mobility of the organic light emitting material is set to 1 × 10^-7cm²It is preferable to set the value to / V · s or more. The reason is 1 × 10^-7cm²If the value is less than / V · s, high-speed response of the organic EL element may be difficult, or emission luminance may decrease. Therefore, the electron mobility of the organic light emitting material is 1.1 × 10^-7~ 2 × 10^-3cm²/ V · s is more preferably set to a value within a range of 1.2 × 10^-7-7 to 1.0 × 10^-3cm²More preferably, the value is in the range of / V · s.
[0083]
Further, it is preferable that the value of the electron mobility is smaller than the hole mobility of the organic light emitting material in the organic light emitting layer 14. If this relationship is reversed, the organic light emitting materials that can be used for the organic light emitting layer 14 may be excessively limited, and the light emission luminance may be reduced. On the other hand, the electron mobility of the organic light emitting material is preferably larger than 1/1000 of the value of the hole mobility. If the electron mobility is excessively small, it becomes difficult for holes and electrons to recombine in the vicinity of the center of the inside of the organic light emitting layer 14, and the light emission luminance may also be reduced. Therefore, it is more preferable that the hole mobility (μh) and the electron mobility (μe) of the organic light emitting material in the organic light emitting layer 14 satisfy the relationship of μh / 2> μe> μh / 500, and μhμ / 3 > Μe 関係> μh / 100.
[0084]
In the first embodiment, it is preferable to use an aromatic ring compound having a styryl group represented by the general formulas (1) to (3) for the organic light emitting layer 14. By using such an aromatic ring compound having a styryl group, the conditions of the electron mobility and the hole mobility of the organic light emitting material in the organic light emitting layer 14 described above can be easily satisfied. Among the aromatic groups having 6 to 40 carbon atoms in the general formulas (1) to (3), preferred aryl groups having 5 to 40 nuclear atoms include phenyl, naphthyl, anthranyl, phenanthryl, pyrenyl, coronyl, biphenyl, Terphenyl, pyrrolyl, furanyl, thiophenyl, benzothiophenyl, oxadiazolyl, diphenylanthranyl, indolyl, carbazolyl, pyridyl, benzoquinolyl and the like.
[0085]
Preferred arylene groups having 5 to 40 nuclear atoms include phenylene, naphthylene, anthranylene, phenanthrylene, pyrenylene, colonylene, biphenylene, terphenylene, pyrrolylene, furanylene, thiophenylene, benzothiophenylene, oxadiazolylene, and diphenylanthranylene. , Indolylene, carbazolylene, pyridylene, benzoquinolylene and the like. The aromatic group having 6 to 40 carbon atoms may be further substituted with a substituent. Preferred examples of the substituent include an alkyl group having 1 to 6 carbon atoms (ethyl group, methyl group, i-propyl group). , An n-propyl group, an s-butyl group, a t-butyl group, a pentyl group, a hexyl group, a cyclopentyl group, a cyclohexyl group, etc., an alkoxy group having 1 to 6 carbon atoms (ethoxy group, methoxy group, i-propoxy group, n-propoxy group, s-butoxy group, t-butoxy group, pentoxy group, hexyloxy group, cyclopentoxy group, cyclohexyloxy group, etc.), aryl group having 5 to 40 nuclear atoms, 5 to 40 nuclear atoms. An amino group substituted with an aryl group, an ester group having an aryl group having 5 to 40 nuclear atoms, an ester group having an alkyl group having 1 to 6 carbon atoms, a cyano group, a nitro group, a halo Is down atom and the like.
[0086]
In addition, it is also preferable to use a fluorescent whitening agent such as a benzothiazole-based, benzimidazole-based, or benzoxazole-based compound, a styrylbenzene-based compound, or a metal complex having an 8-quinolinol derivative as a ligand in the organic light-emitting layer 14. . In addition, an organic light-emitting material having a distyrylarylene skeleton, for example, 4,4′-bis (2,2-diphenylvinyl) biphenyl or the like is used as a host, and the host is provided with a strong fluorescent dye from blue to red, for example, a coumarin or a host. It is also preferable to use the same fluorescent dye doped together.
[0087]
Method of forming organic light emitting layer
Next, a method for forming the organic light emitting layer 14 will be described. Such a forming method is not limited to a specific method. For example, a method such as a vacuum evaporation method, a spin coating method, a casting method, an LB method, and a sputtering method can be employed. For example, in the case of forming by a vacuum deposition method, a deposition temperature of 50 to 450 ° C. and a degree of vacuum of 1 × 10^-7~ 1 × 10^-3It is preferable to adopt the conditions of Pa, a film formation rate of 0.01 to 50 nm / sec, and a substrate temperature of −50 to 300 ° C.
[0088]
Alternatively, the organic light emitting layer 14 can also be formed by dissolving a binder and an organic light emitting material in a predetermined solvent to form a solution, and then thinning the solution by spin coating or the like. The organic light-emitting layer 14 is formed by appropriately selecting a forming method and forming conditions, and forming a thin film formed by deposition from a material compound in a gaseous state, or solidifying from a material compound in a solution state or a liquid phase state. It is preferable to use a molecular deposition film that is a thin film. In general, this molecular deposition film can be sufficiently distinguished from a thin film (molecule accumulation film) formed by the LB method by a difference in an aggregated structure or a higher-order structure and a functional difference caused by the difference.
[0089]
Organic light-emitting layer thickness
The thickness of the organic light emitting layer 14 is not particularly limited, and an appropriate thickness can be appropriately selected depending on the situation. However, in practice, a value in the range of 5 nm to 5 μm is often preferable. The reason for this is that if the thickness of the organic light emitting layer is less than 5 nm, the emission luminance and durability may decrease, while if the thickness of the organic light emitting layer 14 exceeds 5 μm, the value of the applied voltage increases. This is because there are many cases. Therefore, the thickness of the organic light emitting layer 14 is more preferably in the range of 10 nm to 3 μm, and more preferably in the range of 20 nm to 1 μm. Is more preferable.
[0090]
(3) Cathode layer
For the cathode layer 16, it is preferable to use a metal, an alloy, an electrically conductive compound, or a mixture thereof having a low work function (for example, less than 4.0 eV). Specifically, one of magnesium, aluminum, indium, lithium, sodium, cesium, silver and the like can be used alone or in combination of two or more. The thickness of the cathode layer 16 is not particularly limited, but is preferably in the range of 10 to 1000 nm, and more preferably in the range of 10 to 200 nm.
[0091]
(4) Other
Although not shown in FIG. 1, a sealing layer for preventing moisture and oxygen from entering the organic EL element 100 is preferably provided so as to cover the entire organic EL element 100. As a preferable material of the sealing layer, a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer; a fluorinated copolymer having a cyclic structure in a copolymer main chain; Examples thereof include polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, and a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene.
[0092]
Further, preferable materials for the sealing layer include a water-absorbing substance having an absorption of 1% or more; a moisture-proof substance having a water absorption of 0.1% or less; In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni. Metals such as MgO, SiO, SiO₂2, GeO, NiO, CaO, BaO, Fe₂O, Y₂O₃, TiO₂Metal oxides such as ；; MgF₂, LiF, AlF₃Ｃａ, CaF₂Metal fluoride such as perfluoroalkane, perfluoroamine, and perfluoropolyether; and a composition in which an adsorbent that adsorbs moisture and oxygen is dispersed in the liquid fluorinated carbon. .
[0093]
In forming the sealing layer, a vacuum evaporation method, a spin coating method, a sputtering method, a casting method, an MBE (molecular beam epitaxy) method, a cluster ion beam evaporation method, an ion plating method, a plasma polymerization method (high-frequency excitation An ion plating method), a reactive sputtering method, a plasma CVD method, a laser CVD method, a thermal CVD method, a gas source CVD method, or the like can be appropriately employed.
[0094]
[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a cross-sectional view of the organic EL element 102 according to the second embodiment, in which an anode layer 10, an inorganic thin film layer 12, an organic light emitting layer 14, and a cathode layer 16 are sequentially formed on a substrate (not shown). It has a laminated structure. By providing the inorganic thin film layer 12 in this manner, the injected holes can be efficiently transported. Therefore, by providing the inorganic thin film layer 12, the organic EL element 102 can be driven at a low voltage and the durability is improved.
[0095]
A characteristic feature of the organic EL element 102 according to the second embodiment is that the inorganic thin film layer 12 is inserted between the anode layer 10 and the organic light emitting layer 14.
[0096]
Except for this point, it has the same structure as the organic EL element 100 of the first embodiment.
[0097]
Therefore, the following description is mainly about the inorganic thin film layer 12 which is a characteristic portion in the second embodiment, and other components, for example, the cathode layer 16 and the like, are described in the first embodiment. Since the configuration is the same as that described above, refer to the description of the first embodiment.
[0098]
First, the inorganic compound constituting the inorganic thin film layer 12 includes the group A (group A-1 or group A-2) and the group B (group B-1 or group B-2) constituting the anode layer 10 described above. Combinations of compounds are included. Therefore, as in the case of the anode layer 10, the total amount of the inorganic thin film layer is set to 100 at. %, 0.5 to 50 at. %, Preferably in the range of 1.0 to 40 at. %, More preferably in the range of 5.0 to 30 at. % Is more preferable. In addition, it is preferable that the film thickness and the formation method are the same as those of the anode layer 10.
[0099]
However, when the inorganic thin film layer 12 is provided between the anode layer 10 and the organic light emitting layer 14, it is necessary to make the compositions of the anode layer 10 and the inorganic thin film layer 14 different. Specifically, the anode layer 10 has a group A (group A-1 or group A-2) / group B (group B-1 or group B-2) = 70 to 90 at. % / 0.5 to 10 at. % On the other hand, the group A (group A-1 or group A-2) / group B (group B-1 or group B-2) = 50 to 90 at. % / 10 at. % To 50 at. % Of an inorganic compound is preferably used. The reason for this is that if the amount of the compound of Group B (Group B-1 or Group B-2) is out of this range, the transparency is lowered or the specific resistance is increased, which is not preferable as an electrode.
[0100]
[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a cross-sectional view of the organic EL device 104 according to the third embodiment. The anode layer 10, the inorganic thin film layer 12, the hole transport layer 13, the organic light emitting layer 14, and the cathode layer 16 are formed on a substrate (not shown). ) Has a structure in which the layers are sequentially stacked.
[0101]
In the third embodiment, in addition to the first and second embodiments, by further providing the hole transport layer 13, the injected holes can be transported efficiently. Therefore, by providing the hole transport layer 13, the organic EL element 104 can be driven at a low voltage and the durability is improved.
[0102]
The organic EL element 104 according to the third embodiment has the same structure as that of the second embodiment except that the hole transport layer 13 is inserted between the inorganic thin film layer 12 and the organic light emitting layer 14. It has the same structure as the organic EL element 102 of the embodiment. Therefore, the following description will focus on the hole transport layer 13 which is a characteristic part of the third embodiment. The other components, for example, the cathode layer 16 and the like, can have the same configuration as those of the first and second embodiments. Therefore, refer to the description of the first and second embodiments.
[0103]
(1) Material of the hole transport layer 13
The hole transport layer 13 is preferably made of an organic compound or an inorganic compound. Examples of such an organic material include a phthalocyanine compound, a diamine compound, a diamine-containing oligomer and a thiophene-containing oligomer. Examples of preferable inorganic compound materials include, for example, amorphous silicon (α-Si), α-SiC, microcrystalline silicon (μC-Si), μC-SiC, II-VI group compound, III -V group compound, Examples thereof include crystalline carbon, crystalline carbon, and diamond. Further, as other kinds of inorganic materials, oxides, fluorides and nitrides may be mentioned, and more specifically, Al₂O₃, SiO, SiOx (1 ≦ x ≦ 2), GaN, InN, GaInN, GeOx (1 ≦ x ≦ 2), LiF, SrO, CaO, BaO, MgF₂, CaF₂, UgF₂, SiNx (1 ≦ x ≦ 4/3), etc., alone or in combination of two or more. Further, the hole mobility is 1 × 10⁶cm²/ V · sec or more (applied voltage 1 × 10⁴~ 1 × 10⁶(V / cm) and the material of the ionization potential is preferably 5.5 eV or less.
[0104]
(2) Structure and method of forming hole transport layer 13
The hole transport layer 13 is not limited to a single-layer structure, and may have a two-layer structure or a three-layer structure, for example. Further, the thickness of the hole transport layer 13 is not particularly limited, but is preferably, for example, a value in the range of 0.5 nm to 5 μm. The method for forming the hole transport layer 13 is not particularly limited, and various methods can be adopted. However, in practice, it is preferable to adopt the same method as the method of forming the hole injection layer.
[0105]
[Fourth embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 4 is a cross-sectional view of the organic EL element 106 according to the fourth embodiment, in which the anode layer 10, the inorganic thin film layer 12, the hole transport layer 13, the organic light emitting layer 14, the electron injection layer 15, and the cathode layer 16 This indicates that the substrate has a structure in which the layers are sequentially laminated on a substrate (not shown). As described above, in the fourth embodiment, the function of injecting electrons efficiently can be exhibited by providing the electron injection layer 15. Therefore, the provision of the electron injection layer 15 facilitates the transfer of electrons to the organic light emitting layer 14 and improves the response performance of the organic EL element 106.
[0106]
The characteristic point of the organic EL element 106 according to the fourth embodiment is that the electron injection layer 15 is inserted between the organic light emitting layer 14 and the cathode layer 16. Except for this point, the organic EL element 106 according to the fourth embodiment has the same structure as the organic EL element 104 according to the third embodiment. Therefore, the following description will focus on the electron injection layer 15 which is a characteristic part of the fourth embodiment, and the other components will be the same as those of the above-described first to third embodiments. Or a configuration generally known in the field of organic EL devices.
[0107]
(1) Material of electron injection layer
The electron injection layer 15 is preferably made of an organic compound or an inorganic compound. In particular, by using an organic compound, it is possible to provide an organic EL device having more excellent electron injectability and durability from a cathode. Here, preferable organic compounds include 8-hydroxyquinoline and oxadiazole, and derivatives thereof, for example, metal chelate oxinoid compounds containing 8-hydroxyquinoline.
[0108]
When the electron injection layer 15 is made of an inorganic compound, it is preferable to use an insulator or a semiconductor as the inorganic compound. If the electron injection layer 15 is made of an insulator or a semiconductor, current leakage can be effectively prevented, and the electron injection property can be improved. Such insulators are selected from the group consisting of alkali metal chalcogenides (oxides, sulfides, selenides, tellurides), alkaline earth metal chalcogenides, alkali metal halides and alkaline earth metal halides. Preferably, at least one metal compound is used. It is preferable that the electron injecting layer 15 is made of such an alkali metal chalcogenide in that the electron injecting property can be further improved.
[0109]
Specifically, preferable alkali metal chalcogenides include, for example, Li₂O, LiO, Na₂S, Na₂Se and NaO are mentioned. Preferred alkaline earth metal chalcogenides include, for example, CaO, BaO, SrO, BeO, BaS, and CaSe. Preferred alkali metal halides include, for example, LiF, NaF, KF, LiCl, KCl, and NaCl. Preferred alkaline earth metal halides include, for example, CaF₂, BaF₂, SrF₂, MgF₂And BeF₂And halides other than the fluoride.
[0110]
When the electron injection layer 15 is formed of a semiconductor, a preferable semiconductor is at least one of Ba, Ca, Sr, Yb, Al, Ga, In, Li, Na, Cd, Mg, Si, Ta, Sb and Zn. One kind of an oxide, a nitride, an oxynitride or the like containing two elements may be used alone or in combination of two or more kinds. Further, the inorganic compound constituting the electron injection layer 15 is preferably a microcrystalline or amorphous insulating thin film. If the electron injecting layer 15 is composed of these insulating thin films, a more uniform thin film is formed, so that pixel defects such as dark spots can be reduced. Examples of such inorganic compounds include the above-described alkali metal chalcogenides, alkaline earth metal chalcogenides, halides of alkali metals, and halides of alkaline earth metals.
[0111]
(2) electron affinity
In addition, the electron affinity of the electron injection layer 15 in the fourth embodiment is preferably set to a value within the range of 1.8 to 3.6 eV. When the value of the electron affinity is less than 1.8 eV, the electron injecting property tends to decrease, leading to an increase in driving voltage and a decrease in luminous efficiency. On the other hand, when the value of the electron affinity exceeds 3.6 eV, light emission A complex with low efficiency is likely to be generated, and generation of a blocking junction can be efficiently suppressed. Therefore, the electron affinity of the electron injection layer is more preferably set to a value within the range of 1.9 to 3.0 eV, and even more preferably set to a value within the range of 2.0 to 2.5 eV. Further, the difference in electron affinity between the electron injection layer 15 and the organic light emitting layer 14 is preferably set to a value of 1.2 eV or less, more preferably 0.5 eV or less. As the difference between the electron affinities is smaller, the electron injection from the electron injection layer 15 to the organic light emitting layer 14 becomes easier, and the organic EL element 106 with improved response performance can be configured.
[0112]
(3) Energy gap
Further, the energy gap (bandgap energy) of the electron injection layer 15 in the fourth embodiment is preferably set to a value of 2.7 eV or more, more preferably 3.0 eV or more. As described above, by setting the value of the energy gap to be a predetermined value or more, for example, a large value of 2.7 eV or more, it is possible to reduce the possibility that holes move to the electron injection layer 15 beyond the organic light emitting layer 14. Can be. Therefore, the efficiency of recombination of holes and electrons is improved, the emission luminance of the organic EL element 106 is increased, and the emission of light from the electron injection layer 15 itself can be avoided.
[0113]
(4) Structure
Next, the structure of the electron injection layer 15 made of an inorganic compound will be described. The structure of the electron injection layer 15 is not particularly limited, and may be, for example, a single-layer structure, a two-layer structure, or a three-layer structure. The thickness of the electron injection layer 15 is not particularly limited, and various thicknesses can be adopted depending on the situation. Practically, for example, it is preferable to set the value in the range of 0.1 nm to 1000 nm. The reason for this is that if the thickness of the electron injection layer 15 made of an inorganic compound is less than 0.1 nm, the electron injection property may decrease, or the mechanical strength may decrease. On the other hand, when the thickness of the electron injection layer 15 made of an inorganic compound exceeds 1000 nm, the resistance becomes high, so that the response performance of the organic EL element 106 is deteriorated, that is, high-speed response becomes difficult, or This is because it may take time. Therefore, the thickness of the electron injection layer 15 made of an inorganic compound is more preferably set to a value in the range of 0.5 to 100 nm, and even more preferably to a value in the range of 1 to 50 nm.
[0114]
(5) Forming method
Next, a method for forming the electron injection layer 15 will be described. The method for forming the electron injection layer 15 is not particularly limited as long as it can be formed as a thin film layer having a uniform thickness. For example, various methods such as a vacuum evaporation method, a spin coating method, a casting method, an LB method, and a sputtering method can be applied.
[0115]
[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, even when a plurality of inorganic compounds are used, the anode layer 16 having a uniform composition ratio of the constituent materials and having excellent etching characteristics and transparency can be obtained. As a result, an object of the present invention is to provide a manufacturing method capable of efficiently obtaining an organic EL element having a low driving voltage and excellent in light emission luminance and durability. That is, the first feature of the fifth embodiment is that the anode layer 16 is formed using a specific target and a sputtering method. In the fifth embodiment, for example, even when a plurality of organic light emitting materials are used, the organic light emitting layer 14 having a uniform composition ratio of the constituent materials can be obtained. As a result, an object of the present invention is to provide a manufacturing method capable of efficiently obtaining an organic EL device having a low driving voltage, a high emission luminance, and excellent durability. That is, the fifth feature of the fifth embodiment is that the organic light-emitting layer 14 is formed from a plurality of organic compounds by using a specific vacuum deposition method.
[0116]
In order to obtain an organic EL element having a characteristic that the composition ratio of the constituent materials is uniform, it is preferable that at least the anode layer 10 and the organic light emitting layer 14 are formed under the same vacuum condition without being exposed to the atmosphere. . The fifth feature of the fifth embodiment is that a vacuum chamber for performing the sputtering method and a vacuum chamber for performing the vacuum evaporation method are commonly used. The reason is to obtain an organic EL element having a uniform composition ratio of constituent materials. Therefore, in the fifth embodiment, in one vacuum chamber, not only the heating device necessary for performing the sputtering method and the substrate holding means, but also the heating device required for performing the vacuum deposition method , A vacuum tube for performing the sputtering method and a vacuum vessel for performing the vacuum deposition method can be shared. As a modification of the fifth embodiment, a configuration in which a vacuum chamber for sputtering and a vacuum chamber for vacuum deposition are separately provided, and these are connected in advance can be adopted. According to such a modification, the same result as in the case where the vacuum chamber is shared can be obtained by moving the substrate into the vacuum chamber for the sputtering method by using a predetermined transfer device after performing the vacuum evaporation method. The configuration of the organic EL element described in the fifth embodiment is the same as that of the fourth embodiment for easy understanding.
[0117]
According to the manufacturing method adopted in the fifth embodiment, the following layers are formed by the corresponding manufacturing methods.
[0118]
Anode layer 10: High frequency magnetron sputtering method
Inorganic thin film layer 12: high frequency magnetron sputtering method
Hole transport layer 13: vacuum evaporation method
Organic light emitting layer 14: vacuum evaporation method
Electron injection layer 15: vacuum evaporation method
Cathode layer 16: Vacuum evaporation method
(1) Formation of anode layer and inorganic thin film layer
In forming the anode layer 10 and the inorganic thin film layer 12 by a high-frequency magnetron sputtering method, a target comprising a compound of Group A (Group A-1 or Group A-2) and Group B (Group B-1 or Group B-2) It is preferable to use Specifically, the target must contain at least a group A (group A-1 or group A-2) and a group B (group B-1 or group B-2) at a predetermined ratio. In addition, a target (average particle diameter of 1 μm or less), which is a raw material, is prepared by a solution method (coprecipitation method) (concentration: 0.01 to 10 mol / l, solvent: polyhydric alcohol, etc., precipitation forming agent: potassium hydroxide, etc.), After being uniformly mixed by using a physical mixing method (stirrer: ball mill, bead mill, etc., mixing time: 1 to 200 hours), sintering (temperature 1200 to 1500 ° C., time 10 to 72 hours, more preferably 24 to 48 hours), and further obtained by molding (press molding, HIP molding, or the like). At this time, it is more preferable that the rate of temperature rise during molding be a value within the range of 1 to 50 ° C./min. The target obtained by these methods has a characteristic that the composition ratio of the constituent materials is uniform. Since the composition ratio and the like can be adjusted only by sputtering conditions, the compounds of Group A (Group A-1 or Group A-2) and Group B (Group B-1 or Group B-2) are separately prepared. It is also preferable to perform sputtering.
[0119]
The sputtering conditions are not particularly limited, but in an inert gas such as argon, the plasma output is adjusted to a target surface area of 1 cm.²0.3-4W per square meter, vacuum 1 × 10^-7~ 1 × 10^-3It is preferable to adopt the conditions of Pa, a deposition rate of 0.01 to 50 nm / sec, a deposition time of 5 to 120 minutes, and a substrate temperature of −50 to 300 ° C. This is because such sputtering conditions are economical, and the dense anode layer 16 and the inorganic thin film layer 12 having a uniform thickness can be formed.
[0120]
(2) Formation of the organic light emitting layer 14
With reference to FIGS. 5 and 6, a method of forming the organic light emitting layer 14 by simultaneously evaporating different evaporation materials will be described. First, a rotation axis 213A for rotating the substrate 203 is set on the substrate 203 using the vacuum evaporation apparatus 201. Next, the evaporation sources 212A to 212F are respectively arranged at positions away from the rotation axis 213A of the substrate 203, and the substrate 203 is rotated. At the same time, evaporation is performed by simultaneously evaporating different evaporation materials from the plurality of evaporation sources 212A to 212F arranged opposite to the substrate 203. Thus, the organic light emitting layer 14 can be obtained.
[0121]
Here, the vacuum deposition apparatus 201 shown in FIGS. 5 and 6 includes a vacuum chamber 210, a substrate holder 211 for fixing a substrate 203 installed in an upper part of the vacuum chamber 210, and a lower part of the substrate holder 211. And a plurality (six) of vapor deposition sources 212A to 212F for filling a vapor deposition material arranged opposite to the vapor deposition material. The inside of the vacuum chamber 210 can be maintained at a predetermined reduced pressure by an exhaust means (not shown). Although the number of evaporation sources is shown in the drawing as six, the number is not limited to this, and may be five or less, or seven or more.
[0122]
The substrate holder 211 includes a holding portion 212 that supports a peripheral portion of the substrate 203, and is configured to horizontally hold the substrate 203 in the vacuum chamber 210. At the center of the upper surface of the substrate holder 211, a rotating shaft 213 for rotating (rotating) the substrate 203 is provided upright in the vertical direction. The rotating shaft 213 is connected to a motor 214 serving as a rotation disturbance unit, and the rotating operation of the motor 214 causes the substrate 203 held by the substrate holder 211 to rotate with the rotating shaft 213 together with the substrate holder 211. It is designed to rotate. That is, at the center of the substrate 203, the rotation axis 213A of the rotation shaft 213 is set in the vertical direction.
[0123]
Next, a method of forming the organic light emitting layer 12 on the substrate 203 from two kinds of organic light emitting materials (host material and dopant material) using the vacuum evaporation apparatus 201 configured as described above will be specifically described. explain. First, a substrate 203 having a square planar shape as shown in FIG. 5 is prepared, and this substrate 203 is locked to the holding portion 212 of the substrate holder 211 to be in a horizontal state. In this regard, the fact that the substrate 203 shown in FIG. 5 is held in a horizontal state indicates that the substrate 203 is engaged with the holding portion 212 of the substrate holder 211 and is in a horizontal state.
[0124]
Here, when the organic light emitting layer 12 is formed, two evaporation sources 212B and 212C adjacent to each other on the virtual circle 221 are filled with a host material and a dopant material, respectively. After the charging, the pressure in the vacuum chamber 210 is reduced to a predetermined degree of vacuum, for example, 1.0 × 10 −4 Torr by the exhaust means. Next, the evaporation sources 212B and 212C are heated, and the host material and the dopant material are simultaneously evaporated from the evaporation sources 212B and 212C, respectively. At the same time, the motor 214 is caused to rotate and oscillate, and the substrate 203 is rotated along the rotation axis 213A at a predetermined speed, for example, 1 to 100 rpm. In this way, the organic light emitting layer 12 is formed by co-evaporating the host material and the dopant material while rotating the substrate 203. At this time, as shown in FIG. 6, the evaporation sources 212B and 212C are provided at positions shifted from the rotation axis 213A of the substrate 203 by a predetermined distance M in the horizontal direction. The angle of incidence on the substrate 203 of a deposition material such as a dopant or a dopant material can be changed regularly. Therefore, the deposition material can be uniformly adhered to the substrate 203, and a thin film layer having a uniform composition ratio of the deposition material can be reliably formed in the film surface of the electron injection layer 15. For example, a thin film layer having a density unevenness of ± 10% (in terms of mol) can be formed. Further, by performing the vapor deposition in this manner, the substrate 203 does not need to revolve, so that no space or equipment is required, and the film can be formed economically with a minimum space. Here, revolving the substrate 203 means to rotate around a rotation axis other than the substrate, and requires a larger space than in the case of rotating.
[0125]
In performing the simultaneous vapor deposition, the shape of the substrate 203 is not particularly limited. As an example, as shown in FIG. 5, when the substrate 203 has a rectangular flat plate shape and the lengths of the sides of the substrate 203 are the same, a virtual circle 221 centered on the rotation axis 213A of the substrate 203. When a plurality of evaporation sources 212A to 212F are arranged along the circumference of the circle and the radius of the virtual circle 221 is M and the length of one side of the substrate 203 is L, M> (1/2) × L It is desirable that the shape is a short flat plate shape that satisfies the following. On the other hand, when the lengths of the sides of the substrate 203 are not the same but different, the length of the longest side is set to L. With this configuration, the incident angles of the evaporation material from the plurality of evaporation sources 212A to 212F with respect to the substrate 203 can be made equal to each other, so that the composition ratio of the evaporation material can be more easily controlled. Further, with such a structure, the vapor deposition material is evaporated at a constant incident angle with respect to the substrate 203, so that it does not enter vertically, and the uniformity of the composition ratio in the film plane is further improved. be able to.
[0126]
In performing the manufacturing method of the fifth embodiment, as shown in FIG. 5, a plurality of evaporation sources 212A to 212F are arranged on the circumference of a virtual circle 221 centered on the rotation axis 213A of the substrate 203. When the number (number) of the plurality of vapor deposition sources 212A to 212F is n, the vapor deposition sources 212A to 212F can be disposed at an angle of 360 ° / n from the center of the virtual circle 221. preferable. For example, when six evaporation sources 212 are provided, it is preferable to provide them at an angle of 60 ° from the center of the virtual circle 221. With such an arrangement, a plurality of deposition materials can be sequentially formed on each portion of the substrate 203 so that a thin film layer having a regularly different composition ratio in the thickness direction of the film can be easily formed. can do.
[0127]
Next, the composition uniformity of the organic light emitting layer 14 formed by the above-described simultaneous vapor deposition method will be described in more detail. As an example, a thin film layer having a thickness of about 1000 angstroms (set value) was simultaneously deposited under the following conditions while using Alq as a host material and Cs as a dopant material while rotating the substrate 203 shown in FIG. 7 at 5 rpm. .
[0128]
Alq deposition rate: 0.1 to 0.3 nm / s
Cs deposition rate: 0.1 to 0.3 nm / s
Alq / Cs film thickness: 1000 Å (set value)
The chemical structural formula of Alq is shown in FIG.
[0129]
Next, the thickness of the obtained thin film layer at the measurement points (4A to 4M) on the glass substrate 203 shown in FIG. 7 is measured using a stylus type film thickness meter, and Cs / Al (Al in Alq) is measured. ) The composition ratio (atomic ratio) was measured using an X-ray photoelectron spectrometer (XPS). The measurement points (4A to 4M) on the glass substrate 203 shown in FIG. 7 are divided into 16 equal parts in advance on the surface of the substrate 203, and square sections each having a side length P of 50 mm are set. It is an arbitrary corner (13 places) in the section. Table 1 shows the obtained results.
[0130]
[Table 1]

On the other hand, a thin film layer having a thickness of about 1000 angstroms (set value) was formed under the same evaporation conditions as in the above simultaneous evaporation method except that the glass substrate 203 was not rotated. The film thickness and the composition ratio (atomic ratio) of Cs / Al at the measurement points (4A to 4M) of the obtained thin film layer were measured, and the results are shown in Table 2.
[0131]
[Table 2]

As is apparent from these results, according to the co-evaporation method described above, at the measurement points (4A to 4M) on the substrate 203, the film thickness is extremely uniform within a range of 1008 to 1093 angstroms. Further, it was confirmed that a thin film layer having an extremely uniform composition ratio of Cs / Al (atomic ratio) in the range of 1.0 to 1.10. On the other hand, when a manufacturing method different from the above-described co-evaporation method is used, the film thickness at the measurement points (4A to 4M) on the substrate 203 is a value within the range of 884 to 1067 angstroms, and the composition of Cs / Al It was confirmed that the ratio was a value within the range of 0.6 to 1.3.
[0132]
【Example】
[Example 1]
(1) Preparation for manufacturing organic EL element (creation of target)
Powders of indium oxide and cerium oxide (average particle diameter of 1 μm or less) were accommodated in a wet ball mill container so that the molar ratio of Ce / (In + Ce) became 0.05, and mixed and pulverized for 72 hours. Next, the obtained pulverized product was granulated and then press-molded to a size of 4 inches in diameter and 5 mm in thickness. After this was stored in a firing furnace, it was heated and fired at a temperature of 1400 ° C. for 36 hours to produce a target 1 for the anode layer 10.
[0133]
(2) Formation of anode layer 10
Next, a transparent glass substrate having a thickness of 1.1 mm, a length of 25 mm, and a width of 75 mm and the obtained target 1 were arranged in a vacuum chamber shared by a high-frequency sputtering device and a vacuum evaporation device, and the high-frequency sputtering device was operated. A transparent electrode film having a thickness of 75 nm was formed as the anode layer 10 to obtain a substrate. Note that the degree of vacuum is 3 × 10^-1In a state where the pressure was reduced to Pa, a gas obtained by mixing oxygen gas with argon gas was sealed, and the ultimate vacuum degree was 5 × 10 5 in the atmosphere.^-4Sputtering was performed under the conditions of Pa, a substrate temperature of 25 ° C., an input power of 100 W, and a deposition time of 14 minutes. Hereinafter, the glass substrate and the anode layer 10 are collectively referred to as a substrate. Subsequently, the substrate was subjected to ultrasonic cleaning with isopropyl alcohol,₂After drying in an atmosphere of (nitrogen gas), the substrate was washed with UV (ultraviolet light) and ozone for 10 minutes. In this state, when the value of the ionization potential of the anode layer 10 on the substrate was measured using AC-1 (manufactured by Riken Keiki Co., Ltd.), it was 6.20 eV. The light transmittance (wavelength: 550 nm) of the substrate on which the anode layer 10 was formed was measured to be 89%.
[0134]
(3) Processing in a vacuum deposition apparatus
The substrate is mounted on the substrate holder of the vacuum chamber, and then the inside of the vacuum chamber is 1 × 10^-6After reducing the pressure to a degree of vacuum equal to or lower than Torr, a hole transport layer 13, an organic light emitting layer 14, an electron injection layer 15 and a cathode layer 16 are sequentially laminated on the anode layer 10 and the inorganic thin film layer 12 of the substrate to form an organic layer. An EL device was obtained. At this time, from the formation of the organic light emitting layer 14 to the formation of the cathode layer 16, the same vacuum condition was maintained without breaking the vacuum state.
[0135]
First, TBDB was vacuum-deposited as a hole transport material at 60 nm. Next, DPVDPAN and D1 were co-evaporated under vacuum in a thickness of 40 nm as light emitting layers. At this time, the deposition rate of DPVDPAN was 40 nm / s, and the deposition rate of D1 was 1 nm / s.
[0136]
The chemical structural formula of TBDB is shown in FIG. The chemical structural formula of DPVDPAN is also shown in FIG. FIG. 8 also shows the chemical structural formula of D1.
[0137]
Next, 20 nm of Alq was vacuum-deposited as an electron injection layer.
[0138]
Finally, Al and Li were vacuum-deposited to form a cathode layer 16 on the electron injection layer 15 to obtain an organic EL device. At this time, the deposition rate of Al was 1 nm / s, the deposition rate of Li was 0.01 nm / s, and the film thickness of Al / Li was 200 nm.
[0139]
(4) Evaluation of Organic EL Device In the obtained organic EL device, a DC voltage of 4.8 V was applied between both electrodes, with the cathode layer 16 being a minus (−) electrode and the anode layer 10 being a plus (+) electrode. The current density at this time was 2.0 mA / cm²And the emission luminance is 164 nit (cd / m²)Met. It was also confirmed that the emission color was blue. Furthermore, as a durability evaluation, 10 mA / cm², The occurrence of a leak current was not particularly observed even after a lapse of 1000 hours or more.
[0140]
[Table 3]

[Table 4]

[Example 2]
Instead of the target 1 in Example 1, the molar ratio of indium (In / (In + Sn + Zn)) composed of indium oxide, tin oxide, zinc oxide, and neodymium oxide was 0.8, and the molar ratio of tin was 0.8. A target 3 having (Sn / (In + Sn + Zn)) of 0.1 and a molar ratio of zinc (Zn / (In + Sn + Zn)) of 0.1 was used. The other manufacturing conditions were the same as in Example 1 to produce an organic EL device. The value of the ionization potential of the anode layer 10 was 5.85 eV. When a DC voltage of 5.3 V was applied between the electrodes in the same manner as in Example 1, the value of the current density was 2.0 mA / cm.²And the emission luminance was 158 nit. It was also confirmed that the emission color was blue.
[0141]
[Example 3]
Instead of the target 1 in Example 1, the molar ratio of indium (In / (In + Sn + Zn)) composed of indium oxide, tin oxide, zinc oxide, and samarium oxide was 0.8, and the molar ratio of tin was 0.8. (Sn / (In + Sn + Zn)) is 0.1, the molar ratio of zinc (Zn / (In + Sn + Zn)) is 0.1, and the molar ratio of samarium (Sm / (In + Sn + Zn + Sm)) in the whole metal is 0. A target 4 of 0.04 was used. The other manufacturing conditions were the same as in Example 1 to produce an organic EL device. The value of the ionization potential of the anode layer 10 was 5.95 eV. When a DC voltage of 5.0 V was applied between the electrodes in the same manner as in Example 1, the value of the current density was 2.0 mA / cm.²And the light emission luminance was 168 nit. It was also confirmed that the emission color was blue.
[0142]
[Example 4]
Instead of the target 1 in Example 1, the molar ratio of indium (In / (In + Sn + Zn)) composed of indium oxide, tin oxide, zinc oxide, and europium oxide was 0.8, and the molar ratio of tin was 0.8. (Sn / (In + Sn + Zn)) is 0.1, the molar ratio of zinc (Zn / (In + Sn + Zn)) is 0.1, and the molar ratio of europium (Eu / (In + Sn + Zn + Eu)) in the whole metal is 0. A target 5 of 0.04 was used. The other manufacturing conditions were the same as in Example 1 to produce an organic EL device. The value of the ionization potential of the anode layer 10 was 5.80 eV. When a DC voltage of 5.1 V was applied between the electrodes in the same manner as in Example 1, the value of the current density was 2.0 mA / cm.²And the emission luminance was 165 nit. It was also confirmed that the emission color was blue.
[0143]
[Example 5]
Instead of the target 1 in Example 1, the molar ratio of indium (In / (In + Sn + Zn)) composed of indium oxide, tin oxide, zinc oxide, and terbium oxide was 0.8, and the molar ratio of tin was 0.8. (Sn / (In + Sn + Zn)) is 0.1, the molar ratio of zinc (Zn / (In + Sn + Zn)) is 0.1, and the molar ratio of terbium (Tb / (In + Sn + Zn + Tb)) in the whole metal is 0. A target 6 of 0.06 was used. The other manufacturing conditions were the same as in Example 1 to produce an organic EL device. The value of the ionization potential of the anode layer 10 was 5.84 eV. When a DC voltage of 5.1 V was applied between the electrodes in the same manner as in Example 1, the value of the current density was 165 mA / cm.²And the emission luminance was 95 nit. It was also confirmed that the emission color was blue.
[0144]
[Example 6]
Instead of the target 1 in Example 1, the molar ratio of indium (In / (In + Sn + Zn)) composed of indium oxide, tin oxide, zinc oxide, and hornium oxide is 0.8, and the molar ratio of tin is 0.8. (Sn / (In + Sn + Zn)) is 0.1, the molar ratio of zinc (Zn / (In + Sn + Zn)) is 0.1, and the molar ratio of honium in the whole metal (Ho / (In + Sn + Zn + Ho)) is 0. 12 was used. The other manufacturing conditions were the same as in Example 1 to produce an organic EL device. The value of the ionization potential of the anode layer 10 was 5.82 eV. When a DC voltage of 5.1 V was applied between the electrodes in the same manner as in Example 1, the value of the current density was 2.0 mA / cm.²And the light emission luminance was 166 nit. It was also confirmed that the emission color was blue.
[0145]
[Example 7]
Instead of the target 1 in Example 1, the molar ratio of indium (In / (In + Sn + Zn)) composed of indium oxide, tin oxide, zinc oxide, and cerium oxide was 0.8, and the molar ratio of tin was 0.8. (Sn / (In + Sn + Zn)) is 0.1, the molar ratio of zinc (Zn / (In + Sn + Zn)) is 0.1, and the molar ratio of cerium (Ce / (In + Sn + Zn + Ce)) in the whole metal is 0. A target 8 of 0.06 was used. The other manufacturing conditions were the same as in Example 1 to produce an organic EL device. The value of the ionization potential of the anode layer 10 was 5.98 eV. When a DC voltage of 4.9 V was applied between the electrodes in the same manner as in Example 1, the value of the current density was 2.0 mA / cm.²And the light emission luminance was 164 nit. It was also confirmed that the emission color was blue.
[0146]
Example 8
Instead of the target 1 in Example 1, the molar ratio of indium (In / (In + Sn)) composed of indium oxide, tin oxide, and cerium oxide is 0.9, and the molar ratio of tin (Sn / ( (In + Sn)) was formed on a substrate formed to a thickness of 75 nm using a target 8 having a thickness of 0.1. A substrate having a thickness of 20 nm was formed using a certain target. The other manufacturing conditions were the same as in Example 1 to produce an organic EL device. The value of the ionization potential of the anode layer 10 was 6.18 eV, and the transmittance was 79%. Further, a DC voltage of 4.8 V was applied between the electrodes as in Example 1 to the obtained organic EL device. The current density at this time was 2.0 mA / cm²And the emission luminance is 162 nit (cd / m²)Met. It was also confirmed that the emission color was blue. Furthermore, as a durability evaluation, 10 mA / cm², The occurrence of a leak current was not particularly observed even after a lapse of 1000 hours or more.
[0147]
[Comparative Example 1]
Instead of the target 1 in Example 1, the molar ratio of indium (In / (In + Sn + Zn)) composed of indium oxide, tin oxide, and zinc oxide is 0.6, and the molar ratio of tin (Sn / ( (In + Sn + Zn)) was 0.3, and a target 9 having a molar ratio of zinc (Zn / (In + Sn + Zn)) of 0.1 was used. Otherwise, an organic EL device was prepared in the same manner as in Example 1. The value of the ionization potential of the anode layer 10 was 5.23 eV. When a DC voltage of 6.0 V was applied between the electrodes in the same manner as in Example 1, the value of the current density was 2.0 mA / cm.²And the light emission luminance was 166 nit. It was also confirmed that the emission color was blue.
[0148]
【The invention's effect】
As described in detail above, according to the organic electroluminescence device of the present invention, by providing an anode layer or the like made of a specific organic compound, the organic electroluminescence device has excellent transparency and durability, and has high light emission even at a low driving voltage. It has become possible to provide an organic EL device capable of obtaining luminance. It was also confirmed that the anode layer and the like made of a specific inorganic compound had excellent etching characteristics.
[0149]
Further, according to the substrate for an organic electroluminescence element of the present invention, an organic electroluminescence element exhibiting such good performance can be easily manufactured.
[0150]
Further, according to the method for manufacturing an organic EL device of the present invention, it is possible to efficiently provide an organic EL device which is excellent in the above-described transparency and durability and which can obtain high emission luminance even at a low driving voltage. Became.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an organic EL device according to a first embodiment.
FIG. 2 is a cross-sectional view of an organic EL device according to a second embodiment.
FIG. 3 is a cross-sectional view of an organic EL device according to a third embodiment.
FIG. 4 is a cross-sectional view of an organic EL device according to a fourth embodiment.
FIG. 5 is a perspective view of a vacuum evaporation apparatus according to a fifth embodiment.
FIG. 6 is a sectional view of a vacuum evaporation apparatus according to a fifth embodiment.
FIG. 7 is a diagram provided for describing measurement points on a substrate.
FIG. 8 is a diagram of a chemical structural formula representing each chemical substance.
[Explanation of symbols]
10mm anode layer
12 Inorganic thin film layer
13 Hole transport layer
14 Organic light emitting layer
15 electron injection layer
16 cathode layer
30mm board
100, 102, 104, 106 organic EL device
201 vacuum deposition equipment
203 substrate
210 vacuum chamber
211 substrate holder
212 holding part
212A, 212B, 212C, 212D, 212E, 212F evaporation source
213 rotating shaft
213A rotation axis
214 motor
221 virtual circle

Claims (19)

An organic electroluminescence device substrate comprising at least an electrode layer and a base material, wherein the electrode layer is at least one compound selected from the following A-1 group and at least one compound selected from the B-1 group A substrate for an organic electroluminescence element, comprising:
Group A-1: Chalcogenide, oxynitride or nitride of Si, Ge, Sn, Pb, Ga, In, Zn, Cd, Mg.
Group B-1: lanthanoid-based chalcogenides, oxynitrides or nitrides. An organic electroluminescence device substrate comprising at least an electrode layer and a base material, wherein the electrode layer is at least one compound selected from Group A-2 and at least one compound selected from Group B-2 A substrate for an organic electroluminescence element, comprising:
Group A-2: chalcogenides, oxynitrides or nitrides of Ge, Sn, Pb, Ga, In, Zn, Cd, Mg.
Group B-2: chalcogenides of lanthanoid elements. The substrate for an organic electroluminescence device according to claim 1, wherein the electrode layer is an anode layer. The organic electroluminescence device substrate according to claim 1, wherein the electrode layer is a cathode layer. The substrate for an organic electroluminescence device according to claim 1, wherein the electrode layer has a specific resistance value of less than 1 Ω · cm. The organic electroluminescence device substrate according to any one of claims 1 to 5, wherein the compound of the A-1 group or the A-2 group is any of chalcogenides or nitrides of Sn, In, and Zn. The organic electroluminescence device according to any one of claims 1 to 6, wherein the compound of the B-1 group or the B-2 group is any of oxides of Ce, Nd, Sm, Eu, Tb, and Ho. Substrate. The total amount of the electrode layer is 100 at. %, The content of the compound of Group B-1 or Group B-2 is 0.5 to 30 at. The substrate for an organic electroluminescence element according to any one of claims 1 to 7, which is a value within a range of%. The organic electroluminescence device substrate according to any one of claims 1 to 8, wherein the thickness of the electrode layer is a value within a range of 1 to 100 nm. At least an anode layer, an organic light-emitting layer, and an organic electroluminescent element having a structure in which a cathode layer is sequentially laminated, wherein the anode layer and the cathode layer, or one of the electrode layers, An organic electroluminescence device comprising at least one compound selected and at least one compound selected from the following group B-1.
Group A-1: Chalcogenide, oxynitride, or nitride of Si, Ge, Sn, Pb, Ga, In, Zn, Cd, or Mg Group B-1: Chalcogenide, nitrogen oxide, or nitride of a lanthanoid element. At least an anode layer, an organic light-emitting layer, and an organic electroluminescence device having a structure in which a cathode layer is sequentially laminated, wherein the anode layer and the cathode layer, or any one of the electrode layers is formed from the following group A-2. An organic electroluminescence device comprising at least one compound selected and at least one compound selected from the following group B-2.
Group A-2: chalcogenides, oxynitrides, or nitrides of Ge, Sn, Pb, Ga, In, Zn, Cd, and Mg Group B-2: chalcogenides of lanthanoid-based elements. The organic electroluminescence device according to claim 10 or 11, wherein a specific resistance value of the anode layer and the cathode layer or any one of the electrode layers is less than 1 Ω · cm. The organic electroluminescence device according to any one of claims 10 to 12, wherein the compound of the A-1 group or the A-2 group is any of chalcogenides or nitrides of Sn, In, and Zn. The compound according to any one of claims 12 to 13, wherein the compound of Group B-1 or Group B-2 is an oxide of any substance of Ce, Nd, Sm, Eu, Tb, and Ho. Organic electroluminescent element. The total amount of the electrode layer is 100 at. %, The content of the compound of Group B-1 or Group B-2 is 0.5 to 30 at. The organic electroluminescent device according to any one of claims 10 to 14, which is a value within a range of%. The organic electroluminescence device according to any one of claims 10 to 15, wherein the thickness of the electrode layer is a value within a range of 1 to 100 nm. Between the anode layer and the organic light emitting layer, and between the cathode layer and the organic light emitting layer, or between any one thereof, at least one compound selected from the group A-1 and the group B-1 An inorganic thin film layer containing at least one compound selected from the group consisting of: an inorganic thin film layer containing at least one compound selected from the group A-2 and at least one compound selected from the group B-2; The organic electroluminescence device according to any one of claims 10 to 16, which is provided. 18. The organic light-emitting layer according to claim 10, wherein the organic light-emitting layer contains at least one styryl group-containing aromatic compound represented by any one of the following general formulas (Chemical Formula 1) to (Chemical Formula 3). The organic electroluminescence device according to claim 1.

Here, in the general formula (Chemical formula 1), Ar ¹ is an aromatic group having 6 to 40 carbon atoms, and Ar ² , Ar ³ , and Ar ⁴ are each a hydrogen atom or a carbon atom having 6 to 40 carbon atoms. An aromatic group, at least one of Ar ¹ , Ar ² , Ar ³ , and Ar ⁴ is an aromatic group, and the condensation number n is an integer of 1 to 6.

Here, in the general formula (Chemical Formula 2), Ar ⁵ is an aromatic group having 6 to 40 carbon atoms, and Ar ⁶ and Ar ⁷ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms. At least one of Ar ⁵ , Ar ⁶ and Ar ⁷ is substituted with a styryl group, and the condensation number m is an integer of 1 to 6.

Here, in the general formula (Chemical formula 3), Ar ⁸ and Ar ¹⁴ are aromatic groups having 6 to 40 carbon atoms, and Ar ^{9 to} Ar ¹³ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms. And at least one of Ar ^{8 to} Ar ¹⁴ is substituted with a styryl group, and the condensed numbers p, q, r, and s are each 0 or 1. The method for manufacturing an organic electroluminescence device according to any one of claims 10 to 18, wherein the electrode layer is formed by a sputtering method, and the organic light emitting layer is formed by a vacuum deposition method. A method for manufacturing a luminescence element.

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