JP2005044528A

JP2005044528A - El device, its manufacturing method, and display device using el device

Info

Publication number: JP2005044528A
Application number: JP2003199979A
Authority: JP
Inventors: Toshiki Inoue; 敏樹井上
Original assignee: Toyota Industries Corp
Current assignee: Toyota Industries Corp
Priority date: 2003-07-22
Filing date: 2003-07-22
Publication date: 2005-02-17

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EL device capable of emitting light with high luminance even by small power consumption. <P>SOLUTION: A transparent electrode 8, a positive hole transportation layer 9, an organic luminescent layer 10 and a reflecting electrode 11 are formed on an uneven surface 7 of a transparent substrate 6 by respectively sequentially stacking them in a curved shape. A luminescent part composed of the transportation layer 9 and the luminescent layer 10 is provided with recessed parts 12a and projecting parts 12b with respect to a light emitting surface 6a; and the transportation layer 9 is so formed that the projecting parts 12b have layer thickness larger than that of the recessed parts 12a. The luminescent layer 10 of the recessed parts 12a preferentially emits light as compared with that of the projecting parts 12b when a voltage is applied between the transparent electrode 8 and the reflecting electrode 11. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、ＥＬ（エレクトロルミネッセンス）装置に関する。
また、この発明は、このようなＥＬ装置の製造方法並びにＥＬ装置をバックライトとして用いた表示装置にも関している。
【０００２】
【従来の技術】
従来の有機ＥＬ装置の構成を図１１に示す。透明基板１の上に透明性電極２を介してホール輸送層３及び有機発光層４が順次形成され、さらに有機発光層４の上に反射性電極５が形成されている。そして、透明性電極２と反射性電極５の間に電界を印加すると、電子と正孔とが再結合する際に放出されるエネルギーによって有機発光層４内の蛍光材料や燐光材料等の発光材料が発光する。透明性電極２の方向へ進んだ光Ｌ１は、ホール輸送層３及び透明性電極２を透過した後、さらに透明基板１を透過して装置外部へ出射し、反射性電極５の方向へ進んだ光Ｌ２は、反射性電極５で反射した後、ホール輸送層３、透明性電極２及び透明基板１を透過して装置外部へ出射する。
この有機ＥＬ装置は、各種表示装置として利用されたり、液晶表示装置等の表示装置のバックライトとして利用されたりしている。
【０００３】
このようなＥＬ装置においては、発光層で発した光をいかに効率よく装置外部へ取り出すかが研究課題となっている。
【０００４】
上記研究課題に対して、有機ＥＬ素子の側面等に反射面を形成する従来技術が提案されている。また、例えば特許文献１に開示されているように、有機発光層を挟む一対の電極のうち、光の出射面側に位置する電極に微小突起を形成し且つ他方の電極に凹面形状を形成して、他方の電極に凹面鏡としての集光性を持たせる従来技術も提案されている。
【０００５】
【特許文献１】
特許第２８４８３８６号公報
【０００６】
【発明が解決しようとする課題】
しかしながら、以上のような従来技術を用いても十分な光取り出し効率を得ることはできておらず、開発の余地があった。
【０００７】
この発明はこのような問題点を解消するためになされたもので、小さな消費電力でも高輝度の発光を行うことができるＥＬ装置を提供することを目的とする。
また、この発明は、このようなＥＬ装置を得ることができるＥＬ装置の製造方法並びにこのようなＥＬ装置を用いた表示装置を提供することも目的としている。
【０００８】
【課題を解決するための手段】
この発明に係る第１のＥＬ装置は、基板上に第１の電極と発光部と第２の電極との積層体からなるＥＬ素子が形成されたＥＬ装置において、発光部は、光の出射面側へ隆起した複数の凸部を備え、優先的に発光させるようにされた複数の優先発光領域を有し、各優先発光領域は、少なくとも凸部の裾を含むように設定されたものである。
【０００９】
ここで、凸部の裾とは、凸部の周辺部、へりのことである。
発光部の凸部では第１の電極あるいは第２の電極との境界面が覆い被さるように位置しているので、たとえこの凸部で発光させたとしても、第１の電極あるいは第２の電極との境界面で反射して発光層内に閉じ込められる光が多くなる。
また、透明基板上に形成されたＥＬ素子から透明基板を介して光を出射するＥＬ装置では、発光部の凸部から発した光は、透明基板へ入射した後に透明基板から出射されることなく再びＥＬ素子に入射し、さらにこのＥＬ素子で一回反射した後に透明基板の出射面から出射される可能性が低い。
同様に、基板上に形成されたＥＬ素子から基板とは反対方向へ光を出射するＥＬ装置においても、発光部の凸部から発した光は、ＥＬ素子から一旦放出された後に再びＥＬ素子に入射し、さらにこのＥＬ素子で反射することにより出射される可能性が低い。
すなわち、光の出射面側へ隆起した発光部の凸部から発した光を効率よく取り出すことが困難である。そこで、このような発光部の凸部の裾を含む所定の範囲から優先的に発光させることにより、小さな消費電力でありながらＥＬ装置全体として光取り出し効率の向上が達成される。
【００１０】
この発明に係る第２のＥＬ装置は、基板上に第１の電極と発光部と第２の電極との積層体からなるＥＬ素子が形成されたＥＬ装置において、発光部は、光の出射面とは反対側へ窪んだ複数の凹部を備え、優先的に発光させるようにされた複数の優先発光領域を有し、各優先発光領域は、いずれか一の凹部に、少なくとも底部を含むように設定されたものである。
【００１１】
ここで、底部は、凹部の最下点等、凹部の一番低い部分を意味している。また、各優先発光領域は、いずれか一の凹部に設けられるので、複数の凹部にまたがることはない。なお、いくつかの優先発光領域は、複数の凹部を含んでいても、複数の凹部の底部を含んでいてもよい。
このような構成としても、第１のＥＬ装置と同様の作用効果を奏する。
【００１２】
なお、第１〜第２のＥＬ装置は、発光部を構成する層の少なくとも一つが、優先発光領域において他の領域よりも薄くなるように構成されていてもよい。
発光部として、少なくとも互いに積層されたホール輸送層と発光層とを備えたものを用いると共に、各優先発光領域におけるホール輸送層に比べて他の領域のホール輸送層の層厚をより厚く設定することができる。
また、発光部として、少なくとも互いに積層された電子輸送層と発光層とを備えたものを用いると共に、各優先発光領域における電子輸送層に比べて他の領域の電子輸送層の層厚をより厚く設定してもよい。
あるいは、発光部として、少なくとも発光層を備えたものを用いると共に、各優先発光領域における発光層に比べて他の領域の発光層の層厚をより厚く設定することもできる。
上記した構成において、発光層についても本構成と同様に設計することも当然に可能である。すなわち、発光層、電子輸送層、ホール輸送層その他電極間に設けることができる少なくとも一つの層の層厚を、優先発光領域と他の領域とで以上のように設定すればよいのであって、二層以上を以上のように設定することも当然に可能である。
【００１３】
この発明に係るＥＬ装置の第１の製造方法は、基板上に第１の電極と発光部と第２の電極とを順次積層形成するＥＬ装置の製造方法において、基板に凹凸面を形成し、この凹凸面上に第１の電極を形成し、基板の凹凸面が設けられていない面が概略水平になるようにし、かつ、前記凹凸面を重力方向において重力の向きとは反対側になるように配置した後、第１の電極の上に下記（１）〜（３）のいずれかの手法によってホール輸送層を形成し、ホール輸送層の上に発光層を形成し、発光層の上に第２の電極を形成する方法である。
【００１４】
（１）ホール輸送材料を分散媒に分散させた分散液を配置した後、凸部上の分散液の一部が凹部側へ移動した状態で分散媒を除去する手法。
この（１）の手法は、例えば、（１ａ）上記分散液を第１の電極上に略均一に配置した後、所定の時間の経過を待ってから乾燥させる手法や、（１ｂ）上記分散液を第１の電極上に配置した後、前記凸部上の分散液の一部が凹部側へ移動し、凸部上の分散液の厚さ（量）が凹部上の分散液の厚さ（量）よりも多くなるのを待って、又は、多くなるための所定の時間待ってから乾燥させる手法等の手法も含まれる。
【００１５】
（２）ホール輸送材料を溶媒に溶解させた溶液を配置した後、凸部上の溶液の一部が凹部側へ移動した状態で溶液を除去する手法。
この（２）の手法は、例えば、（２ａ）上記溶液を第１の電極上に略均一に配置した後、所定の時間の経過を待ってから乾燥させる手法や、（２ｂ）上記分散液を第１の電極上に配置した後、前記凸部上の溶液の一部が凹部側へ移動し、凸部上の溶液の厚さ（量）が凹部上の溶液の厚さ（量）よりも多くなるのを待って、又は、多くなるための所定の時間待ってから乾燥させる手法等の手法も含まれる。
【００１６】
（３）ホール輸送材料を融解し、又はガラス状にしてこれを配置した後、ホール輸送材料が凸部上から凹部側へ一部が移動した状態でホール輸送材料を固定する手法。
この（３）の手法には、第１の電極の上にホール輸送材料を配置等によってホール輸送層を形成し、その後、ホール輸送材料を溶融して液化し、ホール輸送材料が凸部上から凹部側へ一部が移動した状態で冷却してホール輸送材料を固定する手法も含まれる。
【００１７】
なお、「分散液等を配置する」とは、「分散液等を載せる」ということを意味するのであって、分散液等を塗布等の方法によって配置することができる。
【００１８】
このような方法により、光の出射面とは反対側へ窪んだ発光層の凹部の底部を含む所定の範囲から優先的に発光させるようにしたＥＬ装置が実現される。
【００１９】
ＥＬ装置の第２の製造方法は、基板上に第１の電極と発光部と第２の電極とを順次積層形成するＥＬ装置の製造方法において、基板に凹凸面を形成し、この凹凸面上に第１の電極を形成し、基板の凹凸面が設けられていない面が概略水平になるようにし、かつ、前記凹凸面を重力方向において重力の向きとは反対側になるように配置した後、第１の電極の上に下記（４）〜（６）のいずれかの手法によって発光層を形成し、発光層の上に第２の電極を形成する方法である。このようにしても、光の出射面とは反対側へ窪んだ発光層の凹部の底部を含む所定の範囲から優先的に発光させるようにしたＥＬ装置が実現される。
【００２０】
（４）発光材料を分散媒に分散させた分散液を配置した後、凸部上の分散液の一部が凹部側へ移動した状態で分散媒を除去する手法。
この（４）の手法は、例えば、（４ａ）上記分散液を第１の電極上に略均一に配置した後、所定の時間の経過を待ってから乾燥させる手法や、（４ｂ）上記分散液を第１の電極上に配置した後、前記凸部上の分散液の一部が凹部側へ移動し、凸部上の分散液の厚さ（量）が凹部上の分散液の厚さ（量）よりも多くなるのを待って、又は、多くなるための所定の時間待ってから乾燥させる手法等の手法も含まれる。
【００２１】
（５）発光材料を溶媒に溶解させた溶液を配置した後、凸部上の溶液の一部が凹部側へ移動した状態で溶液を除去する手法。
この（５）の手法は、例えば、（５ａ）上記溶液を第１の電極上に略均一に配置した後、所定の時間の経過を待ってから乾燥させる手法や、（５ｂ）上記分散液を第１の電極上に配置した後、前記凸部上の溶液の一部が凹部側へ移動し、凸部上の溶液の厚さ（量）が凹部上の溶液の厚さ（量）よりも多くなるのを待って、又は、多くなるための所定の時間待ってから乾燥させる手法等の手法も含まれる。
【００２２】
（６）発光材料を融解し、又はガラス状にしてこれを配置した後、発光材料が凸部上から凹部側へ一部が移動した状態で発光材料を固定する手法。
この（６）の手法には、第１の電極の上に発光材料を配置等によって発光層を形成し、その後、発光材料を溶融して液化し、発光材料が凸部上から凹部側へ一部が移動した状態で冷却して発光材料を固定する手法も含まれる。
【００２３】
ＥＬ装置の第３の製造方法は、基板上に第１の電極と発光部と第２の電極とを順次積層形成するＥＬ装置の製造方法において、基板に凹凸面を形成し、この凹凸面上に第１の電極を形成し、第１の電極の上に発光層を形成し、基板の凹凸面が設けられていない面が概略水平になるようにし、かつ、前記凹凸面を重力方向において重力の向きとは反対側になるように配置した後、発光層の上に下記（７）〜（９）のいずれかの手法によって電子輸送層を形成し、電子輸送層の上に第２の電極を形成する方法である。このような方法によっても、光の出射面とは反対側へ窪んだ発光層の凹部の底部を含む所定の範囲から優先的に発光させるようにしたＥＬ装置が実現される。
【００２４】
（７）電子輸送材料を分散媒に分散させた分散液を配置した後、凸部上の分散液の一部が凹部側へ移動した状態で分散媒を除去する手法。
この（７）の手法は、例えば、（７ａ）上記分散液を発光層上に略均一に配置した後、所定の時間の経過を待ってから乾燥させる手法や、（７ｂ）上記分散液を発光層上に配置した後、前記凸部上の分散液の一部が凹部側へ移動し、凸部上の分散液の厚さ（量）が凹部上の分散液の厚さ（量）よりも多くなるのを待って、又は、多くなるための所定の時間待ってから乾燥させる手法等の手法も含まれる。
【００２５】
（８）電子輸送材料を溶媒に溶解させた溶液を配置した後、凸部上の溶液の一部が凹部側へ移動した状態で溶液を除去する手法。
この（８）の手法は、例えば、（８ａ）上記溶液を発光層上に略均一に配置した後、所定の時間の経過を待ってから乾燥させる手法や、（８ｂ）上記分散液を発光層上に配置した後、前記凸部上の溶液の一部が凹部側へ移動し、凸部上の溶液の厚さ（量）が凹部上の溶液の厚さ（量）よりも多くなるのを待って、又は、多くなるための所定の時間待ってから乾燥させる手法等の手法も含まれる。
【００２６】
（９）電子輸送材料を融解し、又はガラス状にしてこれを配置した後、電子輸送材料が凸部上から凹部側へ一部が移動した状態で電子輸送材料を固定する手法。
この（９）の手法には、発光層の上に発光材料を配置等によって電子輸送層を形成し、その後、電子輸送材料を溶融して液化し、電子輸送材料料が凸部上から凹部側へ一部が移動した状態で冷却して発光材料を固定する手法も含まれる。
【００２７】
また、これらの製造方法を適宜組み合わせることも当然に可能である。すなわち、前記したように複数の層について層厚を変化させるために、これらの製造方法を組み合わせて用いることができる
さらに、本明細書において「基板に凹凸面を形成する」とは、基板上に直接凹凸を形成する場合に限定されず、例えば、基板上に前記していない層を一層以上設け、当該層の少なくとも一つに凹凸を設けたり、第一の電極に凹凸を形成たりすることも含まれる。
【００２８】
この発明に係る表示装置は、上述したこの発明に係るＥＬ装置あるいはこの発明に係る製造方法により製造されたＥＬ装置をバックライトとして使用したものである。ＥＬ装置で効率よく取り出された光により照明が行われる。
【００２９】
【発明の実施の形態】
以下、この発明の実施の形態を添付図面に基づいて説明する。
実施の形態１．
図１に実施の形態１に係る有機ＥＬ装置Ａの断面を示す。有機ＥＬ装置Ａは透明基板６を有しており、透明基板６の一対の主面のうちの一方の面をこの有機ＥＬ装置Ａの出射面６ａとし、他方の面に凹部と凸部とが不規則に形成され、ここに凹凸面７を形成している。この透明基板６の凹凸面７上に沿って透明性電極８が形成され、透明性電極８の表面上に沿ってホール輸送層９が形成され、さらにホール輸送層９の表面上に有機発光層１０が形成されている。ここで、ホール輸送層９と有機発光層１０とによりこの発明の発光部が構成されている。さらに、有機発光層１０の表面上に沿って反射性電極１１が積層形成され、これら透明性電極８、発光部及び反射性電極１１によりＥＬ素子が構成されている。
【００３０】
透明性電極８は均一な膜厚を有しており、透明基板６の凹凸面７に対応した湾曲形状を有している。ホール輸送層９と有機発光層１０からなる発光部は、透明性電極８の表面に対応した湾曲形状を有し、出射面となる透明基板６の出射面６ａに対して窪んだ凹部１２ａと隆起した凸部１２ｂとを備えており、ホール輸送層９は凹部１２ａに比べて凸部１２ｂの方がより厚い層厚を有するように形成されている。このホール輸送層９の表面上に形成された有機発光層１０及び有機発光層１０の表面上に形成された反射性電極１１はいずれも均一な層厚を有している。
透明性電極８及び反射性電極１１がそれぞれこの発明の第１の電極及び第２の電極を構成している。
【００３１】
ここで、図１１に示した従来のＥＬ装置において、ホール輸送層３の厚さを２００Å（２×１０^−８ｍ）、４００Å（４×１０^−８ｍ）、６００Å（６×１０^−８ｍ）及び８００Å（８×１０^−８ｍ）に設定した他は同じ構成の４種類のＥＬ装置を作成し、それぞれ電極間の印加電圧を変化させて発光させたときの輝度特性を測定したところ、図２に示すような結果が得られた。ホール輸送層３の層厚が小さいほど効率よく発光することがわかる。
【００３２】
このため、凹部１２ａに比べて凸部１２ｂの方がより厚い層厚を有するように形成されたホール輸送層９を有するこの実施の形態１のＥＬ装置にあっては、透明性電極８と反射性電極１１の間に電圧を印加したときに、図３に示すように、凹部１２ａの底部を含む領域の有機発光層１０が他の領域より優先的に発光することとなる。凸部１２ｂの有機発光層１０は実質的に発光しないか、あるいは発光しても低輝度の発光となる。
【００３３】
凹部１２ａの有機発光層１０で発した光のうち、透明性電極８の方向へ発した光Ｌ３の大部分はそのまま有機発光層１０からホール輸送層９、透明性電極８及び透明基板６を透過して出射面６ａから出射し、反射性電極１１の方向へ発した光Ｌ４も反射性電極１１で反射した後、ホール輸送層９、透明性電極８及び透明基板６を透過して出射面６ａから出射する。また、凹部１２ａの有機発光層１０から出射面６ａに対してほぼ平行に発した光Ｌ５も、反射性電極１１で反射され、ホール輸送層９、透明性電極８及び透明基板６を通って出射面６ａから出射するようになる。
【００３４】
これに対して、凸部１２ｂの有機発光層１０ではホール輸送層９との境界面が覆い被さるように位置しているので、たとえこの凸部１２ｂで発光させたとしても、凹部１２ａから発光する場合に比べて、ホール輸送層９との境界面あるいは透明性電極８との境界面で反射して有機発光層１０内に閉じ込められる光が多くなる。また、凸部１２ｂの有機発光層１０から発した光は、ホール輸送層９及び透明性電極８を介して透明基板６へ入射した後に透明基板６の出射面６ａから出射されることなく再びＥＬ素子に入射し、さらにこのＥＬ素子で一回反射した後に透明基板６の出射面６ａから出射される可能性が低い。すなわち、出射面６ａに対して隆起した凸部１２ｂの有機発光層１０から発した光を効率よく取り出すことが困難である。
【００３５】
この実施の形態１に係る有機ＥＬ装置Ａの有機発光層１０では、取り出し効率の高い凹部１２ａを取り出し効率の低い凸部１２ｂに比べて優先的に発光させているため、凸部１２ｂに流れる電流密度が抑制され、従来よりも小さな電流によって従来と同等の輝度で発光させることができ、また従来と同等の電流を流すことにより従来よりも高い輝度での発光が可能となる。
また、凸部１２ｂの有機発光層１０が発光するため、出射面の垂直方向への集光性を生じ、特に有機ＥＬ装置の正面輝度の向上がなされる。
【００３６】
この有機ＥＬ装置Ａにおいては、有機発光層１０と透明性電極８との間にホール輸送層９が存在するため、有機発光層１０として電子輸送性の発光層を用いても、反射性電極１１から有機発光層１０に注入された電子がホール輸送層９との界面でブロックされ、有機発光層１０内に閉じ込められるため、発光効率が向上する。
【００３７】
このような有機ＥＬ装置Ａの製造方法について説明する。平板状の透明基板６の上面にこれから形成しようとする凹部と凸部の配置に対応したパターンのマスクを用いてフォトレジスト等によりパターニングし、この状態でエッチングを施すことにより図４（ａ）に示すような凹凸面７を形成する。
【００３８】
次に、図４（ｂ）に示すように、透明基板６の凹凸面７上に透明性電極８を均一な膜厚に形成する。これにより、透明性電極８は凹凸面７に対応した湾曲形状をなし、透明基板６に対して窪んだ凹部８ａと隆起した凸部８ｂとを有する。
【００３９】
このようにして湾曲形成された透明性電極８の上に、図４（ｃ）に示すように、液状のホール輸送材料９ｃを塗布する。ここで、液状のホール輸送材料９ｃは重力の影響を受け、透明基板６に対して窪んだ凹部８ａから隆起した凸部８ｂへと次第に流れる。この状態で、常温放置あるいは加熱することにより、ホール輸送材料９ｃを硬化させて、図５（ａ）に示すようにホール輸送層９を形成する。液状のホール輸送材料９ｃが重力の影響を受けて流れたことにより、ホール輸送層９は、透明性電極８の凹部８ａ上に位置する部分がより薄く、凸部８ｂ上に位置する部分がより厚く形成されている。
【００４０】
次いで、図５（ｂ）に示すように、ホール輸送層９の上に有機発光層１０を形成し、さらに有機発光層１０の上に反射性電極１１を形成すると、図５（ｃ）に示すように、これら有機発光層１０及び反射性電極１１がホール輸送層９の湾曲した表面に応じて湾曲形状となり、有機ＥＬ装置Ａが製造される。
有機ＥＬ装置Ａは、さらに、ガラス製のキャップで封止されたり、その表面にＳｉＮ等の薄膜を形成することにより封止されたりする。
【００４１】
なお、上記「液状のホール輸送材料９ｃ」とは、（ａ）ホール輸送材料を分散媒に分散させた分散液、（ｂ）ホール輸送材料を溶媒に溶解させた溶液、又は（ｃ）ホール輸送材料を融解して得られる液体又はガラス状の物体のことを意味する。上記（ａ）や（ｂ）のように分散液や溶液を用いる場合には、前記したように乾燥させるなどして分散媒や溶媒を除去してホール輸送層９を作製する。上記（ｃ）のような液体等を用いる場合には、当該液体等を冷却して固定し（固化し）てホール輸送層９を作製する。また、ホール輸送材料を公知の方法によって積層後、加熱固化してホール輸送材料を融解させ、これを再度固化して図１に示すホール輸送層９を作製してもよい。
【００４２】
ホール輸送材料としては低分子材料であっても高分子材料であってもどのような材料であっても採用できる。具体的には、低分子材料では、例えばＴＰＤやＴＦＴＥ等のホール輸送材料をＴＨＦやジクロロエタン等の有機溶媒に分散又は溶解した分散液又は溶液を用いることができる。高分子材料では、例えば、アニリン系共重合体、ポリアリールアルカン誘導体、ポリフェニレンビニレン及びその誘導体、ポリチオフェン及びその誘導体、ポリ−Ｎ−ビニルカルバゾール誘導体、チオフェンオリゴマーなどの導電性高分子オリゴマー等を、これらの材料を分散又は溶解可能な分散媒又は溶媒に分散又は溶解させた分散媒又は溶液を用いることができる。
【００４３】
透明性電極８の表面上へのホール輸送材料９ｃの塗布方法としては、スプレー塗布、スピンコート、フローコート、ディッピング等の方法を選択することができる。
【００４４】
有機発光層１０は、公知の低分子タイプの材料でも公知の高分子タイプの材料でも使用することができ、例えば、低分子タイプの発光材料を真空蒸着法により成膜したり、高分子タイプの発光材料を塗布して成膜したりすることで形成できる。
【００４５】
透明性電極８の材料としては、有機発光層１０から可視光領域の光を取り出す場合には、例えば、可視光領域で透過率の高いＩＴＯ（インジウム−亜鉛−オキサイド）が好適であるが、これに限定されず、例えば５０ｎｍ以下、好ましくは０．５〜２０ｎｍの範囲の膜厚のＡｌ、Ｃｒ、Ｍｏ、Ａｌ合金、Ａｌ／Ｍｏ積層体等の金属によって透明電極を構成してもよい。
反射性電極１１の材料としては、電極としての機能を有し且つ少なくとも可視光に対して反射性を有すればよく、例えばＡｌ、Ｃｒ、Ｍｏ、Ａｌ合金、Ａｌ／Ｍｏ積層体等の各種の金属、合金、金属化合物等を用いることができる。
透明性電極８及び反射性電極１１は、スパッタリング法、イオンプレーティング法、真空蒸着法、電子ビーム蒸着法、スピンコート法等の公知の薄膜形成法により形成される。
【００４６】
実施の形態２．
実施の形態２に係る有機ＥＬ装置の断面を図６に示す。このＥＬ装置は、図１に示す実施の形態１のＥＬ装置において、有機発光層１０の表面上に電子輸送層１３を均一な層厚で形成し、この電子輸送層１３の上に反射性電極１１を形成したものである。つまり、本実施の形態においては、発光部がホール輸送層９と有機発光層１０と電子輸送層１３とにより構成されている。
電子輸送層１３は、低分子タイプでも高分子タイプでもよく、公知の薄膜形成法により形成することができる。
【００４７】
有機発光層１０と透明性電極８との間にホール輸送層９が、有機発光層１０と反射性電極１１との間に電子輸送層１３がそれぞれ存在するため、陽極から有機発光層１０へのホール注入・輸送と、陰極から有機発光層１０への電子の注入・輸送が効率的となり、有機発光層１０としてキャリア輸送性や注入性の低い発光層にすることもできる。
【００４８】
本実施の形態においても、実施の形態１と同様に、ホール輸送層９は凹部１２ａに比べて凸部１２ｂの方がより厚い層厚を有しているため、取り出し効率の高い凹部１２ａの有機発光層１０が取り出し効率の低い凸部１２ｂに比べて優先的に発光し、小さな電流で高輝度の発光を行うことが可能となる。
【００４９】
実施の形態３．
実施の形態３に係る有機ＥＬ装置の断面を図７に示す。このＥＬ装置は、図６に示す実施の形態２のＥＬ装置において、ホール輸送層９を均一な層厚で形成し、有機発光層１０を凹部１２ａに比べて凸部１２ｂの方がより厚い層厚を有するように形成したものである。
このような構成としても、取り出し効率の高い凹部１２ａの有機発光層１０が取り出し効率の低い凸部１２ｂに比べて優先的に発光し、小さな電流で高輝度の発光を行うことが可能となる。
【００５０】
実施の形態３においては、均一な層厚で形成するホール輸送層９の材料は、低分子タイプでも高分子タイプでもよく、公知の薄膜形成法により透明性電極８の表面上に沿って形成することができる。ホール輸送層９は透明性電極８の表面に対応した湾曲形状をなし、透明基板６に対して窪んだ凹部９ａと隆起した凸部９ｂとを有する。
【００５１】
有機発光層１０の材料としては、高分子タイプの液状の発光材料を使用する。湾曲形成されたホール輸送層９の表面上に液状の発光材料を塗布すると、発光材料は重力の影響を受け、透明基板６に対して窪んだホール輸送層９の凹部９ａから隆起した凸部９ｂへと次第に流れる。この状態で、常温放置あるいは加熱することにより、発光材料を硬化させて有機発光層１０を形成する。液状の発光材料が重力の影響を受けて流れたことにより、有機発光層１０は、ホール輸送層９の凹部９ａ上に位置する部分がより薄く、凸部９ｂ上に位置する部分がより厚く形成される。
【００５２】
また、低分子タイプの発光材料も採用することができる。このタイプの材料を採用する場合には、塗布法によって有機発光層１０を形成できる材料が好適に選択される。
【００５３】
なお、上記「液状の発光材料」とは、（ａ）発光材料を分散媒に分散させた分散液、（ｂ）発光材料を溶媒に溶解させた溶液、又は（ｃ）発光材料を融解して得られる液体又はガラス状の物体のことを意味する。上記（ａ）や（ｂ）のように分散液や溶液を用いる場合には、前記したように乾燥させるなどして分散媒や溶媒を除去して有機発光層１０を作製する。上記（ｃ）のような液体等を用いる場合には、当該液体等を冷却して固定し（固化し）て有機発光層１０を作製する。また、発光材料を公知の方法によって積層後、加熱固化して発光材料を融解させ、これを再度固化して図７に示す有機発光層１０を作製してもよい。
このような有機発光層１０の表面上に電子輸送層１３及び反射性電極１１をそれぞれ均一な層厚で順次形成すると、図７に示す有機ＥＬ装置が製造される。
【００５４】
実施の形態４．
実施の形態４に係る有機ＥＬ装置の断面を図８に示す。このＥＬ装置は、図６に示す実施の形態２のＥＬ装置において、ホール輸送層９及び発光層１０を均一な層厚で形成し、電子輸送層１３を凹部１２ａに比べて凸部１２ｂの方がより厚い層厚を有するように形成したものである。
このような構成としても、取り出し効率の高い凹部１２ａの有機発光層１０が取り出し効率の低い凸部１２ｂに比べて優先的に発光し、小さな電流で高輝度の発光を行うことが可能となる。
【００５５】
この実施の形態４においては、均一な層厚で形成するホール輸送層９の材料は、低分子タイプでも高分子タイプでもよく、公知の薄膜形成法により透明性電極８の表面上に沿って形成することができる。ホール輸送層９は透明性電極８の表面に対応した湾曲形状をなし、そのホール輸送層９の表面上に有機発光層１０を均一な層厚で形成する。
有機発光層１０は、ホール輸送層９の表面に対応した湾曲形状をなし、透明基板６に対して窪んだ凹部１０ａと隆起した凸部１０ｂとを有する。
【００５６】
電子輸送層１３の材料としては、高分子タイプの液状の電子輸送材料を使用する。湾曲形成された有機発光層１０の表面上に液状の電子輸送材料を塗布すると、電子輸送材料は重力の影響を受け、透明基板６に対して窪んだ有機発光層１０の凹部１０ａから隆起した凸部１０ｂへと次第に流れる。この状態で、常温放置あるいは加熱することにより、電子輸送材料を硬化させて電子輸送層１３を形成する。液状の電子輸送材料が重力の影響を受けて流れたことにより、電子輸送層１３は、有機発光層１０の凹部１０ａ上に位置する部分がより薄く、凸部１０ｂ上に位置する部分がより厚く形成される。
【００５７】
また、低分子タイプの電子輸送材料も採用することができる。このタイプの材料を採用する場合には、塗布法によって電子輸送層１３を形成できる材料が好適に選択される。
【００５８】
なお、上記「液状の電子輸送材料」とは、（ａ）電子輸送材料を分散媒に分散させた分散液、（ｂ）電子輸送材料を溶媒に溶解させた溶液、又は（ｃ）電子輸送材料を融解して得られる液体又はガラス状の物体のことを意味する。上記（ａ）や（ｂ）のように分散液や溶液を用いる場合には、前記したように乾燥させるなどして分散媒や溶媒を除去して電子輸送層１３を作製する。上記（ｃ）のような液体等を用いる場合には、当該液体等を冷却して固定し（固化し）て電子輸送層１３を作製する。また、電子輸送材料を公知の方法によって積層後、加熱固化して電子輸送材料を融解させ、これを再度固化して図８に示す電子輸送層１３を作製してもよい。
このような電子輸送層１３の表面上に反射性電極１１を均一な層厚で形成すると、図８に示す有機ＥＬ装置が製造される。
【００５９】
実施の形態５．
実施の形態５に係る有機ＥＬ装置の断面を図９に示す。このＥＬ装置は、図８に示す実施の形態４のＥＬ装置において、ホール輸送層９を省略したものである。透明性電極８の表面上に有機発光層１０を均一な層厚で形成し、有機発光層１０の上に電子輸送層１３を凹部１２ａに比べて凸部１２ｂの方がより厚い層厚を有するように形成した後、電子輸送層１３の上に反射性電極１１を均一な層厚で形成する。
このような構成としても、取り出し効率の高い凹部１２ａの有機発光層１０が取り出し効率の低い凸部１２ｂに比べて優先的に発光し、小さな電流で高輝度の発光を行うことが可能となる。
【００６０】
有機発光層１０と反射性電極１１との間に電子輸送層１３が存在するため、有機発光層１０としてホール輸送性の発光層を用いても高い発光効率が得られる。
【００６１】
実施の形態６．
上述した実施の形態２〜４のように、発光部をホール輸送層９と有機発光層１０と電子輸送層１３とにより構成し、これらホール輸送層９、有機発光層１０及び電子輸送層１３のうち二層あるいは三層すべてをそれぞれ凹部に比べて凸部の方がより厚い層厚を有するように形成することもできる。
このようにしても、取り出し効率の高い凹部１２ａの有機発光層１０が取り出し効率の低い凸部１２ｂに比べて優先的に発光し、小さな電流で高輝度の発光を行うことが可能となる。
【００６２】
実施の形態７．
この発明の実施の形態７に係る液晶表示装置の断面を図１０に示す。この液晶表示装置は、液晶パネルＢの後方にバックライトとして実施の形態１に係る有機ＥＬ装置Ａを配置したものである。液晶パネルＢは、互いに平行に配置されると共にそれぞれ対向する面に透明電極１４が形成された一対のガラス基板１５を有しており、これら一対のガラス基板１５の間に液晶が封じ込まれて液晶層１６が形成されている。さらに、一対のガラス基板１５の外側にはそれぞれ偏光板１７が配置されている。
【００６３】
この液晶表示装置では、昼間など周囲が十分明るい場合には、液晶パネルＢを透過して有機ＥＬ装置Ａ内に入射した外光を反射性電極１１で反射させて照明光として利用し、一方、周囲が暗い場合には、有機ＥＬ装置Ａの有機発光層１０を発光させて照明光として利用することができる。これらの照明光は、液晶パネルＢの後面に入射し、液晶層１６の配向状態に応じた表示光が液晶パネルＢの前面から出射されることにより表示が行われる。
【００６４】
ここで、液晶パネルＢを透過して有機ＥＬ装置Ａの透明基板６に入射した外光は、透明基板６、透明性電極８、ホール輸送層９及び有機発光層１０を透過して反射性電極１１で反射される。このとき、反射性電極１１が湾曲形状を有しているため、散乱機能を有し、外光は反射性電極１１の表面で散乱して種々の角度で反射する。これらの反射光が有機発光層１０、ホール輸送層９及び透明性電極８の境界面及び透明基板６の凹凸面７を通る際に屈折率差に起因してさらに散乱され、透明基板６の出射面６ａから液晶パネルＢに向けて出射する。これにより均一な照明光を得ることができる。
一方、有機ＥＬ装置Ａの凹部１２ａの有機発光層１０から優先的に発した光は、有機発光層１０、ホール輸送層９及び透明性電極８の境界面及び透明基板６の凹凸面７を通る際に屈折率差に起因して散乱され、透明基板６の出射面６ａから液晶パネルＢに向けて出射する。これにより均一な照明光を得ることができる。
【００６５】
すなわち、外光の反射光により照明する場合も、有機発光層１０で発した光により照明する場合も、均一な照明が行われると共に、散乱光が液晶パネルＢの前面から種々の角度で出射することにより、液晶表示装置の視野角特性を向上させることができる。
【００６６】
図１０の液晶表示装置では、実施の形態１に係る有機ＥＬ装置Ａを液晶パネルＢのバックライトとして配置したが、同様にして実施の形態２〜６に係る有機ＥＬ装置をバックライトとして利用することもできる。
【００６７】
なお、実施の形態１において、ホール輸送層９を均一な層厚で形成し、有機発光層１０を凹部１２ａに比べて凸部１２ｂの方がより厚い層厚を有するように形成しても同様の効果が得られる。また、実施の形態５において、電子輸送層１３を均一な層厚で形成し、有機発光層１０を凹部１２ａに比べて凸部１２ｂの方がより厚い層厚を有するように形成しても同様の効果が得られる。
【００６８】
上記の実施の形態１〜６では、透明基板６の凹凸面７に凹部と凸部とが不規則に形成されていたが、複数の凹部と凸部とが規則的に形成された凹凸面とすることもできる。また、凹部と凸部は、それぞれ散在する点状に形成されてもよく、ストライプ状に形成されていてもよい。
透明基板６が出射面６ａに対して隆起した凸部のみを平面上に有するものでもよい。この場合でも、発光部の凸部のへりを含む所定の範囲から優先的に発光させることにより、ＥＬ装置全体として光取り出し効率の向上が可能となる。
透明基板６が出射面６ａに対して窪んだ凹部のみを平面上に有するものでもよい。この場合でも、発光部の凹部の底部を含む所定の範囲から優先的に発光させることにより、ＥＬ装置全体として光取り出し効率の向上が可能となる。
【００６９】
実施の形態１〜６では、透明基板６上に少なくとも透明性電極８、有機発光層１０及び反射性電極１１が順次積層され、有機発光層１０で発した光が透明性電極８及び透明基板６を透過して出射されるタイプの有機ＥＬ装置について説明したが、これに限るものではなく、この発明は、基板上に反射性電極、発光層及び透明性電極を順次積層して発光層で発した光が基板とは反対側の透明性電極を透過して出射されるタイプのＥＬ装置にも適用される。この場合、反射性電極及び透明性電極がそれぞれこの発明の第１の電極及び第２の電極となり、基板は可視光に対して透明でも不透明でも構わない。
【００７０】
なお、以上、有機ＥＬ装置について説明したが、この発明は、無機ＥＬ装置にも同様にして適用することができる。
【００７１】
【発明の効果】
以上説明したように、この発明によれば、発光部が光の出射面に対して隆起した複数の凸部を備え、この凸部のへりを含む所定の範囲から優先的に発光させるようにしたので、従来より小さな電流によって従来と同等の輝度で発光させることができ、また従来と同等の電流を流すことによって従来よりも高い輝度で発光させることが可能となる。
また、発光部が光の出射面に対して窪んだ複数の凹部を備え、この凹部の底部を含む所定の範囲から優先的に発光させるようにしても、従来より小さな電流で発光させることができ、また従来と同等の電流を流すことによって従来よりも高い輝度で発光させることが可能となる。
この発明のＥＬ装置を液晶表示装置のバックライトとして使用すれば、均一な照明及び視野角特性の向上がなされ、これにより良好な視認性が得られることとなる。
【図面の簡単な説明】
【図１】この発明の実施の形態１に係る有機ＥＬ装置の構成を示す断面図である。
【図２】有機ＥＬ装置のホール輸送層の厚さを変化させたときの印加電圧に対する輝度特性を示すグラフである。
【図３】実施の形態１の有機ＥＬ装置における光の出射の様子を示す部分断面図である。
【図４】実施の形態１に係る有機ＥＬ装置の製造方法を工程順に示す断面図である。
【図５】実施の形態１に係る有機ＥＬ装置の製造方法を工程順に示す断面図である。
【図６】実施の形態２に係る有機ＥＬ装置の構成を示す断面図である。
【図７】実施の形態３に係る有機ＥＬ装置の構成を示す断面図である。
【図８】実施の形態４に係る有機ＥＬ装置の構成を示す断面図である。
【図９】実施の形態５に係る有機ＥＬ装置の構成を示す断面図である。
【図１０】実施の形態７に係る液晶表示装置の構成を示す断面図である。
【図１１】従来の有機ＥＬ装置の構成を示す断面図である。
【符号の説明】
６透明基板、７凹凸面、８透明性電極、９ホール輸送層、１０有機発光層、１１反射性電極、１３電子輸送層、１４透明電極、１５ガラス基板、１６液晶層、１７偏光板、６ａ出射面、８ａ，９ａ，１０ａ，１２ａ凹部、８ｂ，９ｂ，１０ｂ，１２ｂ凸部、Ａ有機ＥＬ装置、Ｂ液晶パネル。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an EL (electroluminescence) device.
The present invention also relates to a method for manufacturing such an EL device and a display device using the EL device as a backlight.
[0002]
[Prior art]
The configuration of a conventional organic EL device is shown in FIG. A hole transport layer 3 and an organic light emitting layer 4 are sequentially formed on the transparent substrate 1 via a transparent electrode 2, and a reflective electrode 5 is formed on the organic light emitting layer 4. When an electric field is applied between the transparent electrode 2 and the reflective electrode 5, a light emitting material such as a fluorescent material or a phosphorescent material in the organic light emitting layer 4 is generated by energy released when electrons and holes are recombined. Emits light. The light L1 traveling in the direction of the transparent electrode 2 passes through the hole transport layer 3 and the transparent electrode 2, and further passes through the transparent substrate 1 to be emitted to the outside of the apparatus, and travels in the direction of the reflective electrode 5. The light L2 is reflected by the reflective electrode 5, and then passes through the hole transport layer 3, the transparent electrode 2 and the transparent substrate 1 and is emitted to the outside of the apparatus.
This organic EL device is used as various display devices or as a backlight of a display device such as a liquid crystal display device.
[0003]
In such an EL device, how to efficiently extract the light emitted from the light emitting layer to the outside of the device is a research subject.
[0004]
In order to solve the above-described research problem, a conventional technique for forming a reflective surface on the side surface of an organic EL element has been proposed. Further, for example, as disclosed in Patent Document 1, among the pair of electrodes sandwiching the organic light emitting layer, a minute protrusion is formed on the electrode located on the light emitting surface side, and a concave shape is formed on the other electrode. A conventional technique has also been proposed in which the other electrode has a light collecting property as a concave mirror.
[0005]
[Patent Document 1]
Japanese Patent No. 2848386
[0006]
[Problems to be solved by the invention]
However, sufficient light extraction efficiency could not be obtained even by using the conventional techniques as described above, and there was room for development.
[0007]
The present invention has been made to solve such problems, and an object of the present invention is to provide an EL device capable of emitting light with high luminance even with small power consumption.
Another object of the present invention is to provide an EL device manufacturing method capable of obtaining such an EL device and a display device using such an EL device.
[0008]
[Means for Solving the Problems]
In a first EL device according to the present invention, an EL device in which an EL element including a laminate of a first electrode, a light emitting unit, and a second electrode is formed on a substrate. The light emitting unit has a light emission surface. A plurality of preferential light emitting areas each having a plurality of convex portions protruding to the side and configured to emit light preferentially, and each preferential light emitting area is set to include at least a skirt of the convex portion; .
[0009]
Here, the skirt of a convex part is the peripheral part and edge of a convex part.
Since the convex portion of the light emitting portion is positioned so as to cover the boundary surface with the first electrode or the second electrode, even if light is emitted from this convex portion, the first electrode or the second electrode The amount of light that is reflected at the boundary surface and confined in the light emitting layer increases.
In addition, in an EL device that emits light from an EL element formed on a transparent substrate through the transparent substrate, light emitted from the convex portion of the light emitting unit is not emitted from the transparent substrate after entering the transparent substrate. There is a low possibility that the light is incident on the EL element again and further reflected once by the EL element and then emitted from the exit surface of the transparent substrate.
Similarly, in an EL device that emits light in the direction opposite to the substrate from the EL element formed on the substrate, the light emitted from the convex portion of the light-emitting portion is once emitted from the EL element and then again to the EL element. There is a low possibility of being emitted by being incident and further reflected by this EL element.
That is, it is difficult to efficiently extract the light emitted from the convex portion of the light emitting portion that protrudes toward the light exit surface. Thus, by preferentially emitting light from a predetermined range including the bottom of the convex portion of the light emitting unit, the light extraction efficiency can be improved as a whole EL device with low power consumption.
[0010]
A second EL device according to the present invention is an EL device in which an EL element formed of a laminate of a first electrode, a light emitting unit, and a second electrode is formed on a substrate. The light emitting unit has a light emission surface. A plurality of preferential emission areas that are configured to emit light preferentially, and each preferential emission area includes at least a bottom portion in any one of the depressions. It is set.
[0011]
Here, the bottom means the lowest part of the recess, such as the lowest point of the recess. In addition, since each priority light emitting area is provided in any one of the recesses, it does not extend over a plurality of recesses. Note that some priority light emitting regions may include a plurality of recesses or may include the bottoms of the plurality of recesses.
Even with such a configuration, the same effects as the first EL device can be obtained.
[0012]
Note that the first to second EL devices may be configured such that at least one of the layers constituting the light emitting unit is thinner in the priority light emitting region than the other regions.
As the light emitting part, at least one having a hole transport layer and a light emitting layer laminated to each other is used, and the layer thickness of the hole transport layer in the other region is set thicker than the hole transport layer in each preferential light emitting region. be able to.
Further, as the light emitting portion, at least one having an electron transport layer and a light emitting layer stacked on each other is used, and the electron transport layers in other regions are made thicker than the electron transport layers in each preferential light emitting region. It may be set.
Alternatively, as the light emitting portion, one having at least a light emitting layer can be used, and the thickness of the light emitting layer in other regions can be set thicker than the light emitting layer in each priority light emitting region.
In the above configuration, the light emitting layer can naturally be designed in the same manner as this configuration. That is, the layer thickness of at least one layer that can be provided between the light-emitting layer, the electron transport layer, the hole transport layer, and other electrodes may be set as described above in the priority light-emitting region and other regions, Of course, it is possible to set two or more layers as described above.
[0013]
A first manufacturing method of an EL device according to the present invention is a method of manufacturing an EL device in which a first electrode, a light emitting unit, and a second electrode are sequentially stacked on a substrate. A first electrode is formed on the concavo-convex surface so that the surface on which the concavo-convex surface of the substrate is not provided is substantially horizontal, and the concavo-convex surface is opposite to the direction of gravity in the direction of gravity. Then, a hole transport layer is formed on the first electrode by any of the following methods (1) to (3), a light emitting layer is formed on the hole transport layer, and the light emitting layer is formed on the light emitting layer. This is a method of forming a second electrode.
[0014]
(1) A method of removing the dispersion medium in a state in which a part of the dispersion on the convex portion has moved to the concave portion side after disposing the dispersion liquid in which the hole transport material is dispersed in the dispersion medium.
The method (1) includes, for example, (1a) a method in which the dispersion liquid is disposed substantially uniformly on the first electrode, and then, after a predetermined period of time has elapsed, (1b) the dispersion liquid. Is disposed on the first electrode, a part of the dispersion on the convex portion moves to the concave side, and the thickness (amount) of the dispersion on the convex portion is the thickness of the dispersion on the concave portion ( A method such as a method of drying after waiting for the amount to be larger than (amount) or waiting for a predetermined time to increase is also included.
[0015]
(2) A method of removing a solution in a state where a part of the solution on the convex portion has moved to the concave portion side after arranging a solution in which the hole transport material is dissolved in a solvent.
The method (2) includes, for example, (2a) a method in which the solution is substantially uniformly disposed on the first electrode, and then a drying is performed after a predetermined time has elapsed, or (2b) the dispersion liquid is After disposing on the first electrode, a part of the solution on the convex portion moves to the concave side, and the thickness (amount) of the solution on the convex portion is larger than the thickness (amount) of the solution on the concave portion. A method such as a method of drying after waiting for the increase or waiting for a predetermined time to increase is also included.
[0016]
(3) A method of fixing the hole transport material in a state where a part of the hole transport material has moved from the convex portion to the concave portion side after the hole transport material is melted or arranged in a glass shape.
In the method (3), a hole transport layer is formed on the first electrode by arranging a hole transport material, and then the hole transport material is melted and liquefied. Also included is a method of fixing the hole transport material by cooling in a state where a part of the hole transport material has moved to the concave side.
[0017]
Note that “dispersing a dispersion or the like” means “loading a dispersion or the like”, and the dispersion or the like can be disposed by a method such as coating.
[0018]
By such a method, an EL device that emits light preferentially from a predetermined range including the bottom of the concave portion of the light emitting layer that is recessed to the side opposite to the light emission surface is realized.
[0019]
A second method for manufacturing an EL device is a method for manufacturing an EL device in which a first electrode, a light emitting unit, and a second electrode are sequentially stacked on a substrate, and an uneven surface is formed on the substrate. After the first electrode is formed, the surface of the substrate on which the uneven surface is not provided is approximately horizontal, and the uneven surface is disposed opposite to the direction of gravity in the direction of gravity. In this method, the light emitting layer is formed on the first electrode by any one of the following methods (4) to (6), and the second electrode is formed on the light emitting layer. This also realizes an EL device that emits light preferentially from a predetermined range including the bottom of the concave portion of the light emitting layer that is recessed to the side opposite to the light emission surface.
[0020]
(4) A method of removing the dispersion medium in a state in which a part of the dispersion on the convex portion has moved to the concave portion side after disposing the dispersion liquid in which the light emitting material is dispersed in the dispersion medium.
The method (4) includes, for example, (4a) a method in which the dispersion liquid is substantially uniformly disposed on the first electrode, and then a drying is performed after a predetermined time has elapsed, or (4b) the dispersion liquid. Is disposed on the first electrode, a part of the dispersion on the convex portion moves to the concave side, and the thickness (amount) of the dispersion on the convex portion is the thickness of the dispersion on the concave portion ( A method such as a method of drying after waiting for the amount to be larger than (amount) or waiting for a predetermined time to increase is also included.
[0021]
(5) A method of removing the solution in a state where a part of the solution on the convex portion has moved to the concave portion side after arranging the solution in which the light emitting material is dissolved in the solvent.
The method (5) includes, for example, (5a) a method in which the solution is substantially uniformly disposed on the first electrode and then dried after waiting for a predetermined time, or (5b) the dispersion liquid. After disposing on the first electrode, a part of the solution on the convex portion moves to the concave side, and the thickness (amount) of the solution on the convex portion is larger than the thickness (amount) of the solution on the concave portion. A method such as a method of drying after waiting for the increase or waiting for a predetermined time to increase is also included.
[0022]
(6) A method of fixing the luminescent material in a state in which the luminescent material is partially moved from the convex portion to the concave portion after the luminescent material is melted or glassy and disposed.
In the method (6), a light emitting layer is formed on the first electrode by arranging a light emitting material or the like, and then the light emitting material is melted and liquefied so that the light emitting material is moved from the convex portion to the concave portion side. A method of fixing the light emitting material by cooling in a state in which the portion is moved is also included.
[0023]
A third method for manufacturing an EL device is a method for manufacturing an EL device in which a first electrode, a light emitting unit, and a second electrode are sequentially stacked on a substrate, and an uneven surface is formed on the substrate. Forming a first electrode on the first electrode, forming a light emitting layer on the first electrode, so that the surface of the substrate not provided with the uneven surface is substantially horizontal, and the uneven surface is Then, the electron transport layer is formed on the light emitting layer by any of the following methods (7) to (9), and the second electrode is formed on the electron transport layer. It is a method of forming. Such a method also realizes an EL device that emits light preferentially from a predetermined range including the bottom of the concave portion of the light emitting layer that is recessed to the side opposite to the light emission surface.
[0024]
(7) A method of disposing the dispersion liquid in which the electron transport material is dispersed in the dispersion medium, and then removing the dispersion medium in a state where a part of the dispersion liquid on the convex part moves to the concave part side.
The method (7) includes, for example, (7a) a method in which the dispersion liquid is disposed substantially uniformly on the light emitting layer, and then a drying process is performed after waiting for a predetermined time. After disposing on the layer, a part of the dispersion on the convex part moves to the concave side, and the thickness (amount) of the dispersion on the convex part is larger than the thickness (amount) of the dispersion on the concave part. A method such as a method of drying after waiting for the increase or waiting for a predetermined time to increase is also included.
[0025]
(8) A method of removing the solution in a state in which a part of the solution on the convex portion has moved to the concave portion side after arranging the solution in which the electron transport material is dissolved in the solvent.
The method (8) includes, for example, (8a) a method in which the above solution is disposed substantially uniformly on the light emitting layer, and then a drying is performed after a predetermined time has elapsed, or (8b) the dispersion is applied to the light emitting layer. After being placed above, a part of the solution on the convex part moves to the concave side, and the thickness (amount) of the solution on the convex part becomes larger than the thickness (amount) of the solution on the concave part. A method such as a method of waiting or drying for a predetermined time to increase is also included.
[0026]
(9) A method of fixing the electron transport material in a state where a part of the electron transport material is moved from the top of the convex portion to the concave portion side after the electron transport material is melted or glassy and disposed.
In the method of (9), an electron transport layer is formed on the light emitting layer by arranging a light emitting material, and then the electron transport material is melted and liquefied. A method is also included in which the luminescent material is fixed by cooling in a state where a part of the luminescent material moves.
[0027]
Moreover, it is naturally possible to combine these manufacturing methods as appropriate. That is, as described above, in order to change the layer thickness for a plurality of layers, these manufacturing methods can be used in combination.
Further, in this specification, “forming a concavo-convex surface on a substrate” is not limited to the case of forming concavo-convex directly on a substrate. For example, one or more layers which are not described above are provided on a substrate, It also includes providing at least one unevenness or forming unevenness on the first electrode.
[0028]
The display device according to the present invention uses the EL device according to the present invention described above or the EL device manufactured by the manufacturing method according to the present invention as a backlight. Illumination is performed by light efficiently extracted by the EL device.
[0029]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows a cross section of an organic EL device A according to the first embodiment. The organic EL device A has a transparent substrate 6, and one surface of the pair of main surfaces of the transparent substrate 6 is an emission surface 6 a of the organic EL device A, and a concave portion and a convex portion are formed on the other surface. The irregular surface 7 is formed irregularly. A transparent electrode 8 is formed along the uneven surface 7 of the transparent substrate 6, a hole transport layer 9 is formed along the surface of the transparent electrode 8, and an organic light emitting layer is formed on the surface of the hole transport layer 9. 10 is formed. Here, the hole transport layer 9 and the organic light emitting layer 10 constitute the light emitting portion of the present invention. Further, a reflective electrode 11 is laminated on the surface of the organic light emitting layer 10, and the EL element is constituted by the transparent electrode 8, the light emitting portion, and the reflective electrode 11.
[0030]
The transparent electrode 8 has a uniform film thickness and has a curved shape corresponding to the uneven surface 7 of the transparent substrate 6. The light-emitting portion composed of the hole transport layer 9 and the organic light-emitting layer 10 has a curved shape corresponding to the surface of the transparent electrode 8, and has a recess 12a and a bulge that are recessed with respect to the emission surface 6a of the transparent substrate 6 serving as the emission surface. The hole transport layer 9 is formed so that the convex portion 12b has a thicker layer thickness than the concave portion 12a. The organic light emitting layer 10 formed on the surface of the hole transport layer 9 and the reflective electrode 11 formed on the surface of the organic light emitting layer 10 both have a uniform layer thickness.
The transparent electrode 8 and the reflective electrode 11 constitute the first electrode and the second electrode of the present invention, respectively.
[0031]
Here, in the conventional EL device shown in FIG. 11, the thickness of the hole transport layer 3 is set to 200 mm (2 × 10 6). ^-8 m), 400 mm (4 × 10 ^-8 m), 600 cm (6 × 10 ^-8 m) and 800cm (8 x 10) ^-8 4 types of EL devices having the same configuration except that set to m) were prepared, and when the luminance characteristics were measured when light was emitted by changing the applied voltage between the electrodes, the results shown in FIG. 2 were obtained. It was. It can be seen that the smaller the layer thickness of the hole transport layer 3 is, the more efficiently light is emitted.
[0032]
Therefore, in the EL device according to the first embodiment having the hole transport layer 9 formed so that the convex portion 12b has a thicker layer thickness than the concave portion 12a, the transparent electrode 8 and the reflective electrode 8 are reflected. When a voltage is applied between the conductive electrodes 11, the organic light emitting layer 10 in the region including the bottom of the recess 12a emits light preferentially over the other regions as shown in FIG. The organic light emitting layer 10 of the convex portion 12b does not emit light substantially or emits light with low luminance even if it emits light.
[0033]
Of the light emitted from the organic light emitting layer 10 in the recess 12a, most of the light L3 emitted in the direction of the transparent electrode 8 is transmitted as it is from the organic light emitting layer 10 through the hole transport layer 9, the transparent electrode 8 and the transparent substrate 6. Then, the light L4 emitted from the emission surface 6a and emitted in the direction of the reflective electrode 11 is also reflected by the reflective electrode 11, and then passes through the hole transport layer 9, the transparent electrode 8 and the transparent substrate 6 to be emitted from the emission surface 6a. Exits from. Further, light L5 emitted from the organic light emitting layer 10 in the recess 12a substantially parallel to the emission surface 6a is also reflected by the reflective electrode 11 and emitted through the hole transport layer 9, the transparent electrode 8 and the transparent substrate 6. The light comes out from the surface 6a.
[0034]
On the other hand, since the organic light emitting layer 10 of the convex portion 12b is positioned so as to cover the boundary surface with the hole transport layer 9, even if light is emitted from the convex portion 12b, light is emitted from the concave portion 12a. Compared to the case, more light is reflected and confined in the organic light emitting layer 10 at the interface with the hole transport layer 9 or the interface with the transparent electrode 8. Further, the light emitted from the organic light emitting layer 10 of the convex portion 12b enters the transparent substrate 6 through the hole transport layer 9 and the transparent electrode 8, and then is emitted again without being emitted from the emission surface 6a of the transparent substrate 6. There is a low possibility that the light is incident on the element and further reflected once by the EL element and then emitted from the emission surface 6a of the transparent substrate 6. That is, it is difficult to efficiently extract the light emitted from the organic light emitting layer 10 of the convex portion 12b raised with respect to the emission surface 6a.
[0035]
In the organic light emitting layer 10 of the organic EL device A according to the first embodiment, the concave portion 12a having a high extraction efficiency emits light preferentially compared to the convex portion 12b having a low extraction efficiency, and thus the current flowing through the convex portion 12b. The density is suppressed, and it is possible to emit light with a luminance equivalent to that of a conventional device with a current smaller than that of the conventional device, and it is possible to emit light with a luminance higher than that of the conventional device by passing a current equivalent to that of the conventional device.
Further, since the organic light emitting layer 10 of the convex portion 12b emits light, the light condensing property in the vertical direction of the emission surface is generated, and in particular, the front luminance of the organic EL device is improved.
[0036]
In this organic EL device A, since the hole transport layer 9 exists between the organic light emitting layer 10 and the transparent electrode 8, even if an electron transporting light emitting layer is used as the organic light emitting layer 10, the reflective electrode 11 is used. Since the electrons injected from the organic light emitting layer 10 to the organic light emitting layer 10 are blocked at the interface with the hole transport layer 9 and confined in the organic light emitting layer 10, the light emission efficiency is improved.
[0037]
A method for manufacturing such an organic EL device A will be described. Patterning is performed on the upper surface of the flat transparent substrate 6 with a photoresist or the like using a mask having a pattern corresponding to the arrangement of the concave portions and convex portions to be formed, and etching is performed in this state to obtain the state shown in FIG. The uneven surface 7 as shown is formed.
[0038]
Next, as shown in FIG. 4B, the transparent electrode 8 is formed on the uneven surface 7 of the transparent substrate 6 with a uniform film thickness. As a result, the transparent electrode 8 has a curved shape corresponding to the uneven surface 7, and has a recessed portion 8 a that is recessed with respect to the transparent substrate 6 and a raised protruding portion 8 b.
[0039]
As shown in FIG. 4C, a liquid hole transport material 9c is applied on the transparent electrode 8 thus curved. Here, the liquid hole transport material 9 c is affected by gravity and gradually flows from the recessed portion 8 a recessed to the transparent substrate 6 to the raised convex portion 8 b. In this state, the hole transport material 9c is cured by standing at room temperature or heating to form the hole transport layer 9 as shown in FIG. As the liquid hole transport material 9c flows under the influence of gravity, the hole transport layer 9 has a thinner portion located on the concave portion 8a of the transparent electrode 8, and a smaller portion located on the convex portion 8b. It is formed thick.
[0040]
Next, as shown in FIG. 5B, when the organic light emitting layer 10 is formed on the hole transport layer 9 and the reflective electrode 11 is further formed on the organic light emitting layer 10, as shown in FIG. 5C. As described above, the organic light emitting layer 10 and the reflective electrode 11 have a curved shape according to the curved surface of the hole transport layer 9, and the organic EL device A is manufactured.
The organic EL device A is further sealed with a glass cap, or sealed by forming a thin film such as SiN on the surface thereof.
[0041]
The “liquid hole transport material 9c” means (a) a dispersion in which the hole transport material is dispersed in a dispersion medium, (b) a solution in which the hole transport material is dissolved in a solvent, or (c) hole transport. It means a liquid or glassy object obtained by melting a material. When using a dispersion or solution as in (a) or (b) above, the hole transport layer 9 is produced by removing the dispersion medium or solvent by drying or the like as described above. When the liquid or the like as in the above (c) is used, the liquid or the like is cooled and fixed (solidified) to produce the hole transport layer 9. Alternatively, the hole transport material may be laminated by a known method, heated and solidified to melt the hole transport material, and solidified again to produce the hole transport layer 9 shown in FIG.
[0042]
As the hole transport material, any material can be employed, whether it is a low molecular material, a high molecular material or the like. Specifically, as the low molecular weight material, for example, a dispersion or solution in which a hole transport material such as TPD or TFTE is dispersed or dissolved in an organic solvent such as THF or dichloroethane can be used. Examples of polymer materials include aniline-based copolymers, polyarylalkane derivatives, polyphenylene vinylene and derivatives thereof, polythiophene and derivatives thereof, poly-N-vinylcarbazole derivatives, and conductive polymer oligomers such as thiophene oligomers. It is possible to use a dispersion medium or a solution in which the above material is dispersed or dissolved in a dispersion medium or solvent that can be dispersed or dissolved.
[0043]
As a method for applying the hole transport material 9c onto the surface of the transparent electrode 8, a method such as spray coating, spin coating, flow coating, dipping, or the like can be selected.
[0044]
The organic light emitting layer 10 may be a known low molecular type material or a known high molecular type material. For example, a low molecular type light emitting material may be formed by vacuum deposition or a high molecular type material may be used. It can be formed by applying a light emitting material and forming a film.
[0045]
As a material for the transparent electrode 8, when light in the visible light region is extracted from the organic light emitting layer 10, for example, ITO (indium-zinc oxide) having high transmittance in the visible light region is preferable. For example, the transparent electrode may be composed of metal such as Al, Cr, Mo, Al alloy, Al / Mo laminate, etc. having a film thickness of 50 nm or less, preferably in the range of 0.5 to 20 nm.
As a material of the reflective electrode 11, it has only to have a function as an electrode and at least reflectivity to visible light. For example, various materials such as Al, Cr, Mo, Al alloy, Al / Mo laminated body, etc. A metal, an alloy, a metal compound, or the like can be used.
The transparent electrode 8 and the reflective electrode 11 are formed by a known thin film forming method such as a sputtering method, an ion plating method, a vacuum evaporation method, an electron beam evaporation method, or a spin coating method.
[0046]
Embodiment 2. FIG.
FIG. 6 shows a cross section of the organic EL device according to the second embodiment. This EL device is the same as the EL device of Embodiment 1 shown in FIG. 1 except that an electron transport layer 13 is formed on the surface of the organic light emitting layer 10 with a uniform layer thickness, and a reflective electrode is formed on the electron transport layer 13. 11 is formed. That is, in the present embodiment, the light emitting part is configured by the hole transport layer 9, the organic light emitting layer 10, and the electron transport layer 13.
The electron transport layer 13 may be a low molecular type or a high molecular type, and can be formed by a known thin film forming method.
[0047]
Since the hole transport layer 9 exists between the organic light emitting layer 10 and the transparent electrode 8, and the electron transport layer 13 exists between the organic light emitting layer 10 and the reflective electrode 11, the anode to the organic light emitting layer 10 is present. Hole injection / transport and electron injection / transport from the cathode to the organic light-emitting layer 10 become efficient, and the organic light-emitting layer 10 can be a light-emitting layer with low carrier transportability and low injectability.
[0048]
Also in the present embodiment, as in the first embodiment, the hole transport layer 9 has a thicker layer thickness at the convex portion 12b than at the concave portion 12a. The light emitting layer 10 emits light preferentially as compared with the convex portion 12b with low extraction efficiency, and light emission with high luminance can be performed with a small current.
[0049]
Embodiment 3 FIG.
FIG. 7 shows a cross section of the organic EL device according to the third embodiment. In this EL device, the hole transport layer 9 is formed with a uniform layer thickness in the EL device of the second embodiment shown in FIG. 6, and the organic light emitting layer 10 is a layer in which the convex portion 12b is thicker than the concave portion 12a. It is formed to have a thickness.
Even with such a configuration, the organic light emitting layer 10 in the recess 12a with high extraction efficiency emits light preferentially as compared with the protrusion 12b with low extraction efficiency, and light emission with high luminance can be performed with a small current.
[0050]
In Embodiment 3, the material of the hole transport layer 9 formed with a uniform layer thickness may be a low molecular type or a high molecular type, and is formed along the surface of the transparent electrode 8 by a known thin film forming method. be able to. The hole transport layer 9 has a curved shape corresponding to the surface of the transparent electrode 8, and has a recessed portion 9 a that is recessed with respect to the transparent substrate 6 and a raised protruding portion 9 b.
[0051]
As the material of the organic light emitting layer 10, a polymer type liquid light emitting material is used. When a liquid light-emitting material is applied on the curved surface of the hole transport layer 9, the light-emitting material is affected by gravity, and the convex portion 9 b that protrudes from the concave portion 9 a of the hole transport layer 9 that is recessed with respect to the transparent substrate 6. It flows gradually. In this state, the organic light emitting layer 10 is formed by curing the light emitting material by standing at room temperature or heating. As the liquid light emitting material flows under the influence of gravity, the organic light emitting layer 10 is formed such that the portion located on the concave portion 9a of the hole transport layer 9 is thinner and the portion located on the convex portion 9b is thicker. Is done.
[0052]
In addition, a light emitting material of a low molecular type can also be employed. When this type of material is employed, a material capable of forming the organic light emitting layer 10 is preferably selected by a coating method.
[0053]
The “liquid luminescent material” means (a) a dispersion in which the luminescent material is dispersed in a dispersion medium, (b) a solution in which the luminescent material is dissolved in a solvent, or (c) by melting the luminescent material. It means the liquid or glassy object obtained. When a dispersion or solution is used as in (a) or (b) above, the organic light emitting layer 10 is produced by removing the dispersion medium or solvent by drying or the like as described above. When the liquid or the like as in the above (c) is used, the liquid or the like is cooled and fixed (solidified) to produce the organic light emitting layer 10. Alternatively, after the light emitting material is laminated by a known method, the light emitting material may be melted by heating and solidified, and then solidified again to produce the organic light emitting layer 10 shown in FIG.
When the electron transport layer 13 and the reflective electrode 11 are sequentially formed with a uniform layer thickness on the surface of the organic light emitting layer 10, the organic EL device shown in FIG. 7 is manufactured.
[0054]
Embodiment 4 FIG.
FIG. 8 shows a cross section of the organic EL device according to the fourth embodiment. In this EL device, the hole transport layer 9 and the light emitting layer 10 are formed with a uniform thickness in the EL device of the second embodiment shown in FIG. 6, and the electron transport layer 13 is formed on the convex portion 12b as compared with the concave portion 12a. Is formed to have a thicker layer thickness.
Even with such a configuration, the organic light emitting layer 10 in the recess 12a with high extraction efficiency emits light preferentially as compared with the protrusion 12b with low extraction efficiency, and light emission with high luminance can be performed with a small current.
[0055]
In the fourth embodiment, the material of the hole transport layer 9 formed with a uniform layer thickness may be a low molecular type or a high molecular type, and is formed along the surface of the transparent electrode 8 by a known thin film forming method. can do. The hole transport layer 9 has a curved shape corresponding to the surface of the transparent electrode 8, and the organic light emitting layer 10 is formed on the surface of the hole transport layer 9 with a uniform layer thickness.
The organic light emitting layer 10 has a curved shape corresponding to the surface of the hole transport layer 9, and has a concave portion 10 a that is recessed with respect to the transparent substrate 6 and a raised convex portion 10 b.
[0056]
As the material of the electron transport layer 13, a polymer type liquid electron transport material is used. When a liquid electron transport material is applied on the curved surface of the organic light emitting layer 10, the electron transport material is affected by gravity, and the convexity raised from the concave portion 10 a of the organic light emitting layer 10 recessed with respect to the transparent substrate 6. It gradually flows to the part 10b. In this state, the electron transport material is cured by standing at room temperature or heating to form the electron transport layer 13. As the liquid electron transport material flows under the influence of gravity, the electron transport layer 13 has a thinner portion located on the concave portion 10a of the organic light emitting layer 10 and a thicker portion located on the convex portion 10b. It is formed.
[0057]
A low molecular type electron transport material can also be employed. When this type of material is employed, a material capable of forming the electron transport layer 13 is preferably selected by a coating method.
[0058]
The “liquid electron transport material” means (a) a dispersion in which an electron transport material is dispersed in a dispersion medium, (b) a solution in which the electron transport material is dissolved in a solvent, or (c) an electron transport material. It means a liquid or glassy object obtained by melting When a dispersion or solution is used as in (a) or (b) above, the electron transport layer 13 is produced by removing the dispersion medium or solvent by drying or the like as described above. When the liquid or the like as in (c) is used, the liquid or the like is cooled and fixed (solidified) to produce the electron transport layer 13. Alternatively, the electron transport material may be laminated by a known method, and then heated and solidified to melt the electron transport material, and then solidified again to produce the electron transport layer 13 shown in FIG.
When the reflective electrode 11 is formed with a uniform layer thickness on the surface of the electron transport layer 13, the organic EL device shown in FIG. 8 is manufactured.
[0059]
Embodiment 5 FIG.
FIG. 9 shows a cross section of the organic EL device according to the fifth embodiment. This EL device is obtained by omitting the hole transport layer 9 from the EL device according to the fourth embodiment shown in FIG. The organic light emitting layer 10 is formed with a uniform layer thickness on the surface of the transparent electrode 8, and the electron transport layer 13 is formed on the organic light emitting layer 10 so that the convex portion 12b is thicker than the concave portion 12a. Then, the reflective electrode 11 is formed on the electron transport layer 13 with a uniform layer thickness.
Even with such a configuration, the organic light emitting layer 10 in the recess 12a with high extraction efficiency emits light preferentially as compared with the protrusion 12b with low extraction efficiency, and light emission with high luminance can be performed with a small current.
[0060]
Since the electron transport layer 13 exists between the organic light emitting layer 10 and the reflective electrode 11, even if a hole transporting light emitting layer is used as the organic light emitting layer 10, high luminous efficiency can be obtained.
[0061]
Embodiment 6 FIG.
Like Embodiment 2-4 mentioned above, a light emission part is comprised with the hole transport layer 9, the organic light emitting layer 10, and the electron carrying layer 13, and these hole transport layer 9, the organic light emitting layer 10, and the electron carrying layer 13 are comprised. Of these, all of the two or three layers can be formed such that the convex portion has a larger layer thickness than the concave portion.
Even in this case, the organic light emitting layer 10 in the concave portion 12a having a high extraction efficiency emits light preferentially compared to the convex portion 12b having a low extraction efficiency, and can emit light with high luminance with a small current.
[0062]
Embodiment 7 FIG.
FIG. 10 shows a cross section of a liquid crystal display device according to Embodiment 7 of the present invention. In this liquid crystal display device, the organic EL device A according to Embodiment 1 is disposed as a backlight behind the liquid crystal panel B. The liquid crystal panel B has a pair of glass substrates 15 arranged in parallel to each other and having transparent electrodes 14 formed on the opposing surfaces, and the liquid crystal is sealed between the pair of glass substrates 15. A liquid crystal layer 16 is formed. Further, a polarizing plate 17 is disposed outside each of the pair of glass substrates 15.
[0063]
In this liquid crystal display device, when the surroundings are sufficiently bright such as in the daytime, external light that has passed through the liquid crystal panel B and entered the organic EL device A is reflected by the reflective electrode 11 and used as illumination light. When the surroundings are dark, the organic light emitting layer 10 of the organic EL device A can emit light and can be used as illumination light. These illumination lights are incident on the rear surface of the liquid crystal panel B, and display is performed by emitting display light according to the alignment state of the liquid crystal layer 16 from the front surface of the liquid crystal panel B.
[0064]
Here, the external light transmitted through the liquid crystal panel B and incident on the transparent substrate 6 of the organic EL device A is transmitted through the transparent substrate 6, the transparent electrode 8, the hole transport layer 9, and the organic light emitting layer 10 to reflect the reflective electrode. 11 is reflected. At this time, since the reflective electrode 11 has a curved shape, it has a scattering function, and external light is scattered on the surface of the reflective electrode 11 and reflected at various angles. These reflected lights are further scattered due to the difference in refractive index when passing through the boundary surface of the organic light emitting layer 10, the hole transport layer 9 and the transparent electrode 8 and the uneven surface 7 of the transparent substrate 6, and are emitted from the transparent substrate 6. The light exits from the surface 6a toward the liquid crystal panel B. Thereby, uniform illumination light can be obtained.
On the other hand, light emitted preferentially from the organic light emitting layer 10 in the recess 12 a of the organic EL device A passes through the boundary surface of the organic light emitting layer 10, the hole transport layer 9 and the transparent electrode 8 and the uneven surface 7 of the transparent substrate 6. At this time, the light is scattered due to the difference in refractive index and emitted from the emission surface 6 a of the transparent substrate 6 toward the liquid crystal panel B. Thereby, uniform illumination light can be obtained.
[0065]
That is, even when illuminating with reflected light of external light or illuminating with light emitted from the organic light emitting layer 10, uniform illumination is performed and scattered light is emitted from the front surface of the liquid crystal panel B at various angles. As a result, the viewing angle characteristics of the liquid crystal display device can be improved.
[0066]
In the liquid crystal display device of FIG. 10, the organic EL device A according to the first embodiment is arranged as the backlight of the liquid crystal panel B. Similarly, the organic EL devices according to the second to sixth embodiments are used as the backlight. You can also.
[0067]
In the first embodiment, the hole transport layer 9 is formed with a uniform layer thickness, and the organic light emitting layer 10 is formed so that the convex portion 12b has a thicker layer thickness than the concave portion 12a. The effect is obtained. In the fifth embodiment, the electron transport layer 13 is formed with a uniform layer thickness, and the organic light emitting layer 10 is formed so that the convex portion 12b has a thicker layer thickness than the concave portion 12a. The effect is obtained.
[0068]
In said Embodiment 1-6, although the recessed part and the convex part were formed irregularly in the uneven surface 7 of the transparent substrate 6, the uneven surface in which the several recessed part and convex part were formed regularly, You can also In addition, the concave portions and the convex portions may be formed in scattered dot shapes, or may be formed in stripe shapes.
The transparent substrate 6 may have only a convex portion raised from the emission surface 6a on the plane. Even in this case, the light extraction efficiency of the entire EL device can be improved by preferentially emitting light from a predetermined range including the edge of the convex portion of the light emitting portion.
The transparent substrate 6 may have only a concave portion that is recessed with respect to the emission surface 6a on the plane. Even in this case, the light extraction efficiency of the entire EL device can be improved by preferentially emitting light from a predetermined range including the bottom of the concave portion of the light emitting unit.
[0069]
In the first to sixth embodiments, at least the transparent electrode 8, the organic light emitting layer 10 and the reflective electrode 11 are sequentially laminated on the transparent substrate 6, and the light emitted from the organic light emitting layer 10 is transmitted to the transparent electrode 8 and the transparent substrate 6. However, the present invention is not limited to this, and the present invention is not limited to this, and the present invention provides a light emitting layer in which a reflective electrode, a light emitting layer, and a transparent electrode are sequentially laminated on a substrate. The present invention is also applied to an EL device in which the transmitted light is transmitted through a transparent electrode on the side opposite to the substrate. In this case, the reflective electrode and the transparent electrode become the first electrode and the second electrode of the present invention, respectively, and the substrate may be transparent or opaque to visible light.
[0070]
Although the organic EL device has been described above, the present invention can be similarly applied to an inorganic EL device.
[0071]
【The invention's effect】
As described above, according to the present invention, the light emitting portion includes a plurality of convex portions raised with respect to the light emission surface, and light is emitted preferentially from a predetermined range including the edge of the convex portion. Therefore, it is possible to emit light with a luminance equal to that of the conventional device with a current smaller than that of the conventional device, and it is possible to emit light with a luminance higher than that of the conventional device by flowing an electric current equivalent to that of the conventional device.
In addition, even if the light emitting portion includes a plurality of concave portions that are recessed with respect to the light emission surface and light is emitted preferentially from a predetermined range including the bottom portion of the concave portions, light can be emitted with a smaller current than before. In addition, it is possible to emit light with higher brightness than in the past by passing a current equivalent to that in the past.
If the EL device of the present invention is used as a backlight of a liquid crystal display device, uniform illumination and viewing angle characteristics can be improved, thereby obtaining good visibility.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of an organic EL device according to Embodiment 1 of the present invention.
FIG. 2 is a graph showing luminance characteristics with respect to applied voltage when the thickness of the hole transport layer of the organic EL device is changed.
FIG. 3 is a partial cross-sectional view showing a state of light emission in the organic EL device of the first embodiment.
4 is a cross-sectional view showing a method of manufacturing the organic EL device according to Embodiment 1 in the order of steps. FIG.
5 is a cross-sectional view showing the method of manufacturing the organic EL device according to Embodiment 1 in the order of steps. FIG.
6 is a cross-sectional view showing a configuration of an organic EL device according to Embodiment 2. FIG.
7 is a cross-sectional view showing a configuration of an organic EL device according to Embodiment 3. FIG.
FIG. 8 is a cross-sectional view showing a configuration of an organic EL device according to a fourth embodiment.
FIG. 9 is a cross-sectional view showing a configuration of an organic EL device according to a fifth embodiment.
10 is a cross-sectional view showing a configuration of a liquid crystal display device according to Embodiment 7. FIG.
FIG. 11 is a cross-sectional view showing a configuration of a conventional organic EL device.
[Explanation of symbols]
6 transparent substrate, 7 uneven surface, 8 transparent electrode, 9 hole transport layer, 10 organic light emitting layer, 11 reflective electrode, 13 electron transport layer, 14 transparent electrode, 15 glass substrate, 16 liquid crystal layer, 17 polarizing plate, 6a Emitting surface, 8a, 9a, 10a, 12a concave portion, 8b, 9b, 10b, 12b convex portion, A organic EL device, B liquid crystal panel.

Claims

In an EL device in which an EL element composed of a laminate of a first electrode, a light emitting unit, and a second electrode is formed on a substrate,
The light-emitting portion includes a plurality of convex portions protruding to the light exit surface side, and has a plurality of priority light-emitting regions adapted to emit light preferentially,
Each priority light-emitting region is an EL device set to include at least a skirt of a convex portion.

In an EL device in which an EL element composed of a laminate of a first electrode, a light emitting unit, and a second electrode is formed on a substrate,
The light emitting unit includes a plurality of concave portions recessed to the opposite side of the light emission surface, and has a plurality of preferential light emitting regions adapted to emit light preferentially,
Each of the priority light emitting areas is an EL device set to include at least a bottom portion in any one of the recesses.

3. The EL device according to claim 1, wherein at least one of the layers constituting the light emitting unit is configured to be thinner than the other regions in the priority light emitting region.

3. The EL device according to claim 1, wherein two or more layers of the plurality of layers constituting the light emitting unit are configured to be thinner than other regions in the priority light emitting region.

The light emitting part includes at least a hole transport layer and a light emitting layer laminated to each other,
3. The EL device according to claim 1, wherein the hole transport layer in another region has a thicker layer thickness than the hole transport layer in each preferential emission region.

The light emitting unit includes at least a light emitting layer,
3. The EL device according to claim 1, wherein the light emitting layer in another region has a thicker layer thickness than the light emitting layer in each priority light emitting region.

The light emitting unit includes at least an electron transport layer and a light emitting layer laminated to each other,
3. The EL device according to claim 1, wherein the electron transport layer in another region has a thicker layer thickness than the electron transport layer in each preferential emission region.

In a manufacturing method of an EL device in which a first electrode, a light emitting unit, and a second electrode are sequentially stacked on a substrate,
Form an uneven surface on the substrate,
A first electrode is formed on the uneven surface,
The surface of the substrate on which the uneven surface is not provided is approximately horizontal, and the uneven surface is disposed on the opposite side of the direction of gravity in the direction of gravity, and is disposed on the first electrode. A hole transport layer is formed by any of the following methods (1) to (3),
A light emitting layer is formed on the hole transport layer;
A method for manufacturing an EL device, comprising forming a second electrode on a light emitting layer.
(1) A method of removing the dispersion medium in a state in which a part of the dispersion on the convex portion has moved to the concave portion side after disposing the dispersion liquid in which the hole transport material is dispersed in the dispersion medium.
(2) A method of removing a solution in a state where a part of the solution on the convex portion has moved to the concave portion side after arranging a solution in which the hole transport material is dissolved in a solvent.
(3) A method of fixing the hole transport material in a state where a part of the hole transport material has moved from the convex portion to the concave portion side after the hole transport material is melted or arranged in a glass shape.

The method for manufacturing an EL device according to claim 8, wherein the light emitting layer is formed by any one of the following methods (4) to (6).
(4) A method of removing the dispersion medium in a state in which a part of the dispersion on the convex portion has moved to the concave portion side after disposing the dispersion liquid in which the light emitting material is dispersed in the dispersion medium.
(5) A method of removing the solution in a state where a part of the solution on the convex portion has moved to the concave portion side after arranging the solution in which the light emitting material is dissolved in the solvent.
(6) A method of fixing the luminescent material in a state in which the luminescent material is partially moved from the convex portion to the concave portion after the luminescent material is melted or glassy and disposed.

Furthermore, the manufacturing method of the EL apparatus of Claim 8 or 9 which forms an electron carrying layer on a light emitting layer, and forms a 2nd electrode on an electron carrying layer.

The method for manufacturing an EL device according to claim 10, wherein the electron transport layer is formed by any one of the following methods (7) to (9).
(7) A method of disposing the dispersion liquid in which the electron transport material is dispersed in the dispersion medium, and then removing the dispersion medium in a state where a part of the dispersion liquid on the convex part moves to the concave part side.
(8) A method of removing the solution in a state in which a part of the solution on the convex portion has moved to the concave portion side after arranging the solution in which the electron transport material is dissolved in the solvent.
(9) A method of fixing the electron transport material in a state where a part of the electron transport material is moved from the top of the convex portion to the concave portion side after the electron transport material is melted or glassy and disposed.

In a manufacturing method of an EL device in which a first electrode, a light emitting unit, and a second electrode are sequentially stacked on a substrate,
Form an uneven surface on the substrate,
A first electrode is formed on the uneven surface,
The surface of the substrate on which the uneven surface is not provided is approximately horizontal, and the uneven surface is disposed on the opposite side of the direction of gravity in the direction of gravity, and is disposed on the first electrode. A light emitting layer is formed by any of the following methods (4) to (6),
A method for manufacturing an EL device, comprising forming a second electrode on a light emitting layer.
(4) A method of removing the dispersion medium in a state in which a part of the dispersion on the convex portion has moved to the concave portion side after disposing the dispersion liquid in which the light emitting material is dispersed in the dispersion medium.
(5) A method of removing the solution in a state where a part of the solution on the convex portion has moved to the concave portion side after arranging the solution in which the light emitting material is dissolved in the solvent.
(6) A method of fixing the luminescent material in a state in which the luminescent material is partially moved from the convex portion to the concave portion after the luminescent material is melted or glassy and disposed.

In a manufacturing method of an EL device in which a first electrode, a light emitting unit, and a second electrode are sequentially stacked on a substrate,
Form an uneven surface on the substrate,
A first electrode is formed on the uneven surface,
Forming a light emitting layer on the first electrode;
The surface on which the uneven surface of the substrate is not provided is approximately horizontal, and the uneven surface is disposed on the side opposite to the direction of gravity in the direction of gravity. 7) to (9) to form an electron transport layer by any method,
A method for manufacturing an EL device, comprising: forming a second electrode on an electron transport layer.
(7) A method of disposing the dispersion liquid in which the electron transport material is dispersed in the dispersion medium, and then removing the dispersion medium in a state where a part of the dispersion liquid on the convex part moves to the concave part side.
(8) A method of removing the solution in a state in which a part of the solution on the convex portion has moved to the concave portion side after arranging the solution in which the electron transport material is dissolved in the solvent.
(9) A method of fixing the electron transport material in a state where a part of the electron transport material is moved from the top of the convex portion to the concave portion side after the electron transport material is melted or glassy and disposed.

The method for manufacturing an EL device according to claim 13, wherein the light emitting layer is formed by any one of the following methods (4) to (6).
(4) A method of removing the dispersion medium in a state in which a part of the dispersion on the convex portion has moved to the concave portion side after disposing the dispersion liquid in which the light emitting material is dispersed in the dispersion medium.
(5) A method of removing the solution in a state where a part of the solution on the convex portion has moved to the concave portion side after arranging the solution in which the light emitting material is dissolved in the solvent.
(6) A method of fixing the luminescent material in a state in which the luminescent material is partially moved from the convex portion to the concave portion after the luminescent material is melted or glassy and disposed.

15. The method for manufacturing an EL device according to claim 13, further comprising forming a hole transport layer on the first electrode and forming a light emitting layer on the hole transport layer.

The method for manufacturing an EL device according to claim 15, wherein the hole transport layer is formed by any one of the following methods (1) to (3).
(1) A method of removing the dispersion medium in a state in which a part of the dispersion on the convex portion has moved to the concave portion side after disposing the dispersion liquid in which the hole transport material is dispersed in the dispersion medium.
(2) A method of removing a solution in a state where a part of the solution on the convex portion has moved to the concave portion side after arranging a solution in which the hole transport material is dissolved in a solvent.
(3) A method of fixing the hole transport material in a state where a part of the hole transport material has moved from the convex portion to the concave portion side after the hole transport material is melted or arranged in a glass shape.

A display device using the EL device according to any one of claims 1 to 6 as a backlight.