JP3743217B2 - Light emitting element - Google Patents

Description

（ここで、Ｒ１〜Ｒ７は同じでも異なっていてもよく、水素、アルキル、アルコキシ、ハロゲン、アリール、アラルキル、アルケニル、アリールエーテル、複素環、シアノ、アルデヒド、カルボニル、エステル、カルバモイル、アミノ、隣接置換基との間に形成される縮合環の中から選ばれる。Ｘは炭素または窒素であるが、窒素の場合には上記Ｒ７は存在しない。）。
【００２１】
これらの置換基の説明の内、アルキル基とは例えばメチル基、エチル基、プロピル基、ブチル基などの飽和脂肪族炭化水素基を示し、これは無置換でも置換されていてもかまわない。また、アルコキシ基とは例えばメトキシ基などのエーテル結合を介した脂肪族炭化水素基を示し、脂肪族炭化水素基は無置換でも置換されていてもかまわない。ハロゲンとはフッ素、塩素、臭素、ヨウ素を示す。また、アリール基とは例えばフェニル基、ナフチル基、ビフェニル基、フェナントリル基、ターフェニル基、ピレニル基などの芳香族炭化水素基を示し、これは無置換でも置換されていてもかまわない。また、アラルキル基とは例えばベンジル基、フェニルエチル基などの脂肪族炭化水素を介した芳香族炭化水素基を示し、脂肪族炭化水素と芳香族炭化水素はいずれも無置換でも置換されていてもかまわない。また、アルケニル基とは例えばビニル基、アリル基、ブタジエニル基などの二重結合を含む不飽和脂肪族炭化水素基を示し、これは無置換でも置換されていてもかまわない。また、アリールエーテル基とは例えばフェノキシ基などのエーテル結合を介した芳香族炭化水素基を示し、芳香族炭化水素基は無置換でも置換されていてもかまわない。また、複素環基とは例えばチエニル基、フリル基、ピロリル基、イミダゾリル基、ピラゾリル基、オキサゾリル基、ピリジル基、ピラジル基、ピリミジル基、キノリニル基、イソキノリル基、キノキサリル基、アクリジニル基、カルバゾリル基などの炭素以外の原子を有する環状構造基を示し、これは無置換でも置換されていてもかまわない。アルデヒド基、カルボニル基、エステル基、カルバモイル基、アミノ基には脂肪族炭化水素、脂環式炭化水素、芳香族炭化水素、複素環などで置換されたものも含み、さらに脂肪族炭化水素、脂環式炭化水素、芳香族炭化水素、複素環は無置換でも置換されていてもかまわない。隣接置換基との間に形成される縮合環とは、Ｒ１とＲ２、Ｒ２とＲ３、Ｒ４とＲ５、Ｒ５とＲ６の部位で共役または非共役の縮合環を形成するものである。そしてこれら縮合環は環内構造に窒素、酸素、硫黄原子を含んでいても良いし、さらに別の環と縮合していてもよい。
【００２２】
また、金属に配位する時には、ピロメテン骨格を有する化合物単独でも混合配位子でも特に限定はされない。混合配位子の場合の第２の配位子としては、アルコキシ、フェノキシ、ハロゲン、アルキル、アリルその他縮合環炭化水素、複素環化合物、または酸素原子を介して結合された芳香環または複素環化合物などを導入することが可能である。
【００２３】
本発明のリガンドに配位できる金属は、特に限定されるものではないが、通常用いられる元素の一例として、ホウ素、ベリリウム、マグネシウム、クロム、鉄、コバルト、ニッケル、銅、亜鉛、白金などを挙げることができる。
【００２４】
そして、優れた色純度特性を持つ赤色発光を得るためには、前記ピロメテン骨格を有する化合物もしくはその金属錯体の中でも、下記一般式（２）で表される化合物もしくはその金属錯体が望ましい。
【００２５】
【化５】

（ここで、Ｒ８〜Ｒ１４のうち少なくとも一つは芳香環を含むかあるいは隣接置換基との間に縮合芳香環を形成し、残りは水素、アルキル、アルコキシ、ハロゲン、アリール、アラルキル、アルケニル、アリールエーテル、複素環、シアノ、アルデヒド、カルボニル、エステル、カルバモイル、アミノ、隣接置換基との間に形成される縮合環の中から選ばれる。Ｘは炭素または窒素であるが、窒素の場合には上記Ｒ１４は存在しない。）。
【００２６】
ここでいう芳香環基とはフェニル基、ナフチル基、アントラニル基のような芳香族炭化水素基のみならず、ピリジル基、キノリル基、チエニル基などの複素環芳香族官能基も含有する。また、隣接置換基との間に形成される縮合芳香環とは、Ｒ８とＲ９、Ｒ９とＲ１０、Ｒ１１とＲ１２、Ｒ１２とＲ１３の部位で縮合芳香環を形成するものである。そしてこれら縮合芳香環は、上記の芳香環基と同じく環内構造に窒素、酸素、硫黄原子を含んでいても良いし、さらに別の芳香環あるいは脂肪族環と縮合していてもよい。
【００２７】
さらに、ピロメテン骨格を有する化合物もしくはその金属錯体を赤色発光材料として用いる場合、高輝度特性を得るためには、蛍光量子収率が高いものがより好ましい。そこで、前記ピロメテン骨格を有する化合物もしくはその金属錯体としては、下記一般式（３）で表されるピロメテン骨格を有する化合物の金属錯体がより好ましい。
【００２８】
【化６】

（ここで、Ｒ１５〜Ｒ２１のうち少なくとも一つは芳香環を含むかあるいは隣接置換基との間に縮合芳香環を形成し、残りは水素、アルキル、アルコキシ、ハロゲン、アリール、アラルキル、アルケニル、アリールエーテル、複素環、シアノ、アルデヒド、カルボニル、エステル、カルバモイル、アミノ、隣接置換基との間に形成される縮合環の中から選ばれる。Ｒ２２およびＲ２３は同じでも異なっていてもよく、ハロゲン、水素、アルキル、アリール、複素環基から選ばれる。Ｘは炭素または窒素であるが、窒素の場合には上記Ｒ２１は存在しない。）。
【００２９】
上記のピロメテン骨格を有する化合物もしくはその金属錯体として、具体的には下記のような構造があげられる。
【００３０】
【化７】

【００３１】
【化８】

【００３２】
【化９】

【００３３】
【化１０】

【００３４】
【化１１】

【００３５】
【化１２】

【００３６】
【化１３】

ドーピング量は、通常多すぎると濃度消光現象が起きるため、通常ホスト物質に対して１０重量％以下で用いることが好ましく、更に好ましくは２重量％以下である。ドーピング方法としては、ホスト材料との共蒸着法によって形成することができるが、ホスト材料と予め混合してから同時に蒸着しても良い。また、前記ピロメテン骨格を有する化合物もしくはその金属錯体は、極めて微量でも発光することから微量のピロメテン骨格を有する化合物もしくはその金属錯体をホスト材料にサンドイッチ状に挟んで使用することも可能である。この場合、一層でも二層以上ホスト材料と積層しても良い。
【００３７】
また、発光材料に添加するドーパント材料は、前記ピロメテン骨格を有する化合物もしくはその金属錯体一種のみに限る必要はなく、複数の前記化合物を混合して用いたり、既知のドーパント材料の一種類以上を前記化合物と混合して用いてもよい。具体的には従来から知られている、ビス（ジイソプロピルフェニル）ペリレンテトラカルボン酸イミドなどのナフタルイミド誘導体、ペリノン誘導体、アセチルアセトンやベンゾイルアセトンとフェナントロリンなどを配位子とするＥｕ錯体などの希土類錯体、４−（ジシアノメチレン）−２−メチル−６−（ｐ−ジメチルアミノスチリル）−４Ｈ−ピランやその類縁体、マグネシウムフタロシアニン、アルミニウムクロロフタロシアニンなどの金属フタロシアニン誘導体、ローダミン化合物、デアザフラビン誘導体、クマリン誘導体、オキサジン化合物などを共存させることが出来るが特にこれらに限定されるものではない。
【００３８】
本発明における電子輸送性材料としては、電界を与えられた電極間において負極からの電子を効率良く輸送することが必要で、電子注入効率が高く、注入された電子を効率良く輸送することが望ましい。そのためには電子親和力が大きく、しかも電子移動度が大きく、さらに安定性に優れ、トラップとなる不純物が製造時および使用時に発生しにくい物質であることが要求される。このような条件を満たす物質として、８−ヒドロキシキノリンアルミニウムに代表されるキノリノール誘導体金属錯体、トロポロン金属錯体、フラボノール金属錯体、ペリレン誘導体、ペリノン誘導体、ナフタレン、クマリン誘導体、オキサジアゾール誘導体、アルダジン誘導体、ビススチリル誘導体、ピラジン誘導体、フェナントロリン誘導体などがあるが特に限定されるものではない。これらの電子輸送材料は単独でも用いられるが、異なる電子輸送材料と積層または混合して使用しても構わない。
【００３９】
以上の正孔輸送層、発光層、電子輸送層に用いられる材料は単独で各層を形成することができるが、高分子結着剤としてポリ塩化ビニル、ポリカーボネート、ポリスチレン、ポリ（Ｎ−ビニルカルバゾール）、ポリメチルメタクリレート、ポリブチルメタクリレート、ポリエステル、ポリスルフォン、ポリフェニレンオキサイド、ポリブタジエン、炭化水素樹脂、ケトン樹脂、フェノキシ樹脂、ポリサルフォン、ポリアミド、エチルセルロース、酢酸ビニル、ＡＢＳ樹脂、ポリウレタン樹脂などの溶剤可溶性樹脂や、フェノール樹脂、キシレン樹脂、石油樹脂、ユリア樹脂、メラミン樹脂、不飽和ポリエステル樹脂、アルキド樹脂、エポキシ樹脂、シリコーン樹脂などの硬化性樹脂などに分散させて用いることも可能である。
【００４０】
発光を司る物質の形成方法は、抵抗加熱蒸着、電子ビーム蒸着、スパッタリング、分子積層法、コーティング法など特に限定されるものではないが、通常は、抵抗加熱蒸着、電子ビーム蒸着が特性面で好ましい。層の厚みは、発光を司る物質の抵抗値にもよるので限定することはできないが、１〜１０００ｎｍの間から選ばれる。
【００４１】
綺麗な赤色表示を行わせるためには、発光スペクトルのピーク波長が５８０ｎｍ以上７２０ｎｍ以下、より好ましくは６００ｎｍ以上７００ｎｍ以下の範囲内であり、半値幅が１００ｎｍ以下であることが重要である。発光スペクトルは、できるだけ単一ピークであることが好ましいが、場合によっては他のピークとの重なりによって複数の極大点を有したり、ピークの裾に肩が現れることもある。本発明において、ピーク波長とは発光中心波長に値する主ピークの波長であり、半値幅とはこれらピーク全体において発光中心波長の高さの半分のところのピーク幅であると定義している。
【００４２】
電気エネルギーとは主に直流電流を指すが、パルス電流や交流電流を用いることも可能である。電流値および電圧値は特に制限はないが、素子の消費電力、寿命を考慮するとできるだけ低いエネルギーで最大の輝度が得られるようにするべきである。
【００４３】
本発明におけるマトリクスとは、表示のための画素が格子状に配置されたものをいい、画素の集合で文字や画像を表示する。画素の形状、サイズは用途によって決まる。例えばパソコン、モニター、テレビの画像および文字表示には、通常一辺が３００μｍ以下の四角形の画素が用いられるし、表示パネルのような大型ディスプレイの場合は、一辺がｍｍオーダーの画素を用いることになる。モノクロ表示の場合は、同じ色の画素を配列すればよいが、カラー表示の場合には、赤、赤、緑、青の画素を並べて表示させる。この場合、典型的にはデルタタイプとストライプタイプがある。そして、このマトリクスの駆動方法としては、線順次駆動方法やアクティブマトリックスのどちらでもよい。線順次駆動の方が構造が簡単であるという利点があるが、動作特性を考慮した場合、アクティブマトリックスの方が優れる場合があるので、これも用途によって使い分けることが必要である。
【００４４】
本発明におけるセグメントタイプとは、予め決められた情報を表示するようにパターンを形成し、決められた領域を発光させることになる。例えば、デジタル時計や温度計における時刻や温度表示、オーディオ機器や電磁調理器などの動作状態表示、自動車のパネル表示などがあげられる。そして、前記マトリクス表示とセグメント表示は同じパネルの中に共存していてもよい。
【００４５】
本発明におけるバックライトとは、主に自発光しない表示装置の視認性を向上させる目的に使用され、液晶表示装置、時計、オーディオ機器、自動車パネル、表示板、標識などに使用される。特に液晶表示装置、中でも薄型化が課題となっているパソコン用途のバックライトとしては、従来方式のものが蛍光灯や導光板からなっているため薄型化が困難であることを考えると本発明におけるバックライトは、薄型、軽量が特徴になる。
【００４６】
【実施例】
以下、実施例および比較例をあげて本発明を説明するが、本発明はこれらの例によって限定されるものではない。
【００４７】
実施例１
ＩＴＯ透明導電膜を１５０ｎｍ堆積させたガラス基板（旭硝子社製、１５Ω／□、電子ビーム蒸着品）を３０×４０ｍｍに切断、エッチングを行った。得られた基板をアセトン、セミコクリン５６で各々１５分間超音波洗浄してから、超純水で洗浄した。続いてイソプロピルアルコールで１５分間超音波洗浄してから熱メタノールに１５分間浸漬させて乾燥させた。この基板を素子を作製する直前に１時間ＵＶ−オゾン処理し、真空蒸着装置内に設置して、装置内の真空度が１×１０^-5Ｐａ以下になるまで排気した。抵抗加熱法によって、まず正孔輸送材料としてＮ，Ｎ’−ジフェニル−Ｎ，Ｎ’−（３−メチルフェニル）−１，１’−ジフェニル−４，４’−ジアミン（ＴＰＤ）を１００ｎｍ蒸着した。次にホスト材料として３，６−ジフェニル−２,５−ジヒドロ−２，５−ジメチルピロロ[３，４−ｃ]ピロール−１，４−ジオン（粉末状態で橙色蛍光）を、ドーパント材料として４,４−ジフルオロ−１,３,５,７−テトラフェニル−４−ボラ−３ａ,４ａ−ジアザ−ｓ−インダセン（ジクロロメタン溶液中の蛍光ピーク波長は６１１ｎｍ）を用いて、ドーパントが１ｗｔ％になるように５０ｎｍの厚さに共蒸着し、ホスト材料を５０ｎｍの厚さに積層した。次にリチウムを０．２ｎｍ、銀を１５０ｎｍ蒸着して陰極とし、５×５ｍｍ角の素子を作製した。この発光素子の発光ピーク波長は６０９ｎｍであり、スペクトル半値幅が５２ｎｍの綺麗な赤色発光を示した。
【００４８】
比較例１
ホスト材料としてトリス（８−キノリノラト）アルミニウム錯体（蛍光ピーク波長５１３ｎｍ）を用いた以外は実施例１と同様にして発光素子を作製した。この発光素子の発光ピーク波長は５２０ｎｍであり、ドーパント材料へのエネルギー移動は殆ど見られず、ホスト材料からの緑色発光を示し、ドーパント材料からの赤色発光を得ることが出来なかった。
【００４９】
実施例２
ドーパント材料としてジフルオロ[３−フェニル−１−[（３−フェニル−２Ｈ−ベンゾ[c]イソインドール−１−イル）メチレン]−１Ｈ−ベンゾ[c]イソインドラト−Ｎ¹,Ｎ²]ボロン（ジクロロメタン溶液中の蛍光ピーク波長は６４５ｎｍ）を用いる以外は実施例１と同様にして発光素子を作製した。この発光素子の発光ピーク波長は６１０ｎｍであり、スペクトル半値幅が５０ｎｍの綺麗な赤色発光を示した。
【００５０】
実施例３
ホスト材料として３，６−ビス（４−メチルフェニル）−２,５−ジヒドロ−２，５−ジメチルピロロ[３，４−ｃ]ピロール−１，４−ジオン（粉末状態で橙色蛍光）を用いる以外は実施例１と同様にして発光素子を作製した。この発光素子の発光ピーク波長は６１０ｎｍであり、スペクトル半値幅が５０ｎｍの綺麗な赤色発光を示した。
【００５１】
実施例４
ドーパント材料としてジフルオロ[３−フェニル−１−[（３−フェニル−２Ｈ−ベンゾ[c]イソインドール−１−イル）メチレン]−１Ｈ−ベンゾ[c]イソインドラト−Ｎ¹,Ｎ²]ボロンを用いる以外は実施例３と同様にして発光素子を作製した。この発光素子の発光ピーク波長は６１０ｎｍであり、スペクトル半値幅が５０ｎｍの綺麗な赤色発光を示した。
【００５２】
実施例５
ＩＴＯ透明導電膜を１５０ｎｍ堆積させたガラス基板（旭硝子社製、１５Ω／□、電子ビーム蒸着品）を３０×４０ｍｍに切断、フォトリソグラフィ法によって３００μｍピッチ（残り幅２７０μｍ）×３２本のストライプ状にパターン加工した。ＩＴＯストライプの長辺方向片側は外部との電気的接続を容易にするために１．２７ｍｍピッチ（開口部幅８００μm）まで広げてある。得られた基板をアセトン、セミコクリン５６で各々１５分間超音波洗浄してから、超純水で洗浄した。続いてイソプロピルアルコールで１５分間超音波洗浄してから熱メタノールに１５分間浸漬させて乾燥させた。この基板を素子を作製する直前に１時間ＵＶ−オゾン処理し、真空蒸着装置内に設置して、装置内の真空度が５×１０^-4Ｐａ以下になるまで排気した。抵抗加熱法によって、まずＮ，Ｎ’−ジフェニル−Ｎ，Ｎ’−（３−メチルフェニル）−１，１’−ジフェニル−４，４’−ジアミン（ＴＰＤ）を１００ｎｍ蒸着した。次にホスト材料として３，６−ジフェニル−２,５−ジヒドロ−２，５−ジメチルピロロ[３，４−ｃ]ピロール−１，４−ジオンを、ドーパント材料として４,４−ジフルオロ−１,３,５,７−テトラフェニル−４−ボラ−３ａ,４ａ−ジアザ−ｓ−インダセンを用いて、ドーパントが１ｗｔ％になるように５０ｎｍの厚さに共蒸着し、ホスト材料を５０ｎｍの厚さに積層した。次に厚さ５０μｍのコバール板にウエットエッチングによって１６本の２５０μｍの開口部（残り幅５０μｍ、３００μｍピッチに相当）を設けたマスクを、真空中でＩＴＯストライプに直交するようにマスク交換し、マスクとＩＴＯ基板が密着するように裏面から磁石で固定した。そしてマグネシウムを５０ｎｍ、アルミニウムを１５０ｎｍ蒸着して３２×１６ドットマトリクス素子を作製した。本素子をマトリクス駆動させたところ、クロストークなく文字表示できた。
【００５３】
【発明の効果】
本発明は、電気エネルギーの利用効率が高く、色純度に優れた赤色発光素子を提供できるものである。[0001]
BACKGROUND OF THE INVENTION
The present invention is an element that can convert electrical energy into light, and can be used in the fields of display elements, flat panel displays, backlights, lighting, interiors, signs, signboards, electrophotographic machines, optical signal generators, and the like. It relates to an element.
[0002]
[Prior art]
In recent years, research on an organic laminated thin film light emitting device in which light is emitted when electrons injected from a cathode and holes injected from an anode are recombined in an organic phosphor sandwiched between both electrodes has been actively conducted. This element is attracting attention because it is thin, has high luminance emission under a low driving voltage, and multicolor emission by selecting a fluorescent material.
[0003]
This study was conducted by C.D. W. Since Tang et al. Have shown that organic laminated thin-film elements emit light with high brightness (Appl. Phys. Lett. 51 (12) 21, p. 913, 1987), many research institutions have studied. A typical structure of an organic laminated thin film light emitting device presented by a research group of Kodak Company is a hole transporting diamine compound on an ITO glass substrate, 8-hydroxyquinoline aluminum as a light emitting layer, and Mg: Ag as a cathode. It is provided sequentially, and is 1000 cd / m with a driving voltage of about 10V. ² Green light emission was possible. Some organic multilayer thin film light emitting elements have different configurations such as those provided with an electron transport layer in addition to the above-described element constituent elements, but basically follow the configuration of Kodak Company.
[0004]
Among multicolor emission, red emission is being studied as a useful emission color. Conventionally, perylene series such as bis (diisopropylphenyl) perylene, perinone series, porphyrin series, Eu complex (Chem. Lett., 1267 (1991)) and the like are known as red light emitting materials.
[0005]
In addition, as a technique for obtaining red light emission, a method of mixing a small amount of a red fluorescent material as a dopant in a host material has been studied. Examples of the host material include tris (8-quinolinolato) aluminum complex, bis (10-benzoquinolinolato) beryllium complex, diarylbutadiene derivative, stilbene derivative, benzoxazole derivative, benzothiazole derivative, and the like. Red light emission is extracted by the presence of 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran, metal phthalocyanine (MgPc, AlPcCl, etc.) compounds, squarylium compounds, and violanthrone compounds. It was.
[0006]
[Problems to be solved by the invention]
However, conventional red light-emitting materials (host material and dopant material) have a wide peak width even when the light emission peak wavelength exceeds 580 nm, so that the color purity is poor and beautiful red light emission cannot be obtained. In addition, rare earth complexes such as Eu complexes have a narrow emission peak width, and beautiful red light emission is obtained, but the maximum luminance is several to several tens of cd / m. ² Therefore, it was a problem that clear display was impossible.
[0007]
An object of the present invention is to solve this problem and provide a red light emitting device having high color purity.
[0008]
[Means for Solving the Problems]
The present invention is an element in which a substance that emits light exists between an anode and a cathode, and emits light with a peak wavelength of 580 nm or more and 720 nm or less by electronic energy, and the element has at least a fluorescence peak wavelength of 540 nm or more and 720 nm or less. 3,4-c] pyrrole derivative and a compound having a pyromethene skeleton or a metal complex thereof. In addition, a compound having a pyromethene skeleton or a metal complex thereof having 10% by weight or less based on the pyrrolo [3,4-c] pyrrole derivative is used as a dopant material. A light emitting element characterized by the above.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, if the anode is transparent for extracting light, a conductive metal oxide such as tin oxide, indium oxide and indium tin oxide (ITO), or a metal such as gold, silver and chromium, copper iodide, sulfide Inorganic conductive materials such as copper and conductive polymers such as polythiophene, polypyrrole, and polyaniline are not particularly limited, but it is particularly desirable to use ITO glass or Nesa glass. The resistance of the transparent electrode is not limited as long as a current sufficient for light emission of the element can be supplied, but it is desirable that the resistance be low from the viewpoint of power consumption of the element. For example, an ITO substrate of 300 Ω / □ or less functions as an element electrode. However, since it is now possible to supply a substrate of about 10 Ω / □, it is particularly desirable to use a low resistance product. The thickness of ITO can be arbitrarily selected according to the resistance value, but is usually used in a range of 100 to 300 nm. Further, soda lime glass, non-alkali glass or the like is used for the glass substrate, and the thickness of the glass substrate only needs to be sufficient to maintain the mechanical strength, so 0.5 mm or more is sufficient. As for the glass material, it is better to use alkali-free glass because it is better to have less ions eluted from the glass. ₂ Since soda lime glass with a barrier coating such as is commercially available, it can be used. The ITO film forming method is not particularly limited, such as an electron beam method, a sputtering method, or a chemical reaction method.
[0010]
The cathode is not particularly limited as long as it can efficiently inject electrons into the organic layer, but is generally platinum, gold, silver, copper, iron, tin, zinc, aluminum, indium, chromium, lithium, sodium, potassium, calcium. Magnesium and the like can be mentioned, but lithium, sodium, potassium, calcium, magnesium or alloys containing these low work function metals are effective for improving the device characteristics by increasing the electron injection efficiency. However, these low work function metals are generally unstable in the atmosphere. For example, the organic layer is doped with a small amount of lithium or magnesium (1 nm or less in the vacuum vapor deposition thickness gauge display) to be stable. Although a method using a high electrode can be cited as a preferred example, it is not particularly limited to these because an inorganic salt such as lithium fluoride can be used. Furthermore, for electrode protection, metals such as platinum, gold, silver, copper, iron, tin, aluminum and indium, or alloys using these metals, and inorganic substances such as silica, titania and silicon nitride, polyvinyl alcohol, vinyl chloride, Preferred examples include laminating hydrocarbon polymers. The method for producing these electrodes is not particularly limited as long as electrical conduction such as resistance heating, electron beam, sputtering, ion plating, and coating can be achieved.
[0011]
Substances responsible for light emission are 1) hole transport layer / light-emitting layer, 2) hole transport layer / light-emitting layer / electron transport layer, 3) light-emitting layer / electron transport layer, and 4) a combination of the above substances Any of mixed forms may be used. That is, as the element structure, in addition to the multilayer laminated structure of the above 1) to 3), only the light emitting material alone or a layer containing the light emitting material and the hole transport material or electron transport material may be provided as in 4).
[0012]
The hole transport layer is formed by laminating and mixing a hole transport material alone or two or more kinds of materials, or a mixture of a hole transport material and a polymer binder. '-Diphenyl-N, N'-di (3-methylphenyl) -4,4'-diphenyl-1,1'-diamine, N, N'-dinaphthyl-N, N'-diphenyl-4,4'- Triphenylamines such as diphenyl-1,1′-diamine, bis (N-allylcarbazole) or bis (N-alkylcarbazole) s, pyrazoline derivatives, stilbene compounds, hydrazone compounds, oxadiazole derivatives and phthalocyanine derivatives , Heterocyclic compounds typified by porphyrin derivatives, in polymer systems, polycarbonates or styrene derivatives, polyvinylcarbazole, Although the run and the like are preferable, and forming a thin film required for device fabrication, and can inject holes from the anode, and is not particularly limited as long as it is a further compound capable of transporting holes.
[0013]
The light emitting material emits light with a peak wavelength of 580 nm to 720 nm by electric energy. If the peak width is 580 nm or less, red light emission with good color purity cannot be obtained even if the peak width is narrow, and if it is 720 nm or more, the visibility is deteriorated, so that efficient high-luminance red light emission cannot be obtained.
[0014]
The light-emitting material includes a compound having a pyrrolo [3,4-c] pyrrole derivative having a fluorescence peak wavelength of 540 nm or more and 720 nm or less and a pyromethene skeleton (also called diazaindacene skeleton) or a metal complex thereof, and using the fluorescent compound as a host material. A preferable method is a doping method in which a compound having a skeleton or a metal complex thereof is used as a dopant material in combination. Further, the dopant material may be included in the entire host material, or may be included partially. The dopant material may be either laminated or dispersed.
[0015]
Energy transfer from the host material to the dopant material requires an overlap between the fluorescence spectrum of the host material and the absorption spectrum (excitation spectrum) of the dopant material. In addition, the Stokes shift (difference between the peak of the excitation spectrum and the peak of the fluorescence spectrum) of a dopant material with good color purity is as narrow as several to several tens of nm, and an attempt is made to obtain high color purity red light emission from a dopant material of 580 nm to 720 nm. Then, the absorption spectrum (excitation spectrum) of the dopant material becomes yellow, yellow-orange, orange, red-orange, and red regions (540 nm to 720 nm). If the fluorescence spectrum of the host material is in the yellow-green, green, blue-green, blue, blue-violet, or purple region on the shorter wavelength side than yellow and the spectrum overlap is small, energy transfer is not performed quickly, and Even if light emission is not obtained, or even if it is obtained, light emission from the host material remains and whitening occurs, so that red light emission with high color purity cannot be obtained. In addition, there are examples using diazaindacene derivatives as dopant materials (Japanese Patent Laid-Open Nos. 9-208946 and 9-118880). Each of the host materials is different from the present invention, and on the other hand, a blue light emitting material is used as the host material. Since it is used, spectrum overlap is small and energy transfer is not sufficiently performed, so that blue light emission from the host material is mixed with light emission from the dopant material, and only white light emission is obtained (Japanese Patent Laid-Open No. Hei 9-). No. 208946). On the other hand, since a green light-emitting material is used as the host material, the light-emitting material is not a red light to be emitted but a green light-emitting color, and is not a light-emitting material intended by the present invention (Japanese Patent Laid-Open No. 9-118880). ).
[0016]
For the above reasons, in order for the dopant material to emit light with high brightness and high color purity at 580 nm to 720 nm, the host material needs to have a fluorescence peak wavelength of 540 nm to 720 nm. As a guideline, those having fluorescence such as yellow, yellow-orange, orange, red-orange, and red are applicable.
[0017]
A pyrrolo [3,4-c] pyrrole derivative is a preferred example of a host material having a fluorescence peak wavelength of 540 nm to 720 nm. If the fluorescence peak wavelength of the basic skeleton itself of the pyrrolo [3,4-c] pyrrole derivative is not less than 540 nm and not more than 720 nm, it is not always necessary to modify it. However, when the fluorescence peak wavelength is not more than 540 nm, When it is desired to increase the wavelength for efficient operation, the wavelength can be increased by introducing at least one of an aromatic ring or a heterocyclic ring into the basic skeleton as a substituent, and it is more suitably used as a host material. I can do it. Introducing at least one of an aromatic ring or a heterocyclic ring as a substituent into the basic skeleton includes introducing the basic skeleton itself as a substituent.
[0018]
Preferable examples of the pyrrolo [3,4-c] pyrrole derivative include the following compounds. 3,6-diphenyl-2,5-dihydro-2,5-dimethylpyrrolo [3,4-c] pyrrole-1,4-dione, 3,6-bis (4-methylphenyl) -2,5-dihydro -2,5-dimethylpyrrolo [3,4-c] pyrrole-1,4-dione, 2,5-dihydro-2,3,5,6-tetraphenylpyrrolo [3,4-c] pyrrole-1, 4-dione, 2,5-dihydro-2,5-bis (4-methylphenyl) -3,6-diphenylpyrrolo [3,4-c] pyrrole-1,4-dione, 3,6-bis (p -Biphenylyl) -2,5-dihydro-2,5-dimethylpyrrolo [3,4-c] pyrrole-1,4-dione, 3,6-bis (2-naphthyl) -2,5-dihydro-2, 5-Dimethylpyrrolo [3,4-c] pyrrole-1,4-dione, 3,6-bis (4-pyridyl) -2,5-di Dro-2,5-dimethylpyrrolo [3,4-c] pyrrole-1,4-dione, 3,6-bis (2-thienyl) -2,5-dihydro-2,5-dimethylpyrrolo [3,4] -C] pyrrole-1,4-dione, 3,6-diphenyl-2,5-dihydro-2,5-dibenzylpyrrolo [3,4-c] pyrrole-1,4-dione, 3,6-bis (4-Methylphenyl) -2,5-dihydro-2,5-dibenzylpyrrolo [3,4-c] pyrrole-1,4-dione, 3,6-bis (p-biphenylyl) -2,5- Dihydro-2,5-dibenzylpyrrolo [3,4-c] pyrrole-1,4-dione, 3,6-bis (2-naphthyl) -2,5-dihydro-2,5-dibenzylpyrrolo [3 , 4-c] pyrrole-1,4-dione, but is not limited thereto.
[0019]
Preferred examples of the dopant include compounds having the following pyromethene skeleton (also known as diazaindacene skeleton). Or its metal complex Can be mentioned.
[0020]
[Formula 4]

(Wherein R1 to R7 may be the same or different, hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl ether, heterocycle, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, adjacent substitution Condensation formed between groups Ring Chosen from the inside. X is carbon or nitrogen, but in the case of nitrogen, R7 does not exist. ).
[0021]
In the description of these substituents, the alkyl group represents, for example, a saturated aliphatic hydrocarbon group such as a methyl group, an ethyl group, a propyl group, or a butyl group, which may be unsubstituted or substituted. The alkoxy group refers to an aliphatic hydrocarbon group via an ether bond such as a methoxy group, and the aliphatic hydrocarbon group may be unsubstituted or substituted. Halogen is fluorine, chlorine, bromine or iodine. The aryl group represents an aromatic hydrocarbon group such as a phenyl group, a naphthyl group, a biphenyl group, a phenanthryl group, a terphenyl group, or a pyrenyl group, which may be unsubstituted or substituted. The aralkyl group is an aromatic hydrocarbon group via an aliphatic hydrocarbon such as a benzyl group or a phenylethyl group, and both the aliphatic hydrocarbon and the aromatic hydrocarbon may be unsubstituted or substituted. It doesn't matter. The alkenyl group refers to an unsaturated aliphatic hydrocarbon group containing a double bond such as a vinyl group, an allyl group or a butadienyl group, which may be unsubstituted or substituted. The aryl ether group refers to an aromatic hydrocarbon group via an ether bond such as a phenoxy group, and the aromatic hydrocarbon group may be unsubstituted or substituted. The heterocyclic group is, for example, thienyl group, furyl group, pyrrolyl group, imidazolyl group, pyrazolyl group, oxazolyl group, pyridyl group, pyrazyl group, pyrimidyl group, quinolinyl group, isoquinolyl group, quinoxalyl group, acridinyl group, carbazolyl group, etc. A cyclic structural group having an atom other than carbon, which may be unsubstituted or substituted. Aldehyde groups, carbonyl groups, ester groups, carbamoyl groups, amino groups include those substituted with aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, heterocyclic rings, etc. The cyclic hydrocarbon, aromatic hydrocarbon and heterocyclic ring may be unsubstituted or substituted. Condensation formed between adjacent substituents Ring and Form a conjugated or non-conjugated fused ring at the R1 and R2, R2 and R3, R4 and R5, and R5 and R6 sites. These condensed rings may contain a nitrogen, oxygen, or sulfur atom in the ring structure, or may be further condensed with another ring.
[0022]
Moreover, when coordinating to a metal, there is no particular limitation on a compound having a pyromethene skeleton alone or a mixed ligand. As the second ligand in the case of a mixed ligand, alkoxy, phenoxy, halogen, alkyl, allyl and other condensed ring hydrocarbons, heterocyclic compounds, or aromatic rings or heterocyclic compounds bonded through an oxygen atom Etc. can be introduced.
[0023]
The metal that can be coordinated to the ligand of the present invention is not particularly limited. Examples of commonly used elements include boron, beryllium, magnesium, chromium, iron, cobalt, nickel, copper, zinc, and platinum. be able to.
[0024]
In order to obtain red light emission having excellent color purity characteristics, the compound having the pyromethene skeleton Or its metal complex Of these, compounds represented by the following general formula (2) Or its metal complex Is desirable.
[0025]
[Chemical formula 5]

(At least one of R8 to R14 contains an aromatic ring or forms a condensed aromatic ring with an adjacent substituent, and the rest are hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl. Condensation formed between ether, heterocycle, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, adjacent substituent Ring Chosen from the inside. X is carbon or nitrogen, but in the case of nitrogen, R14 does not exist. ).
[0026]
The aromatic ring group here includes not only an aromatic hydrocarbon group such as a phenyl group, a naphthyl group and an anthranyl group, but also a heterocyclic aromatic functional group such as a pyridyl group, a quinolyl group and a thienyl group. The condensed aromatic ring formed between adjacent substituents is one that forms a condensed aromatic ring at the sites of R8 and R9, R9 and R10, R11 and R12, and R12 and R13. And these condensed aromatic rings may contain nitrogen, oxygen and sulfur atoms in the ring structure in the same manner as the above aromatic ring group, and may be further condensed with another aromatic ring or aliphatic ring.
[0027]
Further, a compound having a pyromethene skeleton Or its metal complex In order to obtain high luminance characteristics, a material having a high fluorescence quantum yield is more preferable. Therefore, the compound having the pyromethene skeleton Or its metal complex Is represented by the following general formula (3) Has a pyromethene skeleton Compound Metal complexes Is more preferable.
[0028]
[Chemical 6]

(At least one of R15 to R21 contains an aromatic ring or forms a condensed aromatic ring with an adjacent substituent, and the rest are hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl. Condensation formed between ether, heterocycle, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, adjacent substituent Ring Chosen from the inside. R22 and R23 may be the same or different and are selected from halogen, hydrogen, alkyl, aryl, and a heterocyclic group. X is carbon or nitrogen, but in the case of nitrogen, R21 does not exist. ).
[0029]
Compound having the above-mentioned pyromethene skeleton Or its metal complex Specifically, the following structures can be mentioned.
[0030]
[Chemical 7]

[0031]
[Chemical 8]

[0032]
[Chemical 9]

[0033]
[Chemical Formula 10]

[0034]
Embedded image

[0035]
Embedded image

[0036]
Embedded image

Since the concentration quenching phenomenon usually occurs when the doping amount is too large, it is preferably used in an amount of not more than 10% by weight, more preferably 2%. weight % Or less. As a doping method, it can be formed by a co-evaporation method with a host material, but it may be pre-mixed with the host material and then simultaneously deposited. In addition, Pyromethene Compound having skeleton Or its metal complex Emits even a very small amount of light, Compound having pyromethene skeleton or metal complex thereof Can be sandwiched between host materials and used. In this case, one or more layers may be laminated with the host material.
[0037]
The dopant material added to the light-emitting material is a compound having the pyromethene skeleton. Or its metal complex It is not necessary to limit to only one type, and a plurality of the compounds may be mixed and used, or one or more kinds of known dopant materials may be mixed with the compound. Specifically, conventionally known rare earth complexes such as naphthalimide derivatives such as bis (diisopropylphenyl) perylenetetracarboxylic imide, perinone derivatives, Eu complexes having acetylacetone, benzoylacetone and phenanthroline as ligands, 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran and its analogs, metal phthalocyanine derivatives such as magnesium phthalocyanine and aluminum chlorophthalocyanine, rhodamine compounds, deazaflavin derivatives, coumarin derivatives, Although an oxazine compound can coexist, it is not limited to these.
[0038]
As the electron transporting material in the present invention, it is necessary to efficiently transport electrons from the negative electrode between electrodes to which an electric field is applied, and it is desirable that the electron injection efficiency is high and the injected electrons are transported efficiently. . For this purpose, it is required that the material has a high electron affinity, a high electron mobility, excellent stability, and a substance that does not easily generate trapping impurities during manufacturing and use. As substances satisfying such conditions, quinolinol derivative metal complexes represented by 8-hydroxyquinoline aluminum, tropolone metal complexes, flavonol metal complexes, perylene derivatives, perinone derivatives, naphthalene, coumarin derivatives, oxadiazole derivatives, aldazine derivatives, Although there are bisstyryl derivatives, pyrazine derivatives, phenanthroline derivatives, etc., there is no particular limitation. These electron transport materials are used alone, but may be laminated or mixed with different electron transport materials.
[0039]
The materials used for the hole transport layer, the light emitting layer, and the electron transport layer can form each layer alone. Polyvinyl chloride, polycarbonate, polystyrene, poly (N-vinylcarbazole) are used as the polymer binder. Solvent-soluble resins such as polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, hydrocarbon resin, ketone resin, phenoxy resin, polysulfone, polyamide, ethyl cellulose, vinyl acetate, ABS resin, polyurethane resin, It can also be used by being dispersed in a curable resin such as phenol resin, xylene resin, petroleum resin, urea resin, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, or silicone resin.
[0040]
The formation method of the substance responsible for light emission is not particularly limited, such as resistance heating evaporation, electron beam evaporation, sputtering, molecular lamination method, coating method, etc., but resistance heating evaporation and electron beam evaporation are usually preferable in terms of characteristics. . The thickness of the layer cannot be limited because it depends on the resistance value of the substance responsible for light emission, but is selected from 1 to 1000 nm.
[0041]
In order to achieve a beautiful red display, it is important that the peak wavelength of the emission spectrum is in the range of 580 nm to 720 nm, more preferably 600 nm to 700 nm, and the half width is 100 nm or less. The emission spectrum is preferably a single peak as much as possible, but in some cases, it may have a plurality of maximum points due to overlapping with other peaks, or a shoulder may appear at the bottom of the peak. In the present invention, the peak wavelength is the wavelength of the main peak worth the emission center wavelength, and the half width is defined as the peak width at half the height of the emission center wavelength in the entire peak.
[0042]
Electrical energy mainly refers to direct current, but pulsed current or alternating current can also be used. The current value and the voltage value are not particularly limited, but the maximum luminance should be obtained with the lowest possible energy in consideration of the power consumption and lifetime of the element.
[0043]
The matrix in the present invention refers to a matrix in which pixels for display are arranged in a lattice pattern, and displays characters and images by a set of pixels. The shape and size of the pixel are determined by the application. For example, a square pixel with a side of 300 μm or less is usually used for displaying images and characters on a personal computer, monitor, television, and a pixel with a side of mm order is used for a large display such as a display panel. . In monochrome display, pixels of the same color may be arranged. However, in color display, red, red, green, and blue pixels are displayed side by side. In this case, there are typically a delta type and a stripe type. The matrix driving method may be either a line sequential driving method or an active matrix. The line-sequential driving has an advantage that the structure is simple. However, the active matrix may be superior in consideration of the operation characteristics, so that it is necessary to properly use it depending on the application.
[0044]
The segment type in the present invention means that a pattern is formed so as to display predetermined information, and a predetermined region is caused to emit light. For example, the time and temperature display in a digital clock or a thermometer, the operation status display of an audio device or an electromagnetic cooker, the panel display of an automobile, and the like can be given. The matrix display and the segment display may coexist in the same panel.
[0045]
The backlight in the present invention is used mainly for the purpose of improving the visibility of a display device that does not emit light, and is used for a liquid crystal display device, a clock, an audio device, an automobile panel, a display board, a sign, and the like. In particular, as a backlight for use in a liquid crystal display device, especially a personal computer for which thinning is a problem, considering that it is difficult to reduce the thickness of the conventional method because it is made of a fluorescent lamp or a light guide plate, The backlight is thin and lightweight.
[0046]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated, this invention is not limited by these examples.
[0047]
Example 1
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam evaporated product) on which an ITO transparent conductive film was deposited to 150 nm was cut into 30 × 40 mm and etched. The obtained substrate was ultrasonically washed with acetone and semicocrine 56 for 15 minutes, respectively, and then washed with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes to dry. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, and placed in a vacuum deposition apparatus, so that the degree of vacuum in the apparatus was 1 × 10. ^-Five It exhausted until it became Pa or less. First, 100 nm of N, N′-diphenyl-N, N ′-(3-methylphenyl) -1,1′-diphenyl-4,4′-diamine (TPD) was deposited as a hole transport material by a resistance heating method. . Next, 3,6-diphenyl-2,5-dihydro-2,5-dimethylpyrrolo [3,4-c] pyrrole-1,4-dione (orange fluorescent in powder state) as a host material and 4 as a dopant material. , 4-Difluoro-1,3,5,7-tetraphenyl-4-bora-3a, 4a-diaza-s-indacene (fluorescence peak wavelength in dichloromethane solution is 611 nm), dopant becomes 1 wt% Thus, it was co-evaporated to a thickness of 50 nm, and the host material was laminated to a thickness of 50 nm. Next, lithium was deposited to 0.2 nm and silver was deposited to 150 nm to prepare a cathode having a 5 × 5 mm square. The light emission peak wavelength of this light emitting element was 609 nm, and it showed beautiful red light emission with a spectral half width of 52 nm.
[0048]
Comparative Example 1
A light emitting device was produced in the same manner as in Example 1 except that tris (8-quinolinolato) aluminum complex (fluorescence peak wavelength 513 nm) was used as the host material. The emission peak wavelength of this light emitting device was 520 nm, energy transfer to the dopant material was hardly observed, green light emission from the host material was exhibited, and red light emission from the dopant material could not be obtained.
[0049]
Example 2
Difluoro [3-phenyl-1-[(3-phenyl-2H-benzo [c] isoindol-1-yl) methylene] -1H-benzo [c] isoindolato-N as dopant material ¹ , N ² A light emitting device was produced in the same manner as in Example 1 except that boron (fluorescence peak wavelength in dichloromethane solution was 645 nm) was used. The light emission peak wavelength of this light emitting element was 610 nm, and beautiful red light emission having a spectral half width of 50 nm was exhibited.
[0050]
Example 3
3,6-bis (4-methylphenyl) -2,5-dihydro-2,5-dimethylpyrrolo [3,4-c] pyrrole-1,4-dione (orange fluorescent in powder state) is used as the host material. A light emitting device was fabricated in the same manner as in Example 1 except for the above. The light emission peak wavelength of this light emitting element was 610 nm, and beautiful red light emission having a spectral half width of 50 nm was exhibited.
[0051]
Example 4
Difluoro [3-phenyl-1-[(3-phenyl-2H-benzo [c] isoindol-1-yl) methylene] -1H-benzo [c] isoindolato-N as dopant material ¹ , N ² A light emitting device was produced in the same manner as in Example 3 except that boron was used. The light emission peak wavelength of this light emitting element was 610 nm, and beautiful red light emission having a spectral half width of 50 nm was exhibited.
[0052]
Example 5
A glass substrate (manufactured by Asahi Glass Co., Ltd., 15Ω / □, electron beam evaporation product) on which an ITO transparent conductive film is deposited to 150 nm is cut into 30 × 40 mm, and 300 μm pitch (remaining width 270 μm) × 32 stripes by photolithography. Pattern processed. One side of the ITO stripe in the long side direction is expanded to a pitch of 1.27 mm (opening width 800 μm) in order to facilitate electrical connection with the outside. The obtained substrate was ultrasonically washed with acetone and semicocrine 56 for 15 minutes, respectively, and then washed with ultrapure water. Subsequently, it was ultrasonically cleaned with isopropyl alcohol for 15 minutes and then immersed in hot methanol for 15 minutes to dry. This substrate was subjected to UV-ozone treatment for 1 hour immediately before producing the device, and placed in a vacuum deposition apparatus, and the degree of vacuum in the apparatus was 5 × 10. ^-Four It exhausted until it became Pa or less. First, N, N′-diphenyl-N, N ′-(3-methylphenyl) -1,1′-diphenyl-4,4′-diamine (TPD) was deposited by a resistance heating method to a thickness of 100 nm. Next, 3,6-diphenyl-2,5-dihydro-2,5-dimethylpyrrolo [3,4-c] pyrrole-1,4-dione as a host material and 4,4-difluoro-1, as a dopant material Using 3,5,7-tetraphenyl-4-bora-3a, 4a-diaza-s-indacene, co-evaporated to a thickness of 50 nm so that the dopant was 1 wt%, and the host material was 50 nm thick Laminated. Next, a mask having 16 μm openings (corresponding to the remaining width of 50 μm and 300 μm pitch) formed by wet etching on a 50 μm thick Kovar plate was replaced by a mask so as to be orthogonal to the ITO stripe in a vacuum. And it fixed with the magnet from the back so that an ITO board | substrate might closely_contact | adhere. Magnesium was deposited with a thickness of 50 nm and aluminum was deposited with a thickness of 150 nm to produce a 32 × 16 dot matrix element. When this element was driven in matrix, characters could be displayed without crosstalk.
[0053]
【The invention's effect】
INDUSTRIAL APPLICABILITY The present invention can provide a red light emitting device that has high use efficiency of electric energy and excellent color purity.

Claims (10)

There is a substance that emits light between the cathode and the anode, and the element emits light with a peak wavelength of 580 nm or more and 720 nm or less by electric energy, and the element has at least a pyrrolo [3,4] fluorescent peak wavelength of 540 nm or more and 720 nm or less. -C] A compound containing a compound represented by the following general formula (1) having a pyrrole derivative and a pyromethene skeleton or a metal complex thereof, and having the pyromethene skeleton having the compound represented by the following general formula (1) or a metal complex thereof as a dopant material, A light-emitting element having 10% by weight or less based on [3,4-c] pyrrole derivative .

(Wherein R1 to R7 may be the same or different, hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl ether, heterocycle, cyano, aldehyde, carbonyl, ester, carbamoyl, amino, adjacent substitution Selected from among the condensed rings formed with the group X is carbon or nitrogen, but in the case of nitrogen, R7 does not exist.) The light emitting device according to claim 1, wherein the metal of the metal complex is at least one selected from boron, beryllium, magnesium, chromium, iron, cobalt, nickel, copper, zinc, and platinum. The light-emitting element according to claim 1, wherein the compound having a pyromethene skeleton is represented by the following general formula (2).

(Here, at least one of R8 to R14 contains an aromatic ring or forms a condensed aromatic ring with an adjacent substituent, and the rest are hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl. An ether, a heterocycle, a cyano, an aldehyde, a carbonyl, an ester, a carbamoyl, an amino, or a condensed ring formed between adjacent substituents, where X is carbon or nitrogen; R14 does not exist.) The light-emitting element according to claim 1, wherein the metal complex of the compound having a pyromethene skeleton is represented by the following general formula (3).

(Here, at least one of R15 to R21 contains an aromatic ring or forms a condensed aromatic ring with an adjacent substituent, and the rest are hydrogen, alkyl, alkoxy, halogen, aryl, aralkyl, alkenyl, aryl. Selected from ethers, heterocycles, cyano, aldehydes, carbonyls, esters, carbamoyl, amino, fused rings formed with adjacent substituents, R22 and R23 may be the same or different and may be halogen, hydrogen, X is carbon or nitrogen, and in the case of nitrogen, R21 does not exist.) 2. The pyrrolo [3,4-c] pyrrole derivative, wherein at least one of an aromatic ring or a heterocyclic ring is introduced as a substituent into the basic skeleton of the pyrrolo [3,4-c] pyrrole derivative. The light emitting element of description. 2. The light emitting device according to claim 1, wherein the substance that controls light emission comprises at least a light emitting material and a hole transport material and / or an electron transport material. The light-emitting element according to claim 1, wherein the substance responsible for light emission has a laminated structure of at least a hole transport layer and a light-emitting layer. 8. The light emitting device according to claim 7 , wherein an anode, a hole transport layer, a light emitting layer, an electron transport layer, and a cathode are sequentially laminated. The light emitting device according to any one of claims 1-8, characterized in that a display for displaying the matrix and / or segment system. It is a backlight, The light emitting element in any one of Claims 1-8 characterized by the above-mentioned.