JP2004022334A - Organic electroluminescence element and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element which achieves improvement in emission luminance and emission efficiency and coexistence of them and endurance and provide a display device which uses the organic EL element, has high emission luminance and has good durability. <P>SOLUTION: The organic electroluminescence element which includes a light-emitting layer containing a host compound and a phosphorescent compound is characterized by that a compound represented by formula (1) is contained in any one of layers constituting the element. In the formula, Ar<SB>1</SB>, Ar<SB>2</SB>and Ar<SB>3</SB>represent a 6-membered aromatic group and Ar<SB>12</SB>and Ar<SB>13</SB>represent the 6-membered aromatic group or a 5-membered monocyclic aromatic group. <P>COPYRIGHT: (C)2004,JPO

Description

【００３３】
【化４】

【００３４】
【化５】

【００３５】
又、別の形態では、ホスト化合物と燐光性化合物の他に、燐光性化合物からの発光の極大波長よりも長波な領域に、蛍光極大波長を有する蛍光性化合物を少なくとも１種含有する場合もある。この場合、ホスト化合物と燐光性化合物からのエネルギー移動で、有機ＥＬ素子としての電界発光は蛍光性化合物からの発光が得られる。蛍光性化合物として好ましいのは、溶液状態で蛍光量子収率が高いものである。ここで、蛍光量子収率は１０％以上、特に３０％以上が好ましい。具体的な蛍光性化合物は、クマリン系色素、ピラン系色素、シアニン系色素、クロコニウム系色素、スクアリウム系色素、オキソベンツアントラセン系色素、フルオレセイン系色素、ローダミン系色素、ピリリウム系色素、ペリレン系色素、スチルベン系色素、ポリチオフェン系色素、又は希土類錯体系蛍光体等が挙げられる。
【００３６】
ここでの蛍光量子収率も、前記第４版実験化学講座７の分光ＩＩの３６２頁（１９９２年版、丸善）に記載の方法により測定することが出来る。
【００３７】
前記燐光性化合物は、前記のような燐光量子収率が、２５℃において０．００１以上である他、前記ホストとなる蛍光性化合物の蛍光極大波長よりも長い燐光発光極大波長を有するものである。これにより、例えば、ホストとなる蛍光性化合物の発光極大波長より長波の燐光性化合物を用いて燐光性化合物の発光、即ち三重項状態を利用した、ホスト化合物の蛍光極大波長よりも長波において電界発光するＥＬ素子を得ることができる。従って、用いられる燐光性化合物の燐光発光極大波長としては特に制限されるものではなく、原理的には、中心金属、配位子、配位子の置換基等を選択することで得られる発光波長を変化させることができる。
【００３８】
例えば、３５０〜４４０ｎｍの領域に蛍光極大波長を有する蛍光性化合物をホスト化合物として用い、例えば、緑の領域に燐光を有するイリジウム錯体を用いることで緑領域に電界発光する有機ＥＬ素子を得ることが出来る。
【００３９】
又、別の形態では、前記のように、ホスト化合物としての蛍光性化合物Ａと燐光性化合物の他に、燐光性化合物からの発光の極大波長よりも長波な領域に、蛍光極大波長を有するもう一つの蛍光性化合物Ｂを少なくとも１種含有する場合もあり、蛍光性化合物Ａと燐光性化合物からのエネルギー移動で、有機ＥＬ素子としての電界発光は蛍光性化合物Ｂからの発光を得ることも出来る。
【００４０】
本明細書の蛍光性化合物が発光する色は、「新編色彩科学ハンドブック」（日本色彩学会編、東京大学出版会、１９８５）の１０８頁の図４．１６において、分光放射輝度計ＣＳ−１０００（ミノルタ製）で測定した結果をＣＩＥ色度座標に当てはめたときの色で決定される。
【００４１】
続いて本発明に用いられるホスト化合物について説明する。
本発明におけるホスト化合物としては、特定構造を有するトリアジン誘導体であり、とりわけ一般式（１）で表される化合物であることを要する。最初に一般式（１）で表される化合物について説明する。
【００４２】
式中、Ａｒ_１、Ａｒ_２及びＡｒ_３は６員芳香族基を表し、Ａｒ_１１、Ａｒ_１２、Ａｒ_{１ ３}は６員芳香族基又は５員単環芳香族基を表す。Ａｒ_１、Ａｒ_２、Ａｒ_３、Ａｒ_１１、Ａｒ_１２及びＡｒ_１３で表される６員芳香族基は、更に縮合環を形成しても良い。具体的には炭化水素芳香族基（フェニル基、ナフチル基、フェナンスリル基、アントリル基、ｐ−トリル基、ｐ−クロロフェニル基等）又は複素芳香族基（ピリジル基、ピラジニル基、ピリミジニル基、ピリダジニル基、キノリル基、トリアジニル基、キナゾキニル基、アクリジニル基等）を表す。
【００４３】
Ａｒ_１１、Ａｒ_１２、Ａｒ_１３で表される５員単環芳香族基としては、ピロリル基、チエニル基、フリル基、イミダゾリル基、ピラゾリル基、オキサゾリル基、チアゾリル基等が挙げられる。Ａｒ_１、Ａｒ_２、Ａｒ_３、Ａｒ_１１、Ａｒ_１２及びＡｒ_１３は更に置換基を有していても良い。
【００４４】
一般式（１）で表される化合物は、好ましくはＡｒ_１、Ａｒ_２、Ａｒ_３、Ａｒ_１１、Ａｒ_１２及びＡｒ_１３が全て単環芳香族基であり、更に好ましくはＡｒ_１、Ａｒ_２及びＡｒ_３が炭化水素芳香族基であり、Ａｒ_１１、Ａｒ_１２、Ａｒ_１３が６員複素芳香族基である場合、又はＡｒ_１１、Ａｒ_１２、Ａｒ_１３の少なくとも１つがチエニル基である場合である。
【００４５】
本発明に用いられるトリアジン誘導体は、更に好ましくは一般式（２）で表される場合である。一般式（２）においてＡｒ_２１、Ａｒ_２２及びＡｒ_２３は、６員芳香族基又は５員単環芳香族基を表し、Ｒ_１、Ｒ_２及びＲ_３は一価の置換基を表す。ｌ、ｍ及びｎはそれぞれ１〜４の整数を表す。Ａｒ_２１、Ａｒ_２２及びＡｒ_２３で表される６員芳香族基、５員芳香族基としては一般式（１）中のＡｒ_１１、Ａｒ_１２、Ａｒ_１３と同様のものが挙げられる。
【００４６】
Ｒ_１、Ｒ_２及びＲ_３で表される一価の置換基としては、アルキル基（メチル基、エチル基、ｉ−プロピル基、ヒドロキシエチル基、メトキシメチル基、トリフルオロメチル基、ｔ−ブチル基、シクロペンチル基、シクロヘキシル基、ベンジル基等）、アリール基（フェニル基、ナフチル基、ｐ−トリル基、ｐ−クロロフェニル基等）、アルケニル基（ビニル基、プロペニル基、スチリル基等）、アルキニル基（エチニル基等）、アルキルオキシ基（メトキシ基、エトキシ基、ｉ−プロポキシ基、ブトキシ基等）、アリールオキシ基（フェノキシ基等）、アルキルチオ基（メチルチオ基、エチルチオ基、ｉ−プロピルキオ基等）、アリールチオ基（フェニルチオ基等）、アミノ基、アルキルアミノ基（ジメチルアミノ基、ジエチルアミノ基、エチルメチルアミノ基等）、アリールアミノ基（アニリノ基、ジフェニルアミノ基等）、ハロゲン原子（フッ素原子、塩素原子、臭素原子、ヨウ素原子等）、シアノ基、ニトロ基、複素環基（ピロール基、ピロリジル基、ピラゾリル基、イミダゾリル基、ピリジル基、ベンズイミダゾリル基、ベンゾチアゾリル基、ベンゾオキサゾリル基等）等が挙げられる。
【００４７】
一般式（２）において、好ましくはＲ_１、Ｒ_２及びＲ_３がアルキル基であり、ｌ、ｍ及びｎが２〜４のときであり、最も好ましくは、Ｒ_１、Ｒ_２及びＲ_３がメチル基であり、ｌ、ｍ及びｎが４のときである。
【００４８】
一般式（２）において、好ましくはＡｒ_２１、Ａｒ_２２又はＡｒ_２３のうち少なくとも１つがチエニル基である。
【００４９】
以下に、具体的化合物例を示すが、本発明におけるホスト化合物がこれらに限定されるものではない。
【００５０】
【化６】

【００５１】
【化７】

【００５２】
【化８】

【００５３】
【化９】

【００５４】
【化１０】

【００５５】
【化１１】

【００５６】
【化１２】

【００５７】
【化１３】

【００５８】
【化１４】

【００５９】
【化１５】

【００６０】
【化１６】

【００６１】
又、ホスト化合物の分子量は６００〜２０００であることが好ましい。分子量が６００〜２０００であるとＴｇ（ガラス転移温度）が上昇し、熱安定性が向上し、素子寿命が改善される。より好ましい分子量は８００〜２０００である。
【００６２】
これらの化合物は公知の方法によって製造が可能であるが、例えば特開２００１−９３６７０等に記載された方法を用いることができる。
【００６３】
以下、有機ＥＬ素子について説明する。
有機ＥＬ素子における発光層は、広義の意味では、陰極と陽極からなる電極に電流を流した際に発光する層のことを指す。具体的には、陰極と陽極からなる電極に電流を流した際に発光する蛍光性化合物を含有する層のことを指す。通常、ＥＬ素子は一対の電極の間に発光層を挟持した構造をとる。
【００６４】
本発明の有機ＥＬ素子は、必要に応じ発光層の他に、正孔輸送層、電子輸送層、陽極バッファー層及び陰極バッファー層等を有し、陰極と陽極で挟持された構造をとる。具体的には以下に示される構造が挙げられる。
（ｉ）陽極／発光層／陰極
（ｉｉ）陽極／正孔輸送層／発光層／陰極
（ｉｉｉ）陽極／発光層／電子輸送層／陰極
（ｉｖ）陽極／正孔輸送層／発光層／電子輸送層／陰極
（ｖ）陽極／陽極バッファー層／正孔輸送層／発光層／電子輸送層／陰極バッファー層／陰極
上記化合物を用いて発光層を形成する方法としては、例えば蒸着法、スピンコート法、キャスト法、ＬＢ法などの公知の方法により薄膜を形成する方法があるが、特に分子堆積膜であることが好ましい。ここで、分子堆積膜とは、上記化合物の気相状態から沈着され形成された薄膜や、該化合物の溶融状態又は液相状態から固体化され形成された膜のことである。通常、この分子堆積膜はＬＢ法により形成された薄膜（分子累積膜）と、凝集構造、高次構造の相違やそれに起因する機能的な相違により区別することができる。
【００６５】
又、この発光層は、特開昭５７−５１７８１号に記載されているように、樹脂などの結着材と共に発光材料として上記化合物を溶剤に溶かして溶液とした後、これをスピンコート法などにより塗布して薄膜形成することにより得ることができる。
【００６６】
このようにして形成された発光層の膜厚については特に制限はなく、状況に応じて適宜選択することができるが、通常は５ｎｍ〜５μｍの範囲である。
【００６７】
次に正孔注入層、正孔輸送層、電子注入層、電子輸送層等、発光層と組み合わせてＥＬ素子を構成するその他の層について説明する。
【００６８】
正孔注入層、正孔輸送層は、陽極より注入された正孔を発光層に伝達する機能を有し、この正孔注入層、正孔輸送層を陽極と発光層の間に介在させることにより、より低い電界で多くの正孔が発光層に注入され、その上、発光層に陰極、電子注入層又は電子輸送層より注入された電子は、発光層と正孔注入層もしくは正孔輸送層の界面に存在する電子の障壁により、発光層内の界面に累積され発光効率が向上するなど発光性能の優れた素子となる。この正孔注入層、正孔輸送層の材料（以下、正孔注入材料、正孔輸送材料という）については、前記の陽極より注入された正孔を発光層に伝達する機能を有する性質を有するものであれば特に制限はなく、従来、光導伝材料において、正孔の電荷注入輸送材料として慣用されているものやＥＬ素子の正孔注入層、正孔輸送層に使用される公知のものの中から任意のものを選択して用いることができる。
【００６９】
上記正孔注入材料、正孔輸送材料は、正孔の注入もしくは輸送、電子の障壁性の何れかを有するものであり、有機物、無機物の何れであってもよい。この正孔注入材料、正孔輸送材料としては、例えばトリアゾール誘導体、オキサジアゾール誘導体、イミダゾール誘導体、ポリアリールアルカン誘導体、ピラゾリン誘導体及びピラゾロン誘導体、フェニレンジアミン誘導体、アリールアミン誘導体、アミノ置換カルコン誘導体、オキサゾール誘導体、スチリルアントラセン誘導体、フルオレノン誘導体、ヒドラゾン誘導体、スチルベン誘導体、シラザン誘導体、アニ燐系共重合体、又、導電性高分子オリゴマー、特にチオフェンオリゴマーなどが挙げられる。正孔注入材料、正孔輸送材料としては、上記のものを使用することができるが、ポルフィリン化合物、芳香族第三級アミン化合物及びスチリルアミン化合物、特に芳香族第三級アミン化合物を用いることが好ましい。
【００７０】
上記芳香族第三級アミン化合物及びスチリルアミン化合物の代表例としては、Ｎ，Ｎ，Ｎ′，Ｎ′−テトラフェニル−４，４′−ジアミノフェニル；Ｎ，Ｎ′−ジフェニル−Ｎ，Ｎ′−ビス（３−メチルフェニル）−〔１，１′−ビフェニル〕−４，４′−ジアミン（ＴＰＤ）；２，２−ビス（４−ジ−ｐ−トリルアミノフェニル）プロパン；１，１−ビス（４−ジ−ｐ−トリルアミノフェニル）シクロヘキサン；Ｎ，Ｎ，Ｎ′，Ｎ′−テトラ−ｐ−トリル−４，４′−ジアミノビフェニル；１，１−ビス（４−ジ−ｐ−トリルアミノフェニル）−４−フェニルシクロヘキサン；ビス（４−ジメチルアミノ−２−メチルフェニル）フェニルメタン；ビス（４−ジ−ｐ−トリルアミノフェニル）フェニルメタン；Ｎ，Ｎ′−ジフェニル−Ｎ，Ｎ′−ジ（４−メトキシフェニル）−４，４′−ジアミノビフェニル；Ｎ，Ｎ，Ｎ′，Ｎ′−テトラフェニル−４，４′−ジアミノジフェニルエーテル；４，４′−ビス（ジフェニルアミノ）クオードリフェニル；Ｎ，Ｎ，Ｎ−トリ（ｐ−トリル）アミン；４−（ジ−ｐ−トリルアミノ）−４′−〔４−（ジ−ｐ−トリルアミノ）スチリル〕スチルベン；４−Ｎ，Ｎ−ジフェニルアミノ−（２−ジフェニルビニル）ベンゼン；３−メトキシ−４′−Ｎ，Ｎ−ジフェニルアミノスチルベンゼン；Ｎ−フェニルカルバゾール、更に米国特許第５，０６１，５６９号明細書に記載されている２個の縮合芳香族環を分子内に有するもの、例えば４，４′−ビス〔Ｎ−（１−ナフチル）−Ｎ−フェニルアミノ〕ビフェニル（ＮＰＤ）、特開平４−３０８６８８号公報に記載されているトリフェニルアミンユニットが３つスターバースト型に連結された４，４′，４″−トリス〔Ｎ−（３−メチルフェニル）−Ｎ−フェニルアミノ〕トリフェニルアミン（ＭＴＤＡＴＡ）などが挙げられる。
【００７１】
更にこれらの材料を高分子鎖に導入した、又はこれらの材料を高分子の主鎖とした高分子材料を用いることもできる。
【００７２】
又、ｐ型−Ｓｉ、ｐ型−ＳｉＣなどの無機化合物も正孔注入材料、正孔輸送材料として使用することができる。この正孔注入層、正孔輸送層は、上記正孔注入材料、正孔輸送材料を、例えば真空蒸着法、スピンコート法、キャスト法、ＬＢ法などの公知の方法により、薄膜化することにより形成することができる。正孔注入層、正孔輸送層の膜厚については特に制限はないが、通常は５ｎｍ〜５μｍ程度である。この正孔注入層、正孔輸送層は、上記材料の一種又は二種以上からなる一層構造であってもよく、同一組成又は異種組成の複数層からなる積層構造であってもよい。
【００７３】
更に、必要に応じて用いられる電子輸送層は、陰極より注入された電子を発光層に伝達する機能を有していればよく、その材料としては従来公知の化合物の中から任意のものを選択して用いることができる。
【００７４】
この電子輸送層に用いられる材料（以下、電子輸送材料という）の例としては、ニトロ置換フルオレン誘導体、ジフェニルキノン誘導体、チオピランジオキシド誘導体、ナフタレンペリレンなどの複素環テトラカルボン酸無水物、カルボジイミド、フレオレニリデンメタン誘導体、アントラキノジメタン及びアントロン誘導体、オキサジアゾール誘導体などが挙げられる。更に、上記オキサジアゾール誘導体において、オキサジアゾール環の酸素原子を硫黄原子に置換したチアジアゾール誘導体、電子吸引基として知られているキノキサ燐環を有するキノキサ燐誘導体も、電子輸送材料として用いることができる。
【００７５】
更にこれらの材料を高分子鎖に導入した、又はこれらの材料を高分子の主鎖とした高分子材料を用いることもできる。
【００７６】
又、８−キノリノール誘導体の金属錯体、例えばトリス（８−キノリノール）アルミニウム（Ａｌｑ）、トリス（５，７−ジクロロ−８−キノリノール）アルミニウム、トリス（５，７−ジブロモ−８−キノリノール）アルミニウム、トリス（２−メチル−８−キノリノール）アルミニウム、トリス（５−メチル−８−キノリノール）アルミニウム、ビス（８−キノリノール）亜鉛（Ｚｎｑ）など、及びこれらの金属錯体の中心金属がＩｎ、Ｍｇ、Ｃｕ、Ｃａ、Ｓｎ、Ｇａ又はＰｂに置き替わった金属錯体も、電子輸送材料として用いることができる。その他、メタルフリー若しくはメタルフタロシアニン、又はそれらの末端がアルキル基やスルホン酸基などで置換されているものも、電子輸送材料として好ましく用いることができる。又、発光層の材料として例示したジスチリルピラジン誘導体も、電子輸送材料として用いることができるし、正孔注入層、正孔輸送層と同様に、ｎ型−Ｓｉ、ｎ型−ＳｉＣなどの無機半導体も電子輸送材料として用いることができる。
【００７７】
この電子輸送層は、上記化合物を、例えば真空蒸着法、スピンコート法、キャスト法、ＬＢ法などの公知の薄膜形成法により製膜して形成することができる。電子輸送層の膜厚は特に制限はないが、通常は５ｎｍ〜５μｍの範囲で選ばれる。この電子輸送層は、これらの電子輸送材料一種又は二種以上からなる一層構造であってもよいし、或いは、同一組成又は異種組成の複数層からなる積層構造であってもよい。
【００７８】
又、本発明においては、蛍光性化合物は発光層のみに限定することはなく、発光層に隣接した正孔輸送層、又は電子輸送層に前記燐光性化合物のホスト化合物となる蛍光性化合物と同じ領域に蛍光極大波長を有する蛍光性化合物を少なくとも１種含有させてもよく、それにより更にＥＬ素子の発光効率を高めることができる。これらの正孔輸送層や電子輸送層に含有される蛍光性化合物としては、発光層に含有されるものと同様に蛍光極大波長が３５０〜４４０ｎｍ、更に好ましくは３９０〜４１０ｎｍの範囲にある蛍光性化合物が用いられる。
【００７９】
又、本発明においては、発光効率、及び耐久性の点から一般式（１）又は一般式（２）で表される化合物を電子輸送層に含有することが好ましい。
【００８０】
本発明の有機ＥＬ素子に好ましく用いられる基盤は、ガラス、プラスチックなどの種類には特に限定はなく、又、透明のものであれば特に制限はない。本発明の有機ＥＬ素子に好ましく用いられる基盤としては例えばガラス、石英、光透過性プラスチックフィルムを挙げることができる。
【００８１】
光透過性プラスチックフィルムとしては、例えばポリエチレンテレフタレート（ＰＥＴ）、ポリエチレンナフタレート（ＰＥＮ）、ポリエーテルスルホン（ＰＥＳ）、ポリエーテルイミド、ポリエーテルエーテルケトン、ポリフェニレンスルフィド、ポリアリレート、ポリイミド、ポリカーボネート（ＰＣ）、セルローストリアセテート（ＴＡＣ）、セルロースアセテートプロピオネート（ＣＡＰ）等からなるフィルム等が挙げられる。
【００８２】
次に、該有機ＥＬ素子を作製する好適な例を説明する。例として、前記の陽極／正孔注入層／正孔輸送層／発光層／電子輸送層／電子注入層／陰極からなるＥＬ素子の作製法について説明する。
【００８３】
まず適当な基板上に、所望の電極用物質、例えば陽極用物質からなる薄膜を、１μｍ以下、好ましくは１０〜２００ｎｍの範囲の膜厚になるように、蒸着やスパッタリングなどの方法により形成させて陽極を作製する。次に、この上に素子材料である正孔注入層、正孔輸送層、発光層、電子輸送層／電子注入層からなる薄膜を形成させる。
【００８４】
更に、陽極と発光層又は正孔注入層の間、及び、陰極と発光層又は電子注入層との間にはバッファー層（電極界面層）を存在させてもよい。
【００８５】
バッファー層とは、駆動電圧低下や発光効率向上のために電極と有機層間に設けられる層のことで、「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日エヌ・ティー・エス社発行）」の第２編第２章「電極材料」（第１２３頁〜第１６６頁）に詳細に記載されており、陽極バッファー層と陰極バッファー層とがある。
【００８６】
陽極バッファー層は、特開平９−４５４７９号、同９−２６００６２号、同８−２８８０６９号等にもその詳細が記載されており、具体例として、銅フタロシアニンに代表されるフタロシアニンバッファー層、酸化バナジウムに代表される酸化物バッファー層、アモルファスカーボンバッファー層、ポリアニ燐（エメラルディン）やポリチオフェン等の導電性高分子を用いた高分子バッファー層等が挙げられる。
【００８７】
陰極バッファー層は、特開平６−３２５８７１号、同９−１７５７４号、同１０−７４５８６号等にもその詳細が記載されており、具体的にはストロンチウムやアルミニウム等に代表される金属バッファー層、フッ化リチウムに代表されるアルカリ金属化合物バッファー層、フッ化マグネシウムに代表されるアルカリ土類金属化合物バッファー層、酸化アルミニウム、酸化リチウムに代表される酸化物バッファー層等が挙げられる。
【００８８】
上記バッファー層はごく薄い膜であることが望ましく、素材にもよるが、その膜厚は０．１〜１００ｎｍの範囲が好ましい。
【００８９】
更に上記基本構成層の他に必要に応じてその他の機能を有する層を積層してもよく、例えば特開平１１−２０４２５８号、同１１−２０４３５９号、及び「有機ＥＬ素子とその工業化最前線（１９９８年１１月３０日エヌ・ティー・エス社発行）」の第２３７頁等に記載されている正孔阻止（ホールブロック）層などのような機能層を有していても良い。
【００９０】
バッファー層は、陰極バッファー層又は陽極バッファー層の少なくとも何れか１つの層内に一般式（１）又は（２）で表される化合物の少なくとも１種が存在して、発光層として機能してもよい。
【００９１】
次に有機ＥＬ素子の電極について説明する。有機ＥＬ素子の電極は、陰極と陽極からなる。
【００９２】
この有機ＥＬ素子における陽極としては、仕事関数の大きい（４ｅＶ以上）金属、合金、電気伝導性化合物及びこれらの混合物を電極物質とするものが好ましく用いられる。このような電極物質の具体例としてはＡｕなどの金属、ＣｕＩ、インジウムチンオキシド（ＩＴＯ）、ＳｎＯ_２、ＺｎＯなどの導電性透明材料が挙げられる。
【００９３】
上記陽極は蒸着やスパッタリングなどの方法によりこれらの電極物質の薄膜を形成させ、フォトリソグラフィー法で所望の形状のパターンを形成してもよく、或いはパターン精度をあまり必要としない場合（１００μｍ以上程度）は、上記電極物質の蒸着やスパッタリング時に所望の形状のマスクを介してパターンを形成してもよい。この陽極より発光を取り出す場合には、透過率を１０％より大きくすることが望ましく、又、陽極としてのシート抵抗は数百Ω／□以下が好ましい。更に膜厚は材料にもよるが、通常１０ｎｍ〜１μｍ、好ましくは１０ｎｍ〜２００ｎｍの範囲で選ばれる。
【００９４】
一方、陰極としては、仕事関数の小さい（４ｅＶ以下）金属（電子注入性金属と称する）、合金、電気伝導性化合物及びこれらの混合物を電極物質とするものが好ましく用いられる。このような電極物質の具体例としては、ナトリウム、ナトリウム−カリウム合金、マグネシウム、リチウム、マグネシウム／銅混合物、マグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ_２Ｏ_３）混合物、インジウム、リチウム／アルミニウム混合物、希土類金属などが挙げられる。これらの中で、電子注入性及び酸化などに対する耐久性の点から、電子注入性金属とこれより仕事関数の値が大きく安定な金属である第二金属との混合物、例えばマグネシウム／銀混合物、マグネシウム／アルミニウム混合物、マグネシウム／インジウム混合物、アルミニウム／酸化アルミニウム（Ａｌ_２Ｏ_３）混合物、リチウム／アルミニウム混合物などが好適である。上記陰極は、これらの電極物質を蒸着やスパッタリングなどの方法で薄膜を形成させることにより作製することができる。又、陰極としてのシート抵抗は数百Ω／□以下が好ましく、膜厚は通常１０ｎｍ〜１μｍ、好ましくは５０〜２００ｎｍの範囲で選ばれる。尚、発光を透過させるため、有機ＥＬ素子の陽極又は陰極の何れか一方が、透明又は半透明であれば発光効率が向上するので好都合である。
【００９５】
次に有機ＥＬ素子の作製方法について説明する。
薄膜化の方法としては、前記の如くスピンコート法、キャスト法、蒸着法などがあるが、均質な膜が得られやすく、かつピンホールが生成しにくいなどの点から、真空蒸着法が好ましい。薄膜化に真空蒸着法を採用する場合、その蒸着条件は、使用する化合物の種類、分子堆積膜の目的とする結晶構造、会合構造などにより異なるが、一般にボート加熱温度５０〜４５０℃、真空度１０^−６〜１０^−３Ｐａ、蒸着速度０．０１〜５０ｎｍ／秒、基板温度−５０〜３００℃、膜厚５ｎｍ〜５μｍの範囲で適宜選ぶことが望ましい。
【００９６】
前記の様に、適当な基板上に所望の電極用物質、例えば陽極用物質からなる薄膜を１μｍ以下、好ましくは１０〜２００ｎｍの範囲の膜厚になるように、蒸着やスパッタリングなどの方法により形成させて陽極を作製した後、該陽極上に前記の通り正孔注入層、正孔輸送層、発光層、電子輸送層／電子注入層からなる各層薄膜を形成させた後、その上に陰極用物質からなる薄膜を１μｍ以下、好ましくは５０〜２００ｎｍの範囲の膜厚になるように、例えば蒸着やスパッタリングなどの方法により形成させて陰極を設け、所望の有機ＥＬ素子が得られる。この有機ＥＬ素子の作製は、一回の真空引きで一貫してこの様に正孔注入層から陰極まで作製するのが好ましいが、作製順序を逆にして、陰極、電子注入層、発光層、正孔注入層、陽極の順に作製することも可能である。このようにして得られた有機ＥＬ素子に、直流電圧を印加する場合には、陽極を＋、陰極を−の極性として電圧５〜４０Ｖ程度を印加すると、発光が観測できる。又、逆の極性で電圧を印加しても電流は流れずに発光は全く生じない。更に、交流電圧を印加する場合には、陽極が＋、陰極が−の状態になったときのみ発光する。尚、印加する交流の波形は任意でよい。
【００９７】
本発明の有機ＥＬ素子は、照明用や露光光源のような一種のランプとして使用しても良いし、画像を投影するタイプのプロジェクション装置や、静止画像や動画像を直接視認するタイプの表示装置（ディスプレイ）として使用しても良い。動画再生用の表示装置として使用する場合の駆動方式は単純マトリクス（パッシブマトリクス）方式でもアクティブマトリクス方式でもどちらでも良い。又、異なる発光色を有する本発明の有機ＥＬ素子を２種以上使用することにより、フルカラー表示装置を作製することが可能である。
【００９８】
【実施例】
以下、実施例を挙げて本発明を詳細に説明するが、本発明の態様はこれに限定されない。
【００９９】
実施例１
〈有機ＥＬ素子の作製〉
有機ＥＬ素子ＯＬＥＤ１−１〜１−１２を以下のように作製した。
【０１００】
陽極として１００ｍｍ×１００ｍｍ×１．１ｍｍのガラス基板上にＩＴＯ（インジウムチンオキシド）を１５０ｎｍ成膜した基板（ＮＨテクノグラス社製ＮＡ−４５）にパターニングを行った後、このＩＴＯ透明電極を設けた透明支持基板をイソプロピルアルコールで超音波洗浄し、乾燥窒素ガスで乾燥し、ＵＶオゾン洗浄を５分間行なった。
【０１０１】
この透明支持基板を市販の真空蒸着装置の基板ホルダーに固定し、一方、モリブデン製抵抗加熱ボートにα−ＮＰＤを２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートにカルバゾール誘導体（ＣＢＰ）を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートにバソキュプロイン（ＢＣＰ）を２００ｍｇ入れ、別のモリブデン製抵抗加熱ボートに燐光性化合物（Ｉｒ−１）を１００ｍｇ入れ、更に別のモリブデン製抵抗加熱ボートにＡｌｑ_３を２００ｍｇ入れ、真空蒸着装置に取付けた。
【０１０２】
次いで、真空槽を４×１０^−４Ｐａまで減圧した後、α−ＮＰＤの入った前記加熱ボートに通電して加熱し、蒸着速度０．１ｎｍ／ｓｅｃで透明支持基板に蒸着し、膜厚４５ｎｍの正孔輸送層を設けた。更に、ＣＢＰとＩｒ−１の入った前記加熱ボートに通電して加熱し、それぞれ蒸着速度０．１ｎｍ／ｓｅｃ、０．０１ｎｍ／ｓｅｃで前記正孔輸送層上に共蒸着して膜厚２０ｎｍの発光層を設けた。尚、蒸着時の基板温度は室温であった。更に、ＢＣＰの入った前記加熱ボートに通電して加熱し、蒸着速度０．１ｎｍ／ｓｅｃで前記発光層の上に蒸着して膜厚１０ｎｍの正孔阻止の役割も兼ねた電子輸送層を設けた。その上に、更に、Ａｌｑ_３の入った前記加熱ボートに通電して加熱し、蒸着速度０．１ｎｍ／ｓｅｃで前記電子輸送層の上に蒸着して更に膜厚４０ｎｍの電子注入層を設けた。尚、蒸着時の基板温度は室温であった。
【０１０３】
引き続きフッ化リチウム０．５ｎｍ及びアルミニウム１１０ｎｍを蒸着して陰極を形成し、有機ＥＬ素子ＯＬＥＤ１−１を作製した。
【０１０４】
発光層のＣＢＰを表１に示す化合物に置き換えた以外は全く同じ方法で、有機ＥＬ素子ＯＬＥＤ１−２〜１−１２を作製した。
【０１０５】
上記で使用した化合物の構造を以下に示す。
【０１０６】
【化１７】

【０１０７】
〈有機ＥＬ素子の評価〉
以下のようにして得られた有機ＥＬ素子の評価を行い、結果を表１に示す。
（発光輝度、発光効率）
有機ＥＬ素子ＯＬＥＤ１−１では、初期駆動電圧３Ｖで電流が流れ始め、発光層のドーパントである燐光性化合物からの緑色の発光を示した。有機ＥＬ素子ＯＬＥＤ１−１の温度２３℃、乾燥窒素ガス雰囲気下で１０Ｖ直流電圧を印加した時の発光輝度（ｃｄ／ｍ^２）、発光効率（ｌｍ／Ｗ）を測定した。
【０１０８】
発光輝度、発光効率は有機ＥＬ素子ＯＬＥＤ１−１を１００とした時の相対値で表した。発光輝度については、ＣＳ−１０００（ミノルタ製）を用いて測定した。
（耐久性）
１０ｍＡ／ｃｍ^２の一定電流で駆動したときに初期輝度が元の半分に低下するのに要した時間である半減寿命時間を指標として表した。半減寿命時間は有機ＥＬ素子ＯＬＥＤ１−１を１００とした時の相対値で表した。
【０１０９】
【表１】

【０１１０】
表１から明らかなように、一般式（１）又は（２）で表されるトリアジン誘導体化合物をホスト化合物に用いた有機ＥＬ素子は、発光輝度及び発光効率が高く、半減寿命時間が長いことから、有機ＥＬ素子として非常に有用であることが判る。
【０１１１】
又、燐光性化合物（Ｉｒ−１）をＩｒ−１２又はＩｒ−９に変更した以外は有機ＥＬ素子ＯＬＥＤ１−１〜１−１２と同様にして作製した有機ＥＬ素子においても同様の効果が得られた。尚、Ｉｒ−１２を用いた素子からは青色の発光が、Ｉｒ−９を用いた素子からは赤色の発光が得られた。
【０１１２】
実施例２
実施例１の有機ＥＬ素子ＯＬＥＤ１−１の電子輸送層におけるＢＣＰを表２に示す化合物に置き換えた以外は全く同じ方法で有機ＥＬ素子ＯＬＥＤ２−１〜２−９を作製した。
【０１１３】
次いで実施例１と同様の方法で発光輝度、発光効率及び半減寿命時間（耐久性）を測定した。得られた結果を表２に示す。
【０１１４】
【表２】

【０１１５】
表２から明らかなように、一般式（１）又は（２）で表されるトリアジン誘導体化合物を電子輸送層に用いた有機ＥＬ素子は、発光輝度、発光効率及び耐久性が改善されているのが分かる。特に耐久性においては、半減寿命時間が顕著に改善されているのが分かる。
【０１１６】
実施例３
実施例１で作製したそれぞれ赤色、緑色、青色発光有機ＥＬ素子を同一基板上に並置し、図１に示すアクティブマトリクス方式フルカラー表示装置を作製した。図１には作製したフルカラー表示装置の表示部Ａの模式図のみを示した。即ち同一基板上に、複数の走査線２及びデータ線３を含む配線部と、並置した複数の画素１（発光の色が赤領域の画素、緑領域の画素、青領域の画素等）とを有し、配線部の走査線２及び複数のデータ線３はそれぞれ導電材料からなり、走査線２とデータ線３は格子状に直交して、直交する位置で画素１に接続している（詳細は図示せず）。前記複数画素１は、それぞれの発光色に対応した有機ＥＬ素子、アクティブ素子であるスイッチングトランジスタと駆動トランジスタそれぞれが設けられたアクティブマトリクス方式で駆動されており、走査線２から走査信号が印加されると、データ線３から画像データ信号を受け取り、受け取った画像データに応じて発光する。この様に各赤、緑、青の画素を適宜、並置することによって、フルカラー表示が可能となる。
【０１１７】
該フルカラー表示装置を駆動することにより、輝度の高く耐久性の良好な、鮮明なフルカラー動画表示が得られた。
【０１１８】
【発明の効果】
本発明によれば発光輝度に優れ、長寿命な有機ＥＬ素子及び該有機ＥＬ素子を有する表示装置が得られるという顕著に優れた効果を奏する。
【図面の簡単な説明】
【図１】フルカラー表示装置の表示部の模式図。
【符号の説明】
Ａ　表示部
１　画素
２　走査線
３　データ線[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an organic electroluminescent element (organic EL element) and a display device, and more particularly, to an organic electroluminescent element excellent in light emission luminance, luminous efficiency and durability, and a display device having the same.
[0002]
[Prior art]
As a light emitting type electronic display device, there is an electroluminescence display (ELD). ELD includes an inorganic electroluminescent element (inorganic EL element) and an organic electroluminescent element. Inorganic electroluminescent devices have been used as flat light sources, but require a high AC voltage to drive the light emitting devices. An organic electroluminescence element has a configuration in which a light-emitting layer containing a compound that emits light is sandwiched between a cathode and an anode. Electrons and holes are injected into the light-emitting layer and recombination causes exciton (exciton) to be generated. An element that emits light by utilizing light emission (fluorescence / phosphorescence) when the exciton is deactivated and emits light at a voltage of about several V to several tens of volts. Because of this, it is rich in viewing angle, has high visibility, and is a thin-film type completely solid-state element.
[0003]
However, development of an organic EL element that emits light with high efficiency and low power consumption is desired for an organic EL element for practical use in the future.
[0004]
For example, in Japanese Patent No. 3,093,796, a stilbene derivative, a distyrylarylene derivative, or a tristyrylarylene derivative is doped with a trace amount of a fluorescent substance, thereby achieving an improvement in light emission luminance and a long life of the device.
[0005]
Also, an element having an organic light emitting layer in which an 8-hydroxyquinophosphorum aluminum complex is used as a host compound and a small amount of a phosphor is added thereto (JP-A-63-264692), and an 8-hydroxyquinophosphorum aluminum complex is used as a host compound An element having an organic light emitting layer doped with a quinacridone dye (Japanese Patent Application Laid-Open No. 3-255190) is known. As described above, by doping the phosphor having a high fluorescence quantum yield, the emission luminance is improved as compared with the conventional device.
[0006]
However, the light emission from the doped small amount of phosphor is light emission from an excited singlet. When light emission from an excited singlet is used, the generation ratio between a singlet exciton and a triplet exciton is 1: 1. 3, the generation probability of the luminescent excited species is 25%, and the light extraction efficiency is about 20%. Therefore, the limit of the external extraction quantum efficiency (ηext) is 5%. However, since an organic EL device using phosphorescence from an excited triplet was reported from Princeton University (MA Baldo et al., Nature, 395, 151-154 (1998)). Research on materials exhibiting phosphorescence at room temperature has been actively conducted (for example, MA Baldo et al., Nature, vol. 403, No. 17, 750-753 (2000), US Pat. No. 6,097, No. 147). When the excited triplet is used, the upper limit of the internal quantum efficiency is 100%, so that the luminous efficiency is up to four times in principle compared to the case of the excited singlet, and the performance almost equal to that of the cold cathode tube is obtained. It is also applicable to applications and is attracting attention.
[0007]
When the phosphorescent compound is used as a dopant, the host needs to have a light emission maximum wavelength in a shorter wavelength region than the light emission maximum wavelength of the phosphorescent compound, but there are other conditions to be satisfied. I understand that.
[0008]
Several reports have been made on phosphorescent compounds in The 10th International International Workshop on Inorganic and Organic Electronic Control (EL'00, Hamamatsu). For example, Ikai et al. Use a hole transporting compound as a host for a phosphorescent compound. M. E. FIG. Tompson et al. Use various electron transporting materials as a host of a phosphorescent compound and dope them with a novel iridium complex. Further, Tsutsui et al. Obtain high luminous efficiency by introducing a hole blocking layer.
[0009]
As for the host compound of the phosphorescent compound, for example, C.I. Adachi @ et @ al. , Appl. Phys. Lett. 77, p. 904 (2000), etc., but it is necessary to take a newer approach to the properties required for the host compound in order to obtain a high-brightness organic electroluminescent device. .
[0010]
However, none of the reports has obtained a configuration capable of achieving both improvement in light emission luminance and durability.
[0011]
[Problems to be solved by the invention]
Accordingly, the present invention has been made in view of the above circumstances, and an object of the present invention is to improve an emission luminance, an emission efficiency, and an organic EL element achieving both of these and durability, and an emission luminance using the organic EL element. And a display device with high durability and good durability.
[0012]
[Means for Solving the Problems]
The object of the present invention is achieved by the following configurations.
[0013]
1. An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein any one of the layers constituting the device contains the compound represented by the general formula (1). Organic electroluminescent element.
[0014]
2. In the general formula (1), Ar₁, Ar₂, Ar₃, Ar₁₁, Ar₁₂And Ar_{1 3}Represents an all-monocyclic aromatic group.
[0015]
3. In the general formula (1), Ar₁, Ar₂And Ar₃Is a hydrocarbon aromatic group, and Ar₁₁, Ar₁₂And Ar₁₃Is a 6-membered heteroaromatic group, the organic electroluminescent device according to the above 1 or 2, wherein
[0016]
4. 4. The organic electroluminescent device according to any one of the above items 1 to 3, comprising a compound represented by the general formula (2).
[0017]
5. In the general formula (2), R₁, R₂And R₃Is an alkyl group, and l, m, and n are 2-4, The organic electroluminescent element of said 4 characterized by the above-mentioned.
[0018]
6. In the general formula (2), Ar₂₁, Ar₂₂Or Ar₂₃6. The organic electroluminescent device according to the above item 4 or 5, wherein at least one of them is a thienyl group.
[0019]
7. 7. The organic electroluminescent device according to any one of the above items 1 to 6, wherein the compound represented by the general formula (1) or (2) is contained in the electron transport layer.
[0020]
8. 8. The organic electroluminescent device according to any one of the above items 1 to 7, wherein the compound represented by the general formula (1) or (2) is contained in the light emitting layer as a host compound.
[0021]
9. 9. The organic electroluminescent device according to any one of items 1 to 8, wherein the phosphorescent compound is an iridium compound, an osmium compound, or a platinum compound.
[0022]
10. 10. The organic electroluminescent device according to the above item 9, wherein the phosphorescent compound is an iridium compound.
[0023]
11. A display device comprising the organic electroluminescence device according to any one of the above items 1 to 10.
[0024]
The present inventors have conducted intensive studies on materials for phosphorescence, and found that a triazine derivative having a specific structure in a molecule is contained in any of layers constituting an organic EL element to form an organic EL element. The present inventors have found that the luminous brightness, luminous efficiency and life of the device are remarkably improved, and have reached the present invention.
[0025]
Examples of using a triazine derivative as an organic EL device material are disclosed in JP-A-5-2630074, JP-A-7-157473, JP-A-8-199163, JP-A-11-292860, and JP-A-11-514143. However, none of the reports apply to a device containing a phosphorescent compound in a light-emitting layer. Japanese Patent Application Laid-Open No. 2002-100476 discloses an example in which the invention is applied to a device containing a phosphorescent compound. However, there is no description about the triazine derivative having a specific structure described in the present invention. No data is disclosed.
[0026]
Hereinafter, the present invention will be described in detail.
The organic EL device of the present invention has a light emitting layer containing a host compound and a phosphorescent compound, and any of the layers constituting the device contains the compound represented by the general formula (1). And
[0027]
In the present invention, the “host compound” means a compound having the largest mixing ratio (mass) in a light-emitting layer composed of two or more compounds, and the other compounds are referred to as “dopant compounds”. . For example, the light-emitting layer is composed of two kinds of compound A and compound B, and if the mixing ratio is A: B = 10: 90, compound A is a dopant compound and compound B is a host compound. Further, the light emitting layer is composed of three kinds of compound A, compound B and compound C, and if the mixing ratio is A: B: C = 5: 10: 85, compound A and compound B are dopant compounds, Compound C is the host compound. Therefore, the phosphorescent compound in the present invention is a kind of the dopant compound.
[0028]
The “phosphorescent compound” in the present invention is a compound in which light emission from an excited triplet is observed, and a compound having a phosphorescence quantum yield of 0.001 or more at 25 ° C. The phosphorescence quantum yield is preferably at least 0.01, more preferably at least 0.1.
[0029]
The phosphorescence quantum yield can be measured by the method described in Spectroscopy II, 4th Edition, Experimental Chemistry Course, Spectroscopy II, p. 398 (1992 edition, Maruzen). The phosphorescence quantum yield in a solution can be measured using various solvents, but the phosphorescent compound used in the present invention only needs to achieve the above-mentioned phosphorescence quantum yield in any arbitrary solvent.
[0030]
The phosphorescent compound used in the present invention is preferably a complex compound containing a metal belonging to Group VIII in the periodic table of elements, and more preferably an iridium compound, an osmium compound, or a platinum compound (platinum complex compound). ), And among them, the most preferable is an iridium compound.
[0031]
Hereinafter, specific examples of the phosphorescent compound used in the present invention are shown, but the invention is not limited thereto. These compounds are described, for example, in Inorg. Chem. 40, 1704-1711.
[0032]
Embedded image

[0033]
Embedded image

[0034]
Embedded image

[0035]
In another embodiment, in addition to the host compound and the phosphorescent compound, at least one fluorescent compound having a fluorescence maximum wavelength may be contained in a region longer than the maximum wavelength of light emission from the phosphorescent compound. . In this case, by the energy transfer from the host compound and the phosphorescent compound, electroluminescence as the organic EL element can be obtained from the fluorescent compound. Preferred as the fluorescent compound is a compound having a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield is preferably 10% or more, particularly preferably 30% or more. Specific fluorescent compounds include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squarium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, Examples include stilbene dyes, polythiophene dyes, and rare earth complex fluorescent materials.
[0036]
The fluorescence quantum yield here can also be measured by the method described in Spectroscopy II, page 362 (1992 edition, Maruzen) of the 4th edition of Experimental Chemistry Lecture 7.
[0037]
The phosphorescent compound has a phosphorescence quantum yield as described above of not less than 0.001 at 25 ° C. and a phosphorescent emission maximum wavelength longer than the fluorescence maximum wavelength of the fluorescent compound serving as the host. . Thereby, for example, light emission of the phosphorescent compound using a phosphorescent compound having a longer wavelength than the emission maximum wavelength of the fluorescent compound serving as the host, that is, utilizing the triplet state, electroluminescence at a wavelength longer than the fluorescence maximum wavelength of the host compound EL element can be obtained. Accordingly, the maximum phosphorescent emission wavelength of the phosphorescent compound used is not particularly limited, and in principle, the emission wavelength obtained by selecting a central metal, a ligand, a substituent of a ligand, and the like. Can be changed.
[0038]
For example, by using a fluorescent compound having a maximum fluorescence wavelength in a region of 350 to 440 nm as a host compound and using, for example, an iridium complex having phosphorescence in a green region, an organic EL device which emits light in the green region can be obtained. I can do it.
[0039]
In another embodiment, as described above, in addition to the fluorescent compound A and the phosphorescent compound as the host compound, another compound having a fluorescent maximum wavelength in a region longer than the maximum wavelength of light emission from the phosphorescent compound. In some cases, at least one kind of the fluorescent compound B is contained. By the energy transfer from the fluorescent compound A and the phosphorescent compound, the electroluminescence as the organic EL device can also obtain the light emission from the fluorescent compound B. .
[0040]
The color emitted by the fluorescent compound of the present specification is shown in FIG. 4.16 on page 108 of the “New Edition of Color Science Handbook” (edited by The Japan Society of Color Science, The University of Tokyo Press, 1985), and is shown in FIG. (Minolta) is determined by the color when the result of measurement is applied to the CIE chromaticity coordinates.
[0041]
Next, the host compound used in the present invention will be described.
The host compound in the present invention is a triazine derivative having a specific structure, particularly, a compound represented by the general formula (1). First, the compound represented by the general formula (1) will be described.
[0042]
Where Ar₁, Ar₂And Ar₃Represents a 6-membered aromatic group, and Ar₁₁, Ar₁₂, Ar_{1 3}Represents a 6-membered aromatic group or a 5-membered monocyclic aromatic group. Ar₁, Ar₂, Ar₃, Ar₁₁, Ar₁₂And Ar₁₃The 6-membered aromatic group represented by may further form a condensed ring. Specifically, a hydrocarbon aromatic group (phenyl group, naphthyl group, phenanthryl group, anthryl group, p-tolyl group, p-chlorophenyl group, etc.) or a heteroaromatic group (pyridyl group, pyrazinyl group, pyrimidinyl group, pyridazinyl group) Quinolyl group, triazinyl group, quinazoquinyl group, acridinyl group, etc.).
[0043]
Ar₁₁, Ar₁₂, Ar₁₃Examples of the 5-membered monocyclic aromatic group represented by are a pyrrolyl group, a thienyl group, a furyl group, an imidazolyl group, a pyrazolyl group, an oxazolyl group, and a thiazolyl group. Ar₁, Ar₂, Ar₃, Ar₁₁, Ar₁₂And Ar₁₃May further have a substituent.
[0044]
The compound represented by the general formula (1) is preferably Ar₁, Ar₂, Ar₃, Ar₁₁, Ar₁₂And Ar₁₃Are all monocyclic aromatic groups, more preferably Ar₁, Ar₂And Ar₃Is a hydrocarbon aromatic group, and Ar₁₁, Ar₁₂, Ar₁₃Is a 6-membered heteroaromatic group, or Ar₁₁, Ar₁₂, Ar₁₃Is a thienyl group.
[0045]
The triazine derivative used in the present invention is more preferably the case represented by the general formula (2). In the general formula (2), Ar₂₁, Ar₂₂And Ar₂₃Represents a 6-membered aromatic group or a 5-membered monocyclic aromatic group;₁, R₂And R₃Represents a monovalent substituent. 1, m and n each represent an integer of 1 to 4. Ar₂₁, Ar₂₂And Ar₂₃As the 6-membered aromatic group and the 5-membered aromatic group represented by₁₁, Ar₁₂, Ar₁₃And the same.
[0046]
R₁, R₂And R₃Examples of the monovalent substituent represented by are an alkyl group (methyl group, ethyl group, i-propyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, t-butyl group, cyclopentyl group, cyclohexyl group, Benzyl group, etc.), aryl group (phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group, etc.), alkenyl group (vinyl group, propenyl group, styryl group, etc.), alkynyl group (ethynyl group, etc.), alkyloxy Group (methoxy group, ethoxy group, i-propoxy group, butoxy group, etc.), aryloxy group (phenoxy group, etc.), alkylthio group (methylthio group, ethylthio group, i-propylquio group, etc.), arylthio group (phenylthio group, etc.) , Amino group, alkylamino group (dimethylamino group, diethylamino group, ethylmethylamino group ), Arylamino group (anilino group, diphenylamino group, etc.), halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.), cyano group, nitro group, heterocyclic group (pyrrole group, pyrrolidyl group, pyrazolyl group) , An imidazolyl group, a pyridyl group, a benzimidazolyl group, a benzothiazolyl group, a benzoxazolyl group, etc.).
[0047]
In the general formula (2), preferably, R₁, R₂And R₃Is an alkyl group, and when l, m and n are 2 to 4, most preferably R₁, R₂And R₃Is a methyl group, and l, m and n are 4.
[0048]
In the general formula (2), preferably, Ar₂₁, Ar₂₂Or Ar₂₃At least one is a thienyl group.
[0049]
Hereinafter, specific compound examples are shown, but the host compound in the present invention is not limited thereto.
[0050]
Embedded image

[0051]
Embedded image

[0052]
Embedded image

[0053]
Embedded image

[0054]
Embedded image

[0055]
Embedded image

[0056]
Embedded image

[0057]
Embedded image

[0058]
Embedded image

[0059]
Embedded image

[0060]
Embedded image

[0061]
Further, the molecular weight of the host compound is preferably from 600 to 2,000. When the molecular weight is from 600 to 2,000, Tg (glass transition temperature) is increased, thermal stability is improved, and the life of the device is improved. A more preferred molecular weight is from 800 to 2,000.
[0062]
These compounds can be produced by a known method. For example, a method described in JP-A-2001-93670 can be used.
[0063]
Hereinafter, the organic EL device will be described.
The light emitting layer in the organic EL element refers to a layer which emits light when a current is applied to an electrode composed of a cathode and an anode in a broad sense. Specifically, it refers to a layer containing a fluorescent compound that emits light when an electric current is applied to an electrode composed of a cathode and an anode. Usually, an EL element has a structure in which a light emitting layer is sandwiched between a pair of electrodes.
[0064]
The organic EL device of the present invention has a structure in which a hole transport layer, an electron transport layer, an anode buffer layer, a cathode buffer layer, and the like are provided in addition to a light emitting layer as necessary, and is sandwiched between a cathode and an anode. Specifically, the structure shown below is mentioned.
(I) anode / light-emitting layer / cathode
(Ii) anode / hole transport layer / light-emitting layer / cathode
(Iii) anode / light-emitting layer / electron transport layer / cathode
(Iv) anode / hole transport layer / light-emitting layer / electron transport layer / cathode
(V) anode / anode buffer layer / hole transport layer / emission layer / electron transport layer / cathode buffer layer / cathode
As a method for forming a light-emitting layer using the above compound, for example, there is a method for forming a thin film by a known method such as a vapor deposition method, a spin coating method, a casting method, and an LB method. preferable. Here, the molecular deposition film refers to a thin film formed by depositing the compound from a gaseous state or a film formed by solidifying the compound from a molten state or a liquid state. In general, this molecular deposition film can be distinguished from a thin film (molecule accumulation film) formed by the LB method by a difference in an aggregated structure and a higher-order structure and a functional difference resulting therefrom.
[0065]
As described in JP-A-57-51781, this light-emitting layer is prepared by dissolving the above compound as a light-emitting material in a solvent together with a binder such as a resin in a solvent, and then spin-coating. To form a thin film.
[0066]
The thickness of the light emitting layer formed in this way is not particularly limited and can be appropriately selected depending on the situation, but is usually in the range of 5 nm to 5 μm.
[0067]
Next, other layers constituting an EL element in combination with a light emitting layer, such as a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer, will be described.
[0068]
The hole injection layer and the hole transport layer have a function of transmitting holes injected from the anode to the light emitting layer, and the hole injection layer and the hole transport layer are interposed between the anode and the light emitting layer. Due to this, many holes are injected into the light-emitting layer at a lower electric field, and furthermore, electrons injected from the cathode, the electron injection layer or the electron transport layer into the light-emitting layer are separated from the light-emitting layer and the hole injection layer or the hole transport layer. Due to the barrier of electrons existing at the interface between the layers, the element is accumulated at the interface within the light emitting layer, and the device has excellent light emitting performance, such as improved luminous efficiency. The material of the hole injection layer and the hole transport layer (hereinafter, referred to as a hole injection material and a hole transport material) has a property of transmitting the holes injected from the anode to the light emitting layer. There is no particular limitation as long as the material is a conventional photoconductive material, which is conventionally used as a hole charge injection / transport material, or a known material used for a hole injection layer or a hole transport layer of an EL element. Any one can be selected from and used.
[0069]
The hole injection material and the hole transport material have any of hole injection or transport and electron barrier properties, and may be any of an organic substance and an inorganic substance. Examples of the hole injection material and the hole transport material include a triazole derivative, an oxadiazole derivative, an imidazole derivative, a polyarylalkane derivative, a pyrazoline derivative and a pyrazolone derivative, a phenylenediamine derivative, an arylamine derivative, an amino-substituted chalcone derivative, and oxazole. Derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, conductive polymer oligomers, especially thiophene oligomers, and the like. As the hole injecting material and the hole transporting material, those described above can be used, and porphyrin compounds, aromatic tertiary amine compounds and styrylamine compounds, particularly aromatic tertiary amine compounds may be used. preferable.
[0070]
Representative examples of the aromatic tertiary amine compound and styrylamine compound include N, N, N ', N'-tetraphenyl-4,4'-diaminophenyl; N, N'-diphenyl-N, N' -Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (TPD); 2,2-bis (4-di-p-tolylaminophenyl) propane; 1,1- Bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ', N'-tetra-p-tolyl-4,4'-diaminobiphenyl; 1,1-bis (4-di-p- Tolaminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl) phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N -Di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N, N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadri Phenyl; N, N, N-tri (p-tolyl) amine; 4- (di-p-tolylamino) -4 '-[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenyl Amino- (2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenylcarbazole, and two of those described in U.S. Pat. No. 5,061,569. Having a condensed aromatic ring in the molecule thereof, for example, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPD), JP-A-4-3086 No. 8,4,4 ', 4 "-tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine in which three triphenylamine units are connected in a starburst form. MTDATA).
[0071]
Further, a polymer material in which these materials are introduced into a polymer chain, or a polymer material in which these materials are used as a polymer main chain, can also be used.
[0072]
Further, inorganic compounds such as p-type Si and p-type SiC can also be used as the hole injection material and the hole transport material. The hole injecting layer and the hole transporting layer are formed by thinning the hole injecting material and the hole transporting material by a known method such as a vacuum evaporation method, a spin coating method, a casting method, and an LB method. Can be formed. The thickness of the hole injection layer and the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm. The hole injecting layer and the hole transporting layer may have a single-layer structure composed of one or more of the above materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.
[0073]
Further, the electron transporting layer used as needed may have a function of transmitting electrons injected from the cathode to the light emitting layer, and any material may be selected from conventionally known compounds. Can be used.
[0074]
Examples of materials used for the electron transporting layer (hereinafter, referred to as electron transporting materials) include heterocyclic tetracarboxylic anhydrides such as nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, and naphthalene perylene; carbodiimides; Examples include fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, and oxadiazole derivatives. Further, in the oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaphosphorus derivative having a quinoxaphosphorus ring known as an electron-withdrawing group may also be used as the electron transport material. it can.
[0075]
Further, a polymer material in which these materials are introduced into a polymer chain, or a polymer material in which these materials are used as a polymer main chain, can also be used.
[0076]
Also, metal complexes of 8-quinolinol derivatives, for example, tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-quinolinol) aluminum, Tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), and the like, and the central metals of these metal complexes are In, Mg, Cu , Ca, Sn, Ga or Pb can also be used as the electron transport material. In addition, metal-free or metal phthalocyanine, or those whose terminals are substituted with an alkyl group, a sulfonic acid group, or the like, can also be preferably used as the electron transport material. Also, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can be used as the electron transporting material, and similarly to the hole injection layer and the hole transporting layer, inorganic materials such as n-type Si and n-type SiC can be used. Semiconductors can also be used as electron transport materials.
[0077]
The electron transport layer can be formed by forming the above compound by a known thin film forming method such as a vacuum evaporation method, a spin coating method, a casting method, and an LB method. The thickness of the electron transport layer is not particularly limited, but is usually selected in the range of 5 nm to 5 μm. The electron transport layer may have a single-layer structure composed of one or more of these electron transport materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.
[0078]
Further, in the present invention, the fluorescent compound is not limited to the light emitting layer alone, and is the same as the fluorescent compound serving as the host compound of the phosphorescent compound in the hole transport layer adjacent to the light emitting layer or the electron transport layer. At least one kind of fluorescent compound having a maximum fluorescence wavelength may be contained in the region, whereby the luminous efficiency of the EL element can be further increased. As the fluorescent compound contained in the hole transport layer or the electron transport layer, the fluorescent compound having a fluorescence maximum wavelength in the range of 350 to 440 nm, more preferably 390 to 410 nm, as in the light emitting layer. Compounds are used.
[0079]
In the present invention, it is preferable that the compound represented by the general formula (1) or the general formula (2) is contained in the electron transport layer from the viewpoint of luminous efficiency and durability.
[0080]
The substrate preferably used for the organic EL device of the present invention is not particularly limited in the type of glass, plastic, and the like, and is not particularly limited as long as it is transparent. Examples of the substrate preferably used for the organic EL device of the present invention include glass, quartz, and a light-transmitting plastic film.
[0081]
Examples of the light-transmitting plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, and polycarbonate (PC). , Cellulose triacetate (TAC), cellulose acetate propionate (CAP) and the like.
[0082]
Next, a preferred example of manufacturing the organic EL device will be described. As an example, a method for manufacturing an EL device including the above-described anode / hole injection layer / hole transport layer / emission layer / electron transport layer / electron injection layer / cathode will be described.
[0083]
First, on an appropriate substrate, a thin film made of a desired electrode material, for example, a material for an anode is formed by a method such as evaporation or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 10 to 200 nm. Make the anode. Next, a thin film composed of a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer / electron injection layer, which are element materials, is formed thereon.
[0084]
Further, a buffer layer (electrode interface layer) may be present between the anode and the light emitting layer or the hole injection layer, and between the cathode and the light emitting layer or the electron injection layer.
[0085]
The buffer layer is a layer provided between the electrode and the organic layer for lowering the driving voltage and improving the luminous efficiency. The “organic EL device and the forefront of its industrialization (published by NTT Corporation on November 30, 1998) )), Vol. 2, Chapter 2, "Electrode Materials" (pages 123 to 166), and includes an anode buffer layer and a cathode buffer layer.
[0086]
The details of the anode buffer layer are described in JP-A-9-45479, JP-A-9-260062, JP-A-8-288069 and the like. Specific examples thereof include a phthalocyanine buffer layer represented by copper phthalocyanine, and vanadium oxide. And a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) or polythiophene.
[0087]
The details of the cathode buffer layer are also described in JP-A-6-325871, JP-A-9-17574, and JP-A-10-74586. Specifically, a metal buffer layer represented by strontium, aluminum, and the like; Examples thereof include an alkali metal compound buffer layer represented by lithium fluoride, an alkaline earth metal compound buffer layer represented by magnesium fluoride, an oxide buffer layer represented by aluminum oxide and lithium oxide.
[0088]
The buffer layer is desirably an extremely thin film, and the thickness is preferably in the range of 0.1 to 100 nm, depending on the material.
[0089]
Further, other layers having other functions may be laminated in addition to the above-mentioned basic constituent layers, if necessary. For example, JP-A-11-204258, JP-A-11-204359, and "Organic EL devices and the forefront of industrialization ( (November 30, 1998, published by NTTS Corporation) ”, page 237, etc., and may have a functional layer such as a hole blocking (hole block) layer.
[0090]
The buffer layer may function as a light emitting layer when at least one compound represented by the general formula (1) or (2) is present in at least one of the cathode buffer layer and the anode buffer layer. Good.
[0091]
Next, the electrodes of the organic EL element will be described. The electrodes of the organic EL element are composed of a cathode and an anode.
[0092]
As the anode in this organic EL element, a metal, an alloy, an electrically conductive compound, or a mixture thereof having a large work function (4 eV or more) is preferably used as an electrode material. Specific examples of such an electrode material include metals such as Au, CuI, indium tin oxide (ITO), and SnO.₂And a transparent conductive material such as ZnO.
[0093]
The anode may be formed into a thin film of these electrode materials by a method such as vapor deposition or sputtering, and a pattern having a desired shape may be formed by a photolithography method, or when a pattern precision is not required much (about 100 μm or more). In the above, a pattern may be formed through a mask having a desired shape at the time of vapor deposition or sputtering of the electrode material. When light is extracted from the anode, the transmittance is desirably greater than 10%, and the sheet resistance of the anode is preferably several hundred Ω / □ or less. Further, although the thickness depends on the material, it is usually selected in the range of 10 nm to 1 μm, preferably 10 nm to 200 nm.
[0094]
On the other hand, as the cathode, those having a low work function (4 eV or less) metal (referred to as an electron injecting metal), an alloy, an electrically conductive compound, and a mixture thereof as an electrode material are preferably used. Specific examples of such an electrode material include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al₂O₃) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among them, a mixture of an electron injecting metal and a second metal which is a metal having a large work function and a stable work function, such as a magnesium / silver mixture, magnesium, / Aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al₂O₃) Mixtures, lithium / aluminum mixtures and the like are preferred. The cathode can be produced by forming a thin film from these electrode substances by a method such as vapor deposition or sputtering. Further, the sheet resistance as the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 1 μm, preferably 50 to 200 nm. In order to transmit light, if one of the anode and the cathode of the organic EL element is transparent or translucent, the luminous efficiency is advantageously improved.
[0095]
Next, a method for manufacturing an organic EL element will be described.
Examples of the method for thinning include the spin coating method, the casting method, and the vapor deposition method as described above, but the vacuum vapor deposition method is preferable because a uniform film is easily obtained and pinholes are hardly generated. When a vacuum deposition method is used for thinning, the deposition conditions vary depending on the type of compound used, the target crystal structure of the molecular deposition film, the association structure, and the like. 10^-6-10^-3It is desirable to appropriately select Pa, a deposition rate of 0.01 to 50 nm / sec, a substrate temperature of −50 to 300 ° C., and a film thickness of 5 nm to 5 μm.
[0096]
As described above, a thin film made of a desired electrode material, for example, an anode material, is formed on a suitable substrate by a method such as vapor deposition or sputtering so as to have a thickness of 1 μm or less, preferably in the range of 10 to 200 nm. After forming an anode, a layer thin film including a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer / electron injection layer is formed on the anode as described above, and then a cathode is formed thereon. A cathode is provided by forming a thin film made of a substance so as to have a thickness of 1 μm or less, preferably in the range of 50 to 200 nm, for example, by vapor deposition or sputtering, and a desired organic EL element is obtained. In the production of this organic EL device, it is preferable to consistently produce the hole injection layer to the cathode in this manner by one evacuation, but the production order is reversed, and the cathode, the electron injection layer, the light emitting layer, A hole injection layer and an anode can be formed in this order. When a DC voltage is applied to the organic EL element obtained in this manner, light emission can be observed by applying a voltage of about 5 to 40 V with the positive polarity of the anode and the negative polarity of the cathode. Even if a voltage is applied in the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the-state. The waveform of the applied alternating current may be arbitrary.
[0097]
The organic EL element of the present invention may be used as a kind of lamp for illumination or an exposure light source, a projection device of a type for projecting an image, or a display device of a type for directly viewing a still image or a moving image. (Display). When used as a display device for reproducing moving images, the driving method may be either a simple matrix (passive matrix) method or an active matrix method. Further, a full-color display device can be manufactured by using two or more kinds of the organic EL elements of the present invention having different emission colors.
[0098]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples, but embodiments of the present invention are not limited thereto.
[0099]
Example 1
<Preparation of organic EL element>
Organic EL elements OLED1-1 to 1-12 were produced as follows.
[0100]
After patterning was performed on a substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) on which 150 nm of ITO (indium tin oxide) was formed on a glass substrate of 100 mm × 100 mm × 1.1 mm as an anode, the ITO transparent electrode was provided. The transparent support substrate was subjected to ultrasonic cleaning with isopropyl alcohol, dried with dry nitrogen gas, and subjected to UV ozone cleaning for 5 minutes.
[0101]
This transparent support substrate was fixed to a substrate holder of a commercially available vacuum evaporation apparatus, while 200 mg of α-NPD was put in a molybdenum resistance heating boat, and 200 mg of carbazole derivative (CBP) was put in another molybdenum resistance heating boat. 200 mg of bathocuproine (BCP) in a molybdenum resistance heating boat, 100 mg of a phosphorescent compound (Ir-1) in another molybdenum resistance heating boat, and Alq in another molybdenum resistance heating boat₃Was placed in a vacuum evaporation apparatus.
[0102]
Then, the vacuum chamber was 4 × 10^-4After the pressure was reduced to Pa, the heating boat containing α-NPD was energized and heated, and was vapor-deposited on a transparent support substrate at a vapor deposition rate of 0.1 nm / sec to provide a hole transport layer having a thickness of 45 nm. Further, the heating boat containing CBP and Ir-1 was energized and heated, and co-deposited on the hole transport layer at a deposition rate of 0.1 nm / sec and 0.01 nm / sec, respectively, to form a 20 nm-thick film. A light emitting layer was provided. In addition, the substrate temperature at the time of vapor deposition was room temperature. Further, an electric current is applied to the heating boat containing the BCP, and the heating boat is heated to be deposited on the light emitting layer at a deposition rate of 0.1 nm / sec to provide a 10 nm-thick electron transport layer also serving as a hole blocking layer. Was. On top of that, Alq₃The heating boat containing the gas was heated by applying an electric current, and was vapor-deposited on the electron transport layer at a vapor deposition rate of 0.1 nm / sec to further provide an electron injection layer having a thickness of 40 nm. In addition, the substrate temperature at the time of vapor deposition was room temperature.
[0103]
Subsequently, 0.5 nm of lithium fluoride and 110 nm of aluminum were vapor-deposited to form a cathode, thereby producing an organic EL device OLED1-1.
[0104]
Organic EL devices OLED1-2 to 1-12 were produced in exactly the same manner except that the CBP of the light emitting layer was replaced by the compounds shown in Table 1.
[0105]
The structure of the compound used above is shown below.
[0106]
Embedded image

[0107]
<Evaluation of organic EL element>
The organic EL device obtained as described below was evaluated, and the results are shown in Table 1.
(Emission luminance, luminous efficiency)
In the organic EL element OLED1-1, a current began to flow at an initial driving voltage of 3 V, and emitted green light from a phosphorescent compound that was a dopant of the light emitting layer. Emission luminance (cd / m) of the organic EL element OLED1-1 when a DC voltage of 10 V was applied in a dry nitrogen gas atmosphere at 23 ° C.²) And luminous efficiency (lm / W) were measured.
[0108]
The light emission luminance and the light emission efficiency were represented by relative values when the organic EL element OLED1-1 was set to 100. The emission luminance was measured using CS-1000 (manufactured by Minolta).
(durability)
10mA / cm²The half-life time, which is the time required for the initial luminance to drop to half of the original brightness when driven at a constant current, is shown as an index. The half life time was represented by a relative value when the organic EL element OLED1-1 was set to 100.
[0109]
[Table 1]

[0110]
As is clear from Table 1, an organic EL device using a triazine derivative compound represented by the general formula (1) or (2) as a host compound has high emission luminance and emission efficiency and a long half-life time. It is found that the organic EL device is very useful as an organic EL device.
[0111]
The same effect can be obtained in an organic EL device manufactured in the same manner as the organic EL devices OLED1-1 to 1-12 except that the phosphorescent compound (Ir-1) is changed to Ir-12 or Ir-9. Was. In addition, the device using Ir-12 emitted blue light, and the device using Ir-9 emitted red light.
[0112]
Example 2
Organic EL devices OLED2-1 to 2-9 were produced in exactly the same manner except that the BCP in the electron transport layer of the organic EL device OLED1-1 of Example 1 was replaced with the compound shown in Table 2.
[0113]
Next, the light emission luminance, light emission efficiency, and half-life time (durability) were measured in the same manner as in Example 1. Table 2 shows the obtained results.
[0114]
[Table 2]

[0115]
As is clear from Table 2, the organic EL device using the triazine derivative compound represented by the general formula (1) or (2) for the electron transport layer has improved light emission luminance, light emission efficiency and durability. I understand. In particular, it can be seen that in the durability, the half life time is remarkably improved.
[0116]
Example 3
The red, green, and blue light-emitting organic EL elements manufactured in Example 1 were juxtaposed on the same substrate, and an active matrix type full-color display device shown in FIG. 1 was manufactured. FIG. 1 shows only a schematic view of the display section A of the manufactured full-color display device. That is, on the same substrate, a wiring portion including a plurality of scanning lines 2 and data lines 3 and a plurality of pixels 1 (pixels in a red region, pixels in a green region, pixels in a blue region, and the like) are arranged side by side. The scanning lines 2 and the plurality of data lines 3 of the wiring portion are each made of a conductive material, and the scanning lines 2 and the data lines 3 are orthogonal to each other in a grid and are connected to the pixel 1 at orthogonal positions (details). Is not shown). The plurality of pixels 1 are driven by an active matrix method provided with an organic EL element corresponding to each emission color, a switching transistor as an active element, and a driving transistor, and a scanning signal is applied from a scanning line 2. Receives an image data signal from the data line 3 and emits light in accordance with the received image data. By arranging the red, green, and blue pixels appropriately as described above, a full-color display can be achieved.
[0117]
By driving the full-color display device, a clear full-color moving image display with high luminance and good durability was obtained.
[0118]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it is excellent in light emission brightness, and it has a remarkably excellent effect that a long-life organic EL element and a display device having the organic EL element can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a display unit of a full-color display device.
[Explanation of symbols]
A Display section
1 pixel
2 scanning line
3 Data line

Claims (11)

An organic electroluminescence device having a light emitting layer containing a host compound and a phosphorescent compound, wherein any one of the layers constituting the device contains a compound represented by the following general formula (1). Organic electroluminescent element.

In the formula, Ar ₁ , Ar ₂ and Ar ₃ represent a 6-membered aromatic group, and Ar ₁₁ , Ar ₁₂ and Ar ₁₃ represent a 6-membered aromatic group or a 5-membered monocyclic aromatic group. In the general formula _{(1), Ar 1, Ar} 2, Ar 3, Ar 11, an organic electroluminescent device according to claim _{1, Ar 12} and _{Ar 13} is characterized in that all represents a monocyclic aromatic group. In the general formula (1), Ar ₁ , Ar ₂ and Ar ₃ are a hydrocarbon aromatic group, and Ar ₁₁ , Ar ₁₂ and Ar ₁₃ are a 6-membered heteroaromatic group. 3. The organic electroluminescent device according to 2. The organic electroluminescence device according to any one of claims 1 to 3, further comprising a compound represented by the following general formula (2).

In the formula, Ar ₂₁ , Ar ₂₂ and Ar ₂₃ represent a 6-membered aromatic group or a 5-membered monocyclic aromatic group, and R ₁ , R ₂ and R ₃ represent a monovalent substituent. 1, m and n each represent an integer of 1 to 4. 5. The organic electroluminescence device according to claim 4, wherein, in the general formula (2), R ₁ , R _2, and R ₃ are an alkyl group, and l, m, and n are 2 to 4. 5. The organic electroluminescence device according to claim 4, wherein in formula (2), at least one of Ar ₂₁ , Ar _{22, and} Ar ₂₃ is a thienyl group. The organic electroluminescent device according to any one of claims 1 to 6, wherein the compound represented by the general formula (1) or (2) is contained in the electron transport layer. The organic electroluminescent device according to any one of claims 1 to 7, wherein the compound represented by the general formula (1) or (2) is contained in the light emitting layer as a host compound. The organic electroluminescence device according to any one of claims 1 to 8, wherein the phosphorescent compound is an iridium compound, an osmium compound, or a platinum compound. The organic electroluminescence device according to claim 9, wherein the phosphorescent compound is an iridium compound. A display device comprising the organic electroluminescence device according to claim 1.

Images