JP4006211B2 - Organic light emitting device - Google Patents

Description

【００１５】
（式中、Ｒ₁およびＲ₂は、置換あるいは無置換の芳香族環、置換あるいは無置換の複素環からなる群より選ばれた縮環構造を有するか、水素原子、ハロゲン原子、ニトロ基、ニトリル基、置換シリル基、置換あるいは無置換のアルキル基、置換あるいは無置換のアルケニル基、置換あるいは無置換のアラルキル基、置換あるいは無置換のアリール基、置換あるいは無置換のアミノ基、置換あるいは無置換のアゾメチン基、置換あるいは無置換のカルボニル基、置換あるいは無置換のアルコキシ基、置換あるいは無置換のエーテル基、置換あるいは無置換の複素環基からなる群より選ばれた基である。Ｘ₁およびＸ₂は、イオウ原子、スルホキシド、スルホンからなる群より選ばれた基であり、同じであっても異なっていてもよい。）
【００１６】
本発明の有機発光素子においては、Ｘ₁およびＸ₂はイオウ原子、スルホキシド、またはスルホンであることが好ましい。
【００１７】
【発明の実施の形態】
以下、本発明を詳細に説明する。
【００１８】
まず、本発明で用いる上記一般式［１］で示される化合物について説明する。
【００１９】
一般式［１］における置換基Ｒ₁、Ｒ₂の具体的な例を以下に示す。
【００２０】
縮環構造としては、ナフタレン環、キノリン環、アントラセン環、フェナンスレン環等が挙げられるが、もちろんこれらに限定されるものではない。
【００２１】
置換のシリル基としては、ジメチルシリル基、トリメチルシリル基、トリエチルシリル基、トリフェニルシリル基、ｔｅｒ−ブチルジメチルシリル基、ｔｅｒ−ブチルジフェニルシリル基等が挙げられるが、もちろんこれらに限定されるものではない。
【００２２】
置換あるいは未置換のアルキル基、アラルキル基としては、メチル基、エチル基、ｎ−プロピル基、ｉｓｏ−プロピル基、ｔｅｒ−ブチル基、オクチル基、ベンジル基、フェネチル基等が挙げられるが、もちろんこれらに限定されるものではない。
【００２３】
置換あるいは無置換のアルケニル基としては、ビニル基、アリル基（２−プロペニル基）、１−プロペニル基、ｉｓｏ−プロペニル基、２−ブテニル基等が挙げられるが、もちろんこれらに限定されるものではない。
【００２４】
置換あるいは未置換のアリール基（芳香環）としては、フェニル基、４−リチウムオキシフェニル基、４−カリウムオキシフェニル基、４−セシウムオキシフェニル基、４−メチルフェニル基、４−エチルフェニル基、３−クロロフェニル基、３，５−ジメチルフェニル基、トリフェニルアミノ基、ビフェニル基、ターフェニル基、ナフチル基、アントラニル基、フェナントリル基、ピレニル基、フェロセニル基等が挙げられるが、もちろんこれらに限定されるものではない。
置換または無置換のアミノ基としては、アミノ基、メチルアミノ基、エチルアミノ基、ジメチルアミノ基、ジエチルアミノ基、メチルエチルアミノ基、ベンジルアミノ基、メチルベンジルアミノ基、アニリノ基、ジフェニルアミノ基、フェニルトリルアミノ基、ジトリルアミノ基等が挙げられるが、もちろんこれらに限定されるものではない。
【００２５】
置換あるいは無置換のアゾメチン基としては、メチルイミノ基、エチルイミノ基、フェニルイミノ基、（４−ジメチルアミノフェニル）イミノ基、（４−シアノフェニル）イミノ基、（４−フルオロフェニル）イミノ基、２−ピリジルイミノ基、９−アントラニルイミノ基、１−ピレニルイミノ基等が挙げられるが、もちろんこれらに限定されるものではない。
【００２６】
置換または無置換のカルボニル基としては、アセチル基、プロピオニル基、イソブチリル基、メタクリロイル基、ベンゾイル基、ナフトイル基、アントライル基、トルオイル基等が挙げられるが、もちろんこれらに限定されるものではない。
【００２７】
置換あるいは未置換のアルコキシ基としては、メトキシ基、エトキシ基、プロポキシ基、２−エチル−オクチルオキシ基、フェノキシ基、４−ブチルフェノキシ基、ベンジルオキシ基等が挙げられるが、もちろんこれらに限定されるものではない。
【００２８】
置換あるいは無置換のエーテル基としては、メトキシメチル基、メトキシジメチルメチル基、メトキシエチル基、エトキシメチル基、フェノキシメチル基等があげられる。
【００２９】
置換あるいは未置換の複素環基としては、ピリジル基、ビピリジル基、メチルピリジル基、チエニル基、ターチエニル基、プロピルチエニル基、フリル基、キノリル基、カルバゾリル基、Ｎ−エチルカルバゾリル基等が挙げられるが、もちろんこれらに限定されるものではない。
【００３０】
また、Ｒ₁、Ｒ₂が有しても良い置換基としては、メチル基、エチル基、ｎ−プロピル基、ｉｓｏ−プロピル基、ｔｅｒ−ブチル基、オクチル基、ベンジル基、フェネチル基等のアルキル基、メトキシ基、エトキシ基、プロポキシ基、２−エチル−オクチルオキシ基、フェノキシ基、４−ブチルフェノキシ基、ベンジルオキシ基等のアルコキシ基、フェニル基、４−メチルフェニル基、４−エチルフェニル基、３−クロロフェニル基、３，５−ジメチルフェニル基、トリフェニルアミノ基、ビフェニル基、ターフェニル基、ナフチル基、アンスリル基、フェナンスリル基、ピレニル基等のアリール基、ピリジル基、ビピリジル基、メチルピリジル基、チエニル基、ターチエニル基、プロピルチエニル基、フリル基、キノリル基、カルバゾリル基、Ｎ−エチルカルバゾリル基等の複素環基が挙げられるが、もちろんこれらに限定されるものではない。
【００３１】
次に一般式［１］で示される化合物についてその代表例を挙げる。Ｘ₁およびＸ₂は、イオウ原子、スルホキシド、スルホンからなる群より選ばれた基であり、同じであっても異なっていてもよい。また、これらの化合物に限定されるものではない。
【００３２】
【化３】

【００３３】
次に、本発明の有機発光素子について図面に沿って説明する。
【００３４】
図１は本発明の有機発光素子の一例を示す断面図である。図１は基板１上に陽極２、発光層３及び陰極４を順次設けた構成のものである。ここで使用する発光素子はそれ自体でホール輸送能、エレクトロン輸送能及び発光性の性能を単一で有している場合や、それぞれの特性を有する化合物を混ぜて使う場合に有用である。
【００３５】
図２は本発明の有機発光素子における他の例を示す断面図である。図２は基板１上に陽極２、ホール輸送層５、電子輸送層６及び陰極４を順次設けた構成のものである。この場合、発光物質はホール輸送性かあるいは電子輸送性のいずれかあるいは両方の機能を有している材料をそれぞれの層に用い、発光性の無い単なるホール輸送物質あるいは電子輸送物質と組み合わせて用いる場合に有用である。また、この場合、発光層はホール輸送層５あるいは電子輸送層６のいずれかから成る。
【００３６】
図３は本発明の有機発光素子における他の例を示す断面図である。図３は基板１上に陽極２、ホール輸送層５、発光層３，電子輸送層６及び陰極４を順次設けた構成のものである。これはキャリヤ輸送と発光の機能を分離したものであり、ホール輸送性、電子輸送性、発光性の各特性を有した化合物と適時組み合わせて用いられ極めて材料選択の自由度が増すとともに、発光波長を異にする種々の化合物が使用できるため、発光色相の多様化が可能になる。さらに、中央の発光層３に各キャリヤあるいは励起子を有効に閉じこめて発光効率の向上を図ることも可能になる。
【００３７】
ただし、図１〜３はあくまでごく基本的な素子構成であり、本発明の化合物を用いた有機発光素子の構成はこれらに限定されるものではない。例えば、電極と有機層界面に絶縁性層を設ける、接着層あるいは干渉層を設ける、ホール輸送層がイオン化ポテンシャルの異なる２層から構成されるなど多様な層構成をとることができる。
【００３８】
本発明に用いられる一般式［１］で示される化合物は、従来の化合物に比べいずれも極めて発光性、電子注入性、電子輸送性の優れた化合物であり、図１〜図３のいずれの形態をも使用することができる。
【００３９】
特に、本発明の一般式［１］で示される化合物を用いた有機層は、発光層として有用であり、電子輸送層としても有用である。
【００４０】
本発明の有機発光素子においては、一般式［１］で示される化合物のうち少なくとも一種類を真空蒸着法や溶液塗布法により陽極２及び陰極４の間に形成する。その有機層の厚みは１０μｍより薄く、好ましくは０．５μｍ以下、より好ましくは０．０５〜０．５μｍの厚みに薄膜化することが好ましい。また、これまで知られている発光性化合物、発光層マトリックス化合物と一緒に使用することができる。
【００４１】
本発明においては、発光層、電子輸送層構成成分として前記一般式［１］で示される化合物を用いるものであるが、必要に応じてこれまで知られているホール輸送性化合物、発光性化合物、発光層マトリックス化合物、電子輸送性化合物、電荷輸送性ポリマー材料、発光性ポリマー材料（例えば以下に示される化合物等）を一緒に使用することもできる。但し、もちろんこれらに限定されるものではない。
【００４２】
【化４】

【００４３】
【化５】

【００４４】
【化６】

【００４５】
【化７】

【００４６】
【化８】

【００４７】
【化９】

【００４８】
本発明の有機発光素子において、一般式［１］で示される化合物を含有する層およびその他の有機化合物を含む層は、一般には真空蒸着法あるいは、適当な溶媒に溶解させて塗布法により薄膜を形成する。特に塗布法で成膜する場合は、適当な結着樹脂と組み合わせて膜を形成することもできる。
【００４９】
上記結着樹脂としては広範囲な結着性樹脂より選択でき、たとえばポリビニルカルバゾール樹脂、ポリカーボネート樹脂、ポリエステル樹脂、ポリアリレート樹脂、ポリスチレン樹脂、アクリル樹脂、メタクリル樹脂、ブチラール樹脂、ポリビニルアセタール樹脂、ジアリルフタレート樹脂、フェノール樹脂、エポキシ樹脂、シリコーン樹脂、ポリスルホン樹脂、尿素樹脂等が挙げられるが、これらに限定されるものではない。また、これらは単独または共重合体ポリマーとして１種または２種以上混合してもよい。
【００５０】
陽極材料としては仕事関数がなるべく大きなものがよく、例えば、金、白金、ニッケル、パラジウム、コバルト、セレン、バナジウム等の金属単体あるいはこれらの合金、酸化錫、酸化亜鉛、酸化錫インジウム（ＩＴＯ），酸化亜鉛インジウム等の金属酸化物が使用できる。また、ポリアニリン、ポリピロール、ポリチオフェン、ポリフェニレンスルフィド等の導電性ポリマーも使用できる。これらの電極物質は単独で用いてもよく、複数併用することもできる。
【００５１】
一方、陰極材料としては仕事関数の小さなものがよく、リチウム、ナトリウム、カリウム、カルシウム、マグネシウム、アルミニウム、インジウム、銀、鉛、錫、クロム等の金属単体あるいは複数の合金として用いることができる。酸化錫インジウム（ＩＴＯ）等の金属酸化物の利用も可能である。また、陰極は一層構成でもよく、多層構成をとることもできる。
【００５２】
本発明で用いる基板としては、特に限定するものではないが、金属製基板、セラミックス製基板等の不透明性基板、ガラス、石英、プラスチックシート等の透明性基板が用いられる。また、基板にカラーフィルター膜、蛍光色変換フィルター膜、誘電体反射膜などを用いて発色光をコントロールする事も可能である。
【００５３】
なお、作成した素子に対して、酸素や水分等との接触を防止する目的で保護層あるいは封止層を設けることもできる。保護層としては、ダイヤモンド薄膜、金属酸化物、金属窒化物等の無機材料膜、フッソ樹脂、ポリパラキシレン、ポリエチレン、シリコーン樹脂、ポリスチレン樹脂等の高分子膜さらには、光硬化性樹脂等が挙げられる。また、ガラス、気体不透過性フィルム、金属などをカバーし、適当な封止樹脂により素子自体をパッケージングすることもできる。
【００５４】
【実施例】
以下に実施例により本発明をさらに具体的に説明していくが、本発明はこれらに限定されるものではない。
【００５５】
［実施例１］
図３に示す構造の素子を作成した。
【００５６】
基板１としてのガラス基板上に陽極２としての酸化錫インジウム（ＩＴＯ）をスパッタ法にて１２０ｎｍの膜厚で成膜したものを透明導電性支持基板として用いた。これをアセトン、イソプロピルアルコール（ＩＰＡ）で順次超音波洗浄し、ＩＰＡで煮沸洗浄、乾燥をした。さらに、ＵＶ／オゾン洗浄したものを透明導電性支持基板として使用した。
【００５７】
正孔輸送材料として、Ｎ，Ｎ’−ジフェニル−Ｎ，Ｎ’−ｍ−トリル−４，４’−ジアミノ−１，１’−ビフェニル（以下ＴＰＤ）濃度が０．５ｗｔ％となるように調整した溶液を、陽極２上に滴下し、最初に５００ＲＰＭの回転で１０秒、次に１０００ＲＰＭの回転で１分間スピンコートを行い膜形成した。この後１０分間、８０℃の真空オーブンで乾燥し、薄膜中の溶剤を完全に除去した。形成されたＴＰＤ膜（ホール輸送層５）の厚みは５０ｎｍであった。
【００５８】
次に、ホール輸送層５の上に発光層３のホスト材料としてトリス（８−キノリノラト）アルミニウム（Ａｌｑ３）、更にドーパントとして前記例示化合物Ｎｏ．１（Ｘ₁＝Ｘ₂＝Ｓ）を共蒸着して２０ｎｍの発光層３を設けた。製膜速度はホストが０．３ｎｍ／ｓｅｃ、ドーパントが０．１ｎｍ／ｓｅｃになるよう調整しながら共蒸着を行った。
【００５９】
更に、電子輸送層６としてＡｌｑ３を真空蒸着法にて４０ｎｍの膜厚に形成した。これら有機層の蒸着時の真空度は４．０×１０^-4Ｐａ、成膜速度は０．３ｎｍ／ｓｅｃの条件であった。
【００６０】
次に、アルミニウム−リチウム合金（リチウム濃度１原子％）からなる蒸着材料を用いて、先ほどの有機層の上に、真空蒸着法により厚さ１０ｎｍの金属層膜を形成し、更に真空蒸着法により厚さ１５０ｎｍのアルミニウム膜を設け、アルミニウム−リチウム合金膜（陰極４）を形成した。蒸着時の真空度は１．０×１０^-4Ｐａ、成膜速度は１．０〜１．２ｎｍ／ｓｅｃの条件で成膜した。
【００６１】
得られた有機ＥＬ素子は、水分の吸着によって素子劣化が起こらないように、乾燥空気雰囲気中で保護用ガラス板をかぶせ、アクリル樹脂系接着材で封止した。
【００６２】
得られた素子の発光スペクトルは５８０ｎｍにピークを持つ橙色で、輝度は９Ｖで２５０ｃｄ／ｍ²、１２Ｖで４００ｃｄ／ｍ²であった。
【００６３】
さらに、窒素雰囲気下で電流密度を２５０ｍＡ／ｃｍ²に保ち１００時間電圧を印加したところ、初期輝度２１０ｃｄ／ｍ²から１００時間後１９０ｃｄ／ｍ²と輝度劣化は小さかった。
【００６４】
［実施例２］
例示化合物Ｎｏ．１（Ｘ₁＝Ｘ₂＝Ｓ）に代えて、例示化合物Ｎｏ．１（Ｘ₁＝Ｘ₂＝ＳＯ₂）を用いて実施例１と同様に素子を作成し、同様な評価を行った。
【００６５】
得られた素子の発光スペクトルは、６３０ｎｍにピークを持つ赤色で、輝度は９Ｖで２１０ｃｄ／ｍ²、１２Ｖで輝度３７０ｃｄ／ｍ²であった。
【００６６】
さらに、窒素雰囲気下で電流密度を２５０ｍＡ／ｃｍ²に保ち１００時間電圧を印加したところ、初期輝度１６０ｃｄ／ｍ²から１００時間後１４０ｃｄ／ｍ²と輝度劣化は小さかった。
【００６７】
［実施例３］
例示化合物Ｎｏ．１（Ｘ₁＝Ｘ₂＝Ｓ）に代えて、例示化合物Ｎｏ．５（Ｘ₁＝Ｘ₂＝Ｓ）を用いて実施例１と同様に素子を作成し、同様な評価を行った。
【００６８】
得られた素子の発光スペクトルは、６５０ｎｍにピークを持つ赤色で、輝度は９Ｖで２２０ｃｄ／ｍ²、１２Ｖで輝度３８０ｃｄ／ｍ²であった。
【００６９】
さらに、窒素雰囲気下で電流密度を２５０ｍＡ／ｃｍ²に保ち１００時間電圧を印加したところ、初期輝度１７０ｃｄ／ｍ²から１００時間後１５０ｃｄ／ｍ²と輝度劣化は小さかった。
【００７０】
［実施例４］
例示化合物Ｎｏ．１（Ｘ₁＝Ｘ₂＝Ｓ）に代えて、例示化合物Ｎｏ．１１（Ｘ₁＝Ｘ₂＝Ｓ）を用い、発光層３のホスト材料としてカルバゾールビフェニルを用いた以外は実施例１と同様に素子を作成し、同様な評価を行った。
【００７１】
得られた素子の発光スペクトルは、５００ｎｍにピークを持つ緑色で、輝度は９Ｖで１２００ｃｄ／ｍ²、１２Ｖで輝度２９００ｃｄ／ｍ²であった。
【００７２】
さらに、窒素雰囲気下で電流密度を２５０ｍＡ／ｃｍ²に保ち１００時間電圧を印加したところ、初期輝度６００ｃｄ／ｍ²から１００時間後５５０ｃｄ／ｍ²と輝度劣化は小さかった。
【００７３】
［比較例１］
例示化合物Ｎｏ．１１（Ｘ₁＝Ｘ₂＝Ｓ）に代えて、下記構造式の比較化合物を用いて実施例４と同様に素子を作成し、同様な評価を行ったところ、ホスト材の発光に由来する発光スペクトルのみが得られた。
【００７４】
【化１０】

【００７５】
【発明の効果】
本発明の一般式［１］で示される化合物を用いた有機発光素子は、実施例および比較例から示される通り、発光波長に多様性があり、種々の発光色相を呈し、低い印加電圧で高輝度な発光が得られ、耐久性にも優れている。
【００７６】
特に、本発明の一般式［１］で示される化合物を用いた有機層は、発光層として有用であり、また、電子輸送層としても有用である。
【００７７】
さらに、素子の作成も真空蒸着あるいはキャスティング法等を用いて作成可能であり、比較的安価で大面積の素子を容易に作成できる。
【図面の簡単な説明】
【図１】本発明における有機発光素子の一例を示す断面図である。
【図２】本発明における有機発光素子の他の例を示す断面図である。
【図３】本発明における有機発光素子の他の例を示す断面図である。
【符号の説明】
１ 基板
２ 陽極
３ 発光層
４ 陰極
５ ホール輸送層
６ 電子輸送層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic light-emitting device, and more particularly to a device that emits light by applying an electric field to a thin film containing an organic compound.
[0002]
[Prior art]
An organic light-emitting element generates an exciton of a fluorescent compound by sandwiching a thin film containing a fluorescent organic compound between an anode and a cathode and injecting electrons and holes from each electrode. It is an element that utilizes light emitted when the child returns to the ground state.
[0003]
In a study of Kodak Company in 1987 (Appl. Phys. Lett. 51, 913 (1987)), ITO was used for the anode and magnesium-silver alloy for the cathode, and an aluminum quinolinol complex was used as the electron transport material and the light emitting material. It is reported that the device has a function separation type two-layer structure using a triphenylamine derivative as a transport material and emits light of about 1000 cd / m ^{2 at} an applied voltage of about 10V. Related patents include US Pat. No. 4,539,507, US Pat. No. 4,720,432, US Pat. No. 4,885,211 and the like.
[0004]
In addition, by changing the type of the fluorescent organic compound, light emission from ultraviolet to infrared is possible, and recently, various compounds have been actively researched. For example, US Pat. No. 5,151,629, US Pat. No. 5,409,783, US Pat. No. 5,382,477, JP-A-2-247278, JP-A-3-255190, JP-A-5-202356. No. 9, JP-A-9-202878, JP-A-9-227576, and the like.
[0005]
In addition to organic light-emitting elements using low molecular materials as described above, organic light-emitting elements using conjugated polymers have been reported by a group of Cambridge University (Nature, 347, 539 (1990)). Yes. In this report, light emission is confirmed in a single layer by forming a film of polyphenylene vinylene (PPV) in a coating system. Related patents for organic light emitting devices using conjugated polymers include US Pat. No. 5,247,190, US Pat. No. 5,514,878, US Pat. No. 5,672,678, and Japanese Patent Laid-Open No. 4-145192. JP, 5-247460, A, etc. are mentioned.
[0006]
As described above, recent advances in organic light-emitting devices are remarkable, and their features are high brightness, variety of emission wavelengths, high-speed response, low profile, and light-emitting devices with low applied voltage. Suggests the possibility to.
[0007]
However, under the present circumstances, light output with higher brightness or higher conversion efficiency is required. In addition, there are still many problems in terms of durability, such as changes over time due to long-term use and deterioration due to atmospheric gas containing oxygen or moisture. Furthermore, when considering application to a full-color display or the like, light emission of blue, green, and red with high color purity is required, but this problem has not been sufficiently solved.
[0008]
Many compounds having a heterocyclic ring have been studied as fluorescent organic compounds used in an electron transport layer, a light emitting layer, and the like. Examples include pyrrole compounds, thiophene compounds, oxazole compounds, oxadiazole compounds, thiadiazole compounds, imidazole compounds, pyrazine compounds, and the like. Among these, oxazole compounds that have relatively many reported examples include, for example, JP-A-5-214335, JP-A-9-188876, JP-A-11-345686, and the like. For example, JP-A-5-222361 and the like, for imidazole compounds, for example, JP-A 2000-95766, and for pyrazine compounds, for example, US Pat. No. 5,077,142 and JP-A-8-73443. Although there are various publications and the like, organic light-emitting elements that have various emission hues, have various emission hues, and have satisfactory emission luminance, durability, and emission wavelength have not been obtained.
[0009]
[Problems to be solved by the invention]
The present invention has been made to solve such problems of the prior art, and an object of the present invention is to provide an organic light emitting device having an extremely high efficiency, high luminance, and long life light output.
[0010]
It is another object of the present invention to provide an organic light emitting device that has various emission wavelengths and exhibits various emission hues.
[0011]
It is another object of the present invention to provide an organic light emitting device that can be easily manufactured and can be produced at a relatively low cost.
[0012]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventors have at least a pair of electrodes composed of an anode and a cathode, and a layer containing one or more organic compounds sandwiched between the pair of electrodes. In the organic light emitting device, at least one of the layers containing the organic compound contains a specific compound, so that the emission wavelength is diverse and exhibits various emission hues. It has been found that an organic light-emitting device having the above can be produced, and the present invention has been completed.
[0013]
That is, the organic light-emitting device of the present invention is an organic light-emitting device having at least a layer containing a pair of electrodes composed of an anode and a cathode and one or more organic compounds sandwiched between the pair of electrodes. At least one of the contained layers contains at least one compound represented by the following general formula [1].
[0014]
[Chemical 2]

[0015]
Wherein R ₁ and R ₂ have a condensed ring structure selected from the group consisting of a substituted or unsubstituted aromatic ring, a substituted or unsubstituted heterocyclic ring, a hydrogen atom, a halogen atom, a nitro group, Nitrile group, substituted silyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted amino group, substituted or unsubstituted X ₁ is a group selected from the group consisting of a substituted azomethine group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted ether group, and a substituted or unsubstituted heterocyclic group. And X ₂ is a group selected from the group consisting of a sulfur atom, sulfoxide and sulfone , and may be the same or different.
[0016]
In the organic light emitting device of the present invention, X ₁ and X ₂ are preferably sulfur atoms, sulfoxides or sulfones.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0018]
First, the compound represented by the general formula [1] used in the present invention will be described.
[0019]
Specific examples of the substituents R ₁ and R ₂ in the general formula [1] are shown below.
[0020]
Examples of the condensed ring structure include a naphthalene ring, a quinoline ring, an anthracene ring, a phenanthrene ring, and the like, but are not limited thereto.
[0021]
Examples of the substituted silyl group include a dimethylsilyl group, a trimethylsilyl group, a triethylsilyl group, a triphenylsilyl group, a ter-butyldimethylsilyl group, and a ter-butyldiphenylsilyl group. Of course, the silyl group is not limited thereto. Absent.
[0022]
Examples of the substituted or unsubstituted alkyl group and aralkyl group include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, a ter-butyl group, an octyl group, a benzyl group, and a phenethyl group. It is not limited to.
[0023]
Examples of the substituted or unsubstituted alkenyl group include a vinyl group, an allyl group (2-propenyl group), a 1-propenyl group, an iso-propenyl group, a 2-butenyl group, and the like. Absent.
[0024]
As the substituted or unsubstituted aryl group (aromatic ring), phenyl group, 4-lithiumoxyphenyl group, 4-potassiumoxyphenyl group, 4-cesiumoxyphenyl group, 4-methylphenyl group, 4-ethylphenyl group, Examples include 3-chlorophenyl group, 3,5-dimethylphenyl group, triphenylamino group, biphenyl group, terphenyl group, naphthyl group, anthranyl group, phenanthryl group, pyrenyl group, and ferrocenyl group. It is not something.
Examples of the substituted or unsubstituted amino group include amino group, methylamino group, ethylamino group, dimethylamino group, diethylamino group, methylethylamino group, benzylamino group, methylbenzylamino group, anilino group, diphenylamino group, phenyl A tolylamino group, a ditolylamino group, etc. are mentioned, but of course, it is not limited to these.
[0025]
Examples of the substituted or unsubstituted azomethine group include methylimino group, ethylimino group, phenylimino group, (4-dimethylaminophenyl) imino group, (4-cyanophenyl) imino group, (4-fluorophenyl) imino group, 2- A pyridylimino group, a 9-anthranylimino group, a 1-pyrenylimino group and the like can be mentioned, but of course not limited thereto.
[0026]
Examples of the substituted or unsubstituted carbonyl group include, but are not limited to, an acetyl group, a propionyl group, an isobutyryl group, a methacryloyl group, a benzoyl group, a naphthoyl group, an anthryl group, and a toluoyl group.
[0027]
Examples of the substituted or unsubstituted alkoxy group include methoxy group, ethoxy group, propoxy group, 2-ethyl-octyloxy group, phenoxy group, 4-butylphenoxy group, benzyloxy group and the like. It is not something.
[0028]
Examples of the substituted or unsubstituted ether group include a methoxymethyl group, a methoxydimethylmethyl group, a methoxyethyl group, an ethoxymethyl group, and a phenoxymethyl group.
[0029]
Examples of the substituted or unsubstituted heterocyclic group include a pyridyl group, a bipyridyl group, a methylpyridyl group, a thienyl group, a tertenyl group, a propylthienyl group, a furyl group, a quinolyl group, a carbazolyl group, and an N-ethylcarbazolyl group. Of course, it is not limited to these.
[0030]
Examples of the substituent that R ₁ and R ₂ may have include alkyl groups such as methyl group, ethyl group, n-propyl group, iso-propyl group, ter-butyl group, octyl group, benzyl group, and phenethyl group. Group, methoxy group, ethoxy group, propoxy group, 2-ethyl-octyloxy group, phenoxy group, 4-butylphenoxy group, alkoxy group such as benzyloxy group, phenyl group, 4-methylphenyl group, 4-ethylphenyl group Aryl group such as 3-chlorophenyl group, 3,5-dimethylphenyl group, triphenylamino group, biphenyl group, terphenyl group, naphthyl group, anthryl group, phenanthryl group, pyrenyl group, pyridyl group, bipyridyl group, methylpyridyl group Group, thienyl group, tertienyl group, propylthienyl group, furyl group, quinolyl group, carbazolyl group Include but are heterocyclic groups such as N- ethyl-carbazolyl group, but the present invention is of course not limited thereto.
[0031]
Next, typical examples of the compound represented by the general formula [1] will be given. X ₁ and X ₂ are groups selected from the group consisting of a sulfur atom, sulfoxide and sulfone , and may be the same or different. Moreover, it is not limited to these compounds.
[0032]
[Chemical 3]

[0033]
Next, the organic light emitting device of the present invention will be described with reference to the drawings.
[0034]
FIG. 1 is a cross-sectional view showing an example of the organic light emitting device of the present invention. FIG. 1 shows a structure in which an anode 2, a light emitting layer 3 and a cathode 4 are sequentially provided on a substrate 1. The light-emitting element used here is useful when it has a single hole transport ability, electron transport ability, and light-emitting performance, or when a compound having each characteristic is mixed.
[0035]
FIG. 2 is a cross-sectional view showing another example of the organic light emitting device of the present invention. FIG. 2 shows a configuration in which an anode 2, a hole transport layer 5, an electron transport layer 6 and a cathode 4 are sequentially provided on a substrate 1. In this case, the luminescent material is a material having either or both of a hole transporting property and an electron transporting property, and is used in combination with a mere hole transporting material or electron transporting material having no light emitting property. Useful in cases. In this case, the light emitting layer is composed of either the hole transport layer 5 or the electron transport layer 6.
[0036]
FIG. 3 is a cross-sectional view showing another example of the organic light emitting device of the present invention. FIG. 3 shows a structure in which an anode 2, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6 and a cathode 4 are sequentially provided on a substrate 1. This is a separation of carrier transport and light emission functions. It is used in combination with compounds having hole transport properties, electron transport properties, and light emission properties in a timely manner. Since various compounds having different values can be used, it is possible to diversify the emission hue. Further, it is possible to effectively confine each carrier or exciton in the central light emitting layer 3 to improve the light emission efficiency.
[0037]
However, FIGS. 1-3 are very basic element structures to the last, and the structure of the organic light emitting element using the compound of this invention is not limited to these. For example, various layer configurations such as providing an insulating layer at the interface between the electrode and the organic layer, providing an adhesive layer or interference layer, and the hole transporting layer are composed of two layers having different ionization potentials can be employed.
[0038]
The compound represented by the general formula [1] used in the present invention is a compound that is extremely excellent in light emitting property, electron injecting property, and electron transporting property as compared with conventional compounds, and any of the forms shown in FIGS. Can also be used.
[0039]
In particular, the organic layer using the compound represented by the general formula [1] of the present invention is useful as a light emitting layer and also as an electron transporting layer.
[0040]
In the organic light emitting device of the present invention, at least one of the compounds represented by the general formula [1] is formed between the anode 2 and the cathode 4 by a vacuum deposition method or a solution coating method. The thickness of the organic layer is thinner than 10 μm, preferably 0.5 μm or less, more preferably 0.05 to 0.5 μm. Moreover, it can be used together with a luminescent compound and a luminescent layer matrix compound known so far.
[0041]
In the present invention, the compound represented by the general formula [1] is used as a light-emitting layer and an electron transport layer constituent component. If necessary, a hole-transport compound, a light-emitting compound, and the like that have been known so far are used. A light emitting layer matrix compound, an electron transporting compound, a charge transporting polymer material, and a light emitting polymer material (for example, compounds shown below) can be used together. However, of course, it is not limited to these.
[0042]
[Formula 4]

[0043]
[Chemical formula 5]

[0044]
[Chemical 6]

[0045]
[Chemical 7]

[0046]
[Chemical 8]

[0047]
[Chemical 9]

[0048]
In the organic light-emitting device of the present invention, the layer containing the compound represented by the general formula [1] and the layer containing another organic compound are generally formed into a thin film by a vacuum deposition method or a coating method by dissolving in a suitable solvent. Form. In particular, when a film is formed by a coating method, the film can be formed in combination with an appropriate binder resin.
[0049]
The binder resin can be selected from a wide range of binder resins such as polyvinyl carbazole resin, polycarbonate resin, polyester resin, polyarylate resin, polystyrene resin, acrylic resin, methacrylic resin, butyral resin, polyvinyl acetal resin, diallyl phthalate resin. , Phenol resin, epoxy resin, silicone resin, polysulfone resin, urea resin and the like, but are not limited thereto. Moreover, you may mix these 1 type, or 2 or more types as a single or copolymer polymer.
[0050]
As the anode material, a material having a work function as large as possible is good. For example, simple metals such as gold, platinum, nickel, palladium, cobalt, selenium, vanadium or alloys thereof, tin oxide, zinc oxide, indium tin oxide (ITO), A metal oxide such as zinc indium oxide can be used. In addition, conductive polymers such as polyaniline, polypyrrole, polythiophene, and polyphenylene sulfide can also be used. These electrode materials may be used alone or in combination.
[0051]
On the other hand, the cathode material preferably has a small work function, and can be used as a single metal or a plurality of alloys such as lithium, sodium, potassium, calcium, magnesium, aluminum, indium, silver, lead, tin, and chromium. A metal oxide such as indium tin oxide (ITO) can also be used. Further, the cathode may have a single layer structure or a multilayer structure.
[0052]
Although it does not specifically limit as a board | substrate used by this invention, Transparent substrates, such as opaque board | substrates, such as a metal board | substrate and a ceramic board | substrate, glass, quartz, a plastic sheet, are used. It is also possible to control the color light by using a color filter film, a fluorescent color conversion filter film, a dielectric reflection film, or the like on the substrate.
[0053]
Note that a protective layer or a sealing layer can be provided on the prepared element for the purpose of preventing contact with oxygen or moisture. Examples of the protective layer include diamond thin films, inorganic material films such as metal oxides and metal nitrides, polymer films such as fluorine resin, polyparaxylene, polyethylene, silicone resin, polystyrene resin, and photo-curing resins. It is done. Further, it is possible to cover glass, a gas impermeable film, a metal, etc., and to package the element itself with an appropriate sealing resin.
[0054]
【Example】
The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.
[0055]
[Example 1]
An element having the structure shown in FIG. 3 was prepared.
[0056]
What formed indium tin oxide (ITO) as the anode 2 with the film thickness of 120 nm on the glass substrate as the board | substrate 1 by the sputtering method was used as a transparent conductive support substrate. This was ultrasonically washed successively with acetone and isopropyl alcohol (IPA), boiled and washed with IPA, and dried. Furthermore, what was UV / ozone cleaned was used as a transparent conductive support substrate.
[0057]
As a hole transport material, N, N′-diphenyl-N, N′-m-tolyl-4,4′-diamino-1,1′-biphenyl (hereinafter referred to as TPD) concentration is adjusted to 0.5 wt%. The resulting solution was dropped on the anode 2, and a film was formed by spin coating first at a rotation of 500 RPM for 10 seconds and then at a rotation of 1000 RPM for 1 minute. Thereafter, the film was dried in a vacuum oven at 80 ° C. for 10 minutes to completely remove the solvent in the thin film. The formed TPD film (hole transport layer 5) had a thickness of 50 nm.
[0058]
Next, tris (8-quinolinolato) aluminum (Alq3) is used as the host material of the light emitting layer 3 on the hole transport layer 5, and the exemplified compound No. 1 is used as the dopant. 1 (X ₁ = X ₂ = S) was co-evaporated to provide a 20 nm light-emitting layer 3. Co-evaporation was performed while adjusting the film-forming speed so that the host was 0.3 nm / sec and the dopant was 0.1 nm / sec.
[0059]
Further, Alq3 was formed as the electron transport layer 6 to a film thickness of 40 nm by vacuum deposition. The degree of vacuum at the time of vapor deposition of these organic layers was 4.0 × 10 ⁻⁴ Pa and the film formation rate was 0.3 nm / sec.
[0060]
Next, using a vapor deposition material made of an aluminum-lithium alloy (lithium concentration 1 atom%), a metal layer film having a thickness of 10 nm is formed on the organic layer by a vacuum vapor deposition method. An aluminum film having a thickness of 150 nm was provided to form an aluminum-lithium alloy film (cathode 4). The degree of vacuum at the time of vapor deposition was 1.0 × 10 ⁻⁴ Pa, and the film formation rate was 1.0 to 1.2 nm / sec.
[0061]
The obtained organic EL device was covered with a protective glass plate in a dry air atmosphere and sealed with an acrylic resin adhesive so that the device did not deteriorate due to moisture adsorption.
[0062]
The emission spectrum of the obtained device was orange having a peak at 580 nm, and the luminance was 250 cd / m ^{2 at} 9V and 400 cd / m ² at 12V.
[0063]
Furthermore, when a voltage was applied for 100 hours while keeping the current density at 250 mA / cm ² under a nitrogen atmosphere, the luminance degradation was small, from initial luminance 210 cd / m ² to 190 cd / m ² after 100 hours.
[0064]
[Example 2]
Exemplified Compound No. 1 (X ₁ = X ₂ = S) 1 (X ₁ = X ₂ = SO ₂ ) was used to produce a device in the same manner as in Example 1, and the same evaluation was performed.
[0065]
Emission spectrum of the obtained element, red having a peak at 630 nm, the luminance was luminance 370cd / m ² at 210 cd / m ^2, 12V at 9V.
[0066]
Furthermore, when a voltage was applied for 100 hours while keeping the current density at 250 mA / cm ² in a nitrogen atmosphere, the luminance degradation was small, from the initial luminance of 160 cd / m ² to 140 cd / m ² after 100 hours.
[0067]
[Example 3]
Exemplified Compound No. 1 (X ₁ = X ₂ = S) 5 (X ₁ = X ₂ = S) was used to produce a device in the same manner as in Example 1, and the same evaluation was performed.
[0068]
Emission spectrum of the obtained element, red having a peak at 650 nm, the luminance was luminance 380 cd / m ² at 220 cd / m ^2, 12V at 9V.
[0069]
Furthermore, when a voltage was applied for 100 hours while keeping the current density at 250 mA / cm ² in a nitrogen atmosphere, the luminance deterioration was small, from the initial luminance of 170 cd / m ² to 150 cd / m ² after 100 hours.
[0070]
[Example 4]
Exemplified Compound No. 1 (X ₁ = X ₂ = S) 11 (X ₁ = X ₂ = S) was used, and a device was prepared in the same manner as in Example 1 except that carbazole biphenyl was used as the host material of the light-emitting layer 3, and the same evaluation was performed.
[0071]
Emission spectrum of the obtained element, green with a peak at 500 nm, the luminance was luminance 2900 cd / m ² at 1200 cd / m ^2, 12V at 9V.
[0072]
Further, when a voltage was applied for 100 hours while keeping the current density at 250 mA / cm ² in a nitrogen atmosphere, the luminance deterioration was small, from the initial luminance of 600 cd / m ² to 550 cd / m ² after 100 hours.
[0073]
[Comparative Example 1]
Exemplified Compound No. A device was prepared in the same manner as in Example 4 using a comparative compound having the following structural formula instead of 11 (X ₁ = X ₂ = S), and the same evaluation was performed. Only the spectrum was obtained.
[0074]
Embedded image

[0075]
【The invention's effect】
The organic light-emitting device using the compound represented by the general formula [1] of the present invention has various emission wavelengths as shown in the examples and comparative examples, exhibits various emission hues, and is high at a low applied voltage. Luminous light emission is obtained and durability is excellent.
[0076]
In particular, the organic layer using the compound represented by the general formula [1] of the present invention is useful as a light emitting layer and also useful as an electron transporting layer.
[0077]
Furthermore, the device can be formed using vacuum deposition, casting method, or the like, so that a device having a relatively large area can be easily manufactured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an organic light emitting device in the present invention.
FIG. 2 is a cross-sectional view showing another example of the organic light emitting device according to the present invention.
FIG. 3 is a cross-sectional view showing another example of the organic light emitting device according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Light emitting layer 4 Cathode 5 Hole transport layer 6 Electron transport layer

Claims (4)

In an organic light emitting device having at least one layer including an anode and a cathode and a layer including one or a plurality of organic compounds sandwiched between the pair of electrodes, at least one of the layers including the organic compound is An organic light-emitting device comprising at least one compound represented by the formula [1].

Wherein R ₁ and R ₂ have a condensed ring structure selected from the group consisting of a substituted or unsubstituted aromatic ring, a substituted or unsubstituted heterocyclic ring, a hydrogen atom, a halogen atom, a nitro group, Nitrile group, substituted silyl group, substituted or unsubstituted alkyl group, substituted or unsubstituted alkenyl group, substituted or unsubstituted aralkyl group, substituted or unsubstituted aryl group, substituted or unsubstituted amino group, substituted or unsubstituted X ₁ is a group selected from the group consisting of a substituted azomethine group, a substituted or unsubstituted carbonyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted ether group, and a substituted or unsubstituted heterocyclic group. And X ₂ is a group selected from the group consisting of a sulfur atom, sulfoxide and sulfone , and may be the same or different. In the general formula [1], organic light emitting device according to claim 1 in which X ₁ and X ₂ is characterized in that it is a sulfur atom. _2. The organic light-emitting device according to claim 1, wherein, in the general formula [1], X ₁ and X ₂ are sulfoxides. In the general formula [1], organic light emitting device according to claim 1 in which X ₁ and X ₂ is characterized in that it is a sulfone.

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