JP4584441B2

JP4584441B2 - Organic electroluminescent device and manufacturing method thereof

Info

Publication number: JP4584441B2
Application number: JP2000348776A
Authority: JP
Inventors: 興利木村
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2000-11-15
Filing date: 2000-11-15
Publication date: 2010-11-24
Anticipated expiration: 2020-11-15
Also published as: JP2002151257A

Description

【０００１】
【発明の属する技術分野】
本発明は、有機電界発光素子及びその製造方法に関するものである。
【０００２】
【従来の技術】
近年の電子機器の小型化、薄型化、軽量化に関する進歩は目覚ましいものがあり、とりわけＯＡ分野においては、デスクトップ型からラップトップ型、ノートブック型へと小型軽量化している。加えて、電子手帳、翻訳機等の新しい小型電子機器の分野も出現し、更には従来の設置型電話の多機能化、小型化に加えて、小型通信機器である、携帯電話、ＰＨＳ、ＰＤＡの開発も進められており、このような電子機器の小型化、薄型化、軽量化の波の中で、マンインターフェイスを支える表示装置にも高性能化が要求されてきている。
そこで、このような要望に応えるため、薄型であること、自発光であること、カラー化が可能であること等の特徴を有する電界発光素子を用いた表示装置が、ＣＲＴ、液晶に代わる小型、中型電子機器向けの表示装置として開発が進められてきた。
【０００３】
薄膜電界発光素子は、無機化合物を利用するもの、有機化合物を利用するもの何れも存在するが、無機薄膜電界発光素子としては、硝子透明電極（例えばＩＴＯ）、絶縁層（例えば窒化珪素）、発光層（例えばＺｎＳ：Ｍｎ）、絶縁層（例えば窒化珪素）、金属電極（例えばＡｌ）の各層が順次積層されているものが一般的である。
このような無機薄膜電界発光素子は、発光輝度は高いが駆動電圧も高い（２００Ｖ程度）ことから専用の駆動ＩＣが必要になったり、発光材料の色選択が必ずしも自由にできないという問題点を抱えている。
これに対して近年有機薄膜を積層した電界発光素子の作製が盛んに試みられるようになった。古くは特開昭５７−５１７８１号公報に、発光体となるべき有機薄膜層を電子及び／又はホールを選択的に輸送する材料の薄膜で挟持し、その両側に電極を設けたものが開示されている。
この有機薄膜電界発光素子は、無機薄膜電界発光素子と比較して駆動電圧が低く（２０Ｖ程度）、発光材料の選択幅も広いため、本質的にフルカラー表示素子を作製するのに適している。
【０００４】
有機薄膜電界発光素子は数種の有機薄膜積層体を電極で挟んだ構造を有しているが、有機薄膜の作製方法としてはいくつかの方法が提案されている。
一般的方法を挙げると、（イ）蒸着による方法、（ロ）塗布による方法がある。
（イ）の方法は、低分子量有機物に一般的に適用される方法であり、薄膜領域（３０００Å程度）で緻密な膜厚制御が可能なため信頼性のある薄膜が得やすい反面、装置が大掛かりとなり、総合的な素子作製時間が長くなる。また、低分子量有機物は蒸着温度において必ずしも安定ではないので材料に制限がある。
（ロ）の方法は、高分子量有機物（ポリマー、オリゴマー）に一般的に適用される方法で、生産性に優れた方法であり、本質的に蒸着できない有機物（蒸着温度で分解してしまうもの）に対して有効な方法であるが、蒸着法に比較すると緻密な膜厚制御はし難く、絶縁性に劣る場合がある。
我々は（ロ）の方法が生産性に優れ好ましい方法とみて検討したが、この方法では、本質的に不溶不融の材料が扱えないことや、電界発光素子用材料の塗布溶液を作製する手間がかかるという問題がある。
【０００５】
本発明で用いる方法はこの欠点を克服するものであり、一般に電解重合法と呼ばれる薄膜形成方法である。
電解重合法は電解反応を利用するため、基本的に電極上にしか薄膜が形成されず、ＩＴＯ等とのアライメントが不必要な点や、塗布で扱うことができない本質的に不溶不融な材料でも電解合成を利用して電極上に膜を作製することができるという利点を有する。
また、電界発光素子用の膜質は均質かつ緻密でなければならないが、導電体上で重合反応（この場合の重合反応とは２量化、３量化も含む。また、ここで扱う電解重合法とは、電解により生成した物が電極上に堆積することを意味し、必ずしも電解生成物が高分子とは限らない）により形成される膜の膜質は電解条件の詳細検討〔単量体種、溶媒種、電解質種、電解条件（定電圧電解、定電流電解、定電位電解等）、添加剤〕を行うことにより塗布法に比較して遥かに優れた膜ができるとともに、蒸着法に匹敵する膜質を得ることも可能である。
更に、このような条件下で作製される膜は、電解反応の性質上（電極上の無数の反応点からほぼ同時に重合が進行する）、アモルファス性の強いものが得られ易いという利点を有する。
【０００６】
電解重合法を有機薄膜電界発光素子の作製に利用する試みは、特開平２−１９５６８１号、特開平５−１３１７１号、特開平８−４５６６７号各公報に記載されているが、特開平２−１９５６８１号公報に記載の技術では、有機物単量体を電極上に蒸着したのち電解反応に供しており、電解膜を得る工程の前段階に蒸着を用いているため工程が煩雑になり電解重合の利点を一部失ってしまっている。
特開平５−１３１７１号公報に記載の技術は、電子輸送層を電解重合法により作製するものであるが、電解重合により得られた高分子を溶媒に溶解し、塗布により電子輸送層を形成しているため、やはり工程が多く電解重合の利点を充分生かしていない。
特開平８−４５６６７号公報記載の技術では、電極として高分子被覆電極を用いて電解重合を行っており、そのため被覆電極を作製する工程が増えると共に、能動的に機能する重合体濃度が減ってしまうため（被覆した高分子中で機能材料が成長するため）、材料が本来持っている電子又はホール輸送能力や発光能力を充分に生かし切ることができない。
【０００７】
このような技術的背景の中で、本発明者らは、特願２０００−３４５７３９号において電解重合を利用し特定の構造を持つ単量体を陽極上で重合させることにより陽極とホール注入／輸送層、あるいは発光層の複合を行い、この複合電極を電界発光素子に使用することを提案したが、陰極上への電解重合を利用した電子注入／輸送材料、発光材料の直接複合については本発明者の知る限り例を見ない。
また、ホール注入／輸送材については多くの研究もあるので、ほぼ好ましい特性を有する材料が提供されているが、電子注入／輸送材については、充分に発光輝度、発光効率を向上させることができる有用な材料が少なく、新規な電子注入／輸送材の開発が望まれている。
【０００８】
【発明が解決しようとする課題】
本発明は、電界発光素子の陰極に好ましく使用し得る材料からなる電極を用いて電解陰極還元反応を行い、電界発光素子用陰極と電子注入／輸送層又は発光層とを直接複合する方法によって電界発光素子を得ることを目的とする。
【０００９】
【課題を解決するための手段】
本発明者は前述した電解重合の利点を損なうことなく均質な膜を作製できる方法について検討を行い、一定の構造を持つ単量体を使用して電解陰極還元反応を行うことにより、電子注入／輸送材料や発光材料を作製できること、またこの時、電界発光素子の陰極に好ましく使用しうる材料からなる電極を用いることにより電界発光素子用陰極と電子注入／輸送層又は発光層を直接複合できることを見出した。
即ち、上記課題は、次の１）〜１１）の発明（以下、本発明１〜１１という）によって解決される。
１）少なくとも可視光を反射する材料からなる陰極上に、次の一般式（１）の化合物を単量体とする電解重合膜が設けられた複合電極を有することを特徴とする有機電界発光素子。
〔化９〕
Ｘ^１Ｙ^１Ｚ^１Ｃ−Ａｒ−ＣＸ^２Ｙ^２Ｚ^２ ………（１）
（式中、Ａｒはｐ−キシレニレン基、Ｘ^１、Ｙ^１、Ｚ^１、Ｘ^２、Ｙ^２、
Ｚ^２は各々水素又はハロゲン、但し、Ｘ^１、Ｙ^１、Ｚ^１の内少なくとも１つ
はハロゲン、Ｘ^２、Ｙ^２、Ｚ^２の内少なくとも１つはハロゲン）
２）前記一般式（１）における、Ｘ^１、Ｙ^１、Ｚ^１の内２つがハロゲンであり、Ｘ^２、Ｙ^２、Ｚ^２の内２つがハロゲンである化合物を単量体とし、電解重合膜が次の構造単位（２）を主骨格上に有するものであることを特徴とする１）記載の有機電界発光素子。
〔化１０〕
−Ａｒ−ＣＬ＝ＣＭ− ………（２）
（式中、Ａｒはｐ−キシレニレン基、Ｌ、Ｍは水素又はハロゲン）
３）前記一般式（１）における、Ｘ^１、Ｙ^１、Ｚ^１、Ｘ^２、Ｙ^２、Ｚ^２が全てハロゲンである化合物を単量体とし、電解重合膜が次の構造単位（２）及び／又は（３）を主骨格上に有するものであることを特徴とする１）記載の有機電界発光素子。
〔化１１〕
−Ａｒ−ＣＬ＝ＣＭ− ………（２）
（式中、Ａｒはｐ−キシレニレン基、Ｌ、Ｍは水素又はハロゲン）
〔化１２〕
−Ａｒ−Ｃ≡Ｃ− ………（３）
（式中、Ａｒはｐ−キシレニレン基）
４）陰極として仕事関数が４ｅＶ以上の導電体からなる電極を用いることを特徴とする１）〜３）の何れかに記載の有機電界発光素子。
５）導電体が金属であり標準水素電極に対して、＋０．５Ｖ以下の酸化還元電位を有することを特徴とする４）記載の有機電界発光素子。
６）陰極としてアルカリ金属、アルカリ土類金属を含む電極を用いることを特徴とする１）〜５）の何れかに記載の有機電界発光素子。
７）電解重合膜がカルボニル金属錯体の存在下に行われる陰極還元反応によって生成されるものであることを特徴とする１）〜６）の何れかに記載の有機電界発光素子。
８）少なくとも一対の電極を、少なくとも単量体及び電解質を含む溶液内に浸漬し、該電極間に電界を与えて単量体の重合を行う電解重合法を利用した有機電界発光素子の製造方法であって、陰極として少なくとも可視光を反射する電極を用い、単量体として次の一般式（１）で表される化合物を用い、該単量体を電解陰極還元反応させて前記電極上に電解重合膜を生成させ、得られた複合電極を素子部材として用いることを特徴とする有機電界発光素子の製造方法。
〔化１３〕
Ｘ^１Ｙ^１Ｚ^１Ｃ−Ａｒ−ＣＸ^２Ｙ^２Ｚ^２ ………（１）
（式中、Ａｒはｐ−キシレニレン基、Ｘ^１、Ｙ^１、Ｚ^１、Ｘ^２、Ｙ^２、
Ｚ^２は各々水素又はハロゲン、但し、Ｘ^１、Ｙ^１、Ｚ^１の内少なくとも１つ
はハロゲン、Ｘ^２、Ｙ^２、Ｚ^２の内少なくとも１つはハロゲン）
９）前記単量体として、Ｘ^１、Ｙ^１、Ｚ^１の内２つがハロゲンであり、Ｘ^２、Ｙ^２、Ｚ^２の内２つがハロゲンである化合物を用い、生成する電解重合膜が次の構造単位（２）を主骨格上に有するものであることを特徴とする８）記載の有機電界発光素子の製造方法。
〔化１４〕
−Ａｒ−ＣＬ＝ＣＭ− ………（２）
（式中、Ａｒはｐ−キシレニレン基、Ｌ、Ｍは水素又はハロゲン）
１０）前記単量体として、Ｘ^１、Ｙ^１、Ｚ^１、Ｘ^２、Ｙ^２、Ｚ^２が全てハロゲンである化合物を用い、生成する電解重合膜が次の構造単位（２）及び／又は（３）を主骨格上に有するものであることを特徴とする８）記載の有機電界発光素子の製造方法。
〔化１５〕
−Ａｒ−ＣＬ＝ＣＭ− ………（２）
（式中、Ａｒはｐ−キシレニレン基、Ｌ、Ｍは水素又はハロゲン）
〔化１６〕
−Ａｒ−Ｃ≡Ｃ− ………（３）
（式中、Ａｒはｐ−キシレニレン基）
１１）カルボニル金属錯体の存在下に電解陰極還元反応を行わせることを特徴とする８）〜１０）の何れかに記載の有機電界発光素子の製造方法。
【００１０】
以下、上記本発明について詳しく説明する。
本発明で用いる電解重合法は、例えば「化学工業」１９８６年６月号、４３頁、「高分子」第３５巻２月号（１９８６）１２４頁等に記載されているが、単量体と電解質とを溶媒に溶かした溶液を所定の電解槽に入れ、一対の電極を浸漬し、電流を通して陽極酸化あるいは陰極還元による重合反応を起こさせ、陰極又は陽極上に有機物の薄膜を形成する方法である。
電解質としては、例えば、アニオンとして、ＢＦ_４ ⁻、ＡｓＦ_６ ⁻、ＳｂＦ_６ ⁻、ＰＦ_６ ⁻、ＣｌＯ_４ ⁻、ＨＳＯ_４ ⁻、ＳＯ_４ ^２−、芳香族スルホン酸イオン；Ｃｌ⁻、Ｂｒ⁻、Ｉ⁻等のハロゲンアニオンが、また、カチオンとして、Ｈ^＋、４級アンモニウムカチオン、リチウム、ナトリウム、カリウム等のアルカリ金属カチオンが挙げられるが、これらに限定されるものではなく、単量体および所望する膜質により適宜選択し得るものである。
また、濃度についても適宜設定できるが、０．０１〜１Ｍ（モル）程度が好ましい。
【００１１】
溶媒としては、例えば、アセトニトリル、ベンゾニトリル、プロピレンカーボネート、テトラヒドロフラン、γ−ブチロラクトン、ジクロルメタン、ジオキサン、ジメチルフォルムアミド、ニトロメタン、ニトロプロパン、ニトロベンゼンなどが挙げられ、これらを二種以上混合して用いてもよい。
しかし、特にこれらの例示した化合物に限られる訳ではなく、単量体及び所望する膜質により適宜選択し得るものである。
電解重合は、定電圧電解、定電流電解、定電位電解、電位あるいは電圧の振幅による電解などの何れを用いてもよいが、量産上は定電流電解、定電圧電解が好ましい。
【００１２】
本発明に使用する単量体は次の一般式（１）で表わされる化合物である。
〔化１７〕
Ｘ^１Ｙ^１Ｚ^１Ｃ−Ａｒ−ＣＸ^２Ｙ^２Ｚ^２ ………（１）
（式中、Ａｒはｐ−キシレニレン基、Ｘ^１、Ｙ^１、Ｚ^１、Ｘ^２、Ｙ^２、
Ｚ^２は各々水素又はハロゲン、但し、Ｘ^１、Ｙ^１、Ｚ^１の内少なくとも１つ
はハロゲン、Ｘ^２、Ｙ^２、Ｚ^２の内少なくとも１つはハロゲンである。）
Ｘ^１Ｙ^１Ｚ^１Ｃ基及びＣＸ^２Ｙ^２Ｚ^２基は、それぞれ独立なハロゲン化メチル基であり、具体例としては、−ＣＨ_２Ｃｌ、−ＣＨ_２Ｂｒ、−ＣＨ_２Ｆ、−ＣＨ_２Ｉ、−ＣＨＣｌ_２、−ＣＨＢｒ_２、−ＣＨＦ_２、−ＣＨＩ_２、−ＣＣｌ_３、−ＣＢｒ_３、−ＣＦ_３、−ＣＩ_３が挙げられる。
この中で特に好ましいのは、ジハロゲン化メチル基、トリハロゲン化メチル基である。
【００１３】
Ｃ−Ｈ結合の振動エネルギーレベルは３０００ｃｍ^−１以上にあることが一般的で、有機結合の振動エネルギーレベルとしては高い部類に属する。このような結合を多く有する有機物（単量体）を電界発光素子材料として用いた場合、励起状態（エネルギーを得た状態）になった有機物（単量体）のエネルギーが有効に発光エネルギーに使用されないで、あるいは他の分子に有効にエネルギーが移動しないで、分子内の振動エネルギーとして一部消費される確率が増えてしまうことになりエネルギー効率を下げる結果となる（振動エネルギー準位が高いため励起エネルギーの一部が振動エネルギーとして使用されてしまう；エネルギー失活）。
このため使用する素子材料中のＣ−Ｈ結合は少ない方が好ましく、最も好ましい単量体はトリハロゲン化メチル基を持つものである。
この単量体を用いることにより、後述する重合生成物の主骨格上に存在する炭素上のＣ−Ｈ結合が少ない生成物を得ることができる。
またこれも後述するがトリハロゲン化メチル基を有する単量体は、電解重合条件を適宜設定することにより、主鎖にＣ＝Ｃ結合を主に有するかＣ≡Ｃ結合を主に有するかを制御することが可能である。
【００１４】
本発明では、好ましくは還元重合系にカルボニル金属錯体を添加して還元反応を実施する。
使用できるカルボニル金属錯体としては、Ｆｅ（ＣＯ）_６、Ｃｏ（ＣＯ）_６、Ｃｒ（ＣＯ）_６、Ｍｏ（ＣＯ）_６、Ｖ（ＣＯ）_６、Ｗ（ＣＯ）_６、Ｍｎ_２（ＣＯ）_６、Ｎｉ（ＣＯ）_４、Ｐｔ（ＣＯ）_４、Ｃ_５Ｈ_５Ｃｒ（ＣＯ）_３等が挙げられるが、好ましくはＣｒ錯体又はＭｏ錯体である。
カルボニル金属錯体を添加して反応させた生成物（重合体）をＩＲスペクトルにより分析してみると、短波数側に存在する炭素−ハロゲンの伸縮振動の吸収レベルが減少していることから、カルボニル金属錯体には、主骨格上の炭素炭素結合の不飽和度を上げる働きがあると推測される。
【００１５】
本発明に使用する電解還元用の電極は、少なくとも可視光を反射でき、かつ電解還元条件において安定なものであれば何でもよいが、作製した電界発光素子の環境安定性の面から仕事関数が４ｅＶ（電子ボルト）以上の導電体を用いることが好ましく、具体例としては、アルミニウム、クロム、鉄、ニッケル、銅、銀、錫、亜鉛、タングステン、イリジウム、白金、金等が挙げられる。
これらの導電体の中でも、標準水素電極に対する酸化還元電位が＋０．５Ｖ以下のものは、自らは酸化性が強く、即ち他に対しては還元性を有する材料であり、本発明の電解還元反応に利用するのに好ましい金属である。
その具体例としては、銅、アルミニウム、鉄等が挙げられる。
またこのような金属上で生成した化合物（重合体）は、そもそも単量体が電極上で電子を注入されること（電解還元）によって生成されたものであるから、この金属に対して好ましい電子注入特性を有するものとなる。
更に仕事関数を下げる目的で、適宜アルカリ金属、アルカリ土類金属を適当量使用することも可能である。これらの元素は通常合金として添加するが、これに限られるわけではなく、例えば微小な島状になっていてもよい。
【００１６】
本発明の電解還元反応により得られる重合体は、下記（２）及び／又は（３）で表される構造単位を主骨格上に有するものである。
〔化１８〕
−Ａｒ−ＣＬ＝ＣＭ− ………（２）
（式中、Ａｒはｐ−キシレニレン基、Ｌ、Ｍは水素、ハロゲン）
〔化１９〕
−Ａｒ−Ｃ≡Ｃ− ………（３）
（式中、Ａｒはｐ−キシレニレン基）
（２）及び／又は（３）の構造単位を主骨格上にいくつ有するかは反応条件により異なり、一概には決定できない。特に前述の如く単量体としてトリハロゲン化メチル基を有するものを使用した場合には、電解還元条件を制御することにより、主に（２）の構造単位を有するか、（３）の構造単位を有するかが異なる。
例えば具体例として、溶媒にテトラヒドロフランを用いたときは主に（２）の構造単位を主骨格上に有する重合体が得られ、溶媒にプロピレンカーボネートを用いたときは主に（３）構造単位をに有する重合体を得る事ができる。
【００１７】
【実施例】
以下、実施例により本発明を具体的に説明するが、本発明はこれらの実施例により限定されるものではない。
【００１８】
実施例１
アルゴン雰囲気下、単量体としてα，α，α′，α′−テトラブロモ−ｐ−キシレン０．７５ｇ、電解質としてテトラｎ−ブチルアンモニウムテトラフルオロボレート１ｇ、添加物としてＭｏ（ＣＯ）_６８０ｍｇをテトラヒドロフラン３０ｍｌに溶解して電解重合溶液を作成した。
作用極に銅電極、対極に白金、参照極にＡｇ／Ａｇ^＋を使用して、−３．０ＶｖｓＡｇ／Ａｇ^＋の定電位で重合を行った。
銅電極を取り出し洗浄後、テトラｎ−ブチルアンモニウムｐ−トルエンスルホネート５０ｍＭ（ミリモル）を含むテトラヒドロフラン溶液に移し、０ＶｖｓＡｇ／Ａｇ^＋の電圧を印加した。
次いで、電圧を印加したまま電極を溶液より取り出し、洗浄処理後乾燥して銅との複合電極を得た。
これとは別に、文献記載の方法〔Ｆ．Ｅ．ｋａｒａｓｚらＪ．ＰｏｌｙｍｅｒＳｃｉ．ＰｏｌｙｍｅｒＣｈｅｍｉｓｔｒｙ，２６，３２４１（１９８８）〕により作成したポリ（パラキシリレンジメチルスルホニウムクロリド）の１．５重量％水溶液を前記複合電極上に塗布した後、アルゴン雰囲気下で１５０度に加熱することにより複合電極上にポリパラフェニレン膜を形成した。
次いでその上にポリエチレンジオキシチオフェンとポリスチレンスルホン酸の混合溶液を塗布し、アルゴン雰囲気下で充分に乾燥した後、スパッタ法によりＩＴＯ電極を作製した。
この電界発光素子に５Ｖの電界を与えたところ発光が観測され、電解還元膜を用いない場合と比較して３０％の輝度向上が得られた。
【００１９】
実施例２
Ｍｏ（ＣＯ）_６を使用しない点を除き、実施例１と同様にして電界発光素子を作製した。
この素子に５Ｖの電界を与えたところ発光が観測され、電解還元膜を用いない場合と比較して２５％の輝度向上が得られた。
【００２０】
実施例３
単量体としてα，α，α，α′，α′，α′−ヘキサクロル−ｐ−キシレン、溶媒としてプロピレンカーボネートを使用し、−２ＶｖｓＡｇ／Ａｇ^＋の定電位で重合を行う点を除き、実施例１と同様にして電界発光素子を作製した。
この素子に５Ｖの電界を与えたところ発光が観測され、電解還元膜を用いない場合と比較して２３％の輝度向上が得られた。
【００２１】
実施例４
単量体としてα，α，α，α′，α′，α′−ヘキサブロモ−ｐ−キシレンを使用した点を除き、実施例３と同様にして電界発光素子を作製した。
この素子に５Ｖの電界を与えたところ発光が観測され、電解還元膜を用いない場合と比較して２４％の輝度向上が得られた。
【００２２】
実施例５
溶媒をテトラヒドロフランに代えた点を除き、実施例４と同様にして電界発光素子を作製した。
この素子に５Ｖの電界を与えたところ発光が観測され、電解還元膜を用いない場合と比較して２８％の輝度向上が得られた。
【００２３】
実施例６
作用極としてアルミニウムを使用する点を除き、実施例１と同様にして電界発光素子を作製した。
この素子に５Ｖの電界を与えたところ発光が観測され、電解還元膜を用いない場合と比較して２０％の輝度向上が得られた。
【００２４】
実施例７
Ｍｏ（ＣＯ）_６を使用しない点を除き、実施例６と同様にして電界発光素子を作製した。
この素子に５Ｖの電界を与えたところ発光が観測され、電解還元膜を用いない場合と比較して１６％の輝度向上が得られた。
【００２５】
実施例８
作用極としてＬｉＡｌを使用する点を除き、実施例１と同様にして電界発光素子を作製した。
この素子に５Ｖの電界を与えたところ発光が観測され、電解還元膜を用いない場合と比較して１４％の輝度向上が得られた。
【００２６】
（参考１）
実施例１、２の電解還元膜のＩＲ（赤外吸収）スペクトルを測定したところ、６２０ｃｍ^−１付近のＣ−Ｂｒ伸縮振動が共に観測されたが、コバルト金属錯体を添加した実施例１の電解還元物の方が強度が弱く、主骨格上の炭素炭素結合の不飽和度が上がっていることが予測された。
また２０５０ｃｍ^−１にＣ≡Ｃ結合に起因すると考えられる吸収も現れたが、コバルト金属錯体を添加した実施例１の電解還元物の方が強度は弱かった。
Ｃ≡Ｃ伸縮振動は置換基が同一で対称性が存在する場合はＩＲ不活性となるので、現れた吸収は非対称性の置換基を有するＣ≡Ｃ伸縮振動に起因するものと考えられる。
この結果は、どちらの化合物がより多くの三重結合を有するかの判断材料にはならないが、メチル基のハロゲンによる２置換体（−ＣＨＸ_２）でも三重結合を生成できることを示している。
【００２７】
（参考２）
実施例３、４、５の電解還元膜のラマンスペクトルを測定したところ、実施例３では２２００ｃｍ^−１に、実施例４、５では２１６０ｃｍ^−１にＣ≡Ｃ結合に起因する吸収があらわれた。
またプロピレンカーボネートを使用した実施例４に対して、テトラヒドロフランを用いた実施例５の方が吸収強度は弱く、より三重結合が少ないことが予測された。
【００２８】
次に、本発明の有機電界発光素子の製造方法に係る実施態様を列記する。
１２）陰極として仕事関数が４ｅＶ以上の導電体からなる電極を用いることを特徴とする前記８）〜１１）の何れかに記載の有機電界発光素子の製造方法。
１３）導電体が金属であり標準水素電極に対して、＋０．５Ｖ以下の酸化還元電位を有することを特徴とする前記８）〜１２）の何れかに記載の有機電界発光素子の製造方法。
１４）陰極としてアルカリ金属、アルカリ土類金属を含む電極を用いることを特徴とする前記８）〜１３）の何れかに記載の有機電界発光素子の製造方法。
１５）電解重合膜が発光層であることを特徴とする前記８）〜１４）の何れかに記載の有機電界発光素子の製造方法。
１６）電解重合膜が電子注入／輸送層であることを特徴とする前記８）〜１５）の何れかに記載の有機電界発光素子の製造方法。
【００２９】
【発明の効果】
本発明１〜３、８〜１０によれば、陰極上にアライメント無しで一段階で電子注入／輸送性に優れた薄膜を作製でき、該薄膜を使用した電界発光素子及びその製造方法を提供できる。
本発明４〜６によれば、環境に対して安定であり、電解還元膜を生成し易く、電子注入し易い電界発光素子を提供できる。
本発明７、１１によれば、カルボニル金属錯体を重合系に用いることにより、一層不飽和度が高く電子注入／輸送性に優れた薄膜を作製でき、該薄膜を使用した電界発光素子を提供できる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescent device and a method for manufacturing the same.
[0002]
[Prior art]
In recent years, there have been remarkable advances in downsizing, thinning, and weight reduction of electronic devices, and particularly in the OA field, the size has been reduced from desktop type to laptop type and notebook type. In addition, the field of new small electronic devices such as electronic notebooks and translators has emerged. Furthermore, in addition to the multi-function and miniaturization of conventional stationary telephones, small communication devices such as mobile phones, PHS, PDAs Development of these devices is also underway, and in the wave of such downsizing, thinning, and weight reduction of electronic devices, display devices that support man interfaces are also required to have high performance.
Therefore, in order to meet such a demand, a display device using an electroluminescent element having features such as being thin, self-luminous, and capable of being colored is a small-sized replacement for CRT, liquid crystal, Development has progressed as a display device for medium-sized electronic devices.
[0003]
Thin film electroluminescent devices include those using inorganic compounds and those using organic compounds, but as inorganic thin film electroluminescent devices, glass transparent electrodes (for example, ITO), insulating layers (for example, silicon nitride), light emission In general, a layer (for example, ZnS: Mn), an insulating layer (for example, silicon nitride), and a metal electrode (for example, Al) are sequentially stacked.
Such an inorganic thin film electroluminescent device has a problem that it has a high emission luminance but a high driving voltage (about 200 V), so that a dedicated driving IC is required and the color selection of the light emitting material is not always free. ing.
On the other hand, in recent years, attempts have been actively made to produce electroluminescent elements in which organic thin films are laminated. In the past, Japanese Patent Application Laid-Open No. 57-51781 discloses an organic thin film layer to be a light emitter sandwiched between thin films of materials that selectively transport electrons and / or holes, and electrodes are provided on both sides thereof. ing.
This organic thin film electroluminescent element has a lower driving voltage (about 20 V) than an inorganic thin film electroluminescent element and has a wide selection range of light emitting materials, and therefore is essentially suitable for producing a full color display element.
[0004]
An organic thin film electroluminescent device has a structure in which several kinds of organic thin film laminates are sandwiched between electrodes, but several methods for producing an organic thin film have been proposed.
General methods include (a) a method by vapor deposition and (b) a method by coating.
Method (a) is a method generally applied to low molecular weight organic substances, and it is easy to obtain a reliable thin film because precise film thickness control is possible in the thin film region (about 3000 mm), but the apparatus is large. Thus, the total device fabrication time is increased. In addition, since low molecular weight organic substances are not always stable at the deposition temperature, the materials are limited.
The method (b) is a method generally applied to high molecular weight organic substances (polymers and oligomers) and is a method with excellent productivity, and organic substances that cannot be essentially deposited (those that decompose at the deposition temperature). However, when compared with the vapor deposition method, it is difficult to control the film thickness precisely, and the insulating property may be inferior.
Although we considered that the method (b) is excellent in productivity and is preferable, this method cannot handle insoluble and infusible materials, and it is troublesome to prepare a coating solution for materials for electroluminescent elements. There is a problem that it takes.
[0005]
The method used in the present invention overcomes this drawback, and is a thin film forming method generally called an electrolytic polymerization method.
Since the electropolymerization method uses an electrolytic reaction, a thin film is basically formed only on the electrode, and there is no need for alignment with ITO, etc., or an essentially insoluble and infusible material that cannot be handled by coating. However, it has an advantage that a film can be formed on the electrode by using electrolytic synthesis.
In addition, the film quality for the electroluminescent element must be uniform and dense, but the polymerization reaction on the conductor (in this case, the polymerization reaction includes dimerization and trimerization. Also, the electropolymerization method treated here is This means that the product formed by electrolysis is deposited on the electrode, and the electrolytic product is not necessarily a polymer). , Electrolyte type, electrolysis conditions (constant voltage electrolysis, constant current electrolysis, constant potential electrolysis, etc.) and additives], a film far superior to the coating method can be obtained and a film quality comparable to the vapor deposition method can be obtained. It is also possible to obtain.
Furthermore, the film produced under such conditions has an advantage that a strong amorphous film can be easily obtained due to the nature of the electrolytic reaction (polymerization proceeds almost simultaneously from countless reaction points on the electrode).
[0006]
Attempts to use the electropolymerization method for the production of an organic thin film electroluminescent device are described in JP-A-2-195561, JP-A-5-13171 and JP-A-8-45667. In the technique described in Japanese Patent No. 1956881, an organic monomer is vapor-deposited on an electrode and then subjected to an electrolysis reaction. Since the vapor deposition is used before the step of obtaining an electrolytic film, the process becomes complicated and the electrolytic polymerization is performed. Some of the benefits have been lost.
The technique described in JP-A-5-13171 is to produce an electron transport layer by an electrolytic polymerization method. A polymer obtained by electrolytic polymerization is dissolved in a solvent, and an electron transport layer is formed by coating. Therefore, there are still many processes, and the advantages of electrolytic polymerization are not fully utilized.
In the technique described in Japanese Patent Application Laid-Open No. 8-45667, electrolytic polymerization is performed using a polymer-coated electrode as an electrode, so that the number of steps for producing a coated electrode increases and the concentration of actively functioning polymer decreases. Therefore, since the functional material grows in the coated polymer, the electron or hole transport capability and light emission capability inherent to the material cannot be fully utilized.
[0007]
In such a technical background, the present inventors have disclosed in Japanese Patent Application No. 2000-345739 that electrolytic polymerization is used to polymerize a monomer having a specific structure on the anode to inject / transport holes and holes. It has been proposed that the composite electrode is used for the electroluminescent device, and the electron injection / transport material utilizing electropolymerization on the cathode and the direct composite of the luminescent material are used in the present invention. As far as the person knows, no example is seen.
In addition, since there are many studies on hole injection / transport materials, materials having almost preferable characteristics have been provided. However, with respect to electron injection / transport materials, light emission luminance and light emission efficiency can be sufficiently improved. There are few useful materials, and development of a novel electron injection / transport material is desired.
[0008]
[Problems to be solved by the invention]
The present invention provides an electrocathode reduction reaction using an electrode made of a material that can be preferably used for a cathode of an electroluminescent device, and an electric field by a method of directly combining an electroluminescent device cathode and an electron injection / transport layer or a luminescent layer. An object is to obtain a light emitting element.
[0009]
[Means for Solving the Problems]
The present inventor has studied a method capable of producing a homogeneous film without impairing the advantages of the above-described electropolymerization, and by performing an electrocathodic reduction reaction using a monomer having a certain structure, It is possible to produce a transport material and a light emitting material, and at this time, by using an electrode made of a material that can be preferably used for the cathode of the electroluminescent device, the electroluminescent device cathode and the electron injection / transport layer or the light emitting layer can be directly combined. I found it.
That is, the above problems are solved by the following inventions 1) to 11 ) (hereinafter referred to as the present inventions 1 to 11 ).
1) An organic electroluminescent device comprising a composite electrode in which an electropolymerized film having a compound of the following general formula (1) as a monomer is provided on a cathode made of a material that reflects at least visible light. .
[Chemical 9]
^{^{^{X 1 Y 1 Z 1 C-}}} Ar-CX 2 Y 2 Z 2 ......... (1)
(In the formula, Ar is a p-xylenylene group, X ¹ , Y ¹ , Z ¹ , X ² , Y ² ,
Z ² is each hydrogen or halogen, provided that at least one of X ¹ , Y ¹ and Z ¹ is halogen, and at least one of X ² , Y ² and Z ² is halogen)
2) In the general formula (1), a compound in which ^two of X ¹ , Y ¹ and Z ¹ are halogens, and ^two of X ² , Y ² and Z ² are halogens is used as a monomer, and electropolymerization is performed. The organic electroluminescence device according to 1), wherein the film has the following structural unit (2) on the main skeleton.
[Chemical Formula 10]
-Ar-CL = CM- (2)
(In the formula, Ar is a p-xylenylene group, L and M are hydrogen or halogen)
3) A compound in which X ¹ , Y ¹ , Z ¹ , X ² , Y ² , and Z ² in the general formula (1) are all halogens is used as a monomer, and the electrolytic polymerization film has the following structural unit (2). And / or (3) on the main skeleton, the organic electroluminescence device according to 1).
[Chemical Formula 11]
-Ar-CL = CM- (2)
(In the formula, Ar is a p-xylenylene group, L and M are hydrogen or halogen)
[Chemical Formula 12]
-Ar-C≡C- (3)
( Wherein Ar is a p-xylenylene group)
4) The organic electroluminescent element according to any one of 1) to 3), wherein an electrode made of a conductor having a work function of 4 eV or more is used as the cathode.
5) The organic electroluminescent device according to 4), wherein the conductor is a metal and has a redox potential of +0.5 V or less with respect to a standard hydrogen electrode.
6) The organic electroluminescent element according to any one of 1) to 5), wherein an electrode containing an alkali metal or an alkaline earth metal is used as a cathode.
7) The organic electroluminescent device according to any one of 1) to 6) , wherein the electropolymerized film is produced by a cathodic reduction reaction performed in the presence of a carbonyl metal complex.
8 ) A method for producing an organic electroluminescent device using an electrolytic polymerization method in which at least a pair of electrodes is immersed in a solution containing at least a monomer and an electrolyte, and an electric field is applied between the electrodes to polymerize the monomer. And using an electrode that reflects at least visible light as a cathode, a compound represented by the following general formula (1) as a monomer, and subjecting the monomer to an electrolytic cathode reduction reaction on the electrode A method for producing an organic electroluminescent element, comprising producing an electrolytic polymer film and using the obtained composite electrode as an element member.
[Chemical 13]
^{^{^{X 1 Y 1 Z 1 C-}}} Ar-CX 2 Y 2 Z 2 ......... (1)
(In the formula, Ar is a p-xylenylene group, X ¹ , Y ¹ , Z ¹ , X ² , Y ² ,
Z ² is each hydrogen or halogen, provided that at least one of X ¹ , Y ¹ and Z ¹ is halogen, and at least one of X ² , Y ² and Z ² is halogen)
9 ) As the monomer, a compound in which ^two of X ¹ , Y ¹ and Z ¹ are halogens and two of X ² , Y ² and Z ² are halogens is used. 8 ) The method for producing an organic electroluminescent element as described in 8 ) above, which comprises the structural unit (2) on the main skeleton.
[Chemical Formula 14]
-Ar-CL = CM- (2)
(In the formula, Ar is a p-xylenylene group, L and M are hydrogen or halogen)
10 ) As the monomer, a compound in which X ¹ , Y ¹ , Z ¹ , X ² , Y ² , and Z ² are all halogens is used, and the resulting electropolymerized film has the following structural unit (2) and / or 8 ) The method for producing an organic electroluminescent element as described in 8 ) above, which has the main skeleton on the main skeleton.
[Chemical 15]
-Ar-CL = CM- (2)
(In the formula, Ar is a p-xylenylene group, L and M are hydrogen or halogen)
[Chemical Formula 16]
-Ar-C≡C- (3)
( Wherein Ar is a p-xylenylene group)
11 ) The method for producing an organic electroluminescent element according to any one of 8 ) to 10 ), wherein an electrolytic cathodic reduction reaction is performed in the presence of a carbonyl metal complex.
[0010]
Hereinafter, the present invention will be described in detail.
The electrolytic polymerization method used in the present invention is described in, for example, “Chemical Industry” June 1986, page 43, “Polymer” Vol. 35, February (1986) page 124, etc. A method in which a solution in which an electrolyte is dissolved in a solvent is placed in a predetermined electrolytic cell, a pair of electrodes is immersed, a polymerization reaction is caused by anodization or cathodic reduction through an electric current, and an organic thin film is formed on the cathode or anode. is there.
Examples of the electrolyte include BF ₄ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , HSO ₄ ⁻ , SO ₄ ²⁻ , aromatic sulfonate ions; Cl ⁻ , Br ⁻ , Halogen anions such as I ⁻ , and cations include H ⁺ , quaternary ammonium cations, alkali metal cations such as lithium, sodium, and potassium, but are not limited thereto, monomers and desired Depending on the film quality to be selected, it can be appropriately selected.
Moreover, although it can set suitably also about a density | concentration, about 0.01-1M (mol) is preferable.
[0011]
Examples of the solvent include acetonitrile, benzonitrile, propylene carbonate, tetrahydrofuran, γ-butyrolactone, dichloromethane, dioxane, dimethylformamide, nitromethane, nitropropane, nitrobenzene, and the like. Good.
However, the compounds are not particularly limited to these exemplified compounds, and can be appropriately selected depending on the monomer and the desired film quality.
For the electropolymerization, any of constant voltage electrolysis, constant current electrolysis, constant potential electrolysis, electrolysis based on potential or voltage amplitude may be used, but in terms of mass production, constant current electrolysis or constant voltage electrolysis is preferable.
[0012]
The monomer used in the present invention is a compound represented by the following general formula (1).
[Chemical Formula 17]
^{^{^{X 1 Y 1 Z 1 C-}}} Ar-CX 2 Y 2 Z 2 ......... (1)
(In the formula, Ar is a p-xylenylene group, X ¹ , Y ¹ , Z ¹ , X ² , Y ² ,
Z ² is each hydrogen or halogen, provided that at least one of X ¹ , Y ¹ and Z ¹ is halogen, and at least one of X ² , Y ² and Z ² is halogen. )
The X ¹ Y ¹ Z ¹ C group and the CX ² Y ² Z ² group are each an independent methyl halide group. Specific examples thereof include —CH ₂ Cl, —CH ₂ Br, —CH ₂ F, and —CH. _{_{_{_{2 I, -CHCl 2, -CHBr 2}}}} , -CHF 2, -CHI 2, -CCl 3, -CBr 3, -CF 3, include -CI _3.
Of these, a dihalogenated methyl group and a trihalogenated methyl group are particularly preferable.
[0013]
The vibration energy level of C—H bond is generally 3000 cm ⁻¹ or more, and belongs to a high class as vibration energy level of organic bond. When an organic substance (monomer) having many such bonds is used as an electroluminescent device material, the energy of the organic substance (monomer) in an excited state (a state in which energy is obtained) is effectively used for the emission energy. If this is not done, or energy is not effectively transferred to other molecules, the probability of partial consumption of vibrational energy in the molecule will increase, resulting in lower energy efficiency (because the vibrational energy level is high). Part of the excitation energy is used as vibration energy; energy deactivation).
For this reason, it is preferable that the number of C—H bonds in the element material used is small, and the most preferable monomer has a trihalogenated methyl group.
By using this monomer, a product with few C—H bonds on carbon present on the main skeleton of the polymerization product described later can be obtained.
In addition, as will be described later, the monomer having a trihalogenated methyl group can be determined whether the main chain mainly has C═C bonds or C≡C bonds by appropriately setting the electropolymerization conditions. It is possible to control.
[0014]
In the present invention, the reduction reaction is preferably carried out by adding a carbonyl metal complex to the reduction polymerization system.
Examples of carbonyl metal complexes that can be used include Fe (CO) ₆ , Co (CO) ₆ , Cr (CO) ₆ , Mo (CO) ₆ , V (CO) ₆ , W (CO) ₆ , and Mn ₂ (CO) _6. , Ni (CO) ₄ , Pt (CO) ₄ , C ₅ H ₅ Cr (CO) _{3, and the} like, preferably Cr complex or Mo complex.
When the product (polymer) reacted by adding a carbonyl metal complex is analyzed by IR spectrum, the absorption level of the carbon-halogen stretching vibration existing on the short wave side is reduced. The metal complex is presumed to have a function of increasing the degree of unsaturation of carbon-carbon bonds on the main skeleton.
[0015]
The electrode for electrolytic reduction used in the present invention may be anything as long as it can reflect at least visible light and is stable under electrolytic reduction conditions. However, the work function is 4 eV from the viewpoint of environmental stability of the produced electroluminescent device. It is preferable to use a conductor more than (electron bolt), and specific examples include aluminum, chromium, iron, nickel, copper, silver, tin, zinc, tungsten, iridium, platinum, gold and the like.
Among these conductors, those having an oxidation-reduction potential of +0.5 V or less with respect to a standard hydrogen electrode are materials that are highly oxidizable by themselves, i.e., those having a reducibility to others, and the electrolytic reduction reaction of the present invention. Preferred metal for use in
Specific examples thereof include copper, aluminum, and iron.
Moreover, since the compound (polymer) produced | generated on such a metal was originally produced | generated when the monomer injected the electron on the electrode (electrolytic reduction), it is a preferable electron with respect to this metal. It has an injection | pouring characteristic.
Further, for the purpose of lowering the work function, an appropriate amount of alkali metal or alkaline earth metal can be used as appropriate. These elements are usually added as an alloy, but the present invention is not limited to this. For example, it may be in the form of minute islands.
[0016]
The polymer obtained by the electrolytic reduction reaction of the present invention has a structural unit represented by the following (2) and / or (3) on the main skeleton.
[Chemical Formula 18]
-Ar-CL = CM- (2)
(In the formula, Ar is a p-xylenylene group, L and M are hydrogen and halogen)
[Chemical Formula 19]
-Ar-C≡C- (3)
( Wherein Ar is a p-xylenylene group)
The number of structural units (2) and / or (3) on the main skeleton varies depending on the reaction conditions and cannot be determined unconditionally. In particular, when a monomer having a trihalogenated methyl group is used as the monomer as described above, it has mainly the structural unit (2) or the structural unit (3) by controlling the electrolytic reduction conditions. Have different.
For example, as a specific example, when tetrahydrofuran is used as a solvent, a polymer mainly having the structural unit (2) on the main skeleton is obtained, and when propylene carbonate is used as the solvent, (3) the structural unit is mainly used. Can be obtained.
[0017]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples.
[0018]
Example 1
Under an argon atmosphere, 0.75 g of α, α, α ′, α′-tetrabromo-p-xylene as a monomer, 1 g of tetra n-butylammonium tetrafluoroborate as an electrolyte, and 80 mg of Mo (CO) ₆ as an additive in tetrahydrofuran An electrolytic polymerization solution was prepared by dissolving in 30 ml.
Polymerization was performed at a constant potential of −3.0 Vvs Ag / Ag ⁺ using a copper electrode as a working electrode, platinum as a counter electrode, and Ag / Ag ⁺ as a reference electrode.
The copper electrode was taken out and washed, then transferred to a tetrahydrofuran solution containing 50 mM (mmol) of tetra n-butylammonium p-toluenesulfonate, and a voltage of 0 V vsAg / Ag ⁺ was applied.
Next, the electrode was taken out from the solution with the voltage applied, dried after washing, and a composite electrode with copper was obtained.
Apart from this, the method described in the literature [F. E. karasz et al. Polymer Sci. A 1.5% by weight aqueous solution of poly (paraxylylene dimethylsulfonium chloride) prepared by Polymer Chemistry, 26, 3241 (1988)] was applied on the composite electrode, and then heated to 150 degrees under an argon atmosphere. A polyparaphenylene film was formed on the composite electrode.
Next, a mixed solution of polyethylene dioxythiophene and polystyrene sulfonic acid was applied thereon, and after sufficiently drying in an argon atmosphere, an ITO electrode was produced by sputtering.
When an electric field of 5 V was applied to the electroluminescent element, light emission was observed, and a luminance improvement of 30% was obtained as compared with the case where no electrolytic reduction film was used.
[0019]
Example 2
An electroluminescent element was produced in the same manner as in Example 1 except that Mo (CO) ₆ was not used.
When an electric field of 5 V was applied to the device, light emission was observed, and a luminance improvement of 25% was obtained compared to the case where no electrolytic reduction film was used.
[0020]
Example 3
Except that α, α, α, α ′, α ′, α′-hexachloro-p-xylene is used as a monomer, propylene carbonate is used as a solvent, and polymerization is carried out at a constant potential of −2 V vs Ag / Ag ⁺ In the same manner as in Example 1, an electroluminescent element was produced.
When an electric field of 5 V was applied to the device, light emission was observed, and a luminance improvement of 23% was obtained as compared with the case where no electrolytic reduction film was used.
[0021]
Example 4
An electroluminescent device was produced in the same manner as in Example 3 except that α, α, α, α ′, α ′, α′-hexabromo-p-xylene was used as the monomer.
When an electric field of 5 V was applied to the device, light emission was observed, and a luminance improvement of 24% was obtained as compared with the case where no electrolytic reduction film was used.
[0022]
Example 5
An electroluminescent device was produced in the same manner as in Example 4 except that the solvent was changed to tetrahydrofuran.
When an electric field of 5 V was applied to the device, light emission was observed, and a luminance improvement of 28% was obtained as compared with the case where no electrolytic reduction film was used.
[0023]
Example 6
An electroluminescent element was produced in the same manner as in Example 1 except that aluminum was used as the working electrode.
When an electric field of 5 V was applied to the device, light emission was observed, and a luminance improvement of 20% was obtained as compared with the case where no electrolytic reduction film was used.
[0024]
Example 7
An electroluminescent element was produced in the same manner as in Example 6 except that Mo (CO) ₆ was not used.
When an electric field of 5 V was applied to the device, light emission was observed, and a luminance improvement of 16% was obtained as compared with the case where no electrolytic reduction film was used.
[0025]
Example 8
An electroluminescent element was produced in the same manner as in Example 1 except that LiAl was used as the working electrode.
When an electric field of 5 V was applied to the device, light emission was observed, and a luminance improvement of 14% was obtained as compared with the case where no electrolytic reduction film was used.
[0026]
(Reference 1)
When the IR (infrared absorption) spectra of the electrolytic reduction films of Examples 1 and 2 were measured, both C-Br stretching vibrations in the vicinity of 620 cm ⁻¹ were observed, but the electrolysis of Example 1 with the addition of a cobalt metal complex was observed. It was predicted that the reduced product had lower strength and the degree of unsaturation of carbon-carbon bonds on the main skeleton increased.
Moreover, although the absorption considered to originate in a C≡C bond also appeared at 2050 cm ⁻¹ , the electrolytic reduced product of Example 1 to which a cobalt metal complex was added had lower strength.
Since the C≡C stretching vibration becomes IR inactive when the substituents are the same and have symmetry, the absorption that appears is considered to be caused by the C≡C stretching vibration having an asymmetric substituent.
This result does not serve as a judgment material as to which compound has more triple bonds, but shows that a triple bond can be formed even with a disubstituted product of a methyl group by halogen (—CHX ₂ ).
[0027]
(Reference 2)
Measurement of the Raman spectrum of the electrolytic reduction membrane of Example 3, 4, 5, the 2200 cm ^-1 Example 3, absorption appeared to be due to the C≡C bond to 2160 cm ^-1 in Examples 4 and 5.
Further, it was predicted that Example 5 using tetrahydrofuran was weaker in absorption intensity than Example 4 using propylene carbonate, and had fewer triple bonds.
[0028]
Next, the embodiment which concerns on the manufacturing method of the organic electroluminescent element of this invention is listed.
12 ) The method for producing an organic electroluminescent element as described in any one of 8 ) to 11 ) above, wherein an electrode made of a conductor having a work function of 4 eV or more is used as the cathode.
13 ) The method for producing an organic electroluminescent element as described in any one of 8 ) to 12 ) above, wherein the conductor is a metal and has a redox potential of +0.5 V or less with respect to a standard hydrogen electrode.
14 ) The method for producing an organic electroluminescent element as described in any one of 8 ) to 13 ) above, wherein an electrode containing an alkali metal or an alkaline earth metal is used as the cathode.
15 ) The method for producing an organic electroluminescent element as described in any one of 8 ) to 14 ) above, wherein the electropolymerized film is a light emitting layer.
16 ) The method for producing an organic electroluminescent element as described in any one of 8 ) to 15 ) above, wherein the electrolytic polymerization film is an electron injection / transport layer.
[0029]
【The invention's effect】
According to the present invention 1 to 3 and 8 to 10 , a thin film having excellent electron injection / transport properties can be produced on the cathode without alignment in one step, and an electroluminescent device using the thin film and a method for producing the same can be provided. .
According to the fourth to sixth aspects of the present invention, it is possible to provide an electroluminescent device that is stable with respect to the environment, easily forms an electrolytic reduction film, and easily injects electrons.
According to the present invention 7 and 11 , by using a carbonyl metal complex in the polymerization system, a thin film having a higher degree of unsaturation and excellent electron injection / transport properties can be produced, and an electroluminescent device using the thin film can be provided. .

Claims

An organic electroluminescent device comprising a composite electrode in which an electropolymerized film comprising a compound of the following general formula (1) as a monomer is provided on a cathode made of a material that reflects at least visible light.
[Chemical formula 1]
^{^{^{X 1 Y 1 Z 1 C-}}} Ar-CX 2 Y 2 Z 2 ......... (1)
(In the formula, Ar is a p-xylenylene group, X ¹ , Y ¹ , Z ¹ , X ² , Y ² ,
Z ² is each hydrogen or halogen, provided that at least one of X ¹ , Y ¹ and Z ¹ is halogen, and at least one of X ² , Y ² and Z ² is halogen)

In the general formula (1), a compound in which ^two of X ¹ , Y ¹ , and Z ¹ are halogens, and ^two of X ² , Y ² , and Z ² are halogens is used as a monomer. The organic electroluminescence device according to claim 1, wherein the organic electroluminescence device has the following structural unit (2) on the main skeleton.
[Chemical formula 2]
-Ar-CL = CM- (2)
(In the formula, Ar is a p-xylenylene group, L and M are hydrogen or halogen)

In the general formula (1), a compound in which X ¹ , Y ¹ , Z ¹ , X ² , Y ² , and Z ² are all halogens is used as a monomer, and the electrolytic polymerization film has the following structural units (2) and / or The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device has (3) on the main skeleton.
[Chemical formula 3]
-Ar-CL = CM- (2)
(In the formula, Ar is a p-xylenylene group, L and M are hydrogen or halogen)
[Chemical formula 4]
-Ar-C≡C- (3)
( Wherein Ar is a p-xylenylene group)

The organic electroluminescent element according to any one of claims 1 to 3, wherein an electrode made of a conductor having a work function of 4 eV or more is used as the cathode.

5. The organic electroluminescent device according to claim 4, wherein the conductor is a metal and has a redox potential of +0.5 V or less with respect to a standard hydrogen electrode.

6. The organic electroluminescent element according to claim 1, wherein an electrode containing an alkali metal or an alkaline earth metal is used as the cathode.

The organic electroluminescent device according to any one of claims 1 to 6 , wherein the electropolymerized film is produced by a cathodic reduction reaction performed in the presence of a carbonyl metal complex.

This is a method for producing an organic electroluminescent device using an electrolytic polymerization method in which at least a pair of electrodes is immersed in a solution containing at least a monomer and an electrolyte, and an electric field is applied between the electrodes to polymerize the monomer. Then, an electrode that reflects at least visible light is used as a cathode, a compound represented by the following general formula (1) is used as a monomer, and the monomer is subjected to an electrolytic cathodic reduction reaction to be electropolymerized on the electrode. A method for producing an organic electroluminescent device, comprising forming a film and using the obtained composite electrode as an element member.
[Chemical formula 5]
^{^{^{X 1 Y 1 Z 1 C-}}} Ar-CX 2 Y 2 Z 2 ......... (1)
(In the formula, Ar is a p-xylenylene group, X ¹ , Y ¹ , Z ¹ , X ² , Y ² ,
Z ² is each hydrogen or halogen, provided that at least one of X ¹ , Y ¹ and Z ¹ is halogen, and at least one of X ² , Y ² and Z ² is halogen)

As the monomer, a compound in which ^two of X ¹ , Y ¹ , and Z ¹ are halogens and two of X ² , Y ² , and Z ² are halogens, and the resulting electropolymerized film has the following structure 9. The method for producing an organic electroluminescent element according to claim 8, wherein the unit (2) is on the main skeleton.
[Chemical formula 6]
-Ar-CL = CM- (2)
(In the formula, Ar is a p-xylenylene group, L and M are hydrogen or halogen)

A compound in which X ¹ , Y ¹ , Z ¹ , X ² , Y ² , and Z ² are all halogens is used as the monomer, and the resulting electropolymerized film has the following structural units (2) and / or (3 ) On the main skeleton. The method for producing an organic electroluminescent device according to claim 8, wherein:
[Chemical formula 7]
-Ar-CL = CM- (2)
(In the formula, Ar is a p-xylenylene group, L and M are hydrogen or halogen)
[Chemical Formula 8]
-Ar-C≡C- (3)
( Wherein Ar is a p-xylenylene group)

The method for producing an organic electroluminescent element according to any one of claims 8 to 10 , wherein an electrolytic cathodic reduction reaction is carried out in the presence of a carbonyl metal complex.