JPH03790A - electroluminescent device - Google Patents

Abstract

PURPOSE:To obtain an electroluminescent element which can be manufactured simply, emits light with high luminance, and has excellent durability by using as a luminescent layer a thin film formed by the wet thin-film method from a mixture of an organic compound having a hole-transfer capability and a fluorescent organic compound. CONSTITUTION:An electroluminescent element provided with a luminescent layer comprising a thin film of an organic substance between two electrodes, wherein the luminescent layer comprises a thin film formed by the wet thin-film method from a mixture of an electron donating organic compound having a hole-transfer capability (e.g. a high-molecular compound, such as polyvinylcarbazol, or a low-molecular compound, such as a compound of formula I or II) and a fluorescent organic compound having an electron-transfer capability (e.g. a compound of formula III or IV). This technique can give an electroluminescent element which can be manufactured simply, emits light with high luminance, and has such excellent durability that the luminous performance is maintained over a long period of time.

Description

Translated fromJapanese

【発明の詳細な説明】〔産業上の利用分野〕本発明は発光性物質からなる発光層を有し、電界を印加
することにより電界印加エネルギーを直接光エネルギー
に変換でき、従来の白熱灯、蛍光灯あるいは発光ダイオ
ード等とは異なり大面積の面状発光体の実現を可能にす
る電界発光素子に関する。[Detailed Description of the Invention] [Industrial Application Field] The present invention has a light-emitting layer made of a light-emitting substance, and by applying an electric field, the applied energy of the electric field can be directly converted into light energy. The present invention relates to an electroluminescent device that, unlike fluorescent lamps or light emitting diodes, enables the realization of large-area planar light emitters.

〔従来の技術〕[Conventional technology]

電界発光素子はその発光励起機構の違いから、（１）発
光層内での電子や正孔の局所的な移動により発光体を励
起し、交流電界でのみ発光する真性電界発光素子と、（
２）電極からの電子と正孔の注入とその発光層内での再
結合により発光体を励起し、直流電界で作動するキャリ
ヤ注入型電界発光素子の二つに分けられる。（１）の真
性電界発光型の発光素子は一般にＺｎＳにＭｎ、　Ｃｕ
等を添加した無機化合物を発光体とするものであるが、
駆動に２００ｖ以上の高い交流電界を必要とすること、
製造コストが高いこと、輝度や耐久性も不十分である等
の多くの問題点を有する。Electroluminescent elements differ in their luminescence excitation mechanisms; (1) intrinsic electroluminescent elements, which excite a luminescent body by local movement of electrons and holes within the luminescent layer, and emit light only in an alternating electric field;
2) Carrier injection type electroluminescent devices that excite a luminescent material by injecting electrons and holes from an electrode and recombining them within a luminescent layer, and operate in a DC electric field. (1) Intrinsic electroluminescence type light emitting device is generally made of ZnS with Mn and Cu.
The luminescent material is an inorganic compound added with
Requiring a high AC electric field of 200V or more for driving;
It has many problems such as high manufacturing cost and insufficient brightness and durability.

（２）のキャリヤ注入型電界発光素子は発光層として薄
膜状有機化合物を用いるようになってから高輝度のもの
が得られるようになった。このような例はたとえば特開
昭５９−１９４３９３、米国特許４，７２０゜４３２、
Ｊｐｎ、Ｊｏｕｒｎａｌ　ｏｆ　Ａｐｐｌｉｅｄ　Ｐｈ
ｙｓｉｃｓ、ｖｏｌ、２７．Ｐ７１３〜７１５に開示さ
れており、通常、正孔注入層や電子注入層が発光層の片
側あるいは両側に設けられたもので、１００Ｖ以下の直
流電界下で高輝度の発光を呈する。The carrier injection type electroluminescent device (2) has become highly luminous since the use of a thin organic compound as a light emitting layer. Such examples include, for example, Japanese Patent Application Laid-Open No. 59-194393, U.S. Patent No. 4,720°432,
Jpn, Journal of Applied Ph.
ysics, vol, 27. P713 to P715, and usually a hole injection layer or an electron injection layer is provided on one side or both sides of a light emitting layer, and exhibits high brightness light emission under a DC electric field of 100 V or less.

しかしながら、従来のキャリヤ注入型電界発光素子は、
多層構造を真空蒸着により形成しなければならないため
素子製造が煩雑であり、そのためその製造コストが高く
なる、あるいは耐久性が劣る等の難点を有する。However, conventional carrier injection type electroluminescent devices
Since the multilayer structure must be formed by vacuum evaporation, the device manufacturing is complicated, and therefore has disadvantages such as high manufacturing cost and poor durability.

〔発明が解決しようとする課題〕[Problem to be solved by the invention]

本発明は上記従来技術の実情に鑑みてなされたものであ
って、その目的はその製造が簡単であると共に高輝度発
光を呈し、しかもその発光性能が長期間に亘って持続す
る耐久性に優れた電界発光素子を提供することにある。The present invention has been made in view of the above-mentioned state of the prior art, and its purpose is to provide a light emitting device that is easy to manufacture, emits high-intensity light, and has excellent durability such that its light emitting performance lasts for a long period of time. An object of the present invention is to provide an electroluminescent device.

〔課題を解決するための手段〕[Means to solve the problem]

本発明者らは、上記目的を解決するため発光層の構成要
素について鋭意検討した結果、正孔輸送能を有する物質
の優れた薄膜形成能を利用すると共に該発光層の耐久性
付与手段として正孔輸送能を有する物質に電子輸送能を
もつ蛍光性有機化合物を混合し、かつこれを、たとえば
スピンコード法などの湿式製膜法で製膜した混合薄膜を
発光層とした場合には高輝度で耐久性に富み、しかもそ
の製造が容易な電界発光素子が得られることを見い出し
、本発明を完成するに至った。In order to solve the above object, the present inventors conducted extensive studies on the constituent elements of the light-emitting layer, and as a result, the present inventors utilized the excellent thin film forming ability of a substance having hole-transporting ability, and discovered that it is possible to utilize the excellent thin film-forming ability of a substance that has a hole-transporting ability, and to use a positive light-emitting layer as a means for imparting durability to the light-emitting layer. High brightness can be achieved when a light-emitting layer is a mixed thin film made by mixing a fluorescent organic compound with electron transporting ability with a substance having hole transporting ability, and using a wet film forming method such as the spin-coding method. The inventors have discovered that an electroluminescent device that is highly durable and easy to manufacture can be obtained by using the method, and has completed the present invention.

すなわち、本発明によれば、二つの電極間に有機物薄膜
層よりなる発光層を設けた電界発光素子において、発光
層として正孔輸送能を有する有機化合物と電子輸送能を
有する発光性有機化合物とからなり、かつこれらを湿式
製膜法で製膜化した混合体薄膜を用いたことを特徴とす
る電界発光素子が提供される。That is, according to the present invention, in an electroluminescent device in which a light emitting layer made of an organic thin film layer is provided between two electrodes, the light emitting layer is made of an organic compound having a hole transporting ability and a luminescent organic compound having an electron transporting ability. Provided is an electroluminescent device characterized in that it uses a thin film of a mixture of the following and formed by a wet film forming method.

以下、図面に沿って本発明の詳細な説明する。The present invention will be described in detail below with reference to the drawings.

第１図は本発明の電界発光素子の模式断面図である。１
はガラス基板ないしは合成樹脂基板であり、２は基板上
に形成された陽極である。２は金、白金、パラジウムな
どの金属の蒸着、スパッタ膜あるいはスズ、インジウム
−スズの酸化薄膜、有機導電性薄膜等で形成され、発光
を取り出すため。FIG. 1 is a schematic cross-sectional view of the electroluminescent device of the present invention. 1
2 is a glass substrate or a synthetic resin substrate, and 2 is an anode formed on the substrate. 2 is formed of a vapor-deposited or sputtered film of metal such as gold, platinum, or palladium, or a thin oxide film of tin, indium-tin, or an organic conductive thin film, in order to extract light emission.

４００ｎ＋＊以上の波長領域で透明であることが望まし
い、３は正孔輸送能を有する有機化合物と電子輸送能を
有する蛍光性有機化合物との混合物を湿式製膜法により
製膜化した薄膜でその厚みは２００〜３０００人であり
、好ましくは４００−１５００人である。It is desirable that it be transparent in the wavelength range of 400n+* or more. 3 is a thin film formed by a wet film forming method from a mixture of an organic compound having a hole transporting ability and a fluorescent organic compound having an electron transporting ability. The thickness is 200-3000 people, preferably 400-1500 people.

正孔輸送能を有する有機化合物としては、ポリビニルカ
ルバゾールのような正孔輸送能に優れた高分子化合物や
正孔輸送能に優れた低分子化合物が挙げられる。低分子
化合物の例としては、トリフェニルアミン類、スチルベ
ン誘導体類、オキサジアゾール類等が挙げられ、その具
体例としては、たとえば以下のようなものが例示される
。Examples of the organic compound having a hole transporting ability include a high molecular compound having an excellent hole transporting ability such as polyvinylcarbazole, and a low molecular compound having an excellent hole transporting ability. Examples of low molecular weight compounds include triphenylamines, stilbene derivatives, oxadiazoles, etc. Specific examples thereof include the following.

また、発光層には必要により、たとえばビスフェノール
−Ａ−ポリカーボネート、ポリスチレンのような樹脂バ
インダーを添加することもできる。Further, a resin binder such as bisphenol-A-polycarbonate or polystyrene may be added to the light-emitting layer if necessary.

蛍光性有機化合物としては、電子輸送能を持ち。As a fluorescent organic compound, it has electron transport ability.

固体で強い蛍光を発する物質であれば、特に薄膜形成能
に優れた物質である必要はない。このような物質として
はたとえば、ペリノン誘導体、キノリン錯体誘導体が挙
げられるが、その具体例としては次のような物質等を挙
げることができる。As long as the substance is solid and emits strong fluorescence, it does not need to be a substance particularly excellent in thin film forming ability. Examples of such substances include perinone derivatives and quinoline complex derivatives, and specific examples thereof include the following substances.

本発明において用いる正孔輸送能を有する有機化合物と
蛍光性有機化合物との混合組成は重量比で１０／９０か
ら９０／１０まで変えることができるが、最適混合比は
混合物の薄膜形成能の観点等から決定される。The mixed composition of the organic compound having hole transport ability and the fluorescent organic compound used in the present invention can be varied from 10/90 to 90/10 in terms of weight ratio, but the optimum mixing ratio is determined from the viewpoint of the thin film forming ability of the mixture. Determined from etc.

また、発光層に樹脂バインダーを配合する場合、その配
合量は正孔輸送能を有する有機化合物と蛍光性有機化合
物の合計量１．００重量部に対して５〜５０重量部使用
することが望ましい。Furthermore, when a resin binder is blended into the light-emitting layer, it is desirable that the blending amount is 5 to 50 parts by weight based on 1.00 parts by weight of the total amount of the organic compound having hole transport ability and the fluorescent organic compound. .

本発明において、発光層を形成するには前記正孔輸送能
を有する有機化合物と蛍光性有機化合物の混合物あるい
はこれらに樹脂バインダーを加えた混合物をジクロルメ
タンなどの溶媒に溶解又は分散して、濃度１．０〜６．
０重量％の溶液又は分散液とし、基板上にスピンコード
法などの湿式製膜法により製膜すればよい。In the present invention, in order to form a light-emitting layer, a mixture of the organic compound having hole transport ability and a fluorescent organic compound, or a mixture of these with a resin binder added thereto, is dissolved or dispersed in a solvent such as dichloromethane, and the concentration is 1. .0-6.
A 0% by weight solution or dispersion may be prepared, and a film may be formed on a substrate by a wet film forming method such as a spin code method.

この場合、溶液又は分散液からの基板の引き上げ方法を
工夫することにより発光層の膜厚や性状を調製すること
も可能である。In this case, it is also possible to adjust the thickness and properties of the light-emitting layer by devising a method for lifting the substrate from the solution or dispersion.

４は陰極であり、金属の真空蒸着により前記混合膜上に
形成される。その材質としては真空蒸着可能なあらゆる
金属が使用され得るが、特にＭｇ、Ａ１．　Ａｇ、Ｉｎ
などの仕事関数が小さい金属が望ましい。4 is a cathode, which is formed on the mixed film by vacuum evaporation of metal. As the material, any metal that can be vacuum-deposited can be used, but especially Mg, A1. Ag, In
A metal with a small work function, such as

本発明の電界発光素子の有機物薄膜層は単一層であるこ
とを特徴としているが、素子の耐久性の向上、正孔や電
子の注入効率の一層の向上の為に、有機物薄膜層と電極
の間に−ないし数層の有機物層を挿入してもよい。The organic thin film layer of the electroluminescent device of the present invention is characterized by being a single layer, but in order to improve the durability of the device and further improve the injection efficiency of holes and electrons, the organic thin film layer and the electrode are One to several organic layers may be inserted in between.

〔効果〕〔effect〕

本発明の電界発光素子はその発光薄膜層として正孔輸送
能を有する有機化合物と蛍光性有機化合物との混合物を
湿式製膜法より製膜した混合体薄膜層を用いたことから
、素子の製造を容易にし、しかも素子の高輝度発光と耐
久性を実現し、広範な有機蛍光物質を電界発光素子用の
発光体に利用できる等の多くの利点を有する。The electroluminescent device of the present invention uses a mixture thin film layer formed from a mixture of an organic compound having a hole transport ability and a fluorescent organic compound by a wet film forming method as its light emitting thin film layer. It has many advantages, such as facilitating the use of electroluminescent devices, achieving high brightness and durability, and allowing use of a wide variety of organic fluorescent materials as light emitters for electroluminescent devices.

〔実施例〕〔Example〕

以下、実施例により本発明を更に詳細に説明する。Hereinafter, the present invention will be explained in more detail with reference to Examples.

実施例１陽極として、インジウム−スズ酸化物（ＩＴＯ）ガラス
（ＩｌＯＹＡ製）を中性洗剤により洗浄し、次いでエタ
ノール中で約１０分間超音波洗浄した。これを沸騰した
エタノール中に約１分間入れ、取り出した後、すぐに送
風乾燥を行った。つぎに正孔輸送能を有する有機化合物
であるポリビニルカルバゾールと蛍光性有機化合物であ
る下記式で示されるペリノン誘導体（りの等モル混合物
をジクロロメタンに溶かし、濃度約４．０重量％の溶液
とし、ＩＴＯ基板上にスピンコード法により製膜した。Example 1 As an anode, indium-tin oxide (ITO) glass (manufactured by IlOya) was cleaned with a neutral detergent and then ultrasonically cleaned in ethanol for about 10 minutes. This was placed in boiling ethanol for about 1 minute, and after being taken out, it was immediately blown dry. Next, an equimolar mixture of polyvinylcarbazole, which is an organic compound having a hole transport ability, and a perinone derivative represented by the following formula, which is a fluorescent organic compound, is dissolved in dichloromethane to make a solution with a concentration of about 4.0% by weight, A film was formed on an ITO substrate by a spin code method.

膜厚は約１０００人であった。またこのときの回転数は
１５００ｒ、ｐ、■であった。The film thickness was about 1000 people. Further, the rotation speed at this time was 1500 r, p, ■.

つぎにこの発光層上に、０．１ｃｄ、厚み１５００人の
阿ｇ−Ａｇ電極を蒸着した。このようにして得られた発
光素子は、ＩＴＯ側にプラスのバイアスをかけた場合に
５５０ｎｍをピークとする黄色の発光を呈した。Next, a 0.1 cd Ag-Ag electrode with a thickness of 1500 mm was deposited on this light emitting layer. The thus obtained light emitting device exhibited yellow light emission with a peak wavelength of 550 nm when a positive bias was applied to the ITO side.

また、駆動電圧６０Ｖ、電流密度１００ｍＡ／ａＩにお
いて、５０ｃｄ／　ｒｒｒの輝度を示した。また、この
発光素子は、湿度を十分に除去した状唐において空気中
で作動させることが可能であった。Further, at a driving voltage of 60 V and a current density of 100 mA/aI, a luminance of 50 cd/rrr was exhibited. Furthermore, this light-emitting element could be operated in air with sufficient humidity removed.

蛍光性有機化合物として下記のキレート化合物を用いた
以外は実施例１と同様にして発光素子を作製した。得ら
れた発光素子は５２０ｎ−をピークとする黄色の発光を
呈した、また駆動電圧６６Ｖ、電流密度１００閣Ａ／ｄ
で１２０ｃｄ／ボの輝度を示した。A light emitting device was produced in the same manner as in Example 1 except that the following chelate compound was used as the fluorescent organic compound. The obtained light emitting device exhibited yellow light emission with a peak of 520 n-, and the driving voltage was 66 V and the current density was 100 A/d.
It showed a brightness of 120 cd/bo.

実施例３蛍光性有機化合物として下記のシクロペンタジェン誘導
体を用いた以外は実施例１と同様にして発光素子を作製
した。Example 3 A light emitting device was produced in the same manner as in Example 1 except that the following cyclopentadiene derivative was used as the fluorescent organic compound.

得られた発光素子は、ＩＴＯ側にプラスのバイアスをか
けた場合に４６０ｎｍをピークとする青色の発光を呈し
た。また、駆動電圧７２Ｖ、電流密度１００■Ａ／ｄに
おいて、１０５ｃｄ／−の輝度を示した。The obtained light emitting device exhibited blue light emission with a peak wavelength of 460 nm when a positive bias was applied to the ITO side. Further, at a driving voltage of 72 V and a current density of 100 A/d, a luminance of 105 cd/- was exhibited.

実施例２実施例４実施例１において、発光層形成成分を下記のものに代え
た以外は実施例１と同様にして発光素子を作製した。Example 2 Example 4 A light emitting device was produced in the same manner as in Example 1 except that the components for forming the light emitting layer were replaced with the following.

〔発光層形成成分〕[Light-emitting layer forming component]

正孔輸送能を有する有機化合物であるＮ、Ｎ’−ジフェ
ニル−Ｎ、Ｎ’−（３−メチルフェニル）−１，１’−
ビフェニル−４，４′−ジアミンと蛍光性有機化合物で
ある前記ペリノン誘導体（Ｉ）およびビス−フェノール
Ａ−ポリカーボネート（樹脂バインダー）を重量比で４
＝４：１としてジクロロメタンに溶解、分散したもの。N,N'-diphenyl-N,N'-(3-methylphenyl)-1,1'- which is an organic compound with hole transport ability
The weight ratio of biphenyl-4,4'-diamine, the perinone derivative (I) which is a fluorescent organic compound, and bis-phenol A-polycarbonate (resin binder) is 4.
= 4:1 dissolved and dispersed in dichloromethane.

得られた発光素子は５５０ｎｍをピークとする黄色発光
を呈した。また駆動電圧５５ｖ、電流密度１００ｍＡ／
ボで７５ｃｄ／ポの輝度を示した。The obtained light emitting device exhibited yellow light emission with a peak wavelength of 550 nm. Also, driving voltage 55v, current density 100mA/
It showed a brightness of 75 cd/po.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明に係る電界発光素子の一例の断面図であ
る。１は基体、２は陽極、３は正孔輸送能を有する有機化合
物と蛍光性有機化合物の混合体薄膜層、４は陰極である
。第FIG. 1 is a sectional view of an example of an electroluminescent device according to the present invention. 1 is a substrate, 2 is an anode, 3 is a thin film layer of a mixture of an organic compound having a hole transport ability and a fluorescent organic compound, and 4 is a cathode. No.

Claims (1)

Translated fromJapanese

【特許請求の範囲】[Claims]（１）二つの電極間に有機物薄膜層よりなる発光層を設
けた電界発光素子において、発光層として正孔輸送能を
有する電子供与性有機化合物と電子輸送能を有する蛍光
性有機化合物とからなり、かつ湿式製膜法で形成された
混合体薄膜を用いたことを特徴とする電界発光素子。(1) In an electroluminescent device in which a light-emitting layer made of a thin organic film layer is provided between two electrodes, the light-emitting layer is made of an electron-donating organic compound having a hole-transporting ability and a fluorescent organic compound having an electron-transporting ability. An electroluminescent device characterized by using a mixture thin film formed by a wet film forming method.