JP2000315582A - Organic el element - Google Patents
Organic el elementInfo
- Publication number
- JP2000315582A JP2000315582A JP11126146A JP12614699A JP2000315582A JP 2000315582 A JP2000315582 A JP 2000315582A JP 11126146 A JP11126146 A JP 11126146A JP 12614699 A JP12614699 A JP 12614699A JP 2000315582 A JP2000315582 A JP 2000315582A
- Authority
- JP
- Japan
- Prior art keywords
- layer
- light
- organic
- cathode
- light emitting
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 229910052751 metal Inorganic materials 0.000 claims abstract description 8
- 239000002184 metal Substances 0.000 claims abstract description 8
- 239000010410 layer Substances 0.000 claims description 136
- 239000000758 substrate Substances 0.000 claims description 27
- 239000000463 material Substances 0.000 claims description 8
- 150000002894 organic compounds Chemical class 0.000 claims description 4
- 239000011368 organic material Substances 0.000 claims description 4
- 239000012044 organic layer Substances 0.000 claims 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 abstract description 5
- 239000011521 glass Substances 0.000 abstract description 5
- RBTKNAXYKSUFRK-UHFFFAOYSA-N heliogen blue Chemical compound [Cu].[N-]1C2=C(C=CC=C3)C3=C1N=C([N-]1)C3=CC=CC=C3C1=NC([N-]1)=C(C=CC=C3)C3=C1N=C([N-]1)C3=CC=CC=C3C1=N2 RBTKNAXYKSUFRK-UHFFFAOYSA-N 0.000 abstract description 3
- 239000000126 substance Substances 0.000 abstract description 3
- 238000002347 injection Methods 0.000 description 13
- 239000007924 injection Substances 0.000 description 13
- 230000031700 light absorption Effects 0.000 description 9
- 238000004544 sputter deposition Methods 0.000 description 5
- 230000004888 barrier function Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000010408 film Substances 0.000 description 4
- 230000004313 glare Effects 0.000 description 4
- 230000005525 hole transport Effects 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 238000007740 vapor deposition Methods 0.000 description 4
- 230000005684 electric field Effects 0.000 description 3
- 238000000206 photolithography Methods 0.000 description 3
- 239000004020 conductor Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- BCMCBBGGLRIHSE-UHFFFAOYSA-N 1,3-benzoxazole Chemical compound C1=CC=C2OC=NC2=C1 BCMCBBGGLRIHSE-UHFFFAOYSA-N 0.000 description 1
- MXVLMYZRJAHEIS-UHFFFAOYSA-N 1-(2-phenylphenyl)naphthalene Chemical compound C1=CC=CC=C1C1=CC=CC=C1C1=CC=CC2=CC=CC=C12 MXVLMYZRJAHEIS-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 238000005401 electroluminescence Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- RHZWSUVWRRXEJF-UHFFFAOYSA-N indium tin Chemical compound [In].[Sn] RHZWSUVWRRXEJF-UHFFFAOYSA-N 0.000 description 1
- NJWNEWQMQCGRDO-UHFFFAOYSA-N indium zinc Chemical compound [Zn].[In] NJWNEWQMQCGRDO-UHFFFAOYSA-N 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 229910001512 metal fluoride Inorganic materials 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 230000006798 recombination Effects 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000004528 spin coating Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
- H10K50/00—Organic light-emitting devices
- H10K50/80—Constructional details
- H10K50/86—Arrangements for improving contrast, e.g. preventing reflection of ambient light
- H10K50/865—Arrangements for improving contrast, e.g. preventing reflection of ambient light comprising light absorbing layers, e.g. light-blocking layers
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Electroluminescent Light Sources (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、透明な基板の一面
上に陽極、有機化合物からなる発光層、陰極を順次形成
してなり、該基板の他面から発光層の光を取り出すよう
にした有機ＥＬ（エレクトロルミネッセンス）素子に関
する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises an anode, a light-emitting layer made of an organic compound, and a cathode formed on one surface of a transparent substrate in order, and the light of the light-emitting layer is extracted from the other surface of the substrate. The present invention relates to an organic EL (electroluminescence) element.
【０００２】[0002]
【従来の技術】この種の有機ＥＬ素子は、ガラス基板等
の透明な基板（透明基板）と、該基板の一面（素子形成
面）上にＩＴＯ（インジウム−錫の酸化物）等の導電性
材料からなる透明な陽極、有機化合物（有機蛍光体）か
らなる発光層、ＡｌやＭｇなどの金属からなる陰極を順
次積層してなる素子部とを有する。2. Description of the Related Art An organic EL device of this type includes a transparent substrate (transparent substrate) such as a glass substrate and a conductive material such as ITO (indium-tin oxide) formed on one surface (device forming surface) of the substrate. It has an element section in which a transparent anode made of a material, a light emitting layer made of an organic compound (organic phosphor), and a cathode made of a metal such as Al or Mg are sequentially laminated.
【０００３】そして、陽極と陰極の間に直流電界を印加
すると、陽極から注入された正孔（ホール）と陰極から
注入された電子とが発光層内にて再結合し、そのエネル
ギーを受けて発光層中の蛍光体が発光し、この発光層か
らの光を基板の他面（出光面）から取り出すようになっ
ている。このような有機ＥＬ素子は、自己発光のため、
視認性に優れ、かつ数Ｖ〜数十Ｖの低電圧駆動が可能な
ため駆動回路を含めた軽量化が可能である。そこで、薄
膜型ディスプレイ、照明、バックライトとしての活用が
期待できる。[0003] When a DC electric field is applied between the anode and the cathode, holes injected from the anode and electrons injected from the cathode recombine in the light emitting layer, and receive the energy to receive the energy. The phosphor in the light emitting layer emits light, and light from this light emitting layer is extracted from the other surface (light emitting surface) of the substrate. Since such an organic EL element emits light by itself,
Since it is excellent in visibility and can be driven at a low voltage of several V to several tens of V, it is possible to reduce the weight including the drive circuit. Therefore, it can be expected to be used as a thin film display, lighting, and backlight.
【０００４】ここで、陰極には上述したように金属膜が
用いられるため、透明基板側からの外部入射光が、陰極
である金属で全反射し、映り込みを起こすなど、コント
ラスト低下の原因となっていた。そこで、公知技術とし
て、透明基板の出光面である他面にカラーフィルタや円
偏向フィルタを配置するなどして、周辺環境の映り込み
（例えば観察者の顔が映る等）を防止する技術が製品化
されている。Here, since the metal film is used for the cathode as described above, externally incident light from the transparent substrate side is totally reflected by the metal serving as the cathode, causing glare and causing a decrease in contrast. Had become. Therefore, as a well-known technology, a technology for preventing reflection of the surrounding environment (for example, a face of an observer is reflected) by disposing a color filter or a circularly polarizing filter on the other surface which is the light emitting surface of the transparent substrate is a product. Has been
【０００５】[0005]
【発明が解決しようとする課題】しかしながら、本発明
者等は、このような事情のもとで有機ＥＬ素子の構造を
検討した結果、出光側に円偏向フィルタを配置すること
で、その光吸収作用により、外部光の反射は低減でき上
記映り込みは防止できるものの、発光層からの光の輝度
が例えば４０％程度に低下してしまうことが明らかにな
った。However, the present inventors have studied the structure of the organic EL element under such circumstances, and as a result, by disposing a circularly polarizing filter on the light exit side, the light absorption of the element has been considered. It has been clarified that, although the reflection of external light can be reduced by the action and the reflection can be prevented, the luminance of the light from the light emitting layer is reduced to, for example, about 40%.
【０００６】本発明は上記問題に鑑み、輝度を低下させ
ることなく、映り込みを防止可能な有機ＥＬ素子を提供
することを目的とする。SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an organic EL device capable of preventing glare without lowering luminance.
【０００７】[0007]
【課題を解決するための手段】本発明者等は、発光層か
らの光の輝度を低下させないため、可視光に対して吸収
効果のある層（光吸収層）を、発光層に対して出光側と
反対の位置、即ち発光層と陰極との間に配置することに
より、陰極からの外部光の反射を吸収させ映り込みを防
止することに着目し、この配置構成としたものについて
鋭意検討を行った。In order to prevent the luminance of light from the light emitting layer from lowering, the present inventors provide a layer having a visible light absorbing effect (light absorbing layer) to the light emitting layer. Paying attention to preventing the reflection by absorbing the reflection of external light from the cathode by arranging it at the position opposite to the side, that is, between the light emitting layer and the cathode, diligently studying this arrangement configuration went.
【０００８】ここで、光吸収層を発光層と陰極との間に
配置する場合、該光吸収層としては、陰極から発光層へ
の電子の注入を妨げない材料を用いることが必要であ
る。本発明者等の検討によれば、通常、有機ＥＬ素子に
おける陰極側の発光層または電子輸送層に用いられる材
料の伝導帯最低準位は−２．７ｅＶ以下である。従っ
て、これら発光層または電子輸送層に電子注入を行う陰
極の伝導帯最低準位も、注入障壁を大きくしないために
は、−２．７ｅＶ以下であることが好ましい。Here, when the light absorbing layer is disposed between the light emitting layer and the cathode, it is necessary to use a material that does not hinder the injection of electrons from the cathode to the light emitting layer. According to the study of the present inventors, the conduction band lowest level of the material used for the light emitting layer or the electron transport layer on the cathode side of the organic EL device is usually -2.7 eV or less. Therefore, the conduction band lowest level of the cathode for injecting electrons into the light emitting layer or the electron transport layer is preferably -2.7 eV or less in order not to increase the injection barrier.
【０００９】従って、発光層と陰極との間に介在する光
吸収層においても、その伝導帯最低準位が−２．７ｅＶ
よりも高くなる（大きくなる）と、光吸収層が電子の注
入障壁として作用し、電子の注入を妨げ、結果として高
輝度な発光が得られなくなるため、伝導帯最低準位が−
２．７ｅＶ以下が好ましい。請求項１記載の発明は、上
記知見に基づいてなされたもので、陰極（５）と発光層
（３）との間に、伝導帯最低準位が−２．７ｅＶ以下で
ある有機材料からなり可視光を吸収する光吸収層（４）
を設けたことを特徴としている。Therefore, even in the light absorbing layer interposed between the light emitting layer and the cathode, the conduction band lowest level is -2.7 eV.
When the height is higher than that, the light absorption layer acts as an electron injection barrier, hinders electron injection, and as a result, high-luminance light emission cannot be obtained.
It is preferably 2.7 eV or less. The invention according to claim 1 has been made based on the above findings, and is made of an organic material having a conduction band lowest level of -2.7 eV or less between the cathode (5) and the light emitting layer (3). Light absorbing layer that absorbs visible light (4)
It is characterized by having provided.
【００１０】本発明によれば、発光層（３）に対して出
光側の基板（１）とは反対側に位置する陰極（５）と、
該発光層との間に光吸収層（４）を設けたから、該光吸
収層によって、該発光層からの出光は吸収されないが、
該陰極に向かう外部光及び該外部光の該陰極からの反射
光は吸収される。また、該光吸収層の伝導帯最低準位が
−２．７ｅＶ以下であるから、該光吸収層が陰極から発
光層へ電子注入する際の注入障壁とならないため、陰極
から発光層への電子注入特性を阻害することが無い。従
って、本発明によれば、輝度を低下させることなく、映
り込みを防止可能な有機ＥＬ素子を提供することができ
る。According to the present invention, a cathode (5) located on the side opposite to the light emitting side substrate (1) with respect to the light emitting layer (3);
Since the light absorbing layer (4) is provided between the light absorbing layer and the light emitting layer, light emitted from the light emitting layer is not absorbed by the light absorbing layer.
External light toward the cathode and reflected light of the external light from the cathode are absorbed. In addition, since the light absorption layer has a conduction band lowest level of -2.7 eV or less, the light absorption layer does not act as an injection barrier when injecting electrons from the cathode to the light emitting layer. Does not impair injection characteristics. Therefore, according to the present invention, it is possible to provide an organic EL element capable of preventing glare without lowering luminance.
【００１１】また、請求項２記載の発明は、光吸収層
（４）よりも陰極（５）側に、可視光を吸収し且つ導電
性を有する導電層（６）を配置したことを特徴としてお
り、該導電層によって、該陰極における外部光の反射を
抑制できるため、請求項１の発明の効果をより高いレベ
ルで実現することができる。請求項３記載の発明は、請
求項２の発明における導電層（６）の具体的配置構成を
提供するもので、陰極（５）を、光吸収層（４）側に位
置する第１の層（５１）と該第１の層よりも該光吸収層
から離れて位置する第２の層（５２）との２層構造を有
するものとし、該導電層を、これら第１及び第２の層の
間に挟んだことを特徴としている。The invention according to claim 2 is characterized in that a conductive layer (6) that absorbs visible light and has conductivity is arranged closer to the cathode (5) than the light absorbing layer (4). Since the reflection of external light on the cathode can be suppressed by the conductive layer, the effect of the first aspect can be realized at a higher level. The invention according to claim 3 provides a specific arrangement of the conductive layer (6) in the invention according to claim 2, wherein the cathode (5) is provided on the first layer located on the light absorption layer (4) side. (51) and a second layer (52) located farther from the light absorbing layer than the first layer, and the conductive layer is composed of the first and second layers. It is characterized by being sandwiched between.
【００１２】また、請求項４記載の発明は、請求項３記
載の陰極（５）の第１の層（５１）を、仕事関数が４以
下の材料よりなるものとしたことを特徴としている。こ
れは、上述のように、陰極の伝導帯最低準位は−２．７
ｅＶ以下であることが好ましく、発光層（３）への電子
注入側となる該第１の層を、そのレベルとするためには
仕事関数が４以下の材料とすることで実現できる。The invention according to claim 4 is characterized in that the first layer (51) of the cathode (5) according to claim 3 is made of a material having a work function of 4 or less. This means that, as described above, the conduction band lowest level of the cathode is -2.7.
It is preferably eV or less, and in order to make the first layer on the electron injection side into the light emitting layer (3) at that level, it can be realized by using a material having a work function of 4 or less.
【００１３】なお、上記各手段の括弧内の符号は、後述
する実施形態に記載の具体的手段との対応関係を示す一
例である。The reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.
【００１４】[0014]
【発明の実施の形態】（第１実施形態）図１は、本実施
形態に係る有機ＥＬ素子１００の概略断面図である。有
機ＥＬ素子１００においては、透明（半透明も含む）な
基板１の一面（素子形成面）１ａ側に陽極２、有機化合
物からなる発光層３、光吸収層４、金属からなる陰極５
が順次積層されており、基板１の他面（出光面）１ｂ側
から発光層３の光を取り出すようになっている。(First Embodiment) FIG. 1 is a schematic sectional view of an organic EL device 100 according to the present embodiment. In the organic EL device 100, an anode 2, a light emitting layer 3 made of an organic compound, a light absorbing layer 4, and a cathode 5 made of a metal are provided on one surface (device forming surface) 1 a of a transparent (including translucent) substrate 1.
Are sequentially laminated, and light of the light emitting layer 3 is extracted from the other surface (light emitting surface) 1b side of the substrate 1.
【００１５】基板１は例えばガラス基板などの可視光に
対して透明性（半透明も含む）を有した基板（本例では
ガラス基板）である。陽極２は透明性を有した導電膜で
あり、例えばインジウム−錫の酸化物（ＩＴＯ）やイン
ジウム−亜鉛の酸化物等の導電性材料からなり、その膜
厚は例えば１００ｎｍから１μｍ程度であり、好ましく
は１５０ｎｍ程度である。本例では、陽極２は１５０ｎ
ｍ程度の厚さのＩＴＯとしている。The substrate 1 is a substrate (a glass substrate in this example) having transparency (including translucent) to visible light, such as a glass substrate. The anode 2 is a conductive film having transparency and is made of a conductive material such as an oxide of indium-tin (ITO) or an oxide of indium-zinc, and has a thickness of, for example, about 100 nm to 1 μm. Preferably, it is about 150 nm. In this example, the anode 2 is 150 n
The thickness of the ITO is about m.
【００１６】発光層３は単一層でも複数層でもよく、正
孔輸送性や電子輸送性を有する有機蛍光体等から構成さ
れている。本例では、発光層３は、陽極（ＩＴＯ）２側
に位置するα−ナフチル・フェニル・ベンゼン（伝導帯
最低準位：−２．３ｅＶ、価電子帯最高準位：−５．３
ｅＶ）を主材料とする正孔輸送層３１と、光吸収層４及
び陰極５側に位置し正孔輸送層３１と接するベンゾオキ
サゾールフェライト亜鉛錯体（伝導帯最低準位：−２．
９ｅＶ、価電子帯最高準位：−５．８ｅＶ）を主材料と
する電子輸送層３２との２層からなる。The light emitting layer 3 may be a single layer or a plurality of layers, and is composed of an organic phosphor having a hole transporting property and an electron transporting property. In this example, the light-emitting layer 3 is formed of α-naphthyl phenyl benzene (conduction band lowest level: -2.3 eV, valence band highest level: -5.3) located on the anode (ITO) 2 side.
eV), a benzoxazole ferrite zinc complex (conduction band lowest level: −2. eV), which is located on the light absorbing layer 4 and the cathode 5 side and is in contact with the hole transport layer 31.
9 eV and the valence band highest level: -5.8 eV).
【００１７】このような正孔輸送層３１と電子輸送層３
２との２層構造の場合、その構造を限定するものではな
いが、正孔輸送層３１の層厚は４０ｎｍ、電子輸送層３
２の層厚は６０ｎｍ程度である。電子輸送層３２と陰極
５との間に位置する光吸収層４は、伝導帯最低準位が−
２．７ｅＶ以下である有機材料からなり、ここを通過す
る可視光を吸収するように厚さ等が設計されている。本
例では、光吸収層４として、図２に示す化学式を有する
銅フタロシアニン（伝導帯最低準位：−３．６ｅＶ、価
電子帯最高準位：−５．３ｅＶ）を５０ｎｍの層厚で位
置した構造とする。Such a hole transport layer 31 and an electron transport layer 3
2, the thickness of the hole transport layer 31 is 40 nm, and the thickness of the electron transport layer 3 is not limited.
The layer thickness of No. 2 is about 60 nm. The light absorption layer 4 located between the electron transport layer 32 and the cathode 5 has a conduction band lowest level of −
It is made of an organic material having a voltage of 2.7 eV or less, and is designed to have a thickness or the like so as to absorb visible light passing therethrough. In the present example, copper phthalocyanine (conduction band lowest level: -3.6 eV, valence band highest level: -5.3 eV) having the chemical formula shown in FIG. Structure.
【００１８】陰極５は金属からなる膜であり、例えばＭ
ｇとＡｇ、ＡｌとＬｉなどの金属原子の混合層を用いる
ことができるが、金属材料のみならず、ＬｉＦ／Ａｌや
ＬｉＯ／Ａｌなどの２層構造のように金属フッ化物や金
属酸化物を含んだものでもよい。本例では、陰極５とし
て、ＬｉＦ／ＡｌまたはＭｇとＡｇの共蒸着層を１００
ｎｍ程度配置した構造とする。The cathode 5 is a film made of metal.
A mixed layer of metal atoms such as g and Ag, and Al and Li can be used. Not only a metal material but also a metal fluoride or a metal oxide such as a two-layer structure of LiF / Al or LiO / Al can be used. It may be included. In this example, a co-evaporated layer of LiF / Al or Mg and Ag
The structure is arranged in about nm.
【００１９】本実施形態における発光層３は、電界印加
時に、陽極２または正孔輸送層３１より正孔を注入する
ことが可能であり、かつ陰極５または電子輸送層３２よ
り電子が注入できる注入機能、注入した電荷を電界の力
で移動させる輸送機能、電子と正孔の再結合の場を提供
し、これを発光につなげる発光機能などを有している。
なお、電子の注入されやすさと正孔の注入されやすさに
は違いがあってもかまわない。The light emitting layer 3 in this embodiment is capable of injecting holes from the anode 2 or the hole transport layer 31 when applying an electric field, and capable of injecting electrons from the cathode 5 or the electron transport layer 32. It has a function, a transport function of moving injected charges by the force of an electric field, and a light-emitting function of providing a field for recombination of electrons and holes and connecting it to light emission.
Note that there may be a difference between the ease of electron injection and the ease of hole injection.
【００２０】かかる有機ＥＬ素子１００は、例えば次の
ようにして製造できる。即ち、ガラス基板等の透明な基
板１を用意し、基板１の一面１ａに、上記ＩＴＯ等の導
電膜をスパッタや蒸着等により形成した後、フォトリソ
グラフィ技術を用いて、パターニングすることで陽極２
を形成する。次に、各種の有機材料を、蒸着法、スパッ
タリング法、スピンコート、スクリーン印刷や微粒子吹
き付け法を用いて成膜することにより、発光層３及び光
吸収層４を形成する。そして、スパッタや蒸着、および
フォトリソグラフィ技術等により、陰極５を形成する。
こうして有機ＥＬ素子１００が出来上がる。The organic EL device 100 can be manufactured, for example, as follows. That is, a transparent substrate 1 such as a glass substrate is prepared, and a conductive film such as ITO is formed on one surface 1a of the substrate 1 by sputtering or vapor deposition, and then patterned by photolithography to form an anode 2.
To form Next, the light-emitting layer 3 and the light-absorbing layer 4 are formed by depositing various organic materials by using an evaporation method, a sputtering method, a spin coating method, a screen printing method, or a fine particle spraying method. Then, the cathode 5 is formed by sputtering, vapor deposition, photolithography, or the like.
Thus, the organic EL element 100 is completed.
【００２１】ところで、本実施形態によれば、光取り出
し側（出光側）の基板１の他面１ｂから外部光が入射し
陰極５に向かうが、陰極５と発光層３との間に光吸収層
４を設けたから、この光吸収層４によって該外部光及び
陰極５からの外部光の反射光は吸収される。また、光吸
収層４は、発光層３に対して、出光側の基板１とは反対
側に位置するから、発光層３からの出光は吸収されな
い。According to the present embodiment, external light enters from the other surface 1 b of the substrate 1 on the light extraction side (light emission side) and travels toward the cathode 5, but light absorption occurs between the cathode 5 and the light emitting layer 3. Since the layer 4 is provided, the external light and the reflected light of the external light from the cathode 5 are absorbed by the light absorbing layer 4. Further, since the light absorbing layer 4 is located on the opposite side of the light emitting layer 3 from the light emitting side of the substrate 1, the light emitted from the light emitting layer 3 is not absorbed.
【００２２】また、光吸収層４の伝導帯最低準位が−
２．７ｅＶ以下であるから、光吸収層４が陰極５から発
光層３へ電子注入する際の注入障壁とならないため、陰
極５から発光層３への電子注入特性を阻害することが無
い。従って、本実施形態によれば、輝度を低下させるこ
となく、映り込みを防止可能な有機ＥＬ素子を提供する
ことができる。The lowest level of the conduction band of the light absorption layer 4 is-
Since it is 2.7 eV or less, the light absorption layer 4 does not act as an injection barrier when injecting electrons from the cathode 5 into the light emitting layer 3, so that the characteristics of electron injection from the cathode 5 to the light emitting layer 3 are not hindered. Therefore, according to the present embodiment, it is possible to provide an organic EL element capable of preventing glare without lowering luminance.
【００２３】（第２実施形態）図３に、本第２実施形態
に係る有機ＥＬ素子２００の概略断面図を示す。本実施
形態は、上記第１実施形態を変形したものであり、光吸
収層４よりも陰極５側に、可視光を吸収し且つ導電性を
有する導電層６を配置したことが、異なる。以下、上記
第１実施形態と異なるところについて述べ、同一部分は
説明を省略することとする。(Second Embodiment) FIG. 3 is a schematic sectional view of an organic EL device 200 according to a second embodiment. This embodiment is a modification of the first embodiment, and is different from the first embodiment in that a conductive layer 6 that absorbs visible light and has conductivity is arranged closer to the cathode 5 than the light absorbing layer 4 is. Hereinafter, points different from the first embodiment will be described, and description of the same portions will be omitted.
【００２４】図３に示す様に、陰極５は、光吸収層４側
に位置する第１の層５１と第１の層５１よりも光吸収層
４から離れて位置する第２の層５２との２層構造を有し
ており、導電層６は、これら第１及び第２の層５１、５
２の間に挟まれている。ここで、陰極５の第１の層５１
は、上述のように、発光層３への電子注入特性を阻害し
ないようにするため、仕事関数が４以下の材料よりなる
ものとし、また、厚すぎると反射面として機能するた
め、ある程度（例えば１００ｎｍ）以下の厚さであるこ
とが好ましい。As shown in FIG. 3, the cathode 5 has a first layer 51 located on the light absorbing layer 4 side and a second layer 52 located farther from the light absorbing layer 4 than the first layer 51. The conductive layer 6 includes the first and second layers 51, 5
It is sandwiched between two. Here, the first layer 51 of the cathode 5
Is made of a material having a work function of 4 or less in order not to hinder the electron injection characteristics into the light emitting layer 3 as described above, and if it is too thick, it functions as a reflective surface. (100 nm) or less.
【００２５】例えば、陰極５の第１の層５１は、仕事関
数が４以下であるＬｉＦ（仕事関数：２．９ｅＶ）とで
き、導電層６は、仕事関数が４ｅＶ〜５ｅＶである黒鉛
とでき、陰極５の第２の層５２は、仕事関数が４．５ｅ
Ｖ程度であるＡｌとできる。また、導電層６としては、
他に炭化シリコン、酸化クロムなどの金属酸化物等が挙
げられる。For example, the first layer 51 of the cathode 5 can be made of LiF having a work function of 4 or less (work function: 2.9 eV), and the conductive layer 6 can be made of graphite having a work function of 4 eV to 5 eV. The work function of the second layer 52 of the cathode 5 is 4.5 e.
Al of about V can be obtained. Further, as the conductive layer 6,
Other examples include metal oxides such as silicon carbide and chromium oxide.
【００２６】ここで、導電層６はスパッタや蒸着および
フォトリソグラフィ技術等により形成された第１の層５
１の上に、蒸着やスパッタ等の方法を用いて形成するこ
とができる。そして、第２の層５２は導電層６のうえに
第１の層５１と同様にして形成できる。本実施形態によ
れば、光吸収層４の効果に加えて、導電層６によって陰
極５における外部光の反射を抑制できるため、上記第１
実施形態にて述べた効果をより高いレベルで実現するこ
とができ、さらなるコントラストの向上が実現可能であ
る。Here, the conductive layer 6 is a first layer 5 formed by sputtering, vapor deposition, photolithography, or the like.
1 can be formed by a method such as vapor deposition or sputtering. Then, the second layer 52 can be formed on the conductive layer 6 in the same manner as the first layer 51. According to the present embodiment, in addition to the effect of the light absorbing layer 4, the reflection of external light on the cathode 5 can be suppressed by the conductive layer 6.
The effects described in the embodiment can be realized at a higher level, and further improvement in contrast can be realized.
【００２７】ちなみに、基板上に第１電極層、第１絶縁
層、無機の蛍光体よりなる発光層、第２絶縁層、第２電
極層を順次積層してなる無機ＥＬ素子においては、出光
側となる基板とは反対側の第２電極層（背面電極）と第
２絶縁層との間に、可視光を吸収する光吸収層を設ける
ものが、従来より公知技術としてあるが、この光吸収層
は絶縁体である。Incidentally, in an inorganic EL device in which a first electrode layer, a first insulating layer, a light emitting layer made of an inorganic phosphor, a second insulating layer, and a second electrode layer are sequentially laminated on a substrate, a light emitting side There is a conventionally known technique in which a light absorbing layer for absorbing visible light is provided between a second electrode layer (back electrode) on the side opposite to the substrate to be formed and the second insulating layer. The layers are insulators.
【００２８】本発明は、光吸収層が陰極から発光層への
電子注入特性を阻害しないように、電流を通す必要があ
るという、有機ＥＬ素子特有の課題に対応するものであ
り、特に、この課題について、光吸収層の材料を工夫し
たものであり、上記無機ＥＬ素子における光吸収層とは
異なるものである。The present invention addresses the problem unique to organic EL devices that it is necessary to pass a current so that the light absorbing layer does not impair the electron injection characteristics from the cathode to the light emitting layer. The problem is that the material of the light absorbing layer is devised, and is different from the light absorbing layer in the inorganic EL device.
【図１】本発明の第１実施形態に係る有機ＥＬ素子の概
略断面図である。FIG. 1 is a schematic sectional view of an organic EL device according to a first embodiment of the present invention.
【図２】銅フタロシアニンの化学構造を示す図である。FIG. 2 is a view showing a chemical structure of copper phthalocyanine.
【図３】本発明の第２実施形態に係る有機ＥＬ素子の概
略断面図である。FIG. 3 is a schematic sectional view of an organic EL device according to a second embodiment of the present invention.
１…基板、１ａ…基板の一面、１ｂ…基板の他面、２…
陽極、３…発光層、４…光吸収層、５…陰極、６…導電
層、５１…陰極の第１の層、５２…陰極の第２の層。DESCRIPTION OF SYMBOLS 1 ... Substrate, 1a ... One surface of a substrate, 1b ... Other surface of a substrate, 2 ...
Anode, 3 ... Light-emitting layer, 4 ... Light absorbing layer, 5 ... Cathode, 6 ... Conductive layer, 51 ... First layer of cathode, 52 ... Second layer of cathode.
フロントページの続き (72)発明者 城戸 淳二 奈良県北葛城郡広陵町馬見北９丁目４番地 ３ Ｆターム(参考） 3K007 AB00 AB17 CA01 CB01 DA01 DB03 EA02 EA04 EB00 Continued on the front page (72) Inventor Junji Kido 9-4, Mamikita, Koryo-cho, Kitatsukatsugi-gun, Nara Prefecture 3F term (reference) 3K007 AB00 AB17 CA01 CB01 DA01 DB03 EA02 EA04 EB00
Claims (4)
極（２）、有機化合物からなる発光層（３）、金属から
なる陰極（５）が順次積層されており、前記基板の他面
（１ｂ）から前記発光層の光を取り出すようにした有機
ＥＬ素子において、 前記陰極と前記発光層との間に、伝導帯最低準位が−
２．７ｅＶ以下である有機材料からなり可視光を吸収す
る光吸収層（４）が設けられていることを特徴とする有
機ＥＬ素子。An anode (2), a luminescent layer (3) made of an organic compound, and a cathode (5) made of a metal are sequentially laminated on one surface (1a) of a transparent substrate (1). In the organic EL device in which light from the light emitting layer is extracted from the other surface (1b), the lowest conduction band level between the cathode and the light emitting layer is-
An organic EL device comprising a light absorbing layer (4) made of an organic material having a voltage of 2.7 eV or less and absorbing visible light.
（５）側に、可視光を吸収し且つ導電性を有する導電層
（６）が配置されていることを特徴とする請求項１に記
載の有機ＥＬ素子。2. A conductive layer (6) that absorbs visible light and has conductivity is disposed closer to the cathode (5) than the light absorbing layer (4). 3. The organic EL device according to claim 1.
に位置する第１の層（５１）とこの第１の層よりも前記
光吸収層から離れて位置する第２の層（５２）との２層
構造を有し、 前記導電層（６）は前記第１層と前記第２の層との間に
挟まれていることを特徴とする請求項２に記載の有機Ｅ
Ｌ素子。3. The cathode (5) includes a first layer (51) located on the side of the light absorbing layer (4) and a second layer located farther from the light absorbing layer than the first layer. The organic layer according to claim 2, wherein the organic layer has a two-layer structure of (52), and the conductive layer (6) is sandwiched between the first layer and the second layer.
L element.
は、仕事関数が４以下の材料よりなることを特徴とする
請求項３に記載の有機ＥＬ素子。4. The first layer (51) of the cathode (5)
4. The organic EL device according to claim 3, wherein the material has a work function of 4 or less.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11126146A JP2000315582A (en) | 1999-05-06 | 1999-05-06 | Organic el element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11126146A JP2000315582A (en) | 1999-05-06 | 1999-05-06 | Organic el element |
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| Publication Number | Publication Date |
|---|---|
| JP2000315582A true JP2000315582A (en) | 2000-11-14 |
Family
ID=14927826
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP11126146A Pending JP2000315582A (en) | 1999-05-06 | 1999-05-06 | Organic el element |
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| Country | Link |
|---|---|
| JP (1) | JP2000315582A (en) |
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