JPH07282981A - Electroluminescence(el) element - Google Patents
Electroluminescence(el) elementInfo
- Publication number
- JPH07282981A JPH07282981A JP6071796A JP7179694A JPH07282981A JP H07282981 A JPH07282981 A JP H07282981A JP 6071796 A JP6071796 A JP 6071796A JP 7179694 A JP7179694 A JP 7179694A JP H07282981 A JPH07282981 A JP H07282981A
- Authority
- JP
- Japan
- Prior art keywords
- transparent electrode
- thin film
- film
- electrode
- semiconductor thin
- 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
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
- H10K50/85—Arrangements for extracting light from the devices
- H10K50/852—Arrangements for extracting light from the devices comprising a resonant cavity structure, e.g. Bragg reflector pair
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、電気−光変換を実現
し、情報通信分野において、表示素子，通信用発光デバ
イス，情報ファイル用読／書ヘッド，印刷装置などに利
用される電界発光素子に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention realizes electro-optical conversion, and in the field of information and communication, an electroluminescent device used for a display device, a light emitting device for communication, a read / write head for information files, a printing device and the like. Regarding
【０００２】[0002]
【従来の技術】例えば、アプライド・フィジクス・レタ
ー，Ｖol．６３，１９９３年，ｐ．５９４−ｐ．５９４
には、微小共振器構造を有する電界発光素子について報
告されているが、これらの素子は、透明電極−導電薄膜
間の界面の凹凸のために生じる光学距離の不均一が、特
性低下の原因となっていた。2. Description of the Related Art For example, Applied Physics Letter, Vol. 63, 1993, p. 594-p. 594
Report on an electroluminescent device having a microcavity structure.However, in these devices, the nonuniformity of the optical distance caused by the unevenness of the interface between the transparent electrode and the conductive thin film causes the deterioration of the characteristics. Was becoming.
【０００３】[0003]
【発明が解決しようとする課題】本発明は、微小共振器
構造を有する電界発光素子の発光スペクトルの半値幅の
減少，ピーク強度や発光効率の増大などの発光特性改善
を図るものである。SUMMARY OF THE INVENTION The present invention is intended to improve the emission characteristics of an electroluminescent device having a microresonator structure, such as a reduction in the half-value width of the emission spectrum and an increase in the peak intensity and the emission efficiency.
【０００４】[0004]
【課題を解決するための手段】以上の課題を達成するた
め、本発明は、発光素子の透明電極と透明基板との間
に、前記発光素子の発光の１部を前記透明基板側に透過
し、１部を膜側に反射する前面反射鏡を持ち、前記前面
反射鏡と背面の金属電極との間が光共振器として機能す
る電界発光素子において、前記透明電極の屈折率をｎ
１、前記透明電極上に形成する半導体性薄膜の屈折率を
ｎ２、前記金属電極と接する前記半導体性薄膜の屈折率
をｎ３、前記透明電極−前記半導体薄膜間の界面の荒さ
をａ１、前記半導体薄膜−前記金属電極間の界面の荒さ
をａ２とするとき、前記透明電極として、In order to achieve the above object, the present invention provides a method for transmitting a part of light emission of the light emitting element to the transparent substrate side between the transparent electrode of the light emitting element and the transparent substrate. In an electroluminescent device having a front reflecting mirror that reflects a part of the film toward the film side, and the space between the front reflecting mirror and the back metal electrode functions as an optical resonator, the transparent electrode has a refractive index of n.
1. The refractive index of the semiconductor thin film formed on the transparent electrode is n2, the refractive index of the semiconductor thin film in contact with the metal electrode is n3, the roughness of the interface between the transparent electrode and the semiconductor thin film is a1, and the semiconductor is When the roughness of the interface between the thin film and the metal electrode is a2, the transparent electrode is:
【０００５】[0005]
【数２】 ｜ｎ１−ｎ２｜×ａ１＜ｎ３×ａ２ …（数２） なる関係を満たす薄膜を用いることを特徴とする。[Equation 2] | n1−n2 | × a1 <n3 × a2 (Equation 2) A thin film satisfying the following relationship is used.
【０００６】[0006]
【作用】素子では、それぞれの薄膜の表面凹凸のために
膜厚の誤差が生じ、光学的距離が一定の長さにはならな
いために、画素平均で観測する場合、発光スペクトルの
共振ピークの半値幅が広くなり、ピーク強度が低下す
る。現実に、この性能の低下に最も効果を及ぼすものは
透明電極の表面平滑性であり、最表面の半導体性薄膜の
表面平滑性がこれに次ぐ。最表面の半導体性薄膜の表面
平滑性の向上には、高真空蒸着や低速蒸着などの、蒸着
条件の改良が有効である。一方、透明電極と半導体性膜
との界面は、透明電極の形成条件の改良による平滑性の
向上とわあわせて、半導体性薄膜に近い屈折率の透明電
極を用いることにより、光学的距離の誤差を小さくする
ことができる。In the device, an error in the film thickness occurs due to the unevenness of the surface of each thin film, and the optical distance does not become a constant length. Therefore, when observing with a pixel average, half of the resonance peak of the emission spectrum is observed. The price range becomes wider and the peak intensity decreases. In reality, the surface smoothness of the transparent electrode has the greatest effect on the deterioration of the performance, and the surface smoothness of the outermost semiconductor thin film is next. In order to improve the surface smoothness of the outermost semiconductor thin film, it is effective to improve the vapor deposition conditions such as high vacuum vapor deposition and low speed vapor deposition. On the other hand, the interface between the transparent electrode and the semiconducting film has an optical distance error due to the use of the transparent electrode having a refractive index close to that of the semiconducting thin film, in addition to the improvement of smoothness due to the improvement of the forming condition of the transparent electrode. Can be made smaller.
【０００７】透明電極−半導体性薄膜間の界面の凹凸の
ために生じる光学距離の不均一の程度は、｜ｎ１−ｎ２
｜×ａ１で表現され、薄膜表面の凹凸のために生じる光
学距離の不均一はｎ３×ａ２で表現される。透明電極と
して、その上に形成する薄膜との屈折率の差が小さく、
表面荒さが小さい薄膜を用いて、上記の関係を達成する
ことにより、透明電極−半導体性薄膜間の界面の凹凸の
ために生じる特性低下を解決することができる。この式
を満たす範囲では、透明電極の特性改変が素子特性に及
ぼす効果は小さく、発光スペクトルの特性は主として最
表面の半導体性薄膜表面の凹凸により支配される。The degree of nonuniformity of the optical distance caused by the unevenness of the interface between the transparent electrode and the semiconductor thin film is | n1-n2.
It is represented by | × a1, and the nonuniformity of the optical distance caused by the unevenness of the thin film surface is represented by n3 × a2. As a transparent electrode, the difference in the refractive index with the thin film formed on it is small,
By achieving the above relationship by using a thin film having a small surface roughness, it is possible to solve the characteristic deterioration caused by the unevenness of the interface between the transparent electrode and the semiconductive thin film. In the range satisfying this formula, the effect of the characteristic modification of the transparent electrode on the element characteristics is small, and the characteristics of the emission spectrum are mainly governed by the unevenness of the outermost surface of the semiconductor thin film.
【０００８】[0008]
【実施例】図１に、微小共振器構造を有する有機電界発
光素子の断面図を示す。硝子基板１０１上に、ＴｉＯ2
とＳｉＯ2 膜を積層した半透明反射膜１０２で形成して
いる。その上に、前部透明電極（ＩＴＯ）１０３，ホー
ル注入層(ジアミン誘導体)１０４，発光層（アルミキレ
ート）１０５，後部Ａｇ：Ｍｇ金属電極１０６を、順に
形成している。１０３，１０４，１０５の、それぞれの
平均膜厚と屈折率の積から得られる光学的距離の和は、
アルミキレートのＥＬ発光のピーク波長の、５３０ｎｍ
と一致させている。EXAMPLE FIG. 1 shows a cross-sectional view of an organic electroluminescent device having a microresonator structure. TiO 2 on the glass substrate 101
And a SiO 2 film are laminated to form a semitransparent reflective film 102. A front transparent electrode (ITO) 103, a hole injection layer (diamine derivative) 104, a light emitting layer (aluminum chelate) 105, and a rear Ag: Mg metal electrode 106 are sequentially formed thereon. The sum of the optical distances obtained from the products of the average film thickness and the refractive index of 103, 104 and 105 is
530nm of the peak wavelength of EL emission of aluminum chelate
Is matched with.
【０００９】図２に、図１の構造の素子を用いた、(｜
ｎ１−ｎ２｜×ａ１)／(ｎ３×ａ２)が１０の素子Ａ
と、０.１ の素子Ｂで得られる発光スペクトルを示す。
本発明を適用した素子である素子Ｂは、素子Ａよりも半
値幅が狭く、発光強度が高い。FIG. 2 shows a device using the element having the structure shown in FIG.
n1-n2 | × a1) / (n3 × a2) is an element A of 10
And the emission spectrum obtained by the device B of 0.1.
Element B, which is an element to which the present invention is applied, has a narrower half-value width and higher emission intensity than element A.
【００１０】図３に、図１の構造の素子を用いた（｜ｎ
１−ｎ２｜×ａ１)／(ｎ３×ａ２）と発光スペクトルの
半値幅との関係を示す。発光スペクトルの半値幅の変化
が顕著なのは、（｜ｎ１−ｎ２｜×ａ１)／(ｎ３×ａ
２）の値が１より大きい範囲である。In FIG. 3, the device having the structure shown in FIG.
The relationship between 1-n2 | xa1) / (n3xa2) and the full width at half maximum of the emission spectrum is shown. The remarkable change in the full width at half maximum of the emission spectrum is (| n1-n2 | × a1) / (n3 × a
The range of 2) is larger than 1.
【００１１】[0011]
【発明の効果】本発明によれば、微小共振器構造を有す
る電界発光素子の、発光スペクトルの半値幅の減少，ピ
ーク強度や発光効率の増大などの発光特性の向上を得る
ことができる。According to the present invention, it is possible to improve the light emitting characteristics of the electroluminescent device having the microresonator structure, such as the reduction of the half value width of the emission spectrum and the increase of the peak intensity and the luminous efficiency.
【図１】半透明反射鏡を有する有機発光素子の断面図。FIG. 1 is a cross-sectional view of an organic light emitting device having a semitransparent reflecting mirror.
【図２】（｜ｎ１−ｎ２｜×ａ１)／(ｎ３×ａ２）が１
０の素子と、０.１ の素子の、発光スペクトルの比較を
示す特性図。FIG. 2 shows that (| n1-n2 | × a1) / (n3 × a2) is 1
The characteristic view which shows the comparison of the emission spectrum of the element of 0 and the element of 0.1.
【図３】（｜ｎ１−ｎ２｜×ａ１)／(ｎ３×ａ２）と発
光スペクトルの半値幅との関係を示す特性図。FIG. 3 is a characteristic diagram showing the relationship between (| n1-n2 | × a1) / (n3 × a2) and the full width at half maximum of the emission spectrum.
１０１…硝子基板、１０２…ＴｉＯ2 膜とＳｉＯ2 膜を
積層した半透明反射膜、１０３…前部透明電極（ＩＴ
Ｏ）、１０４…ジアミン誘導体（ＴＡＤ）のホール注入
層、１０５…アルミキレート（ＡＬＱ）の発光層、１０
６…Ａｇ：Ｍｇ金属電極、２０１…本発明から外れた特
性の透明電極を用いた素子の発光スペクトル、２０２…
本発明の示す特性の透明電極を用いた素子の発光スペク
トル。101 ... Glass substrate, 102 ... Semi-transparent reflective film in which TiO 2 film and SiO 2 film are laminated, 103 ... Front transparent electrode (IT
O), 104 ... Hole injection layer of diamine derivative (TAD), 105 ... Light emitting layer of aluminum chelate (ALQ), 10
6 ... Ag: Mg metal electrode, 201 ... Emission spectrum of device using transparent electrode having characteristics deviating from the present invention, 202 ...
The emission spectrum of the element which used the transparent electrode of the characteristic which this invention shows.
Claims (2)
前記発光素子の発光の１部を前記透明基板側に透過し、
１部を膜側に反射する前面反射鏡を持ち、前記前面反射
鏡と背面の金属電極との間が光共振器として機能する電
界発光素子において、前記透明電極の屈折率をｎ１、前
記透明電極上に形成する半導体性薄膜の屈折率をｎ２、
前記金属電極と接する前記半導体性薄膜の屈折率をｎ
３、前記透明電極−前記半導体薄膜間の界面の荒さをａ
１、前記半導体薄膜−前記金属電極間の界面の荒さをａ
２とするとき、前記透明電極として、 【数１】 ｜ｎ１−ｎ２｜×ａ１＜ｎ３×ａ２ …（数１） なる関係を満たす薄膜を用いることを特徴とする電界発
光素子。1. A transparent electrode of a light emitting device and a transparent substrate,
Part of the light emitted from the light emitting element is transmitted to the transparent substrate side,
In an electroluminescent device having a front reflecting mirror for reflecting a part of the film toward a film side, and between the front reflecting mirror and a metal electrode on the back side functioning as an optical resonator, a refractive index of the transparent electrode is n1, and the transparent electrode is The refractive index of the semiconductor thin film formed above is n2,
The refractive index of the semiconductor thin film in contact with the metal electrode is n
3. Roughness of the interface between the transparent electrode and the semiconductor thin film is a
1. Roughness of the interface between the semiconductor thin film and the metal electrode is a
In the case of 2, the electroluminescent device is characterized in that, as the transparent electrode, a thin film satisfying the following relationship: | n1-n2 | × a1 <n3 × a2 (Equation 1) is used.
面反射鏡以外の前記半導体薄膜の一部に有機膜を用いる
電界発光素子。2. The electroluminescent device according to claim 1, wherein an organic film is used as a part of the semiconductor thin film other than the transparent electrode and the front reflector.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6071796A JPH07282981A (en) | 1994-04-11 | 1994-04-11 | Electroluminescence(el) element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6071796A JPH07282981A (en) | 1994-04-11 | 1994-04-11 | Electroluminescence(el) element |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07282981A true JPH07282981A (en) | 1995-10-27 |
Family
ID=13470890
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6071796A Pending JPH07282981A (en) | 1994-04-11 | 1994-04-11 | Electroluminescence(el) element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07282981A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09180883A (en) * | 1995-10-27 | 1997-07-11 | Toyota Central Res & Dev Lab Inc | Micro-light resonating organic electroluminescent element |
| JP2000323279A (en) * | 1999-03-10 | 2000-11-24 | Fuji Photo Film Co Ltd | Organic luminescent element for exposure light source |
| US6903506B2 (en) | 2001-03-27 | 2005-06-07 | Konica Corporation | Organic electroluminescent element, displaying apparatus, light emitting method, displaying method and transparent substrate |
| US7132789B2 (en) | 2003-08-18 | 2006-11-07 | Seiko Epson Corporation | Organic EL device, method of manufacturing the same and electronic apparatus |
-
1994
- 1994-04-11 JP JP6071796A patent/JPH07282981A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH09180883A (en) * | 1995-10-27 | 1997-07-11 | Toyota Central Res & Dev Lab Inc | Micro-light resonating organic electroluminescent element |
| JP2000323279A (en) * | 1999-03-10 | 2000-11-24 | Fuji Photo Film Co Ltd | Organic luminescent element for exposure light source |
| US6903506B2 (en) | 2001-03-27 | 2005-06-07 | Konica Corporation | Organic electroluminescent element, displaying apparatus, light emitting method, displaying method and transparent substrate |
| US7132789B2 (en) | 2003-08-18 | 2006-11-07 | Seiko Epson Corporation | Organic EL device, method of manufacturing the same and electronic apparatus |
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