JPS6342840B2 - - Google Patents
Info
- Publication number
- JPS6342840B2 JPS6342840B2 JP56072059A JP7205981A JPS6342840B2 JP S6342840 B2 JPS6342840 B2 JP S6342840B2 JP 56072059 A JP56072059 A JP 56072059A JP 7205981 A JP7205981 A JP 7205981A JP S6342840 B2 JPS6342840 B2 JP S6342840B2
- Authority
- JP
- Japan
- Prior art keywords
- light emitting
- emitting layer
- light
- thin film
- zns
- 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.)
- Expired
Links
- 239000010409 thin film Substances 0.000 claims description 24
- SBIBMFFZSBJNJF-UHFFFAOYSA-N selenium;zinc Chemical compound [Se]=[Zn] SBIBMFFZSBJNJF-UHFFFAOYSA-N 0.000 claims description 22
- 239000000463 material Substances 0.000 claims description 10
- 229910004613 CdTe Inorganic materials 0.000 claims description 2
- UHYPYGJEEGLRJD-UHFFFAOYSA-N cadmium(2+);selenium(2-) Chemical compound [Se-2].[Cd+2] UHYPYGJEEGLRJD-UHFFFAOYSA-N 0.000 claims description 2
- 239000010410 layer Substances 0.000 description 58
- 238000010586 diagram Methods 0.000 description 6
- 239000000758 substrate Substances 0.000 description 5
- 239000011521 glass Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000010030 laminating Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 238000004544 sputter deposition Methods 0.000 description 1
- 238000007738 vacuum evaporation Methods 0.000 description 1
Landscapes
- Illuminated Signs And Luminous Advertising (AREA)
Description
本発明はエレクトロルミネツセンス形式の薄膜
発光素子に関する。
従来、かかる薄膜発光素子は、第１図に示す如
く、ガラス基板１の上に、ITO、In2O3、SnO2等
の透明導電層２を形成し、その上にY2O3、
Si3N4、PbTiO3等の絶縁層３を設け、その上に
ZnS、ZnSe等の発光層４を更にその上に背面電
極５を、真空蒸着法、スパツタ法等によつて形成
されている。このように構成された薄膜発光素子
は透明導電層の背面電極間に交流又はパルス電界
を印加することによつて、発光層を励起して発光
が得られるものである。
従来の発光層には、ZnS、ZnSe及びZnSと
ZnSeの混晶であるZnSSeの３種がそれぞれ単独
で用いられていた。ZnSは発光効率が高く、高輝
度の発光素子が得られるので最もよく使用される
が、しきい電圧が高いため高駆動電圧になる欠点
があつた。ZnSeは、逆にしきい電圧が低いため
に駆動電圧も低く押さえられるが、発光効率が低
く、高輝度の発光素子が得られない欠点があつ
た。またZnSSeの如き混合層はZnSおよびZnSe
双方の欠点を解消せんとして用いられているが、
輝度は、ZnSeよりは高いがZnSより低く不充分
であり、駆動電圧もZnSよりは低いがZnSeより
高いため輝度、駆動電圧を総合した評価として
は、いま一歩のところがある。
従つて本発明の目的は、従来の交流又はパルス
電界を印加して使用する場合の上述の欠点を解消
し、低駆動電圧にて高輝度の発光を得ることにあ
る。
本発明の素子の特徴は、従来単独層であつた発
光層が２種類以上の材質からなり、しかもZnSSe
の如く混合する手段ではなく、順次濃度勾配をつ
けずに積層し、複数層で構成することにより、低
駆動電圧にて高輝度の発光を得るものである。
第２図は本発明の実施例を示す薄膜発光素子の
構造図であり、発光層４１がZnS発光層４２およ
びZnSe発光層４３の複数層で構成される。ここ
で発光層４１の膜厚すなわちZnS発光層４２の膜
厚およびZnSe発光層４３の膜厚の和は従来の発
光層４の膜厚に等しい。その結果、ZnSSeを発光
層に用いた場合に比べて低電圧でしかも高輝度の
薄膜発光素子を得た。
第３図は本発明の他の実施例を示す薄膜発光素
子の構造図であり、発光層４４がZnSe発光層４
５を２層のZnS発光層４６および４６′で挾持し
た３層で構成される。この構造においても、発光
層４４の膜厚を従来の発光層４の膜厚と等しくし
た結果、第２図に示した構造の薄膜発光素子と同
程度の駆動電圧および輝度を得、従来法に比べ、
発光層を複数層で構成する本発明が有用であるこ
とが判明した。
第４図は本発明のもう１つの実施例を示す薄膜
発光素子の構造図であり、発光層４７がZnS発光
層４８を２層のZnSe発光層４９および４９′で挾
持した３層で構成される。この構造においても発
光層４７の膜厚を従来の発光層４の膜厚と等しく
した結果、第２図および第３図に示した構造の薄
膜発光素子と同程度の低い駆動電圧で、ZnSのみ
を発光層に用いた従来法の素子と同程度の高輝度
を得た。第２図、第３図および第４図に示した構
造の薄膜発光素子を比較して、(1)第４図に示した
素子が同一駆動電圧で最も高輝度である。一方、
(2)ZnSとZnSeでは、発光効率はZnSの方が高く、
しきい電圧はZnSeの方が低い。(1)および(2)から
本発明の効果を最大限に生かす方法は、発光効率
の高い発光層をしきい電圧の低い発光層で挾持し
た複数層で発光層を構成するところにあると言え
る。
以上は発光層の材質がZnSおよびZnSeの場合
について述べたが、他にCdS、CdSe、CdTeにつ
いても種々検討したところ、各々単独で用いるよ
りも本発明による構成の方が低駆動電圧でしかも
高輝度の素子を得た。
また、絶縁層は、１層に限らず２層に分割し、
発光層を挾持した構造にしても本発明の効果は損
われない。
次に実施例について説明する。
実施例 １
基板１に透明ガラス、透明導電層２にIn2O3、
絶縁層３にY2O3を用い、発光層４１がZnS発光
層４２およびZnSe発光層４３の積層で構成され
る本発明による第２図の如き薄膜発光素子を交流
電圧駆動した場合、のしきい電圧は100Vで最大
輝度は450fLであつた。
実施例 ２
基板１に透明ガラス、透明導電層２にIn2O3、
絶縁層３にY2O3を用い、発光層４４がZnSe発光
層４５をZnS発光層４６および４６′で挾持した
構造で構成される本発明による第３図の如き薄膜
発光素子のしきい電圧は、103Vで最大輝度は
460fLであつた。
実施例 ３
基板１に透明ガラス、透明導電層２にIn2O3、
絶縁層３にY2O3を用い、発光層４７がZnS発光
層４８をZnSe発光層４９および４９′で挾持した
構造で構成される本発明による第４図の如き薄膜
発光素子のしきい電圧は102Vで最大輝度は830fL
であつた。
この場合の電圧駆動はパルス電圧である。
実施例１、２および３のしきい電圧と最大輝度
を、ZnS、ZnSe、ZnSSe各々を単独で発光層と
した従来例と比較して第１表に示す。また、第４
図の構造の本発明による薄膜発光素子の輝度―電
圧特性（曲線ａ）を、ZnSおよびZnSeを発光層
とする従来例（それぞれ曲線ｂおよび曲線ｃ）を
比較して第５図に示す。
The present invention relates to thin film light emitting devices of the electroluminescent type. Conventionally, such a thin film light emitting device has a transparent conductive layer 2 made of ITO, In 2 O 3 , SnO 2 or the like formed on a glass substrate 1 as shown in FIG.
An insulating layer 3 of Si 3 N 4 , PbTiO 3 , etc. is provided, and
A light emitting layer 4 made of ZnS, ZnSe or the like is further formed thereon with a back electrode 5 by vacuum evaporation, sputtering or the like. The thin film light emitting device constructed in this way can emit light by exciting the light emitting layer by applying an alternating current or pulsed electric field between the back electrodes of the transparent conductive layer. Conventional light emitting layers include ZnS, ZnSe and ZnS.
Three types of ZnSSe, which is a mixed crystal of ZnSe, were used individually. ZnS is the most commonly used material because it has high luminous efficiency and can produce high-brightness light-emitting elements, but it has the disadvantage of having a high driving voltage due to its high threshold voltage. ZnSe, on the other hand, has a low threshold voltage and can therefore be kept at a low driving voltage, but has the disadvantage of low luminous efficiency and the inability to produce high-luminance light-emitting elements. Also, mixed layers such as ZnSSe are ZnS and ZnSe.
It is used to eliminate the shortcomings of both, but
The brightness is higher than ZnSe but lower than ZnS and is insufficient, and the driving voltage is also lower than ZnS but higher than ZnSe, so it is still far from being evaluated as a comprehensive evaluation of brightness and driving voltage. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the above-mentioned drawbacks when using conventional alternating current or pulsed electric fields, and to obtain high-intensity light emission with a low driving voltage. A feature of the device of the present invention is that the light-emitting layer, which was conventionally a single layer, is made of two or more types of materials, and that ZnSSe
Rather than using a means of mixing as described above, high luminance light emission can be obtained at a low driving voltage by sequentially laminating layers without creating a concentration gradient and configuring a plurality of layers. FIG. 2 is a structural diagram of a thin film light emitting device showing an embodiment of the present invention, in which a light emitting layer 41 is composed of multiple layers of a ZnS light emitting layer 42 and a ZnSe light emitting layer 43. Here, the thickness of the light-emitting layer 41, that is, the sum of the thicknesses of the ZnS light-emitting layer 42 and the ZnSe light-emitting layer 43, is equal to the thickness of the conventional light-emitting layer 4. As a result, we obtained a thin-film light-emitting device with lower voltage and higher brightness than when ZnSSe is used for the light-emitting layer. FIG. 3 is a structural diagram of a thin film light emitting device showing another embodiment of the present invention, in which the light emitting layer 44 is a ZnSe light emitting layer 4.
5 sandwiched between two ZnS light emitting layers 46 and 46'. In this structure as well, as a result of making the film thickness of the light emitting layer 44 equal to that of the conventional light emitting layer 4, driving voltage and brightness comparable to those of the thin film light emitting element having the structure shown in FIG. 2 can be obtained, which is superior to the conventional method. compared,
It has been found that the present invention in which the light-emitting layer is composed of multiple layers is useful. FIG. 4 is a structural diagram of a thin film light emitting device showing another embodiment of the present invention, in which a light emitting layer 47 is composed of three layers in which a ZnS light emitting layer 48 is sandwiched between two ZnSe light emitting layers 49 and 49'. Ru. In this structure as well, the thickness of the light emitting layer 47 is made equal to the thickness of the conventional light emitting layer 4, and as a result, only ZnS The device achieved high brightness comparable to that of a conventional device that uses 200% as the light-emitting layer. Comparing the thin film light emitting devices having the structures shown in FIGS. 2, 3, and 4, (1) the device shown in FIG. 4 has the highest luminance at the same driving voltage. on the other hand,
(2) Between ZnS and ZnSe, ZnS has higher luminous efficiency;
ZnSe has a lower threshold voltage. From (1) and (2), it can be said that the way to make the most of the effects of the present invention is to configure the light emitting layer with multiple layers in which a light emitting layer with high luminous efficiency is sandwiched between light emitting layers with low threshold voltage. . The above description is based on the case where the material of the light-emitting layer is ZnS and ZnSe, but various studies were also conducted on CdS, CdSe, and CdTe, and it was found that the structure according to the present invention has a lower driving voltage and higher speed than using each one alone. A brightness element was obtained. In addition, the insulating layer is not limited to one layer but is divided into two layers,
Even if the structure is such that the light emitting layer is sandwiched, the effects of the present invention are not impaired. Next, an example will be described. Example 1 Transparent glass for substrate 1, In 2 O 3 for transparent conductive layer 2,
When a thin film light emitting device according to the present invention as shown in FIG. 2, in which Y 2 O 3 is used for the insulating layer 3 and the light emitting layer 41 is composed of a laminated layer of a ZnS light emitting layer 42 and a ZnSe light emitting layer 43, is driven with an AC voltage, The threshold voltage was 100V and the maximum brightness was 450fL. Example 2 Transparent glass for substrate 1, In 2 O 3 for transparent conductive layer 2,
The threshold voltage of a thin film light emitting device according to the present invention as shown in FIG . The maximum brightness at 103V is
It was 460fL. Example 3 Transparent glass for substrate 1, In 2 O 3 for transparent conductive layer 2,
The threshold voltage of the thin film light emitting device according to the present invention as shown in FIG . is 102V and maximum brightness is 830fL
It was hot. The voltage drive in this case is a pulse voltage. Table 1 shows the threshold voltage and maximum brightness of Examples 1, 2, and 3 in comparison with conventional examples in which each of ZnS, ZnSe, and ZnSSe was used as a single light emitting layer. Also, the fourth
FIG. 5 shows a comparison of the brightness-voltage characteristics (curve a) of the thin film light emitting device according to the present invention having the structure shown in the figure with that of a conventional example having ZnS and ZnSe as light emitting layers (curves b and c, respectively).
【表】
以上詳細に述べた如く、発光層を２種類以上の
材質の異なる複数層で構することにより、高輝度
を維持しながらしきい電圧の低い薄膜発光素子を
得ることができる。[Table] As described in detail above, by constructing the light emitting layer with a plurality of layers made of two or more different materials, it is possible to obtain a thin film light emitting element with a low threshold voltage while maintaining high brightness.
第１図は従来の薄膜発光素子の構造図、第２
図、第３図および第４図は本発明による薄膜発光
素子の実施例を示す構造図、第５図は本発明によ
る薄膜発光素子の電圧―輝度特性を従来の素子と
比較した図である。
１……基板、２……透明導電層、３……絶縁
層、４，４１，４４，４７……発光層、４２，４
６，４６′，４８……ZnS発光層、４３，４５，
４９，４９′……ZnSe発光層、５……背面電極、
ａ……本発明による素子の輝度―電圧特性を示す
曲線、ｂ……ZnSを発光層とする従来の輝度―電
圧特性を示す曲線、ｃ……ZnSeを発光層とする
従来の輝度―電圧特性を示す曲線。
Figure 1 is a structural diagram of a conventional thin film light emitting device, Figure 2
3 and 4 are structural diagrams showing examples of the thin film light emitting device according to the present invention, and FIG. 5 is a diagram comparing the voltage-luminance characteristics of the thin film light emitting device according to the present invention with a conventional device. 1... Substrate, 2... Transparent conductive layer, 3... Insulating layer, 4, 41, 44, 47... Light emitting layer, 42, 4
6, 46', 48...ZnS light emitting layer, 43, 45,
49, 49′...ZnSe light emitting layer, 5... Back electrode,
a...Curve showing the brightness-voltage characteristics of the device according to the present invention, b...Curve showing the brightness-voltage characteristics of a conventional device using ZnS as a light-emitting layer, c...Curve showing conventional brightness-voltage characteristics using ZnSe as a light-emitting layer A curve that shows
Claims (1)
ルス駆動型の薄膜発光素子において、該発光層が
２種類以上の材質の異なる複数層で構成され、か
つ各発光層が２種類以上の材質の混合層を含まな
いことを特徴とする薄膜発光素子。 ２ 前記発光層が、ZnS、ZnSe、CdS、CdSeお
よびCdTeのうち２種類以上の材質からなること
を特徴とする特許請求の範囲第１項記載の薄膜発
光素子。 ３ 前記発光層に用いる材質の１つがZnSである
ことを特徴とする特許請求の範囲第１項記載の薄
膜発光素子。 ４ 前記発光層に用いる材質が、ZnSおよび
ZnSeであることを特徴とする特許請求の範囲第
１項記載の薄膜発光素子。 ５ 前記発光層が発光効率の高い発光層をしきい
電圧の低い発光層で挾持した３層以上の複数層で
構成されることを特徴とする特許請求の範囲第１
項および第２項記載の薄膜発光素子。 ６ 前記発光層がZnS発光層をZnSe発光層で挾
持した３層以上の複数層で構成されることを特徴
とする特許請求の範囲第１項および第５項記載の
薄膜発光素子。[Scope of Claims] 1. In an AC-driven or pulse-driven thin film light-emitting element including an insulating layer and a light-emitting layer, the light-emitting layer is composed of a plurality of layers made of two or more different materials, and each light-emitting layer is made of two or more different materials. A thin film light emitting device characterized in that it does not include a mixed layer of more than one type of material. 2. The thin film light emitting device according to claim 1, wherein the light emitting layer is made of two or more materials selected from ZnS, ZnSe, CdS, CdSe and CdTe. 3. The thin film light emitting device according to claim 1, wherein one of the materials used for the light emitting layer is ZnS. 4 The material used for the light emitting layer is ZnS and
The thin film light emitting device according to claim 1, which is made of ZnSe. 5. Claim 1, wherein the light-emitting layer is composed of three or more layers in which a light-emitting layer with high luminous efficiency is sandwiched between light-emitting layers with a low threshold voltage.
The thin film light emitting device according to Items 1 and 2. 6. The thin film light emitting device according to claims 1 and 5, wherein the light emitting layer is composed of three or more layers in which a ZnS light emitting layer is sandwiched between ZnSe light emitting layers.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56072059A JPS57187893A (en) | 1981-05-12 | 1981-05-12 | Thin film light emitting element |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56072059A JPS57187893A (en) | 1981-05-12 | 1981-05-12 | Thin film light emitting element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57187893A JPS57187893A (en) | 1982-11-18 |
| JPS6342840B2 true JPS6342840B2 (en) | 1988-08-25 |
Family
ID=13478428
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56072059A Granted JPS57187893A (en) | 1981-05-12 | 1981-05-12 | Thin film light emitting element |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57187893A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0357833A (en) * | 1989-07-25 | 1991-03-13 | Honda Motor Co Ltd | Control device of on-vehicle engine |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59181485A (en) * | 1983-03-31 | 1984-10-15 | 柊元 宏 | Light emitting element |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5380993A (en) * | 1976-10-29 | 1978-07-17 | Secr Defence Brit | Electroluminescence panel |
-
1981
- 1981-05-12 JP JP56072059A patent/JPS57187893A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5380993A (en) * | 1976-10-29 | 1978-07-17 | Secr Defence Brit | Electroluminescence panel |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0357833A (en) * | 1989-07-25 | 1991-03-13 | Honda Motor Co Ltd | Control device of on-vehicle engine |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57187893A (en) | 1982-11-18 |
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