Electroluminescent device and process for producing the same

• US 4,877,994 A
• Filed: 03/23/1988
• Issued: 10/31/1989
• Est. Priority Date: 03/25/1987
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Fuyama, Moriaki, Sato, Akira, Nakayama, Takahiro, Hashimoto, Kenichi, Tamura, Katsumi, Taguchi, Kazuo, Onisawa, Kenichi, Abe, Yoshio
• Primary Examiner(s): Yusko, Donald J.
• Assistant Examiner(s): Horabik, Michael
• Application Number:
  US07/172,415
• Time in Patent Office: 587 Days
• Field of Search: 313/503, 313/505, 313/506, 313/509, 427/66, 427/69, 427/70, 428/690, 428/691, 428/917, 252/301.4 S, 252/301.4 H
• US Class Current: 313/503
• CPC Class Codes: H05B 33/10 Apparatus or processes specially adapted to the manufacture of electroluminescent light sources
• CPC Class Codes: H05B 33/145 Arrangements of the electroluminescent material
• CPC Class Codes: H05B 33/22 characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

An electroluminescent device comprising an electroluminescent layer capable of emitting light under application of AC voltage, the electroluminescent layer comprising strontium sulfide as a matrix and containing at least one of halides and sulfides of cerium, europium, thulium, terbium and samarium, and having a lattice constant of not more than 6.04 Å and a half-width value at the (111) face of not more than 0.21 degree has a higher brightness than an electroluminescent device having an electroluminescent layer comprising ZnS as a matrix.

Claims

1. An electroluminescent device which comprises:

transparent electrodes formed on a transparent substrate;

a first insulating layer formed on the transparent electrodes;

an electroluminescent layer containing strontium sulfide as a matrix and having a lattice constant of not more than 6.07Å and

a half-width at the (111) face of not more than 0.21 degree, formed on the first insulating layer;

a second insulating layer formed on the electroluminescent layer; and

back side electrodes formed on the second insulating layer.

2. An electroluminescent device according to claim 1 wherein the electroluminescent layer comprises strontium sulfide as a matrix and contains at least one of halides and sulfides of cerium, europium, thulium, terbium and samarium, and has good crystallinity so as to increase the brightness of the electroluminescent device.

3. An electroluminescent device of high brightness, which comprises an electroluminescent layer capable of emitting light under application of AC voltage, the electroluminescent layer comprising strontium sulfide as a matrix and containing at least one of halides and sulfides of cerium, europium, thulium, terbium and samarium, and having a lattice constant of not more than 6.07Å

and a halfwidth value at the (111) face of not more than 0.21 degree.

4. An electroluminescent device according to claim 3, wherein the lattice constant is from 6.02 to 6.07Å

.

5. An electroluminescent device according to claim 3, wherein the content of sulfur in the strontium sulfide in the electroluminescent layer is at least 0.66 in terms of a fluorescent X-ray diffraction intensity ratio of I(S)/I(Sr)+I(S).

6. An electroluminescent device according to claim 3, wherein the electroluminescent layer is formed by electron beam vapor deposition in vacuum of 9×

10^-5 to 5×

10^-4 Torr in the presence of sulfur vapors.

7. An electroluminescent device which comprises a transparent substrate, stripe-shaped transparent electrodes, a first insulating layer, an electroluminescent layer capable of emitting light under application of AC voltage, a second insulating layer and stripe-shaped back side electrodes, laid one upon another, the electroluminescent layer comprising strontium sulfide as a matrix and containing at least one of halides and sulfides of cerium, europium, thulium, terbium and samarium, and having a lattice consant of not more than 6.07Å

and a half-width value at the (111) face of not more than 0.21 degree.

8. An electroluminescent device according to claim 7, wherein the lattice constant is from 6.02 to 6.07Å

.

9. An electroluminescent device according to claim 7, wherein the content of sulfur in the strontium sulfide in the electroluminescent layer is at least 0.66 in terms of a fluorescent X-ray diffraction intensity ratio of I(S)/I(Sr)+I(S).

10. An electroluminescent device according to claim 7, wherein the electroluminescent layer is formed by electron beam vapor deposition in vacuum of 9×

10^-5 to 5×

10^-4 Torr in the presence of sulfur vapors.

11. An electroluminescent device according to claim 7, wherein a ZnS layer is provided on each side of the electroluminescent layer.

12. An electroluminescent device according to claim 7 wherein the transparent electrodes are formed on the substrate, the first insulating layer is formed on the transparent electrodes, the electroluminescent layer is formed on the first insulating layer, the second insulating layer is formed on the electroluminescent layer and the back side electrodes are formed on the second insulating layer.

13. A process for producing an electroluminescent device comprising an electroluminescent layer containing strontium sulfide as a matrix, which comprises:

forming a transparent electrode film on a transparent substrate;

patterning the transparent electrode film to form transparent electrodes;

forming a first insulating layer on the transparent electrodes;

forming the electroluminescent layer on the first insulating layer by electron beam vapor deposition in vacuum of 9×

10^-5 to 5×

10^-4 Torr in the presence of sulfur vapors;

forming a second insulating layer on the electroluminescent layer; and

forming back side electrodes on the second insulating layer.

14. A process according to claim 13, wherein the electroluminescent layer is formed by simultaneous vapor deposition of a mixture containing the strontium sulfide as the matrix by electron beam evaporation and sulfur by resistance heating.

15. A process according to claim 13, further comprising:

forming a first ZnS layer between the first insulating layer and the electroluminescent layer; and

forming a second ZnS layer between the electroluminescent layer and the second insulating layer.

16. A process according to claim 13, wherein the first insulating layer includes a first SiO₂ film and a first Ta₂ O₅ film formed on the first SiO₂ film, and the second insulating layer includes a second Ta₂ O₅ film and a second SiO₂ film formed on the second Ta₂ O₅ film.

17. A process according to claim 13, wherein the substrate is a glass substrate, the transparent electrodes are formed in a stripe-shaped pattern, and the back side electrodes are metallic electrodes formed in a stripe-shaped pattern so as to cross the transparent electrodes at right angles.

18. A process according to claim 13, wherein the electroluminescent layer has a lattice constant of not more than 6.07Å

, a half-width value at the (111) face of not more than 0.21 degree, and the content of sulfur in the strontium sulfide of the electroluminescent layer is at least 0.66 in terms of a fluorescent x-ray diffraction intensity ratio of I(S)/I(Sr)+I(S).

19. A process according to claim 13, wherein the electroluminescent layer comprises strontium sulfide as a matrix and contains at least one of halides and sulfides of cerium, europium, thulium, terbium and samarium.