Electroluminescent device

• US 20060049745A1
• Filed: 09/08/2005
• Published: 03/09/2006
• Est. Priority Date: 03/12/2003
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Handa, Keishin, Aramaki, Shinji, Aya, Tetsuya
• Granted Patent: US 7,462,984 B2
• Time in Patent Office: Days
• US Class Current: 313/503
• CPC Class Codes: H10K 50/841 Self-supporting sealing arrangements
• CPC Class Codes: H10K 50/844 Encapsulations
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 59/871 Self-supporting sealing arrangements
• CPC Class Codes: H10K 59/873 Encapsulations
• CPC Class Codes: H10K 59/877 comprising scattering means

Abstract

The electroluminescent device successively comprises a cathode, an electroluminescent layer, a transparent electrode layer, an evanescent light-scattering layer comprising a matrix composed of a low-refractive material containing light-scattering particles, and a transparent sheet/plate. Such an electroluminescent device is decreased in total reflection not only at a boundary surface between a transparent substrate and an outside air layer but also at a boundary surface of the transparent electrode layer on its light extraction side, and therefore, is considerably improved in light extraction efficiency. In addition, in the electroluminescent device provided with a barrier layer, the transparent electrode layer and the electroluminescent layer can be well protected so that deterioration of electroluminescent pigments and occurrence of dark spots can be effectively prevented, resulting in enhanced life of the device.

Claims

1. An electroluminescent device successively comprising a cathode, an electroluminescent layer, a transparent electrode layer and a transparent sheet/plate, wherein an evanescent light-scattering layer (A) comprising a matrix composed of a low-refractive material containing light-scattering particles is provided between the transparent electrode layer and the transparent sheet/plate.

5. An electroluminescent device according to any one of claims 1 to 4, wherein the evanescent light-scattering layer (A) contains the light-scattering particles in an amount of 1 to 40% by volume, and not less than 60% by weight of the light-scattering particles have a particle size of 20 to 400 nm.

6. An electroluminescent device according to any one of claims 1 to 4, wherein a thickness of the evanescent light-scattering layer (A) is not less than 2 times an average particle size of the light-scattering particles.

7. An electroluminescent device according to any one of claims 1 to 4, wherein not less one-third by weight of the light-scattering particles are present within a region extending at a distance of 600 nm or less from a boundary surface between the transparent electrode layer and the barrier layer.

8. An electroluminescent device according to any one of claims 1 to 4, wherein the light-scattering particles are composed of silica, colloidal silica, titania, zirconia, ITO (indium tin oxide), ATO (antimony tin oxide) or alumina.

22. An electroluminescent device according to any one of claims 1 to 4, 12, 15, 19 and 20, wherein the transparent sheet/plate is a transparent substrate.

23. An electroluminescent device according to any one of claims 1 to 4, 12, 15, 19 and 20, wherein the cathode is formed on a transparent substrate, and the transparent sheet/plate is a protective cover.

2. An electroluminescent device successively comprising a cathode, an electroluminescent layer, a transparent electrode layer and a transparent sheet/plate, wherein an evanescent light-scattering layer (A) comprising a matrix composed of a low-refractive material containing light-scattering particles is provided between the transparent electrode layer and the transparent sheet/plate, and the matrix constituting the evanescent light-scattering layer (A) has a refractive index lower than that of the transparent electrode layer.

3. An electroluminescent device successively comprising a cathode, an electroluminescent layer, a transparent electrode layer and a transparent sheet/plate, wherein an evanescent light-scattering layer (A) comprising a matrix composed of a low-refractive material containing light-scattering particles is provided between the transparent electrode layer and the transparent sheet/plate, and a barrier layer is provided between the evanescent light-scattering layer (A) and the transparent electrode layer to prevent a material within the evanescent light-scattering layer (A) from being transferred into the transparent electrode layer.

9. An electroluminescent device according to claim 3 or 4, wherein the barrier layer has a refractive index which is substantially identical to or higher than that of the transparent electrode layer.

10. An electroluminescent device according to claim 3 or 4, wherein the barrier layer has a thickness of 50 to 400 nm.

11. An electroluminescent device according to claim 3 or 4, wherein the barrier layer has a thickness of 100 to 200 nm.

4. An electroluminescent device successively comprising a cathode, an electroluminescent layer, a transparent electrode layer and a transparent sheet/plate, wherein an evanescent light-scattering layer (A) comprising a matrix composed of a low-refractive material containing light-scattering particles is provided between the transparent electrode layer and the transparent sheet/plate, a barrier layer is provided between the evanescent light-scattering layer (A) and the transparent electrode layer to prevent a material within the evanescent light-scattering layer (A) from being transferred into the transparent electrode layer, and the matrix constituting the evanescent light-scattering layer (A) has a refractive index which is substantially identical to that of the transparent sheet/plate and lower than that of the transparent electrode layer.

12. An electroluminescent device successively comprising a cathode, an electroluminescent layer, a transparent electrode layer and a transparent sheet/plate, wherein the transparent electrode layer contains light-scattering particles.

13. An electroluminescent device according to claim 12, wherein the transparent electrode layer contains the light-scattering particles in an amount of 1 to 40% by volume, and not less than 60% by weight of the light-scattering particles have a particle size of 30 to 400 nm.

14. An electroluminescent device according to claim 12, wherein a thickness of the transparent electrode layer is not less than 2 times an average particle size of the light-scattering particles.

18. An electroluminescent device according to claim 12 or 15, wherein the light-scattering particles are composed of silica, colloidal silica, titania, zirconia, ITO (indium tin oxide), ATO (antimony tin oxide) or alumina.

15. An electroluminescent device successively comprising a cathode, an electroluminescent layer, a transparent electrode layer and a transparent sheet/plate, wherein an evanescent light-scattering layer (B) containing light-scattering particles is provided between the transparent electrode layer and the transparent sheet/plate, and a matrix constituting the evanescent light-scattering layer (B) has a refractive index which is substantially identical to that of the transparent electrode layer.

16. An electroluminescent device according to claim 15, wherein the evanescent light-scattering layer (B) contains the light-scattering particles in an amount of 1 to 40% by volume, and not less than 60% by weight of the light-scattering particles have a particle size of 30 to 400 nm.

17. An electroluminescent device according to claim 15, wherein a thickness of the evanescent light-scattering layer (B) is not less than 2 times an average particle size of the light-scattering particles.

19. An electroluminescent device successively comprising a cathode, an electroluminescent layer, a transparent electrode layer and a transparent sheet/plate, wherein the transparent electrode layer is provided on its surface facing the transparent sheet/plate, with light-scattering roughness.

21. An electroluminescent device according to claim 19 or 20, wherein the surface on which the light-scattering roughness are provided has a surface roughness Ra of 5 to nm.

20. An electroluminescent device successively comprising a cathode, an electroluminescent layer, a transparent electrode layer and a transparent sheet/plate, wherein a high-refractive layer having a refractive index substantially identical to that of the transparent electrode layer is provided between the transparent electrode layer and the transparent sheet/plate, and the high-refractive layer is provided on its surface facing the transparent sheet/plate, with light-scattering roughness.