Composite electrode for light-emitting device

• US 20070252155A1
• Filed: 03/23/2006
• Published: 11/01/2007
• Est. Priority Date: 03/23/2006
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Eastman Kodak Company
• Inventors: Cok, Ronald
• Granted Patent: US 7,564,063 B2
• Time in Patent Office: Days
• US Class Current: 257/79
• CPC Class Codes: H10K 50/805 Electrodes
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 59/805 Electrodes
• CPC Class Codes: H10K 59/877 comprising scattering means

Abstract

A multi-layer composite electrode for a light-emitting device, comprising: a transparent, conductive layer; a reflective, conductive layer in electrical contact with the transparent, conductive layer; and a light-scattering layer formed between the transparent, conductive layer and the reflective, conductive layer over only a first portion of the transparent, conductive layer, wherein the light-scattering layer is relatively less conductive than the reflective, conductive layer and the reflective, conductive layer is in electrical contact with the transparent, conductive layer over a second portion of the transparent, conductive layer where the light-scattering layer is not formed. Also disclosed is a method of making such a multi-layer composite electrode in a light emitting device, and an organic light-emitting diode (OLED) device comprising such a composite electrode.

Claims

1. A multi-layer composite electrode for a light-emitting device, comprising:

a transparent, conductive layer;

a reflective, conductive layer in electrical contact with the transparent, conductive layer; and

a light-scattering layer formed between the transparent, conductive layer and the reflective, conductive layer over only a first portion of the transparent, conductive layer, wherein the light-scattering layer is relatively less conductive than the reflective, conductive layer and the reflective, conductive layer is in electrical contact with the transparent, conductive layer over a second portion of the transparent, conductive layer where the light-scattering layer is not formed.

2. The composite electrode of claim 1, further comprising a protective layer formed between the transparent, conductive layer and the light-scattering layer.

3. The composite electrode of claim 2, wherein the protective layer is conductive.

4. The composite electrode of claim 2, wherein the protective layer comprises zinc oxide, indium tin oxide, or indium zinc oxide.

5. The composite electrode of claim 2, wherein the protective layer has an optical refractive index greater than or equal to the optical refractive index of the transparent, conductive layer.

6. The composite electrode of claim 2, wherein the protective layer is deposited using chemical vapor deposition or atomic layer deposition.

7. The composite electrode of claim 1, wherein the reflective, conductive layer comprises a metal or metal alloy.

8. The composite electrode of claim 1, wherein the transparent, conductive layer and the reflective, conductive layer are substantially planar in the first portions and/or second portions.

9. The composite electrode of claim 1, wherein the scattering layer comprises transparent refractive particles or reflective particles.

10. The composite electrode of claim 1, wherein the scattering layer comprises conductive particles.

11. An organic light-emitting diode (OLED) device, comprising:

a substrate;

a transparent electrode;

a reflective electrode; and

one or more layers of organic light-emitting material formed between the transparent and reflective electrodes;

wherein the reflective electrode comprises a multi-layer composite electrode according to claim 1.

12. An organic light-emitting diode (OLED) device according to claim 11, comprising:

a substrate;

a bottom transparent electrode formed over the substrate;

one or more layers of organic light-emitting material formed over the bottom transparent electrode; and

a composite electrode formed over the one or more layers of organic light-emitting material, the composite electrode comprising a transparent, conductive layer formed over the one or more layers of organic light-emitting material;

a reflective, conductive layer formed over and in electrical contact with the transparent, conductive layer; and

a light-scattering layer formed between the transparent, conductive layer and the reflective, conductive layer over only a first portion of the transparent, conductive layer, wherein the light-scattering layer is relatively less conductive than the reflective, conductive layer and the reflective, conductive layer is in electrical contact with the transparent, conductive layer over a second portion of the transparent, conductive layer where the light-scattering layer is not formed.

13. The organic light-emitting diode (OLED) device of claim 12, further comprising an optical isolation layer having a refractive index less than the refractive index of the substrate formed between the substrate and the bottom transparent electrode.

14. The OLED device of claim 12, further comprising a protective layer formed over the transparent, conductive layer between the transparent, conductive layer and the light-scattering layer.

15. An organic light-emitting diode (OLED) device according to claim 11, comprising:

a substrate;

a bottom electrode formed over the substrate;

one or more layers of organic light-emitting material formed over the bottom electrode;

a transparent top electrode formed over the one or more layers of organic light-emitting material; and

a cover over the transparent top electrode;

wherein the bottom electrode comprises a composite electrode comprising a reflective, conductive layer formed over the substrate;

a transparent, conductive layer formed over and in electrical contact with the reflective, conductive layer; and

a light-scattering layer formed between the transparent, conductive layer and the reflective, conductive layer over only a first portion of the transparent, conductive layer, wherein the light-scattering layer is relatively less conductive than the reflective, conductive layer and the reflective, conductive layer is in electrical contact with the transparent, conductive layer over a second portion of the transparent, conductive layer where the light-scattering layer is not formed.

16. The organic light-emitting diode (OLED) device of claim 15, further comprising an optical isolation layer having a refractive index less than the refractive index of the cover formed between the cover and the top transparent electrode.

17. A method of making a multi-layer composite electrode in a light emitting device, comprising the steps of:

providing a substrate having a light-emitting layer coated thereon;

coating a transparent, conductive layer over the light-emitting layer;

forming a light-scattering layer over only a first portion of the transparent, conductive layer; and

coating a reflective, conductive layer over the light-scattering layer and the transparent, conductive layer, wherein the light-scattering layer is relatively less conductive than the reflective, conductive layer and the reflective, conductive layer is coated in electrical contact with the transparent, conductive layer over a second portion of the transparent, conductive layer where the light-scattering layer is not formed.

18. The method of claim 17, wherein the transparent, conductive layer comprises a metal oxide layer sputter-coated over the light-emitting layer;

the light-scattering layer comprises light-scattering particles and a binder ink-jet deposited over the first portion of the transparent, conductive layer; and

the reflective, conductive layer is a metallic layer evaporated or sputter-coated over the light-scattering layer and the transparent, conductive layer.

19. The method of claim 17, further comprising chemical vapor depositing or atomic layer depositing a protective layer over the transparent, conductive layer, and wherein the light-scattering layer is formed over the protective layer.

20. The method of claim 17, wherein the scattering layer is formed by uniformly coating a layer over the first and second portions, and pattern-wise removing the layer over the second portions.