OLED device having improved light output

• US 7,417,370 B2
• Filed: 03/23/2006
• Issued: 08/26/2008
• 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: Boroson, Michael L., Cok, Ronald S.
• Primary Examiner(s): Epps; Georgia Y.
• Assistant Examiner(s): WILLIAMS, DON J
• Application Number:
  US11/387,492
• Publication Number:
  US 20070222372A1
• Time in Patent Office: 887 Days
• Field of Search: 250/201.1, 250/221, 250/214.1, 250/226, 250/552, 345/176, 345/39, 345/45, 345/46, 345/47, 385/14, 385/15, 313/504, 313/506, 313/512, 313/509, 313/511, 428/213, 428/690, 428/917, 257/40, 257/72, 257/79, 257/89
• US Class Current: 313/504
• CPC Class Codes: H10K 50/85 Arrangements for extracting light from the devices
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 50/856 comprising reflective means

Abstract

A bottom-emitting organic light-emitting diode (OLED) device, comprising: a transparent substrate; an optical isolation cavity formed over the substrate having a refractive index lower than the refractive index of the substrate; a transparent electrode formed over the optical isolation cavity; one or more layers of organic light-emitting material formed over the transparent electrode; a second electrode formed over the one or more layers of organic light-emitting material; and a light-scattering layer formed over the optical isolation cavity; wherein the transparent electrode or a second layer formed between the optical isolation cavity and the transparent electrode comprises one or more openings leading to the optical isolation cavity, and the cavity is formed by etching a sacrificial layer deposited between the substrate and the transparent electrode or the second layer through the one or more openings.

Claims

1. A bottom-emitting organic light-emitting diode (OLED) device, comprising:

a transparent substrate through which light is emitted;

an optical isolation cavity formed over the substrate having a refractive index lower than the refractive index of the substrate;

a transparent electrode formed over the optical isolation cavity;

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

a second electrode formed over the one or more layers of organic light-emitting material, said second electrode being reflective; and

a light-scattering layer formed over the optical isolation cavity;

wherein the transparent electrode or a second layer formed between the optical isolation cavity and the transparent electrode comprises one or more openings leading to the optical isolation cavity, and the cavity is formed by etching a sacrificial layer deposited between the substrate and the transparent electrode or the second layer through the one or more openings.

2. The OLED device of claim 1, wherein the light-scattering layer is located between the optical isolation cavity and the transparent electrode.

3. The OLED device of claim 1, wherein the light-scattering layer is adjacent to and in contact with either the transparent electrode or the second electrode.

4. The OLED device of claim 1, wherein the scattering layer is formed between the transparent electrode and the second electrode.

5. The OLED device of claim 1, wherein the second electrode comprises a transparent, conductive layer formed over the one or more layers of organic light-emitting material and a reflective, conductive layer formed over and in electrical contact with the transparent, conductive layer, and the scattering layer is formed between the transparent and reflective conductive layers.

6. The OLED device of claim 5, wherein the light-scattering layer is 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.

7. The OLED device of claim 1, wherein the second electrode is transparent and a reflective scattering layer is formed over the second electrode.

8. The OLED device of claim 1, wherein the optical isolation cavity is filled with a gas.

9. The OLED device of claim 8, wherein the gas is air, helium, nitrogen, or argon.

10. The OLED device of claim 1, further comprising a short reduction layer formed between the transparent electrode and the second electrode.

11. The OLED device of claim 1, wherein the optical isolation cavity is at least 1 micrometer thick.

12. The OLED device of claim 1, comprising a second layer formed over the optical isolation cavity that comprises one or more openings leading to the optical isolation cavity and wherein the second layer comprises a silicon nitride or a silicon oxide.

13. The OLED device of claim 1, comprising a transparent electrode formed over the optical isolation cavity that comprises one or more openings leading to the optical isolation cavity.

14. A method of making a bottom-emitting organic light-emitting diode (OLED) device, comprising:

providing a transparent substrate through which light may be transmitted;

forming a first sacrificial layer over the substrate;

forming a second layer over the first sacrificial layer, the second layer being etchant resistant relative to the first sacrificial layer and having openings exposing portions of the first sacrificial layer;

etching the sacrificial layer away through the openings in the second layer to form an optical isolation cavity over the substrate having a refractive index lower than the refractive index of the substrate;

forming a transparent electrode over the optical isolation cavity;

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

forming a second electrode over the one or more layers of organic light-emitting material, said second electrode being reflective; and

forming a light-scattering layer formed over the optical isolation cavity.

15. The method of claim 14, wherein the sacrificial layer comprises polysilicon or a silicon oxide.

16. The method of claim 14, wherein the second layer comprises a silicon, a silicon nitride or a silicon oxide.