LED DEVICE STRUCTURE TO IMPROVE LIGHT OUTPUT

• US 20090294785A1
• Filed: 05/29/2008
• Published: 12/03/2009
• Est. Priority Date: 05/29/2008
• Status: Active Grant

• Current Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Original Assignee: Global OLED Technology LLC (LG Display Co., Ltd.)
• Inventors: Cok, Ronald S.
• Granted Patent: US 8,390,008 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• 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

Abstract

A light-emitting device, including a substrate; a LED element formed over the substrate including a transparent or semi-transparent electrode, a reflective electrode, and one or more layers, at least one of which is light-emitting, formed between the transparent or semi-transparent electrode and reflective electrode, the transparent or semi-transparent electrode and reflective electrode defining a single, controllable light-emitting area, wherein the LED element emits light into a waveguide defined by the transparent or semi-transparent electrode, reflective electrode, and the one or more layers; and one or more first topographical features and one or more second topographical features different from the first topographical features formed over the substrate within the single, controllable light-emitting area, wherein the first and second topographical features disrupt the waveguiding of light within the single, controllable light-emitting area to increase the emission of light in at least one direction.

Claims

1. A light-emitting device, comprising:

(a) a substrate;

(b) a LED element formed over the substrate including a transparent or semi-transparent electrode, a reflective electrode, and one or more layers, at least one of which is light-emitting, formed between the transparent or semi-transparent electrode and reflective electrode, the transparent or semi-transparent electrode and reflective electrode defining a single, controllable light-emitting area, wherein the LED element emits light into a waveguide defined by the transparent or semi-transparent electrode, reflective electrode, and the one or more layers; and

(c) one or more first topographical features and one or more second topographical features different from the first topographical features formed over the substrate within the single, controllable light-emitting area, wherein the first and second topographical features disrupt the waveguiding of light within the single, controllable light-emitting area to increase the emission of light in at least one direction.

2. The light-emitting device according to claim 1, wherein the light-emitting device is a display device having a plurality of individually addressable light emitting pixels and the single, controllable light-emitting area is a sub-pixel.

3. The light-emitting device according to claim 1, wherein the light-emitting layers comprise one or more light-emitting organic layers, or one or more light-emitting layers having one or more inorganic layers having quantum dots within a polycrystalline semiconductor matrix.

4. The light-emitting device according to claim 1, wherein the LED element forms a microcavity.

5. The light-emitting device according to claim 1, wherein the single, controllable light-emitting area is divided into at least first and second portions, the first topographical features formed within the first portion and the second topographical feature formed within the second portion.

6. The light-emitting device according to claim 1, wherein the first and second topographical features are intermixed within the single, controllable light-emitting area.

7. The light-emitting device according to claim 1, wherein the first and second topographical features have the same shape but differ in their distribution over an area, have different shapes, or have different shapes and differ in their distribution over an area.

8. The light-emitting device according to claim 1, wherein the first or second topographical features are indentations formed in the substrate or a layer formed over the substrate.

9. The light-emitting device according to claim 1, wherein the first or second topographical features are circularly symmetric in the plane of the controllable light-emitting area, are symmetric in two orthogonal dimensions in the plane of the controllable light-emitting area, have angled walls, have curved walls, have a rectangular cross section in the plane of the light-emitting area, or have an oval cross section in the plane of the light-emitting area.

10. The light-emitting device according to claim 1, wherein the first or second topographical features are located in an irregular pattern.

11. The light-emitting device according to claim 1, further comprising a plurality of light-emitting areas.

12. The light-emitting device according to claim 11, wherein the first or second topographical features in a first light-emitting area are different in shape, distribution, or shape and distribution from the first or second topographical features in a second light-emitting area.

14. The light-emitting device according to claim 11, wherein the LED element in a first light-emitting area has a different thickness than the thickness of an LED element in a second light-emitting area.

15. The light-emitting device according to claim 11, wherein the topographical features are distributed rectangularly or hexagonally in the light light-emitting area.

16. The light-emitting device according to claim 1, wherein the one or more layers emit broadband light.

17. The light-emitting device according to claim 1, wherein the LED device is an area illumination lamp or a display.

18. The light-emitting device according to claim 1, wherein the topographical feature is defined by a feature in an insulating layer located under the light emitting layer.

19. The light-emitting device according to claim 1, wherein the topographical features have surfaces at an angle that is less than 45 degrees to the plane of the light-emitting area.

13. The light-emitting device according to claim 112, wherein materials in the one or more layers in a first light-emitting area different from materials of the one or more layers in a second light-emitting area.

20. A method of forming a light emitting device, comprising:

(a) providing a substrate;

(b) forming an LED element over the substrate, the LED element comprising a transparent or semi-transparent electrode, a reflective electrode, and one or more layers, at least one of which is light-emitting, formed between the transparent or semi-transparent electrode and reflective electrode, the transparent or semi-transparent electrode and reflective electrode defining a single, controllable light-emitting area, wherein the LED element emits light into a waveguide defined by the transparent or semi-transparent electrode, reflective electrode, and one or more layers;

(c) forming first topographical features and second topographical features different from the first topographic features over the substrate, wherein the first and second topographical features disrupt the waveguiding of light within the single, controllable light-emitting area to emit waveguided light.