Feedback and coupling structures and methods

• US 20040206965A1
• Filed: 04/16/2003
• Published: 10/21/2004
• Est. Priority Date: 04/16/2003
• Status: Active Grant

• Current Assignee: MT Technology Enterprises, LLC
• Original Assignee: Zeolux Corporation
• Inventors: Evans, Allan Kenneth
• Granted Patent: US 6,911,674 B2
• Time in Patent Office: Days
• US Class Current: 257/83
• CPC Class Codes: H01S 5/0424 lateral current injection
• CPC Class Codes: H01S 5/1215 Multiplicity of periods
• CPC Class Codes: H01S 5/187 using Bragg reflection
• CPC Class Codes: H01S 5/36 comprising organic materials
• CPC Class Codes: H10K 50/85 Arrangements for extracting light from the devices
• CPC Class Codes: H10K 50/858 comprising refractive means, e.g. lenses
• CPC Class Codes: Y10S 257/918 Light emitting regenerative switching device, e.g. light emitting scr arrays, circuitry

Abstract

A light emitting device may include a light emitting layer such as an organic semiconductor material, one or more feedback structures, and a coupling structure. The one or more feedback structures may cause light emitted by the light emitting layer to be fed back through it along an axis in the plane of the device, thereby promoting the stimulated emission of light in the light emitting layer. The coupling structure couples some fraction of the feedback light out of the device. The coupled light may be emitted along an axis substantially normal to the plane of the device or at predetermined angles. The coupling and feedback structures may have a corrugated structure, a continuous variation of refractive index along an axis in the device plane, a period refractive index, or any combination thereof. The coupling and feedback structures may be separate, share common portion or combined together.

Claims

1. A light emitting diode device comprising:

a light emitting diode; and

a vertical coupling structure,

wherein the vertical coupling structure changes a propagation direction of a portion of a substantially horizontal stimulated light emission within the light emitting diode such that the portion of the substantially horizontal stimulated light emission exits the light emitting diode as output light.

2. The device of claim 1, wherein the output light propagates substantially normal to a plane substantially parallel to the light emitting diode.

3. The device of claim 1, wherein the output light propagates at +θ

°

to a normal to a plane substantially parallel to the light emitting diode.

4. The device of claim 1, wherein the vertical coupling structure is corrugated.

5. The device of claim 1, wherein the vertical coupling structure has an oscillating refractive index along a plane substantially parallel to the light emitting diode.

6. The device of claim 1, wherein the vertical coupling structure has a continuous variation in refractive index.

7. The device of claim 1, wherein the vertical coupling structure has a discontinuous variation in refractive index.

8. The device of claim 1, wherein the vertical coupling structure is periodic.

9. The device of claim 1, wherein the vertical coupling structure includes a first dielectric material and a second dielectric material.

10. The device of claim 1, further comprising a light feedback structure.

11. The device of claim 10, wherein the light feedback structure is corrugated.

12. The device of claim 10, wherein the light feedback structure has an oscillating refractive index along a plane substantially parallel to the light emitting diode.

13. The device of claim 10, wherein the light feedback structure has a continuous variation in refractive index.

14. The device of claim 10, wherein the light feedback structure has a discontinuous variation in refractive index.

15. The device of claim 10, wherein the light feedback structure is periodic.

16. The device of claim 1, wherein the vertical coupling structure includes part of a light feedback structure.

17. The device of claim 1, wherein the vertical coupling structure includes a light feedback structure.

18. The device of claim 1, wherein the light emitting diode includes a high index of refraction area sandwiched between low index refraction areas.

19. The device of claim 18, wherein the high index of refraction area includes a light emitting material.

20. The device of claim 1, wherein the light emitting diode includes a light emitting material, the light emitting material being one of:

an organic semiconductor material;

a combination of organic and inorganic semiconductor materials;

or

an organometallic semiconductor material;

or

an inorganic semiconductor material.

21. A method of generating light comprising:

energizing a light emitting material such the light emitting material emits light;

reflecting at least a portion of the light emitted by the light emitting material back through the light emitting material to stimulate the emission of stimulated light; and

altering a direction of a portion of the stimulated light such that the portion of the stimulated light is coupled away from the light emitting material.

22. The method of claim 21, wherein the stimulated light is laser light.

23. The method of claim 22, wherein the portion of the stimulated light is vertically coupled away from the light emitting material.

24. An emissive device comprising:

a grating;

an anode adjacent the grating;

a hole injection layer adjacent the anode;

a hole transport layer adjacent the hole injection layer;

an emissive layer adjacent the hole injection layer;

an electron transport layer adjacent emissive layer;

an electron injection layer adjacent the electron transport layer;

a cathode adjacent the electron injection layer; and

a planarizing layer adjacent the cathode,

wherein the hole transport layer and the anode have an index of refraction higher than the electron transport layer such that the hole transport layer, the anode and the electron transport layer form a waveguide, and

wherein the grating feeds back a portion of a light incident thereon toward the anode and couples another portion of the light incident thereon away from anode.

25. The device of claim 24, wherein a portion of light propagating in the device plane that is incident on the photoresist grating is fed back in a direction 180°

to original direction of propagation and another portion of the light incident on the grating is coupled in directions normal to the plane of the device.

26. The device of claim 24, wherein the emissive layer being one of:

an organic semiconductor material;

a combination of organic and inorganic semiconductor materials;

or

an organometallic semiconductor material;

or

an inorganic semiconductor material.

27. The device of claim 24, wherein the grating is a photoresist grating.

28. A feedback enhanced emitter comprising:

a light emitter;

a feedback structure; and

a coupling structure,

wherein the feedback structure reflects light generated by the light emitter back into the light emitter, and

wherein the coupling structure changes the propagation direction of a portion of a stimulated light emission within the light emitter such that the portion of the stimulated light emission exits the light emitter as output light.

29. The emitter of claim 28, wherein the output light propagates substantially normal to a plane substantially parallel to the light emitter.

30. The emitter of claim 28, wherein the output light propagates at ±

θ

to a normal to a plane substantially parallel to the light emitter.

31. The emitter of claim 28, wherein the coupling structure is corrugated.

32. The emitter of claim 28, wherein the coupling structure has an oscillating refractive index along a plane substantially parallel to the light emitter.

33. The emitter of claim 28, wherein the coupling structure has a continuous variation in refractive index.

34. The emitter of claim 28, wherein the coupling structure has a discontinuous variation in refractive index.

35. The emitter of claim 28, wherein the coupling structure is periodic.

36. The emitter of claim 28, wherein the coupling structure includes a first dielectric material and a second dielectric material.

37. The emitter of claim 28, wherein the light feedback structure is corrugated.

38. The emitter of claim 28, wherein the light feedback structure has an oscillating refractive index along a plane substantially parallel to the light emitter.

39. The emitter of claim 28, wherein the light feedback structure has a continuous variation in refractive index.

40. The emitter of claim 28, wherein the light feedback structure has a discontinuous variation in refractive index.

41. The emitter of claim 28, wherein the light feedback structure is periodic.

42. The emitter of claim 28, wherein the coupling structure includes part of a light feedback structure.

43. The emitter of claim 28, wherein the coupling structure includes a light feedback structure.

44. The emitter of claim 28, wherein the light emitter includes a high index of refraction area sandwiched between low index refraction areas.

45. The emitter of claim 44, wherein the high index of refraction area includes a light emitting material.

46. The emitter of claim 28, wherein the light emitter includes a light emitting material, the light emitting material being one of:

an organic semiconductor material;

a combination of organic and inorganic semiconductor materials;

or

an organometallic semiconductor material;

or

an inorganic semiconductor material.

47. The emitter of claim 28, wherein the light emitter is a light emitting diode.

48. A method of generating light comprising:

energizing a light emitting material to generate a first light;

reflecting at least a portion of the first light back to the light emitting material to stimulate an emission of a second light along a first axis; and

altering a propagation direction at least a portion of the second light to at least a second axis,

wherein the first axis and the at least a second axis are not substantially parallel.

49. The method of claim 48, wherein the first axis is orthogonal to the at least a second axis.