Light-Emitting Devices Having Multiple Encapsulation Layers With at Least One of the Encapsulation Layers Including Nanoparticles and Methods of Forming the Same

• US 20110068362A1
• Filed: 11/24/2010
• Published: 03/24/2011
• Est. Priority Date: 04/06/2004
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Negley, Gerald H., Tarsa, Eric
• Granted Patent: US 8,946,755 B2
• Time in Patent Office: Days
• US Class Current: 257/99
• CPC Class Codes: H01L 33/52 Encapsulations
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin
• CPC Class Codes: H05B 33/04 Sealing arrangements , e.g. against humidity

Abstract

A light-emitting device includes an active region that is configured to emit light responsive to a voltage applied thereto. A first encapsulation layer at least partially encapsulates the active region and includes a matrix material and nanoparticles, which modify at least one physical property of the first encapsulation layer. A second encapsulation layer at least partially encapsulates the first encapsulation layer.

Claims

1. A light-emitting device, comprising:

an active region that is configured to emit light responsive to a voltage applied thereto;

a first encapsulation layer that at least partially encapsulates the active region, the first encapsulation layer comprising a first matrix material and serving a first encapsulation layer function corresponding to a first encapsulation layer physical property; and

a second encapsulation layer that at least partially encapsulates the first encapsulation layer, the second encapsulation layer comprising a second matrix material and first nanoparticles and serving a second encapsulation layer function corresponding to a second encapsulation layer physical property, the second encapsulation function being different from the first encapsulation layer function;

wherein the first encapsulation layer is arranged between the active region and the second encapsulation layer and defines a separation therebetween;

wherein the first nanoparticles modify the second encapsulation layer physical property including at least one of light scattering, diffraction, thermal conductivity, mechanical strength, abrasion resistance, and optical stability.

2. The light-emitting device of claim 1,

wherein the first matrix material comprises at least one of silicone, a silicone compound, an optical gel, epoxy resin, glass, sol-gel, aerogel, and an optically stable polymer, and

wherein the second matrix material comprises at least one of silicone, a silicone compound, an optical gel, epoxy resin, glass, sol-gel, aerogel, and an optically stable polymer.

3. The light-emitting device of claim 1, wherein the first encapsulation layer and the second encapsulation layer are substantially transparent.

4. The light-emitting device of claim 1,

wherein the first nanoparticles comprise TiO₂, diamond, silicon carbide, scattering particles, fillers, phosphors, and/or light conversion materials.

5. The light-emitting device of claim 1, wherein an outer surface of the first encapsulation layer, opposite the active region, is shaped so that light rays from the active region are incident on the first encapsulation layer at an angle that is less than or equal to critical angle.

6. The light-emitting device of claim 1, wherein the first encapsulation layer physical property comprises mechanical strength, and

wherein the second encapsulation layer physical property comprises thermal conductivity.

7. The light-emitting device of claim 1, wherein the first encapsulation layer physical property comprises thermal conductivity, and

wherein the second encapsulation layer physical property comprises light scattering.

8. The light-emitting device of claim 1, wherein the second encapsulation layer comprises light conversion materials.

9. The light-emitting device of claim 1, further comprising a third encapsulation layer that at least partially encapsulates the second encapsulation layer, the third encapsulation layer comprising a third matrix material and second nanoparticles and serving a third encapsulation layer function corresponding to a third encapsulation layer physical property;

wherein the third encapsulation layer physical property comprises at least one of a third physical property of light scattering, diffraction, thermal conductivity, mechanical strength, abrasion resistance, and optical stability,

wherein the third encapsulation layer function is different from the first encapsulation layer function and the second encapsulation layer function, and

wherein the second nanoparticles comprise at least one of TiO₂, diamond, silicon carbide, scattering particles, fillers, phosphors, and light conversion materials.

10. The light-emitting device of claim 1, wherein the first encapsulation layer is substantially free of nanoparticles.

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

forming an active region that is configured to emit light responsive to a voltage applied thereto;

forming a first encapsulation layer that at least partially encapsulates the active region, the first encapsulation layer comprising a first matrix material and serving a first encapsulation layer function corresponding to a first encapsulation layer physical property; and

forming a second encapsulation layer that at least partially encapsulates the first encapsulation layer, the second encapsulation layer including a second matrix material and first nanoparticles and serving a second encapsulation layer function corresponding to a second encapsulation layer physical property,

wherein the first encapsulation layer function is different from the second encapsulation layer function,

wherein the first encapsulation layer is arranged between the active region from the second encapsulation layer and provides a separation therebetween, and

wherein the second encapsulation layer physical property comprises light scattering, diffraction, thermal conductivity, mechanical strength, abrasion resistance, and optical stability that is different from the first encapsulation layer physical property.

12. The method of claim 11, wherein the first matrix material comprises at least one of silicone, a silicone compound, an optical gel, epoxy resin, glass, sol-gel, aerogel, and an optically stable polymer,

wherein the second matrix material comprises at least one of silicone, a silicone compound, an optical gel, epoxy resin, glass, sol-gel, aerogel, and an optically stable polymer.

13. The method of claim 11, wherein the first encapsulation layer and the second encapsulation layer are substantially transparent.

14. The method of claim 11, wherein the first nanoparticles comprise at least one of TiO₂, diamond, silicon carbide, scattering particles, fillers, phosphors, and light conversion material.

15. The method of claim 11, wherein an outer surface of the first encapsulation layer, opposite the active region, is shaped so that light rays from the active region are incident on the first encapsulation layer at an angle that is less than or equal to a critical angle.

16. The method of claim 11, wherein the first encapsulation layer physical property includes mechanical strength, and

wherein the second encapsulation layer physical property includes thermal conductivity.

17. The method of claim 11, wherein the first encapsulation layer physical property includes thermal conductivity, and

wherein the second encapsulation layer physical property includes diffraction.

18. The method of claim 11, wherein the second encapsulation layer includes phosphors.

19. The method of claim 11, further comprising forming a third encapsulation layer that at least partially encapsulates the second encapsulation layer, the third encapsulation layer including a third matrix material and second nanoparticles and serving a third encapsulation layer function corresponding to a third encapsulation layer physical property;

wherein the third encapsulation layer physical property includes at least one of a third physical property of light scattering, diffraction, thermal conductivity, mechanical strength, abrasion resistance, and optical stability, and

wherein the second nanoparticles include at least one of TiO₂, diamond, silicon carbide, scattering particles, fillers, phosphors, and light conversion materials.

20. A method of forming a light-emitting device, wherein the first encapsulation layer is substantially free of nanoparticles.

21. A light-emitting device, comprising:

an active region that is configured to emit light responsive to a voltage applied thereto;

a first encapsulation layer that at least partially encapsulates the active region, the first encapsulation layer comprising a first material and serving a first encapsulation layer function corresponding to a first encapsulation layer physical property; and

a second encapsulation layer that at least partially encapsulates the first encapsulation layer, the second encapsulation layer comprising a second material and serving a second encapsulation layer function corresponding to a second encapsulation layer physical property, the second encapsulation layer function being different from the first encapsulation layer function,

wherein the first material modifies a physical property of the first encapsulation layer including at least one of thermal conductivity, mechanical strength, abrasion resistance, and optical stability, and

wherein the second material modifies a physical property of the second encapsulation layer including at least one of light scattering, diffraction, thermal conductivity, mechanical strength, abrasion resistance, and optical stability.

22. The light emitting device of claim 21, wherein the second encapsulation layer physical property comprises a wavelength conversion property that converts a wavelength of light received from the first encapsulation layer.

23. The light emitting device of claim 21, wherein the first material comprises a first matrix material that performs the first encapsulation layer function to separate the active region from the second encapsulation layer.

24. The light emitting device of claim 21, wherein the second material comprises a second matrix material and first nanoparticles that perform the second encapsulation layer function to modify the physical property of the second encapsulation layer.

25. The light emitting device of claim 21, further comprising a third encapsulation layer that at least partially encapsulates the second encapsulation layer, the third encapsulation layer comprising a third material that performs a third encapsulation layer function corresponding to a third encapsulation layer physical property,

wherein the third encapsulation layer function is different from the first encapsulation layer function and the second encapsulation payer function, and

wherein the third encapsulation layer physical property includes at least one of light scattering, diffraction, thermal conductivity, mechanical strength, abrasion resistance, and optical stability.

26. The light emitting device of claim 21, wherein the second encapsulation layer physical property comprises a wavelength conversion property that converts a wavelength of light received from the first encapsulation layer,

wherein the third encapsulation physical property comprises a thermal conductivity property that is configured to transfer thermal energy from the first and second encapsulation layers.

27. The light emitting device of claim 26, wherein the third material comprises a third matrix material and second nanoparticles that perform the third encapsulation layer function to modify the third encapsulation layer physical property,

wherein the second nanoparticles comprise at least one of TiO₂, diamond, silicon carbide, scattering particles, fillers, phosphors, and light conversion materials.