Coated phosphors and light emitting devices including the same

Patent metadata

Field	Value
Publication number	US-9537052-B2
Application number	US-201414246375-A
Country	US
Kind code	B2
Filing date	Apr 7, 2014
Priority date	Jun 3, 2011
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

Provided according to embodiments of the invention are method of coating a phosphor that include contacting the phosphor with a sol comprising at least one of silica, alumina, borate and a precursor thereof, to form a coating on the phosphor; and heating the phosphor. Also provided are phosphors that are coated with alumina, silica and/or borate, and light emitting devices that include such phosphors.

First claim

That which is claimed:

1. A method of coating a phosphor comprising:
(a) contacting a nitride phosphor with a sol comprising: at least one of silica, alumina, borate and a precursor thereof, and an acid catalyst; and
(b) heating the phosphor at a temperature in a range of 200° C. to 600° C., thereby forming a coated phosphor,
wherein the sol comprises at least one of colloidal silica and colloidal alumina, and
wherein the sol does not include a precursor of silica, a precursor of alumina, or a precursor of borate.

2. The method of claim 1 , wherein the sol further comprises a solvent.

3. The method of claim 2 , wherein the solvent comprises at least one solvent selected from the group consisting of water, methanol, ethanol, propanol, butanol, 2-ethoxyethanol, formamide, dimethylformamide, dioxane and tetrahydrofuran.

4. The method of claim 1 , wherein the acid catalyst comprises hydrochloric acid.

5. The method of claim 1 , wherein the acid catalyst comprises acetic acid.

6. The method of claim 1 , wherein the sol comprises a tetraalkylorthosilicate.

7. The method of claim 1 , wherein the sol comprises a trialkylborate.

8. The method of claim 1 , wherein the sol comprises alumina and/or aluminum sulfate.

9. The method of claim 1 , wherein the phosphor is stirred in the sol for a time in a range of 0.1 to 40 hours.

10. A coated phosphor comprising:
a nitride phosphor in particulate form coated with alumina, silica and/or borate, wherein the phosphor has a du′v′ of less than 0.0015 after 840 hours at 85° C. and 85% relative humidity.

11. The coated phosphor of claim 10 , wherein the phosphor has an average particle size in a range of 2 to 25 microns.

12. The coated phosphor of claim 10 , further comprising a green and/or yellow phosphor.

13. The method of claim 1 , wherein the nitride phosphor is reacted with the sol for a time in a range of from 16 to 24 hours.

14. The method of claim 1 , wherein, prior to contacting the nitride phosphor with the sol, the sol is reacted for a time in a range of 24 to 32 hours.

15. The method of claim 1 , further comprising heating the coated phosphor at 200° C. for 2-6 hours.

Assignees

• Cree Inc

Inventors

• Seibel Ii Harry A
• Collins Brian Thomas

Classifications

• H10W72/5363

  the connected ends being wedge-shaped · CPC title

• H10W72/536

  the connected ends being ball-shaped · CPC title

• C09K11/0883

  Arsenides; Nitrides; Phosphides · CPC title

• C09K11/883

  with zinc or cadmium · CPC title

• C09K11/025 Primary

  non-luminescent particle coatings or suspension media · CPC title