Green emitting phosphor for use in UV light emitting diodes

• US 6,469,322 B1
• Filed: 05/30/2000
• Issued: 10/22/2002
• Est. Priority Date: 02/06/1998
• Status: Expired due to Term

• Current Assignee: Current Lighting Solutions, LLC (f/k/a GE Lighting Solutions, LLC) (American Industrial Partners)
• Original Assignee: General Electric Company
• Inventors: Beers, William W., Comanzo, Holly A., Srivastava, Alok M.
• Primary Examiner(s): Tran, Minh Loan
• Application Number:
  US09/583,196
• Time in Patent Office: 875 Days
• Field of Search: 257/88, 257/89, 257/98, 257/99, 257/100, 257/103, 313/501, 313/502, 313/503, 313/512
• US Class Current: 257/89
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: C09K 11/7734 Aluminates
• CPC Class Codes: C09K 11/7768 with alkaline earth metals
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: C09K 11/778 Borates
• CPC Class Codes: C09K 11/7786 with alkaline earth metals
• CPC Class Codes: C09K 11/7789 Oxysulfides
• CPC Class Codes: C09K 11/7794 Vanadates; Chromates; Molybdates; Tungstates
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21V 3/12 the coatings comprising photoluminescent substances
• CPC Class Codes: F21V 7/28 characterised by coatings
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: F21Y 2115/30 Semiconductor lasers
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A green-emitting phosphor is provided, which has the general formula Ln_xBO₃: Ce³⁺_y, Tb³⁺_z, where Ln includes one or more lanthanide-type elements, such as Sc, Y, La, Gd, and Lu. x+y+z=1; 0≦x≦0.98; 0≦y≦0.5; and 0≦z≦0.5. The phosphor efficiently converts light in the UV/blue region of the spectrum (250-400 nm) to light of longer wavelength, with a peak emission intensity of about 545 nm. The phosphor is used alone, or in a phosphor blend for converting UV/blue light from a GaN-base light emitting diode to green or white light, respectively.

Claims

1. A light source comprising:

a light emitting component which emits light at a first wavelength; and

a phosphor material positioned to receive the light emitted by the light emitting component, the phosphor material including a green-emitting phosphor which converts a portion of the light of the first wavelength to light of a second, longer wavelength, the green-emitting phosphor having the general formula Ln_xBO₃;

Ce³⁺_y, Tb³⁺_z, where;

x=1−

(y+z);

0<

x≦

0.98;

0.01≦

y≦

0.5;

0.02≦

z≦

0.5; and

Ln includes one or more of Sc, Y, La, Gd, Lu, and other lanthanide elements.

2. The light source of claim 1, wherein the light emitting component is selected from the group consisting of light emitting diodes and laser diodes.

3. The light source of claim 2, wherein the light emitting component emits light in at least one of the blue and the UV regions of the electromagnetic spectrum.

4. The light source of claim 3, wherein the light emitting component includes a GaN-based semiconductor material.

5. The light source of claim 1, wherein Ln is selected from the group consisting of Y, Sc, La, and Gd, and combinations thereof.

6. The light source of claim 1, wherein Ln consists of Y and Gd in approximately equal proportions.

7. The light source of claim 1, wherein the ratio of Ce:

Tb is about 2;

1.

8. The fight source of claim 7, wherein the phosphor material further includes at least one of a blue-emitting phosphor and a red-emitting phosphor.

9. The light source of claim 8, wherein the blue emitting phosphor is selected from the group consisting of:

(Ba, Sr, Ca)₅(PO₄)₃Cl;

Eu²⁺;

Mn²⁺;

Y₂O₃;

Bi³⁺, Eu²⁺; and

mixtures thereof.

10. The light source of claim 8, wherein the red emitting phosphor is selected from the group consisting of:

Ca₈Mg(SiO₄)₄Cl₂;

Eu²⁺, Mn²⁺;

Y₂O₃;

Bi³⁺,Eu²⁺;

Y₂O₂S;

Eu; and

mixtures thereof.

11. The light source of claim 1, further including:

a housing; and

a reflective coating disposed on an interior surface of the housing, the light emitting component being positioned within the housing.

12. The light source of claim 11, wherein the phosphor material is dispersed in a medium which encapsulates the light emitting component.

13. The light source of claim 1, wherein said second wavelength light is used to excite a second phosphor material.

14. A light source comprising:

a housing, the housing being closed by a window;

a light emitting component positioned within the housing which emits light at a first wavelength; and

a phosphor material, the phosphor material being deposited on the window and positioned to receive the light emitted by the light emitting component, the phosphor material including a green-emitting phosphor which converts a portion of the light of the first wavelength to light of a second, longer wavelength, the green-emitting phosphor having the general formula Ln_xBO₃;

Ce³⁺_y, Tb³⁺_z, where;

x=1−

(y+z);

0<

x≦

0.98;

0.01≦

y≦

0.5;

0.02≦

z≦

0.5; and

Ln includes one or more of Sc, Y, La, Gd, Lu, and other lanthanide elements.

15. A method of converting UV/blue light to light in the green region of the electromagnetic spectrum comprising:

converting the UV/blue light with a phosphor of the general formula Ln_xBO₃;

Ce³⁺_Y, Tb³⁺_z where;

Ln includes one or more of Sc, Y, La, Gd, Lu, and other lanthanide elements;

x=1−

(y+z);

0<

x≦

0.98;

0.01≦

y≦

0.5; and

0.01≦

z≦

0.5.

16. The method of claim 15, wherein Ln is selected from the group consisting of Y, Sc, La, and Gd, and combinations thereof.

17. The method of claim 15, wherein Ln consists of Y and Gd in approximately equal proportions.

18. The method of claim 15, wherein the ratio of Ce:

Tb is about 2;

1.

19. A phosphor material having the general formula Ln_xBO₃:

Ce³⁺_y, Tb³⁺_z where;

Ln includes one or more of Sc, Y, La, Gd, Lu, and other lanthanide elements;

x=1−

(y+z);

0<

x≦

0.98;

0.01≦

y≦

0.5; and

0.01≦

z≦

0.5.