Efficient, green-emitting phosphors, and combinations with red-emitting phosphors

• US 7,427,366 B2
• Filed: 07/05/2005
• Issued: 09/23/2008
• Est. Priority Date: 07/06/2004
• Status: Expired due to Fees

• Current Assignee: Lightscape Materials, Inc.
• Original Assignee: Sarnoff Corporation (SRI International, Inc.)
• Inventors: Yocom, Perry Niel, Tian, Yongchi, Frederickson, Gerard, Yang, Liyou
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US11/174,856
• Publication Number:
  US 20060012287A1
• Time in Patent Office: 1,176 Days
• Field of Search: 252/301.4 S, 313/530, 313/503, 257/98
• US Class Current: 252/301.40S
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/584 with zinc or cadmium
• CPC Class Codes: C09K 11/623 with zinc or cadmium
• CPC Class Codes: C09K 11/7421 with alkaline earth metals
• CPC Class Codes: C09K 11/7718 with alkaline earth metals
• CPC Class Codes: C09K 11/7731 with alkaline earth metals
• CPC Class Codes: C09K 11/7733 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7738 with alkaline earth metals
• CPC Class Codes: C09K 11/7786 with alkaline earth metals
• CPC Class Codes: C09K 11/7789 Oxysulfides
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H05B 33/14 characterised by the chemical or physical composition or the arrangement of the electroluminescent material , or by the simultaneous addition of the electroluminescent material in or onto the light source

Abstract

Provided among other things is a phosphor of the formula
Sr_1-x3Ca_x3Ga₂S₄:Eu:xGa₂S₃  (I)
wherein x is 0 to about 0.2 (or about 0.0001 to about 0.2), wherein x3 is 0.0001 to 1, and wherein a minor part of the europium component is substituted with praseodymium in an efficiency enhancing amount.

Claims

1. A mixture of two or more phosphors, one of a first emission energy and the second of a lower emission energy, comprising:

the first phosphor of the formula (I)

Sr_1-x3Ca_x3Ga₂S₄;

Eu;

xGa₂S₃ 

 

(I)

wherein x is 0 to about 0.2, wherein x3 is 0.0001 to 1, and wherein a minor part of the europium component is substituted with praseodymium in an efficiency enhancing amount;

and the second phosphor of the formula (II);

Sr_x2Ca_1-x2S;

Eu²⁺, Y 

 

(II)

wherein x2 is a number from 0 to 1.0, and Y is one or more halides in atomic or ionic form.

2. The phosphor mixture of claim 1, wherein the median grain size of the phosphor of formula I is from 2 to 4.5 microns.

3. The phosphor mixture of claim 1, wherein the first phosphor emits with an emission peak having wavelength from 492 nm to 560 nm.

4. The phosphor mixture of claim 3, wherein the second phosphor emits with an emission peak having wavelength from 605 nm to 670 nm.

5. The phosphor mixture of claim 1, wherein the second phosphor emits with an emission peak having wavelength from 605 nm to 670 nm.

6. A light emitting device comprising:

a light source producing a light output; and

the phosphor mixture of claim 1, located to convert at least a portion of the light output to a higher wavelength.

7. The light emitting device of claim 6, further comprising one or more additional phosphors located to convert at least a portion of the light output to a higher wavelength.

8. The light emitting device of claim 6, wherein the phosphors are selected to sufficiently convert the light output so that a total light output for the device has a white chromaticity.

9. The light emitting device of claim 6, wherein the second phosphor is effective to convert the light output to increase light having wavelength from 605 nm to 660 nm.

10. The light emitting device of claim 6, wherein the first phosphor is effective to convert the light output to increase light having wavelength from 492 nm to 560 nm.

11. The light emitting device of claim 6, further comprising a third phosphor effective to convert the light output to increase light having wavelength from 530 nm to 610 nm.

12. The light emitting device of claim 6, wherein the light source is an LED providing light in the range from 215 nm to 515 nm.