Methods of determining and making red nitride compositions

• US 9,318,669 B2
• Filed: 01/30/2012
• Issued: 04/19/2016
• Est. Priority Date: 01/30/2012
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Seibel, Harry A. II, Collins, Brian T.
• Primary Examiner(s): COUGHLIN, ANDREW J
• Application Number:
  US13/361,276
• Publication Number:
  US 20130193836A1
• Time in Patent Office: 1,541 Days
• US Class Current: 1/1
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: G01J 3/28 Investigating the spectrum using colour filters G01J3/51
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials

Abstract

Provided according to embodiments of the invention are methods of making a Ca_1-x-ySr_xEu_yAlSiN₃ phosphor composition that include selecting a Color Rendering Index (CRI) R9 value, determining an Eu concentration based on predetermined values to obtain the selected CRI R9 value and making the Ca_1-x-ySr_xEu_yAlSiN₃ phosphor having the determined Eu concentration. Also provided are methods for determining concentrations of Eu in a Ca_1-x-ySr_xEu_yAlSiN₃ phosphor that will achieve a CRI R9 value. Related computer products are also disclosed.

Claims

1. A light emitting device, comprising:

a solid state lighting source;

a first phosphor composition that is configured to emit first emitted light at a first emission wavelength; and

a second phosphor composition that is configured to emit second emitted light at a second emission wavelength that is different from the first emission wavelength and that is different from a wavelength of light emitted from the solid state lighting source, the second phosphor composition including a first activator concentration that results in a first specific saturated color coefficient value and a first general saturated color coefficient value of a combined emission of the light emitted from the solid state lighting source, the first emitted light and the second emitted light,

wherein the first specific saturated color coefficient value is greater than a second specific saturated color coefficient value of another device that is substantially the same as the light emitting device with the exception of having a third phosphor instead of the second phosphor, the third phosphor comprising a third phosphor composition having substantially a same composition as the second phosphor composition except the second activator concentration is greater than the first activator concentration and having a second general saturated color coefficient value that is substantially the same as the first general saturated color coefficient value.

2. The device according to claim 1, wherein the light emitted from the solid state lighting source includes a dominant wavelength in a range of about 380 to about 470 nm, and

wherein the second emission wavelength includes a dominant wavelength in a range of about 530 to about 565 nm.

3. A light emitting device, comprising:

a solid state lighting source;

a first phosphor composition that is configured to emit first emitted light at a first emission wavelength; and

a second phosphor composition that is configured to emit second emitted light at a second emission wavelength that is different from the first emission wavelength and that is different from a wavelength of light emitted from the solid state lighting source, the second phosphor composition including an activator concentration that results in a specific saturated color coefficient value of a combined emission of the light emitted from the solid state lighting source, the first emitted light and the second emitted light wherein the second phosphor composition includes a Ca_1-x-ySr_xEu_yAlSiN₃ phosphor composition, and

wherein the specific saturated color coefficient value is greater than that of another device that is substantially the same as the light emitting device with the exception of having a third phosphor composition instead of the second phosphor composition wherein the third phosphor composition is configured to emit light at the second emission wavelength when excited by light having a same wavelength as the light emitted from the solid state lighting source, the third phosphor composition having substantially a same composition as the second phosphor composition except the third phosphor composition includes the Ca_1-x-ySr_xEu_yAlSiN₃ phosphor composition having a greater concentration of the activator than the second phosphor composition.

4. The device according to claim 3, wherein y is in a range from about 0 to about 0.025, and

wherein the specific saturated color coefficient value comprises a Color Rendering Index (CRI) R9 value in a range of about 0 to about 80.

5. The device according to claim 3, wherein the Ca_1-x-ySr_xEu_yAlSiN₃ phosphor composition emits light including a wavelength at peak frequencies of emitted light of about 630 nm, wherein y is in a range of about 0.002 to about 0.007, and wherein the specific saturated color coefficient value comprises a Color Rendering Index (CRI) R9 value of about 20.

6. The device according to claim 5, wherein the third phosphor composition comprises Ca_1-x-ySr_xEu_yAlSiN₃ with an about eighty percent increase in y relative to the second phosphor composition and about a fifty percent decrease in the CRI R9 value without a substantial change in a general CRI value relative to that of the combined emission.

7. The device according to claim 5, wherein the third phosphor composition comprises Ca_1-x-ySr_xEu_yAlSiN₃ with an about two hundred percent increase in y relative to the second phosphor composition and about a one hundred percent decrease in the CRI R9 value without a substantial change in a general CRI value relative to that of the combined emission.

8. The device according to claim 3, wherein the Ca_1-x-ySr_xEu_yAlSiN₃ phosphor composition emits light including a wavelength at peak frequencies of emitted light of about 630 nm and y is in a range of about 0.005 to about 0.012, and wherein the specific saturated color coefficient value comprises a Color Rendering Index (CRI) R9 value in a range of about 20 to about zero as a function of y.

9. The device according to claim 3, wherein the activator comprises Eu and wherein the specific saturated color coefficient value comprises a Color Rendering Index (CRI) R9 value.

10. The device according to claim 9, wherein the Eu concentration is negatively correlated with the CRI R9 value.

11. The device according to claim 3, wherein a diffuse reflectance of the second phosphor composition and a wavelength at peak frequencies of the second emitted light are indicative of the specific saturated color coefficient value.

12. The device according to claim 3, wherein a diffuse reflectance of the second phosphor composition and a wavelength at peak frequencies of the second emitted light are indicative of a concentration of the activator in the second phosphor composition.

13. The device according to claim 3, wherein the activator concentration has a greater contribution to the specific saturated color coefficient value than the light emitted from solid state lighting source and the first emitted light.

14. The device according to claim 3, wherein a potency of the second phosphor composition that determines a conversion efficiency of the second phosphor composition is less than that of the third phosphor composition.

15. The device according to claim 3, wherein a load factor that corresponds to a relative amount of the second phosphor composition in the device is negatively correlated to an Eu concentration in the second phosphor composition to provide a substantially same specific saturated color coefficient value.

16. The device according to claim 3, wherein a same desired specific saturated color coefficient value corresponds to less of the second phosphor composition than the third phosphor composition having the greater activator concentration.

17. The device according to claim 3, wherein the Ca_1-x-ySr_xEu_yAlSiN₃ phosphor composition emits light including a wavelength at peak frequencies of emitted light of about 630 nm,

wherein the specific saturated color coefficient value comprises a Color Rendering Index (CM) R9 value, and

wherein the third phosphor composition comprises Ca_1-x-ySr_xEu_yAlSiN₃ with an increase of y of about 0.001 relative to the second phosphor composition and a decrease relative to the CRI R9 value in a range of about 3 to about 5 as a function of y.

18. A light emitting device, comprising:

a solid state lighting source;

a first phosphor composition positioned to receive light emitted from the solid state lighting source and to emit first emitted light; and

a second phosphor composition comprising Ca_1-x-ySr_xEu_yAlSiN₃ and configured to receive light that is emitted from the solid state lighting source and to emit second emitted light,

wherein a Color Rendering Index (CRI) R9 value of a combination of the light emitted from the solid state light emitter, the first emitted light and the second emitted light is greater than that of another device that is substantially the same as the light emitting device with the exception of having a third phosphor composition instead of the second phosphor composition, the third phosphor composition comprising a Ca_1-x-ySr_xEu_yAlSiN₃ phosphor composition having a greater Eu concentration than the second phosphor composition.

19. The device according to claim 18, wherein the Eu concentration of the second phosphor composition further corresponds to a selected potency that determines a conversion efficiency of the second phosphor composition, and

wherein a potency of the Ca_1-x-ySr_xEu_yAlSiN₃ phosphor composition having the greater Eu concentration is greater than the selected potency.

20. The device according to claim 18, wherein the second phosphor composition comprising Ca_1-x-ySr_xEu_yAlSiN₃ emits light including a wavelength at peak frequencies of emitted light of about 630 nm and a y value is in a range of about 0.003 to about 0.015, and wherein the CRI R9 value is in a range of about 20 to about zero corresponding to the y value.

21. The device according to claim 18, wherein the Eu concentration is negatively correlated with the CRI R9 value.

22. The device according to claim 18, wherein a diffuse reflectance of the second phosphor composition and a wavelength at peak frequencies of the second emitted light are indicative of the Eu concentration in the second phosphor composition.

23. The device according to claim 18, wherein the second phosphor composition comprising Ca_1-x-ySr_xEu_yAlSiN₃ emits light including a wavelength at peak frequencies of emitted light of about 630 nm, wherein y is in a range of about 0.003 to about 0.007, and wherein the CRI R9 value is in a range of about 18 to about 22.

24. The device according to claim 23, wherein the Ca_1-x-ySr_xEu_yAlSiN₃ phosphor composition having the greater Eu concentration comprises an about eighty percent increase in y relative to the second phosphor composition and an about fifty percent decrease in the CRI R9 value.

25. The device according to claim 18,

wherein the combination of the light emitted from the solid state light emitter, the first emitted light and the second emitted light is visually indistinguishable from a center point of a region in two-dimensional color space, and

wherein the two-dimensional color space includes a 1931 CIE Chromaticity Diagram and wherein the center point corresponds to a ccx value in a range of about 0.335 to about 0.480 and a ccy value in a range of about 0.335 to about 0.435.

26. The device according to claim 25, wherein the center point corresponds to a ccx value in a range of about 0.414 to about 0.485 and a ccy value in a range of about 0.380 to about 0.435.