Luminescent Particles, Methods of Identifying Same and Light Emitting Devices Including the Same

• US 20100127613A1
• Filed: 11/17/2009
• Published: 05/27/2010
• Est. Priority Date: 11/17/2008
• Status: Active Grant

• Current Assignee: Creeled Incorporated
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Le Toquin, Ronan P., Collins, Brian Thomas
• Granted Patent: US 9,464,225 B2
• Time in Patent Office: Days
• US Class Current: 313/503
• CPC Class Codes: C09K 11/0883 Arsenides; Nitrides; Phosphides
• CPC Class Codes: C09K 11/77347 Silicon Nitrides or Silicon Oxynitrides
• CPC Class Codes: C09K 11/77348 Silicon Aluminium Nitrides or Silicon Aluminium Oxynitrides

Abstract

A luminescent particle includes a luminescent compound that is configured to perform a photon down conversion on a portion of received light and a reflectance reducing outer surface of the luminescent particle that is operable to increase the portion of received light that is absorbed in the luminescent particle.

Claims

1. A luminescent particle, comprising:

a luminescent compound that is configured to perform a photon down conversion on a portion of received light; and

a reflectance reducing outer surface of the luminescent particle that is operable to increase the portion of received light that is absorbed in the luminescent particle.

2. The luminescent particle according to claim 1,

wherein a plurality of first luminescent particles including the luminescent particle may include a first size range and a first diffuse reflectance at a dominant wavelength of light, and

where a plurality of second luminescent particles not including the luminescent particle may include a second size range and a second diffuse reflectance at the dominant wavelength of light.

3. The luminescent particle according to claim 2,

wherein the dominant wavelength of light is about 450 nm,

wherein the first size range and the second size range are substantially similar,

wherein the first diffuse reflectance is substantially less than the second diffuse reflectance.

4. The luminescent particle according to claim 3, wherein the first diffuse reflectance comprises about ninety-five percent of the second diffuse reflectance.

5. The luminescent particle according to claim 3, wherein the first diffuse reflectance comprises about ninety-two percent of the second diffuse reflectance.

6. The luminescent particle according to claim 3, wherein the first diffuse reflectance comprises about ninety percent of the second diffuse reflectance.

7. The luminescent particle according to claim 2,

wherein the dominant wavelength of light is about 450 nm,

wherein the first size range includes particles that are smaller than particles in the second size range,

wherein the first diffuse reflectance is substantially similar to the second diffuse reflectance.

8. The luminescent particle according to claim 7, wherein a difference between the first diffuse reflectance and the second diffuse reflectance is less than about five percent.

9. The luminescent particle according to claim 2,

wherein the dominant wavelength of light corresponds to substantially blue light in the visible spectrum,

wherein a first weight percent of the plurality of first particles is mixed with an encapsulant to yield an emission color that is a combination of the dominant wavelength and light emitted from the plurality of first particles via a photon down converting characteristic thereof,

wherein a second weight percent of the plurality of second particles is mixed with the encapsulant to yield the emission color that is a combination of the dominant wavelength and light emitted from the plurality of second particles via a photon down converting characteristic thereof, and

wherein the first weight percent is less than the second weight percent.

10. The luminescent particle according to claim 9, wherein the first weight percent is about ninety percent of the second weight percent.

11. The luminescent particle according to claim 9, wherein the first weight percent is about seventy-five percent of the second weight percent.

12. The luminescent particle according to claim 9, wherein the first weight percent is about sixty-seven percent of the second weight percent.

13. The luminescent particle according to claim 2,

wherein the dominant wavelength of light corresponds to substantially blue light in the visible spectrum,

wherein a first ratio of a plurality of yellow emitting light conversion particles to the plurality of first particles are arranged in an emission path of the dominant wavelength of light to yield a warm white emission color that is a combination of the dominant wavelength and light emitted from the plurality of first particles via a photon down converting characteristic thereof and the plurality of yellow emitting light conversion particles,

wherein a second ratio of the plurality of yellow emitting light conversion particles to the plurality of second particles are arranged in an emission path of the dominant wavelength of light to yield the warm white emission color that is a combination of the dominant wavelength and light emitted from the plurality of second particles via a photon down converting characteristic thereof and the plurality of yellow emitting light conversion particles, and

wherein the first ratio is substantially greater than the second ratio.

14. The luminescent particle according to claim 13,

wherein the first ratio comprises a first percent weight ratio, and

wherein the second ratio comprises a second percent weight ratio.

15. The luminescent particle according to claim 13, wherein the second ratio comprises about eighty-percent of the first ratio.

16. The luminescent particle according to claim 13, wherein the second ratio comprises about sixty-five percent of the first ratio.

17. The luminescent particle according to claim 13, wherein the second ratio comprises about fifty percent of the first ratio.

18. A method of identifying a potency to excitation characteristic in a luminescent particle, the method comprising:

comparing a photon down converting performance of a first group of luminescent particles that includes the luminescent particle according to claim 1 with a second group of luminescent particles that does not include the luminescent particle according to claim 1.

19. The method according to claim 18, wherein comparing the photon down converting performance comprises estimating respective reflectance signatures corresponding to each of the first and second groups of luminescent particles.

20. The method according to claim 19, wherein comparing the photon down converting performance further comprises comparing estimated reflectance signatures corresponding to each of the first and second groups of luminescent particles to determine which of the first and second groups includes a higher absorption rate.

21. The method according to claim 20, wherein the absorption rate is substantially inversely related to the reflectance.

22. The method according to claim 20, wherein comparing the estimated reflectance signatures comprises:

estimating a first diffuse reflectance of the first group of luminescent particles;

estimating a second diffuse reflectance of the second group of luminescent particles; and

identifying that the first diffuse reflectance is less than the second diffuse reflectance as indication that the first group of luminescent particles include a greater potency to excitation characteristic than the second group of luminescent particles.

23. The method according to claim 22, wherein estimating the first diffuse reflectance comprises:

directing light including a dominant wavelength of light at the first group of luminescent particles;

receiving reflected light including the dominant wavelength of light from the first group of luminescent particles; and

estimating the diffuse reflectance as a function of the received reflected light from the first group of luminescent particles, and

wherein estimating the second diffuse reflectance comprises;

directing light including the dominant wavelength of light at the second group of luminescent particles;

receiving reflected light including the dominant wavelength of light from the second group of luminescent particles; and

estimating the diffuse reflectance as a function of the received reflected light from the second group of luminescent particles.

24. The method according to claim 23, wherein the dominant wavelength of light corresponds to a substantially blue light in the visible spectrum.

25. The method according to claim 23,

wherein the dominant wavelength of light is in a range of about 380 to about 470 nm, and

wherein the luminescent particle absorbs at least some of the light emitted from the light emitting source and emits light having a maximum emission at a wavelength in a range of about 500 to about 700 nm.

26. The method according to claim 25, wherein the dominant wavelength of light is about 450 nm.

27. The method according to claim 18, wherein the first group of luminescent particles correspond to a first particle size range and the second group of luminescent particles correspond to a second particle size range, and

wherein the first particle size range is substantially similar to the second particle size range.

28. The method according to claim 27,

wherein the first particle size range provides that about fifty percent of the first group of particles are less than a first size, and

wherein the second particle size range provides that about fifty percent of the second group of particles are less than a second size that is less than about 1.0 micrometer different from the first size.

29. The method according to claim 28,

wherein the dominant wavelength of light is about 450 nm,

wherein the photon down converting performance of the first group of luminescent particles corresponds to a first diffuse reflectance,

wherein the photon down converting performance of the second group corresponds to a second diffuse reflectance, and

wherein the first diffuse reflectance comprises about ninety-five percent of the second diffuse reflectance.

30. The method according to claim 28,

wherein the dominant wavelength of light is about 450 nm,

wherein the photon down converting performance of the first group of luminescent particles corresponds to a first diffuse reflectance,

wherein the photon down converting performance of the second group corresponds to a second diffuse reflectance, and

wherein the first diffuse reflectance comprises about ninety-two percent of the second diffuse reflectance.

31. The method according to claim 28,

wherein the dominant wavelength of light is about 450 nm,

wherein the photon down converting performance of the first group of luminescent particles corresponds to a first diffuse reflectance,

wherein the photon down converting performance of the second group corresponds to a second diffuse reflectance, and

wherein the first diffuse reflectance comprises about ninety percent of the second diffuse reflectance.

32. The method according to claim 18,

wherein the first group of luminescent particles corresponds to a first particle size range and the second group of luminescent particles corresponds to a second particle size range, and

wherein the first particle size range includes particles that are substantially smaller than the particles in the second particle size range.

33. The method according to claim 32,

wherein the first particle size range provides that about fifty percent of the first group of particles are less than a first size,

wherein the second particle size range provides that about fifty percent of the second group of particles are less than a second size, and

wherein the first size is about seventy-five percent the value of the second size.

34. The method according to claim 33,

wherein the first size is about 6.4 micrometers, and

wherein the second size is about 8.6 micrometers.

35. The method according to claim 33,

wherein dominant wavelength of light is about 450 nm,

wherein the photon down converting performance of the first group of luminescent particles corresponds to a first diffuse reflectance,

wherein the photon down converting performance of the second group corresponds to a second diffuse reflectance, and

wherein a difference between the first diffuse reflectance and the second diffuse reflectance is about five percent of the second diffuse reflectance.

36. The method according to claim 18,

wherein the first group of luminescent particles corresponds to a first particle size range and the second group of luminescent particles corresponds to a second particle size range, and

wherein the first particle size range includes substantially larger particles than particles in the second particle size range.

37. The method according to claim 36,

wherein the first particle size range provides that about fifty percent of the first group of particles are less than a first size,

wherein the second particle size range provides that about fifty percent of the second group of particles are less than a second size, and

wherein a value of the second size is about fifty percent that of a value of the first size.

38. The method according to claim 37,

wherein the first size is about 12.8 micrometers, and

wherein the second size is about 6.4 micrometers.

39. The method according to claim 37,

wherein dominant wavelength of light is about 450 nm,

wherein the photon down converting performance of the first group of luminescent particles corresponds to a first diffuse reflectance,

wherein the photon down converting performance of the second group corresponds to a second diffuse reflectance, and

wherein a difference between the first diffuse reflectance is about ninety percent of the second diffuse reflectance.

40. The method according to claim 37, wherein dominant wavelength of light is about 450 nm,

wherein the photon down converting performance of the first group of luminescent particles corresponds to a first diffuse reflectance,

wherein the photon down converting performance of the second group corresponds to a second diffuse reflectance, and

wherein a difference between the first diffuse reflectance is about eighty percent of the second diffuse reflectance.

41. The method according to claim 18, wherein the luminescent particle includes a phosphor composition that absorbs in the blue portion of the visible spectrum and emits in the red portion of the visible spectrum.

42. The method according to claim 41, wherein the luminescent particle is configured to be in a light path of a light emitting source and to perform a photon down conversion on a portion of the light received therefrom.

43. A light emitting device comprising:

the luminescent particle of claim 1; and

a light emitting source.

44. The light emitting device according to claim 43,

wherein the luminescent particle is dispersed within a silicone encapsulant,

wherein the light emitting source emits radiation with a maximum emission at a wavelength in a range of about 380 to about 470 nm, and wherein the luminescent particle absorbs at least some of the light emitted from the light emitting source and emits light having a maximum emission at a wavelength in a range of about 500 to about 700 nm.

45. The light emitting device according to claim 43,

wherein a plurality of first luminescent particles including the luminescent particle may include a first size range and a first diffuse reflectance at a dominant wavelength of light,

where a plurality of second luminescent particles not including the luminescent particle may include a second size range that is substantially similar to the first size range and a second diffuse reflectance at the dominant wavelength of light.