Package design for producing white light with short-wavelength LEDS and down-conversion materials

• US 7,750,359 B2
• Filed: 06/20/2006
• Issued: 07/06/2010
• Est. Priority Date: 06/23/2005
• Status: Active Grant

• Current Assignee: Rensselaer Polytechnic Institute
• Original Assignee: Rensselaer Polytechnic Institute
• Inventors: Gu, Yimin, Narendran, Nadarajah
• Primary Examiner(s): Dang; Trung
• Application Number:
  US11/795,171
• Publication Number:
  US 20080105887A1
• Time in Patent Office: 1,477 Days
• Field of Search: 257/98, 257/E21.001, 257/E23.001
• US Class Current: 257/98
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: C09K 11/595 with zinc or cadmium
• CPC Class Codes: C09K 11/642 with zinc or cadmium
• CPC Class Codes: C09K 11/7774 Aluminates
• CPC Class Codes: C09K 11/7777 Phosphates
• CPC Class Codes: H01L 33/504 Elements with two or more 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
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Abstract

A broad bandwidth light source including: a solid state light emitting device that generates short wavelength light; and quantum dot material and phosphor material that are each irradiated by some of the short wavelength light. The short wavelength light has a spectrum with a first peak wavelength shorter than about 500 nm. The quantum dot material absorbs some of the short wavelength light and reemits it as long wavelength light having a spectrum with a second peak wavelength longer than about 600 nm. The phosphor material absorbs some of the short wavelength light and reemits it as mid wavelength light having a spectrum with a peak wavelength between the first and second peak wavelength. The light source is configured such that some of each light (short, mid, and long wavelength) is emitted coincidentally as a light having a chromaticity value near the blackbody locus and a color rendering index greater than 80.

Claims

1. A method of producing visible light having a chromaticity value near a blackbody locus and a color rendering index greater than about 80, the visible light produced using a short wavelength solid state light emitting device, a quantum dot material and a phosphor material spaced apart from the quantum dot material, the method comprising:

a) generating short wavelength light having a first spectrum with a first peak wavelength using the short wavelength solid state light emitting device, the first peak wavelength being shorter than about 500 nm;

b) irradiating the quantum dot material or the spaced apart phosphor material with at least a portion of the short wavelength light such that a first fraction of the short wavelength light is absorbed and reemitted by the quantum dot material or the spaced apart phosphor material as longer wavelength light having a second spectrum with a second peak wavelength, the second peak wavelength being longer than the first peak wavelength;

c) irradiating another of the quantum dot material or the spaced apart phosphor material with at least another portion of the short wavelength light such that a second fraction of the short wavelength light is absorbed and reemitted by the other of the quantum dot material or the spaced apart phosphor material as light having a third spectrum with a third peak wavelength, the third peak wavelength being either between the first peak wavelength and the second peak wavelength or longer than the second peak wavelength; and

d) emitting a third fraction of the short wavelength light and combining the third fraction of the short wavelength light with at least a portion of the second wavelength light, and at least a portion of the third wavelength light as the visible light.

2. A method according to claim 1, wherein the chromaticity value of the visible light emitted in step (d) is within an area bounded by about 0.01 of an x chromaticity value and about 0.01 of a y chromaticity value of the blackbody locus on a CIE-1931 diagram.

3. A method according to claim 1, wherein the color rendering index of the visible light emitted in step (d) is greater than about 85.

4. A method according to claim 1, wherein the color rendering index of the visible light emitted in step (d) is greater than about 90.

5. A method according to claim 1, wherein the visible light emitted in step (d) has a correlated color temperature less between about 1000K and about 16000K.

6. A method according to claim 1, wherein the visible light emitted in step (d) has a correlated color temperature between about 3300K and about 3600K.

7. A method according to claim 1, wherein the first peak wavelength of the short wavelength light generated in step (a) by the short wavelength solid state light emitting device is between about 200 nm and about 500 nm.

8. A method according to claim 1, wherein the second peak wavelength of the long wavelength light emitted in step (b) by the quantum dot material is between about 600 nm and about 700 nm.

9. A method according to claim 1, wherein a full width half maximum of the second spectrum of the long wavelength light generated in step (b) by the quantum dot material is less than about 50 nm.

10. A method according to claim 1, wherein step (b) further includes irradiating the quantum dot material with at least a portion of the mid wavelength light such that a fourth fraction of the mid wavelength light is absorbed and reemitted by the quantum dot material as additional long wavelength light.

11. A method according to claim 1, wherein the third peak wavelength of the mid wavelength light emitted in step (c) by the phosphor material is between about 500 nm and about 600 nm.

12. A method according to claim 1, wherein a full width half maximum of the third spectrum of the mid wavelength light generated in step (c) by the phosphor material is less than about 150 nm.

32. A broad bandwidth light source according to claim 2, wherein the short wavelength solid state light emitting device, the quantum dot material, and the phosphor material are configured such that the color rendering index of the visible light emitted from the broad bandwidth light source is greater than about 90.

13. A broad bandwidth light source comprising:

a short wavelength solid state light emitting device to generate short wavelength light having a first spectrum with a first peak wavelength, the first peak wavelength being shorter than about 500 nm;

a quantum dot material and a phosphor material optically coupled to the short wavelength solid state light emitting device, the quantum dot material or the phosphor material to be irradiated by a first portion of the short wavelength light, the quantum dot material or the phosphor material adapted to absorb a first fraction of incident light having the first spectrum and to reemit the absorbed light as longer wavelength light having a second spectrum with a second peak wavelength, the second peak wavelength being longer than the first peak wavelength peak; and

another of the quantum dot material or the phosphor material to be irradiated by a second portion of the short wavelength light, the other of the quantum dot material or the phosphor material adapted to absorb a second fraction of incident light having the first spectrum and to reemit the absorbed light as light having a third spectrum with a third peak wavelength, the third peak wavelength either being between the first peak wavelength and the second peak wavelength or longer than the second peak wavelength,

wherein the short wavelength solid state light emitting device, the quantum dot material, and the phosphor material are configured such that a first amount of the short wavelength light, a second amount of the longer wavelength light, and a third amount of the third wavelength light are emitted substantially coincidentally from the broad bandwidth light source as a visible light having a chromaticity value near a blackbody locus and a color rendering index greater than 80;

and further comprising an optical element optically coupled to the quantum dot material and the phosphor material for controlling back coupling of light from the quantum dot material and the phosphor material into the short wavelength solid state light emitting device.

14. A broad bandwidth light source according to claim 13, wherein the short wavelength solid state light emitting device is one of a short wavelength light emitting diode (LED), a short wavelength resonant cavity LED, or a short wavelength diode laser.

15. A broad bandwidth light source according to claim 13, wherein the first peak wavelength of the short wavelength light generated by the short wavelength solid state light emitting device is between about 200 nm and about 500 nm.

16. A broad bandwidth light source according to claim 13, wherein a full width half maximum of the first spectrum of the short wavelength light generated by the short wavelength solid state light emitting device is less than about 50 nm.

17. A broad bandwidth light source according to claim 13, wherein the quantum dot material includes a plurality of quantum dots dispersed within a matrix material that is substantially transmissive to the visible light.

18. A broad bandwidth light source according to claim 17, wherein the plurality of quantum dots include at least one of CdSe quantum dots, ZnS quantum dots, CdTe quantum dots, PbTe quantum dots, ZnSe quantum dots, Si quantum dots, Ge quantum dots, or PbSe quantum dots.

19. A broad bandwidth light source according to claim 17, wherein the matrix material includes at least one of UV curable clear resin, thermal curable sol-gel resin, UV curable sol-gel resin, polycarbonate, polystyrene, polymethyl methacrylate (PMMA), polyethylene, epoxies, silicones, silica, or titania.

20. A broad bandwidth light source according to claim 13, wherein the second peak wavelength of the long wavelength light emitted by the quantum dot material is between about 600 nm and about 700 nm.

21. A broad bandwidth light source according to claim 13, wherein a full width half maximum of the second spectrum of the long wavelength light generated by the quantum dot material is less than about 50 nm.

22. A broad bandwidth light source according to claim 13, wherein:

the quantum dot material or the phosphor material is further optically coupled to the other of the quantum dot material or the phosphor material to be irradiated by a portion of the longer wavelength light; and

the other of the quantum dot material or the phosphor material is further adapted to absorb a third fraction of incident light having the first spectrum.

23. A broad bandwidth light source according to claim 22, wherein the quantum dot material is disposed within the broad bandwidth light source such that the second portion of the short wavelength light with which the phosphor material is irradiated is transmitted through the quantum dot material before being incident on the phosphor material.

24. A broad bandwidth light source according to claim 13, wherein the phosphor material includes a plurality of phosphor particles dispersed within a matrix material that is substantially transmissive to the visible light.

25. A broad bandwidth light source according to claim 24, wherein the plurality of phosphor particles include at least one of ZnS:

Cu—

Al;

ZnSiO₄;

Mn²⁺;

Sr₃SiO₅;

Eu²⁺;

BaMgAl₁₀O₁₇;

Eu²⁺Mn²⁺;

SrAlO₄;

Eu,Dy;

(YGdCe)₃Al₅O₁₂;

Eu;

YAG;

Ce;

Sr₄Al₁₄O₂₅;

Eu;

(Ce, Tb)MgAl₁₁O₁₉;

YAG;

Ce;

or (La, Ce, Tb)PO₄.

26. A broad bandwidth light source according to claim 24, wherein the matrix material includes at least one of UV curable clear resin, thermal curable sol-gel resin, UV curable sol-gel resin, polycarbonate, polystyrene, polymethyl methacrylate (PMMA), polyethylene, epoxies, silicones, silica, or titania.

27. A broad bandwidth light source according to claim 13, wherein the phosphor material includes at least one of bulk ZnS:

Cu—

Al;

bulk ZnSiO₄;

Mn²⁺;

bulk Sr₃SiO₅;

Eu²⁺;

bulk BaMgAl₁₀O₁₇;

Eu²⁺Mn²⁺;

bulk SrAlO₄;

Eu,Dy;

bulk (YGdCe)₃Al₅O₁₂;

Eu;

bulk Sr₄Al₁₄O₂₅;

Eu;

bulk (Ce, Tb)MgAl₁₁O₁₉;

or bulk (La, Ce, Tb)PO₄.

28. A broad bandwidth light source according to claim 13, wherein the third peak wavelength of the longer wavelength light emitted by the phosphor material is between either about 500 nm and about 600 nm or about 600 nm and 700 nm.

29. A broad bandwidth light source according to claim 13, wherein a full width half maximum of the third spectrum of the longer wavelength light generated by the phosphor material is less than about 150 nm.

30. A broad bandwidth light source according to claim 13, wherein the short wavelength solid state light emitting device, the quantum dot material, and the phosphor material are configured such that the chromaticity value of the visible light emitted from the broad bandwidth light source is within an area bounded by about 0.01 of an x chromaticity value and about 0.01 of a y chromaticity value of the blackbody locus on a CIE-1931 diagram.

31. A broad bandwidth light source according to claim 13, wherein the short wavelength solid state light emitting device, the quantum dot material, and the phosphor material are configured such that the color rendering index of the visible light emitted from the broad bandwidth light source is greater than about 85.

33. A broad bandwidth light source according to claim 13, wherein the short wavelength solid state light emitting device, the quantum dot material, and the phosphor material are configured such that the color rendering index of the visible light emitted from the broad bandwidth light source has a correlated color temperature between about 1000K and about 16000K.

34. A broad bandwidth light source according to claim 13, wherein the short wavelength solid state light emitting device, the quantum dot material, and the phosphor material are configured such that the color rendering index of the visible light emitted from the broad bandwidth light source has a correlated color temperature between about 3300K and about 3600K.

36. The broad bandwidth light source of claim 13, wherein the phosphor material is separate from the quantum dot material.

37. The broad bandwidth light source of claim 13, wherein the phosphor material is spaced apart from the quantum dot material.

35. A broad bandwidth light source for producing visible light having a chromaticity value near a blackbody locus and a color rendering index greater than about 80, the broad bandwidth light source comprising:

means for generating short wavelength light having a first spectrum with a first peak wavelength, the first peak wavelength being shorter than about 500 nm;

means for absorbing and reemitting a first fraction of the short wavelength light as longer wavelength light having a second spectrum with a second peak wavelength, the second peak wavelength being longer than the first peak wavelength; and

means for absorbing and reemitting a second fraction of the short wavelength light as light having a third spectrum with a third peak wavelength, the third peak wavelength being either between the first peak wavelength and the second peak wavelength or longer than the second peak wavelength,

wherein a third fraction of the short wavelength light, at least a portion of the longer wavelength light, and at least a portion of the light having the third spectrum are emitted as the visible light;

and further comprising an optical element optically coupled

to the means for absorbing and reemitting a first fraction of the short wavelength light and

to the means for absorbing and reemitting a second fraction of the short wavelength light

 

for controlling back coupling of light from

the means for absorbing and reemitting a first fraction of the short wavelength light and

the means for absorbing and reemitting a second fraction of the short wavelength light

 

into the means for generating short wavelength light.

38. A broad bandwidth light source comprising:

a short wavelength solid state light emitting device to generate short wavelength light having a first spectrum with a first peak wavelength, the first peak wavelength being shorter than about 500 nm;

a quantum dot material having a plurality of quantum dots and a phosphor material having a plurality of phosphor particles, the plurality of quantum dots and the plurality of phosphor particles being

optically coupled to the short wavelength solid state light emitting device to be irradiated by a first portion of the short wavelength light and

mixedly dispersed within a matrix material that is substantially transmissive to visible light, the mixedly dispersed plurality of quantum dots and plurality of phosphor materials adapted to

absorb a first fraction of incident light having the first spectrum and reemit the absorbed light as mid wavelength light and long wavelength light,

wherein the mid wavelength light and the long wavelength light combine with a second fraction of incident light that is transmitted through the mixedly dispersed plurality of quantum dots and plurality of phosphor particles to produce broad bandwidth light as a visible light as visible light; and

an optical element optically coupled to the mixedly dispersed plurality of quantum dots and plurality of phosphor particles for controlling back coupling of light from the mixedly dispersed plurality of quantum dots and plurality of phosphor particles into the short wavelength solid state light emitting device.