Lighting device having highly luminescent quantum dots

• US 9,425,365 B2
• Filed: 08/20/2012
• Issued: 08/23/2016
• Est. Priority Date: 08/20/2012
• Status: Active Grant

• Current Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Original Assignee: Pacific Light Technologies Corp. (Ams-Osram AG)
• Inventors: Kurtin, Juanita N.
• Primary Examiner(s): Santiago, Mariceli
• Application Number:
  US13/589,823
• Publication Number:
  US 20140049155A1
• Time in Patent Office: 1,464 Days
• Field of Search: 313498-512, 313482-487, 257 98-100
• US Class Current: 1/1
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/08 containing inorganic luminescent materials
• CPC Class Codes: H01L 33/501 characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/507 the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body

Abstract

Lighting devices having highly luminescent quantum dots are described. In an example, a lighting apparatus includes a housing structure or a substrate. The lighting apparatus also includes a light emitting diode supported within the housing structure or disposed on the substrate, respectively. The lighting apparatus also includes a light conversion layer disposed above the light emitting diode. The light conversion layer includes a plurality of quantum dots. Each quantum dot includes an anisotropic nanocrystalline core having a first semiconductor material and having an aspect ratio between, but not including, 1.0 and 2.0. Each quantum dot also includes a nanocrystalline shell having a second, different, semiconductor material at least partially surrounding the anisotropic nanocrystalline core.

Claims

1. A lighting apparatus, comprising:

a housing structure;

a light emitting diode supported within the housing structure; and

a light conversion layer disposed above the light emitting diode, the light conversion layer comprising a plurality of quantum dots, each quantum dot having higher wavelength emission and lower wavelength absorption with little to no overlap between emission and absorption and each quantum dot comprising;

an anisotropic nanocrystalline core comprising a first semiconductor material and having an aspect ratio approximately in the range of 1.01-1.2; and

a nanocrystalline shell comprising a second, different, semiconductor material at least partially surrounding the anisotropic nanocrystalline core.

2. The lighting apparatus of claim 1, wherein the light emitting diode is a UV or visible spectrum light emitting diode, and wherein the light conversion layer is a down-shifting layer.

3. The lighting apparatus of claim 2, wherein the light emitting diode is a blue light emitting diode.

4. The lighting apparatus of claim 1, wherein the quantum dots vary in size and emission color, and wherein the light conversion layer is to provide white light.

5. The lighting apparatus of claim 1, wherein the housing is a cup-shaped housing.

6. The lighting apparatus of claim 1, wherein the light conversion layer comprises a combination of red quantum dots with yellow phosphors, green phosphors, or both.

7. The lighting apparatus of claim 6, wherein the light conversion layer comprises a matrix material, and wherein the combination of red quantum dots with yellow phosphors, green phosphors, or both, is embedded in the matrix material.

8. The lighting apparatus of claim 1, wherein the light conversion layer comprises red quantum dots and no phosphors, the lighting apparatus further comprising a second light conversion layer disposed on the light conversion layer, the second light conversion layer comprising yellow phosphors, green phosphors, or both.

9. The lighting apparatus of claim 8, wherein the light conversion layer comprises a first matrix material, and the red quantum dots are embedded in the matrix material, and wherein the second light conversion layer comprises a second matrix material, and the yellow phosphors, green phosphors, or both, are embedded in the second matrix material.

10. The lighting apparatus of claim 1, wherein the light conversion layer is disposed on the light emitting diode.

11. The lighting apparatus of claim 1, wherein the light conversion layer is situated remotely from the light emitting diode.

12. The lighting apparatus of claim 1, wherein each quantum dot further comprises a nanocrystalline outer shell at least partially surrounding the nanocrystalline shell, the nanocrystalline outer shell comprising a third semiconductor material different from the first and second semiconductor materials.

13. The lighting apparatus of claim 1, wherein each quantum dot further comprises an insulator layer encapsulating the nanocrystalline shell and anisotropic nanocrystalline core.

14. The lighting apparatus of claim 13, wherein one or more of the quantum dots further comprises a coupling agent covalently bonded to an outer surface of the insulator layer.

15. The lighting apparatus of claim 13, wherein, for each quantum dot, the anisotropic nanocrystalline core has an aspect ratio approximately in the range of 1.1-1.2.

16. The lighting apparatus of claim 1, wherein the light conversion layer comprises a matrix material, and wherein the plurality of quantum dots is embedded in the matrix material.

17. The lighting apparatus of claim 16, wherein each of the plurality of quantum dots is cross-linked with, polarity bound by, or tethered to the matrix material.

18. The lighting apparatus of claim 16, wherein each of the plurality of quantum dots is bound to the matrix material by a covalent, dative, or ionic bond.

19. The lighting apparatus of claim 1, wherein, for each quantum dot, the anisotropic nanocrystalline core is positioned off-center within the nanocrystalline shell.

20. The lighting apparatus of claim 19, wherein the anisotropic nanocrystalline core is off-set along a long axis of the nanocrystalline shell, and is off-set along a short axis of the nanocrystalline shell.

21. The lighting apparatus of claim 1, wherein, for each quantum dot, the anisotropic nanocrystalline core has an aspect ratio approximately in the range of 1.1-1.2.

22. A lighting apparatus, comprising:

a substrate;

a light emitting diode disposed on the substrate; and

a light conversion layer disposed above the light emitting diode, the light conversion layer comprising a plurality of quantum dots, each quantum dot having higher wavelength emission and lower wavelength absorption with little to no overlap between emission and absorption and each quantum dot comprising;

an anisotropic nanocrystalline core comprising a first semiconductor material and having an aspect ratio approximately in the range of 1.01-1.2; and

a nanocrystalline shell comprising a second, different, semiconductor material at least partially surrounding the anisotropic nanocrystalline core.

23. The lighting apparatus of claim 22, wherein the light emitting diode is a UV or visible spectrum light emitting diode, and wherein the light conversion layer is a down-shifting layer.

24. The lighting apparatus of claim 23, wherein the light emitting diode is a blue light emitting diode.

25. The lighting apparatus of claim 22, wherein the quantum dots vary in size and emission color, and wherein the light conversion layer is to provide white light.

26. The lighting apparatus of claim 22, wherein the light conversion layer is disposed on and conformal with a top surface of the light emitting diode, but not along sidewalls of the light emitting diode.

27. The lighting apparatus of claim 22, wherein the light conversion layer is disposed on and conformal with a top surface of the light emitting diode and with sidewalls of the light emitting diode.

28. The lighting apparatus of claim 22, wherein the light conversion layer is disposed on a top surface of the light emitting diode, but not along sidewalls of the light emitting diode, the light conversion layer having a bulb-like geometry.

29. The lighting apparatus of claim 22, wherein the light conversion layer comprises a combination of red quantum dots with yellow phosphors, green phosphors, or both.

30. The lighting apparatus of claim 29, further comprising:

a sealing layer encapsulating the light conversion layer and the light emitting diode, wherein the combination of red quantum dots with yellow phosphors, green phosphors, or both, is embedded in a matrix material of the light conversion layer, and wherein the sealing layer is distinct from the matrix material.

31. The lighting apparatus of claim 29, wherein the light conversion layer comprises a matrix material, and wherein the combination of red quantum dots with yellow phosphors, green phosphors, or both, is embedded in the matrix material.

32. The lighting apparatus of claim 22, wherein the light conversion layer comprises red quantum dots and no phosphors, the lighting apparatus further comprising a second light conversion layer disposed on the light conversion layer, the second light conversion layer comprising yellow phosphors, green phosphors, or both.

33. The lighting apparatus of claim 32, wherein the light conversion layer comprises a first matrix material, and the red quantum dots are embedded in the matrix material, and wherein the second light conversion layer comprises a second matrix material, and the yellow phosphors, green phosphors, or both, are embedded in the second matrix material.

34. The lighting apparatus of claim 32, further comprising:

a sealing layer encapsulating the light conversion layer, the second light conversion layer, and the light emitting diode, wherein the red quantum dots are embedded in a first matrix material of the first light conversion layer, wherein the yellow phosphors, green phosphors, or both, are embedded in a second matrix material of the second light conversion layer, and wherein the sealing layer is distinct from the first and second matrix materials.

35. The lighting apparatus of claim 22, wherein the light conversion layer is disposed on the light emitting diode.

36. The lighting apparatus of claim 22, wherein the light conversion layer is situated remotely from the light emitting diode.

37. The lighting apparatus of claim 22, wherein each quantum dot further comprises a nanocrystalline outer shell at least partially surrounding the nanocrystalline shell, the nanocrystalline outer shell comprising a third semiconductor material different from the first and second semiconductor materials.

38. The lighting apparatus of claim 22, wherein each quantum dot further comprises an insulator layer encapsulating the nanocrystalline shell and anisotropic nanocrystalline core.

39. The lighting apparatus of claim 38, wherein one or more of the quantum dots further comprises a coupling agent covalently bonded to an outer surface of the insulator layer.

40. The lighting apparatus of claim 22, wherein the light conversion layer comprises a matrix material, and wherein the plurality of quantum dots is embedded in the matrix material.

41. The lighting apparatus of claim 40, wherein each of the plurality of quantum dots is cross-linked with, polarity bound by, or tethered to the matrix material.

42. The lighting apparatus of claim 40, wherein each of the plurality of quantum dots is bound to the matrix material by a covalent, dative, or ionic bond.

43. The lighting apparatus of claim 22, wherein, for each quantum dot, the anisotropic nanocrystalline core is positioned off-center within the nanocrystalline shell.

44. The lighting apparatus of claim 43, wherein the anisotropic nanocrystalline core is off-set along a long axis of the nanocrystalline shell, and is off-set along a short axis of the nanocrystalline shell.