Quantum dots having a nanocrystalline core, a nanocrystalline shell surrounding the core, and an insulator coating for the shell

• US 9,666,766 B2
• Filed: 08/21/2013
• Issued: 05/30/2017
• Est. Priority Date: 08/21/2013
• 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., Zhao, Weiwen
• Primary Examiner(s): Smoot, Stephen W
• Assistant Examiner(s): Booker, Vicki B
• Application Number:
  US13/972,723
• Publication Number:
  US 20150053914A1
• Time in Patent Office: 1,378 Days
• CPC Class Codes: B01J 13/08 Simple coacervation, i.e. addition of highly hydrophilic material combined with spraying B01J13/043; combined with mechanical division B01J13/04
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 19/007 Tellurides or selenides of metals C01B19/002 takes precedence
• CPC Class Codes: C01P 2002/60 Compounds characterised by their crystallite size
• CPC Class Codes: C01P 2002/84 by UV- or VIS- data
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• CPC Class Codes: C09K 11/883 with zinc or cadmium
• 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: Y10S 977/774 Exhibiting three-dimensional carrier confinement, e.g. quantum dots
• CPC Class Codes: Y10S 977/824 Group II-VI nonoxide compounds, e.g. CdxMnyTe
• CPC Class Codes: Y10S 977/892 Liquid phase deposition
• CPC Class Codes: Y10S 977/896 Chemical synthesis, e.g. chemical bonding or breaking
• CPC Class Codes: Y10S 977/95 Electromagnetic energy

Abstract

Semiconductor nanocrystal structures having silica insulator coatings encapsulating the nanocrystals and methods of fabricating semiconductor nanocrystal structures having silica insulator coatings encapsulating the nanocrystals involve adding a silicon-containing silica precursor species to a solution of nanocrystals, subsequently forming a silica-based insulator layer on the nanocrystals from a reaction involving the silicon-containing silica precursor species, and adding additional amounts of the silicon-containing silica precursor species after initial formation of the silica-based insulator layer while continuing to form the silica-based insulator layer to finally encapsulate each of the nanocrystals.

Claims

1. A semiconductor structure, comprising:

an oblong-shaped semiconductor nanocrystal; and

a non-oblong-shaped insulator coating formed by two bulbous portions separated by a waist portion encapsulating the oblong-shaped semiconductor nanocrystal.

2. The semiconductor structure of claim 1, wherein the non-oblong-shaped insulator coating is a silica coating.

3. The semiconductor structure of claim 1, wherein the non-oblong-shaped insulator coating is bonded directly to the semiconductor nanocrystal.

4. The semiconductor structure of claim 1, wherein the oblong-shaped semiconductor nanocrystal comprises an anisotropic nanocrystalline core comprising a first semiconductor material, and comprises a nanocrystalline shell comprising a second, different, semiconductor material at least partially surrounding the anisotropic nanocrystalline core.

5. The semiconductor structure of claim 4, wherein the anisotropic nanocrystalline core has an aspect ratio between, but not including, 1.0 and 2.0.

6. 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 comprising;

an oblong-shaped semiconductor nanocrystal; and

a non-oblong-shaped insulator coating formed by two bulbous portions separated by a waist portion encapsulating the oblong-shaped semiconductor nanocrystal.

7. The lighting apparatus of claim 6, wherein the light emitting diode is a UV or visible spectrum light emitting diode, and wherein the light conversion layer is a down- or up-shifting layer.

8. The lighting apparatus of claim 7, wherein the light emitting diode is a blue light emitting diode, and wherein the light conversion layer is a down-shifting layer.

9. The lighting apparatus of claim 6, wherein the quantum dots vary in size and emission color, and wherein the light conversion layer is to provide white light.

10. The lighting apparatus of claim 6, wherein the housing is a cup-shaped housing.

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

12. The lighting apparatus of claim 6, 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.

13. The lighting apparatus of claim 6, wherein the light conversion layer is disposed on the light emitting diode.

14. The lighting apparatus of claim 6, wherein the light conversion layer is situated remotely from the light emitting diode.

15. The lighting apparatus of claim 6, wherein, for each quantum dot, the non-oblong-shaped insulator coating is a silica coating.

16. The lighting apparatus of claim 6, wherein, for each quantum dot, the non-oblong-shaped insulator coating is bonded directly to the oblong-shaped semiconductor nanocrystal.

17. The lighting apparatus of claim 6, wherein the oblong-shaped semiconductor nanocrystal of each quantum dot comprises an anisotropic nanocrystalline core comprising a first semiconductor material, and comprises a nanocrystalline shell comprising a second, different, semiconductor material at least partially surrounding the anisotropic nanocrystalline core.

18. The lighting apparatus of claim 6, wherein the light conversion layer comprises a matrix material, and wherein the plurality of quantum dots is embedded in the matrix material.

19. 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 comprising;

an oblong-shaped semiconductor nanocrystal; and

a non-oblong-shaped insulator coating formed by two bulbous portions separated by a waist portion encapsulating the oblong-shaped semiconductor nanocrystal.

20. The lighting apparatus of claim 19, wherein the light emitting diode is a UV or visible spectrum light emitting diode, and wherein the light conversion layer is a down- or up-shifting layer.

21. The lighting apparatus of claim 20, wherein the light emitting diode is a blue light emitting diode, and wherein the light conversion layer is a down-shifting layer.

22. The lighting apparatus of claim 19, wherein the quantum dots vary in size and emission color, and wherein the light conversion layer is to provide white light.

23. The lighting apparatus of claim 19, 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.

24. The lighting apparatus of claim 19, 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.

25. The lighting apparatus of claim 19, 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.

26. The lighting apparatus of claim 19, wherein the light conversion layer comprises a combination of red quantum dots with yellow phosphors, green phosphors, or both.

27. The lighting apparatus of claim 26, further comprising:

a protective cover encapsulating the light conversion layer and the light emitting diode.

28. The lighting apparatus of claim 19, 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.

29. The lighting apparatus of claim 28, further comprising:

a protective cover encapsulating the light conversion layer, the second light conversion layer, and the light emitting diode.

30. The lighting apparatus of claim 19, wherein the light conversion layer is disposed on the light emitting diode.

31. The lighting apparatus of claim 19, wherein the light conversion layer is situated remotely from the light emitting diode.

32. The lighting apparatus of claim 19, wherein, for each quantum dot, the non-oblong-shaped insulator coating is a silica coating.

33. The lighting apparatus of claim 19, wherein, for each quantum dot, the non-oblong-shaped insulator coating is bonded directly to the oblong-shaped semiconductor nanocrystal.

34. The lighting apparatus of claim 19, wherein the oblong-shaped semiconductor nanocrystal of each quantum dot comprises an anisotropic nanocrystalline core comprising a first semiconductor material, and comprises a nanocrystalline shell comprising a second, different, semiconductor material at least partially surrounding the anisotropic nanocrystalline core.

35. The lighting apparatus of claim 19, wherein the light conversion layer comprises a matrix material, and wherein the plurality of quantum dots is embedded in the matrix material.