QUANTUM DOT WHITE AND COLORED LIGHT-EMITTING DEVICES

• US 20100140585A1
• Filed: 02/04/2010
• Published: 06/10/2010
• Est. Priority Date: 04/01/1998
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.), Massachusetts Institute of Technology
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.), Massachusetts Institute of Technology
• Inventors: Bawendi, Moungi G., Jensen, Klavs F., Moon, Ronald L., Miller, Jeffrey N., Heine, Jason
• Granted Patent: US 8,053,972 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• 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 11/02 Use of particular materials as binders, particle coatings or suspension media therefor
• CPC Class Codes: C09K 11/565 with zinc cadmium
• CPC Class Codes: C09K 11/883 with zinc or cadmium
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• 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: H01S 3/169 Nanoparticles, e.g. doped nanoparticles acting as a gain material
• CPC Class Codes: Y02B 20/00 Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
• CPC Class Codes: Y10S 977/95 Electromagnetic energy

Abstract

A light-emitting device comprising a population of quantum dots (QDs) embedded in a host matrix and a primary light source which causes the QDs to emit secondary light and a method of making such a device. The size distribution of the QDs is chosen to allow light of a particular color to be emitted therefrom. The light emitted from the device may be of either a pure (monochromatic) color, or a mixed (polychromatic) color, and may consist solely of light emitted from the QDs themselves, or of a mixture of light emitted from the QDs and light emitted from the primary source. The QDs desirably are composed of an undoped semiconductor such as CdSe, and may optionally be overcoated to increase photoluminescence.

Claims

1. A white light emitting device comprising:

a primary light source; and

at least a first layer in optical communication with the primary light source and comprising a matrix including a polydisperse size distribution of quantum dots adapted to convert light from the light source to a mixed color or white light;

wherein the matrix is physically separated from the primary light source and is formed in a concentric conformation.

2. The white light emitting device of claim 1, wherein the primary light source comprises a blue LED light source and wherein the matrix comprises a first population of quantum dots of a material and size adapted to emit red secondary light and a second population of quantum dots of a material and size adapted to emit green secondary light.

3. The white light emitting device of claim 1, wherein the primary light source comprises a UV or laser light source and wherein the matrix comprises a first population of quantum dots of a material and size adapted to emit red secondary light, a second population of quantum dots of a material and size adapted to emit green secondary light, and a third population of quantum dots of a material and size adapted to emit blue secondary light.

4. The white light emitting device of claim 2, wherein the quantum dots in the first and second population each comprise a core comprising a material independently selected from the group comprising CdS, CdSe, CdTe, InP, alloys thereof, and mixtures thereof.

5. The white light emitting device of claim 4, wherein the quantum dots in the first and second population each comprise one or more shell layers comprising a material independently selected from the group comprising ZnS, ZnSe, ZnTe, alloys thereof, and mixtures thereof.

6. The white light emitting device of claim 2, wherein the polymer includes a polystyrene.

7. The white light emitting device of claim 6, wherein the polystyrene is functionalized with amine groups that bind to the quantum dots.

8. The white light emitting device of claim 2, wherein the polymer includes a polystyrene.

9. The white light emitting device of claim 6, wherein the polystyrene is functionalized with amino groups that bind to the quantum dots.

10. The white light emitting device of claim 2, wherein the quantum dots in the first and second population have a size distribution having less than 10% rms deviation in diameter of the core.

11. The white light emitting device of claim 3, wherein the quantum dots in the first, second and third population have a size distribution having less than 10% rms deviation in diameter of the core.

12. The white light emitting device of claim 1, comprising a medium between the primary light source and the matrix.

13. The white light emitting device of claim 12, wherein the medium comprises air.

14. The white light emitting device of claim 12, wherein the medium comprises a liquid.

15. The white light emitting device of claim 12, wherein the medium comprises a polymer.

16. The white light emitting device of claim 12, wherein the medium comprises a glass.

17. The white light emitting device of claim 1, wherein the matrix is formed in a cylindrical conformation.

19. The white light emitting device of claim 1, wherein the matrix is selected from the group comprising a liquid, a polymer, an epoxy, a silica, a glass, a silica gel, and combinations thereof.

18. The white light emitting device of claim 18, wherein light from the primary light source is configured to hit the side or base of the cylinder.