Quantum dot white and colored light emitting diodes

• US 20030127659A1
• Filed: 12/26/2002
• Published: 07/10/2003
• Est. Priority Date: 04/01/1998
• Status: Active Grant

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.)
• Inventors: Bawendi, Moungi G., Jensen, Klavs F., Moon, Ronald L., Miller, Jeffrey N., Heine, Jason
• Granted Patent: US 6,890,777 B2
• Time in Patent Office: Days
• US Class Current: 257/89
• 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

An electronic device comprising a population of quantum dots embedded in a host matrix and a primary light source which causes the dots to emit secondary light of a selected color, and a method of making such a device. The size distribution of the quantum dots 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 dots themselves, or of a mixture of light emitted from the dots and light emitted from the primary source. The dots desirably are composed of an undoped semiconductor such as CdSe, and may optionally be overcoated to increase photoluminescence.

Claims

1. A method of producing an electronic device, comprising:

providing at least one population of quantum dots of a selected size distribution, the dots having a surface adapted to allow the dots to disperse in a host matrix;

dispersing the quantum dots in said host matrix; and

providing a solid state primary light source capable of causing the quantum dots to photoluminesce secondary light of a color characteristic of their size distribution.

2. The method of claim 1, where the step of providing a population of dots includes growing the dots by precipitation from a solution.

3. The method of claim 1, where the quantum dots comprise at least one material selected from the group consisting of CdS, CdSe, CdTe, ZnS, and ZnSe.

4. The method of claim 3, where the quantum dots further comprise an overcoating of at least one material selected from the group consisting of ZnS, ZnSe, CdS, CdSe, CdTe, and MgSe.

5. The method of claim 4, where the overcoating is produced by precipitation from a solution.

6. The method of claim 1, where the step of providing includes coating the quantum dots with a material having an affinity for the host matrix.

7. The method of claim 6, where the host matrix comprises a polymer and the coating comprises a related monomer.

8. The method of claim 1, where the host matrix comprises at least one material selected from the group consisting of polymers, silica glasses, and silica gels.

9. The method of claim 1, where the host matrix comprises a polymer selected from the group consisting of polystyrene, polyimides, and epoxies.

10. The method of claim 1, where the primary light source is selected from the group consisting of a light-emitting diode, a solid-state laser, and a solid-state ultraviolet source.

11. The method of claim 1, where the size distribution is characterized by an rms deviation in diameter of the quantum dots of less than 10%.