Quantum dot white and colored light emitting diodes

• US 6,914,265 B2
• Filed: 12/26/2002
• Issued: 07/05/2005
• Est. Priority Date: 04/01/1998
• Status: Expired due to Term

• Current Assignee: Lumileds LLC (Apollo Global Management, Inc.)
• Original Assignee: Lumileds Lighting US LLC (Apollo Global Management, Inc.), Massachusetts Institute of Technology
• Inventors: Heine, Jason, Bawendi, Moungi G., Jensen, Klavs F., Moon, Ronald L., Miller, Jeffrey N.
• Primary Examiner(s): TRAN, MINH LOAN
• Application Number:
  US10/329,909
• Publication Number:
  US 20030127660A1
• Time in Patent Office: 922 Days
• Field of Search: 257/98, 257/100, 257/14, 257/89, 313501-503, 428/46, 428/372, 428/373, 428/474.4, 428/474.7, 428/403
• 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 11/02 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 prepolymer colloid, comprising:

a liquid or semisolid precursor material capable of being reacted to form a solid, transparent, substantially nonconductive host matrix; and

a population of photoluminescent quantum dots of a selected size distribution dispersed in the precursor material, each dot of said population having a substantially uniform surface energy.

2. The colloid of claim 1, where the precursor material is a monomer which is capable of being reacted to form a polymer.

3. The colloid of claim 2, where the precursor material comprises a monomer selected from the group consisting of styrene, acids, peroxides, anhydrides, amines, and alcohols.

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

5. The colloid of claim 4, 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.

6. The colloid of claim 1, where the quantum dots are coated with a material having an affinity for the precursor material.

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