Quantum dot white and colored light emitting diodes
View Patent ↗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.
1. A method of producing an electronic device, comprising:
providing at least one population of quantum dots of a selected size distribution;
disposing a coating on a surface of the dots that is 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 coating comprises at least one material selected from the group consisting of ZnS, ZnSe, CdS, CdSe, CdTe, and MgSe.
5. The method of claim 4 , where disposing a coating comprises precipitating from a solution.
6. The method of claim 1 , where disposing a coating 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%.