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 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%.