Semiconductor nanoparticle-based light-emitting devices and associated materials and methods
Embodiments of the present invention relate to a formulation for use in the fabrication of a light-emitting device, the formulation including a population of semiconductor nanoparticles incorporated into a plurality of discrete microbeads comprising an optically transparent medium, the nanoparticle-containing medium being embedded in a host light-emitting diode encapsulation medium. A method of preparing such a formulation is described. There is further provided a light-emitting device including a primary light source in optical communication with such a formulation and a method of fabricating the same.
1. A formulation for use in the fabrication of a light-emitting device, said formulation comprising:
a population of semiconductor quantum dots dispersed into a plurality of microbeads, the microbeads comprising an optically transparent medium, said microbeads being embedded in a host light-emitting diode (LED) encapsulation medium, wherein the semiconductor quantum dots comprise surface-bound ligands selected to provide compatibility with the transparent medium.
2. A formulation according to claim 1 , wherein each of said microbeads incorporates a plurality of said dispersed semiconductor quantum dots.
3. A formulation according to claim 2 , wherein said microbeads possess an average diameter of around 20 nm to around 0.5 mm.
4. A formulation according to claim 1 , wherein said optically transparent medium comprises a material selected from the group consisting of a polymer, a resin, a monolith, a glass, a sol gel, an epoxy, a silicone, and a (meth)acrylate.
5. A formulation according to claim 1 , wherein said optically transparent medium comprises a material selected from the group consisting of poly(methyl(meth)acrylate), poly(ethylene glycol dimethacrylate), poly(vinyl acetate), poly(divinyl benzene), poly(thioether), silica, polyepoxide, and combinations thereof.
6. A formulation according to claim 1 , wherein said optically transparent medium comprises a material selected from the group consisting of a copolymer of poly(methyl(meth)acrylate), poly(ethylene glycol dimethacrylate) and poly(vinyl acetate); polystyrene, polydivinyl benzene and a polythiol; and a 30 copolymer of 3-(trimethoxysilyl)propylmethacrylate and tetramethoxy silane.
7. A formulation according to claim 1 , wherein at least some of the microbeads include a core comprising a first optically transparent medium and one or more outer layers of the same or one or more different optically transparent media deposited on said core.
8. A formulation according to claim 7 , wherein said semiconductor quantum dots are confined to the core of the microbeads or are dispersed throughout the core and/or one or more of the outer layers of the microbeads.
9. A formulation according to claim 1 , wherein said LED encapsulation medium comprises a material selected from the group consisting of a polymer, an epoxy, a silicone, and a (meth)acrylate.
10. A formulation according to claim 1 , wherein said LED encapsulation medium is selected from the group consisting of silica glass, silica gel, siloxane, sol gel, hydrogel, agarose, cellulose, epoxy, polyether, polyethylene, polyvinyl, poly-diacetylene, polyphenylene-vinylene, polystyrene, polypyrrole, polyimide, polyimidazole, polysulfone, poly thiophene, polyphosphate, poly(meth)acrylate, polyacrylamide, polypeptide, polysaccharide, and combinations thereof.
11. A formulation according to claim 1 , wherein said semiconductor quantum dots contain ions selected from group consisting of groups 11, 12, 13, 14, 15 and 16 of the periodic table, transition metal ions and d-block metal ion.
12. A formulation according to claim 1 , wherein said semiconductor quantum dots contain one or more semiconductor materials selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, InP, InAs, InSb, AlP, Al 2 S 3 , AlAs, AlSb, GaN, GaP, GaAs, GaSb, PbS, PbSe, Si, Ge, MgS, MgSe, MgTe, and combinations thereof.
13. The formulation of claim 1 , wherein the surface-bound ligands are polymerizable monomers.
14. The formulation of claim 1 , wherein the surface-bound ligands comprise functional groups capable of associating with the optically transparent medium.