Semiconductor nanoparticle-based light-emitting devices and associated materials and methods

• US 8,921,827 B2
• Filed: 11/19/2009
• Issued: 12/30/2014
• Est. Priority Date: 11/19/2008
• Status: Active Grant

• Current Assignee: Nanoco Technologies Limited (Nanoco Group Plc)
• Original Assignee: Nanoco Technologies Limited (Nanoco Group Plc)
• Inventors: Pickett, Nigel, Harris, James
• Primary Examiner(s): Luu, Chuong A
• Application Number:
  US12/622,012
• Publication Number:
  US 20100123155A1
• Time in Patent Office: 1,867 Days
• Field of Search: 257/98, 257/301, 257/13, 257/9, 257/789, 257/100, 257/40, 257/79, 977/786, 977/787, 977/834
• US Class Current: 257/13
• CPC Class Codes: B82Y 15/00 Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors
• 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 11/70 containing phosphorus
• CPC Class Codes: C09K 11/883 with zinc or cadmium
• CPC Class Codes: G01N 33/588 with semiconductor nanocrystal label, e.g. quantum dots
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2924/00012 Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/181 Encapsulation
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/04 with a quantum effect structure or superlattice, e.g. tunnel junction
• CPC Class Codes: H01L 33/501 characterised by the materials, e.g. binder
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

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.

Claims

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, Al₂S₃, 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.