Surface-modified nanoparticles
The surfaces of nanoparticles (QDs) are modified with amphiphilic macromolecules, for example, amphiphilic copolymers. The surface modification renders the QDs more compatible with oxygen-excluding matrices, such as epoxy resin, polyurethane resin, polyester resins or any hydrophilic inorganic/organic hybrid resin such as (meth)acrylate-functionalized polyhedral oligomeric silsesquioxane (POSS).
1. A display comprising:
a light-emitting element; and
a film in optical communication with the light emitting element, the film comprising:
a matrix material; and
a population of surface-modified nanoparticles dispersed in the matrix material, each surface-modified nanoparticle comprising:
a nanoparticle having a core and an external surface; and
amphiphilic block copolymers on the external surface of the nanoparticle,
wherein the block copolymers are any one of a polyalkylene glycol-poly(alkylene sulfide) block copolymer and a block copolymer consisting of a first block that is a reversible addition fragmentation chain transfer agent (RAFT-CTA) and a second block that is a polyalkylene glycol.
2. The display recited in claim 1 wherein the amphiphilic block copolymers are adsorbed on the external surface of the nanoparticle.
3. The display recited in claim 1 wherein the nanoparticle comprises a luminescent semiconductor material.
4. The display recited in claim 1 wherein the nanoparticle is selected from the group consisting of CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe, InP, InAs, InSb, AlP, AlS, AlAs, AlSb, GaN, GaP, GaAs, GaSb, PbS, PbSe, Si, Ge and combinations thereof.
5. The display recited in claim 1 wherein the surface-modified nanoparticles do not contain cadmium.
6. The display recited in claim 1 wherein the nanoparticle is a core-shell nanoparticle wherein the core is substantially comprised of a first material and the shell is substantially comprised of a second material different from the first material.
7. The display recited in claim 6 wherein the core-shell nanoparticle comprises a plurality of shells with adjacent shells substantially comprised of different materials.
8. The display recited in claim 6 wherein the core-shell nanoparticle comprises a shell material selected from the group consisting of ZnS, ZnO, MgS, MgSe, MgTe and GaN.
9. The display recited in claim 6 wherein the core-shell nanoparticle comprises a core comprised substantially of InP, first shell comprised substantially of ZnS, and a second shell comprised substantially of ZnO.
10. The display in claim 1 wherein the block copolymer comprises a block that has affinity for an epoxy resin.
11. The display recited in claim 1 wherein the polyalkylene glycol-poly(alkylene sulfide) block copolymer has the general formula
where m and n are positive integers.
12. The display recited in claim 11 , wherein m ranges from 5 to 500 and n ranges from 5 to 500.
13. The display recited in claim 11 , wherein m ranges from 5 to 50 and n ranges from 5 to 50.
14. The display recited in claim 11 , wherein m is 10 and n is 45.
15. The display recited in claim 1 , wherein the block copolymer consisting of a first block that is a reversible addition fragmentation chain transfer agent (RAFT-CTA) and a second block that is a polyalkylene glycol has the general formula
where n is a positive integer.
16. The display recited in claim 15 , wherein n ranges from 10 to 113.
17. The display recited in claim 1 , wherein the matrix material is an epoxy resin.
18. The display recited in claim 1 , wherein the matrix material is a silicone.
19. The display recited in claim 1 , wherein the matrix material is an acrylate resin.
20. The display recited in claim 1 , wherein the matrix material is a polyurethane resin.
21. The display recited in claim 1 , wherein the light-emitting element is a light-emitting diode (LED).