Semiconductor nanoparticle-based materials
In various embodiment, a primary particle includes a primary matrix material containing a population of semiconductor nanoparticles, with each primary particle further comprising an additive to enhance the physical, chemical and/or photo-stability of the semiconductor nanoparticles. A method of preparing such particles is described. Composite materials and light-emitting devices incorporating such primary particles are also described.
1. A composite material comprising:
(a) a particle comprising:
a microbead comprising a primary matrix material;
a population of semiconductor nanoparticles contained within the microbead, the nanoparticles comprising at least one surface-bound ligand;
a first additive to enhance the physical, chemical and/or photo-stability of the semiconductor nanoparticles
and, a surface coating disposed on the surface of the microbead; wherein, the primary matrix material, the surface bound ligand, the additive, and the surface coating are different materials; and
(b) a secondary matrix material in the form of one or more secondary particles containing one or more secondary additives to enhance the physical, chemical and/or photo-stability of the semiconductor nanoparticles, wherein
(c) the particle of (a) is dispersed within the secondary matrix material of (b) and wherein the first additive and the one or more secondary additives are the same or different.
2. A composite material according to claim 1 , wherein said microbeads possess an average diameter of around 20 nm to around 0.5 mm.
3. A composite material according to claim 1 , wherein said primary matrix material 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.
4. A composite material according to claim 1 , wherein said first additive mechanically seals the primary matrix material.
5. A composite material according to claim 1 , wherein said first additive reduces a porosity of the primary matrix material.
6. A composite material according to claim 4 , wherein said first additive is selected from the group consisting of fumed silica, ZnO, TiO 2 , ZrO, Mg stearate, and Zn stearate.
7. A composite material according to claim 1 , wherein said first additive is a capping agent.
8. A composite material according to claim 7 , wherein said first additive is selected from the group consisting of tetradecyl phosphonic acid, oleic acid, stearic acid, polyunsaturated fatty acids, sorbic acid, Zn methacrylate, Mg stearate, Zn stearate, and isopropyl myristate.
9. A composite material according to claim 1 , wherein said surface coating comprises a material providing the primary particle with a protective barrier to prevent the passage or diffusion of potentially deleterious species from the external environment through the matrix material to the semiconductor nanoparticles.
10. A composite material according to claim 1 , wherein the surface coating is a barrier that hinders or prevents the passage of oxygen or an oxidizing agent through the primary matrix material.
11. A composite material according to claim 1 , wherein the surface coating is a barrier that hinders or prevents the passage of free radical species through the matrix material.
12. A composite material according to claim 1 , wherein the surface coating is a barrier that hinders or prevents moisture passing through the matrix material.
13. A composite material according to claim 1 , wherein the surface coating has a thickness of up to around 500 nm.
14. A composite material according to claim 13 , wherein the thickness of the surface coating is selected from the range of around 5 to 100 nm.
15. A composite material according to claim 1 , wherein the surface coating comprises an inorganic material.
16. A composite material according to claim 15 , wherein the inorganic material is selected from the group consisting of a dielectric, a metal oxide, a metal nitride, and a silica-based material.
17. A composite material according to claim 1 , wherein the surface coating comprises a polymeric material.
18. A composite material according to claim 17 , wherein the polymeric material is a saturated or unsaturated hydrocarbon polymer, or is a polymer incorporating one or more heteroatoms or heteroatom-containing functional groups.
19. A composite material according to claim 1 , wherein said semiconductor nanoparticles contain ions selected from group 11, 12, 13, 14, 15 and/or 16 of the periodic table, or one or more types of transition metal ion or d-block metal ion.
20. A composite material according to claim 1 , wherein said secondary matrix material 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.
21. A light-emitting device including a primary light source in optical communication with a formulation comprising a composite material according to claim 1 embedded in a host light-emitting diode encapsulation medium.
22. A composite material comprising:
(a) a particle comprising:
a microbead comprising a primary matrix material;
a population of semiconductor nanoparticles contained within the microbead, the nanoparticles comprising at least one surface-bound ligand; and
a first additive to enhance the physical, chemical and/or photo-stability of the semiconductor nanoparticles wherein, the primary matrix material, the surface bound ligand and the first additive are different materials; and
(b) a secondary matrix material in the form of one or more secondary particles containing one or more secondary additives to enhance the physical, chemical and/or photo-stability of the semiconductor nanoparticles, wherein the additive is selected from the group consisting of a reducing agent, a free radical scavenger, and a hydride reactive agent, and wherein (c) the particle of (a) is dispersed within the secondary matrix material of (b) and wherein the first additive and the secondary additives are the same or different.
23. A composite material according to claim 22 , wherein said first additive is selected from the group consisting of ascorbic acid palmitate, alpha tocopherol, octane thiol, butylated hydroxyanisole, butylated hydroxy toluene, a gallate ester, and a metabisulfite.
24. A composite material according to claim 22 , wherein said first additive is a benzophenone.
25. A composite material according to claim 22 , wherein said first additive is selected from the group consisting of 1,4-butandiol, 2-hydroxyethyl methacrylate, allyl methacrylate, 1,6 heptadiene-4-01, 1,7 octadiene, and 1,4 butadiene.