Semiconductor nanoparticle-based materials

• US 20110068321A1
• Filed: 09/23/2010
• Published: 03/24/2011
• Est. Priority Date: 09/23/2009
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Nanoco Technologies Limited (Nanoco Group Plc)
• Inventors: Pickett, Nigel, Naasani, Imad, Harris, James
• Granted Patent: US 8,847,197 B2
• Time in Patent Office: Days
• US Class Current: 257/13
• CPC Class Codes: C09K 11/025 non-luminescent particle coatings or suspension media
• 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: H01L 2224/48091 Arched
• 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 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/56 Materials, e.g. epoxy or silicone resin

Abstract

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.

Claims

1. A primary particle comprising:

a primary matrix material containing a population of semiconductor nanoparticles,

wherein (i) each primary particle further comprises an additive to enhance the physical, chemical and/or photo-stability of the semiconductor nanoparticles, and (ii) said primary particles are provided in the form of microbeads.

2. A primary particle according to claim 1, wherein said microbeads possess an average diameter of around 20 nm to around 0.5 mm.

3. A primary particle 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 primary particle according to claim 1, wherein said additive mechanically seals the primary particle.

5. A primary particle according to claim 1, wherein said additive reduces a porosity of the primary particle.

6. A primary particle according to claim 4, wherein said additive is selected from the group consisting of fumed silica, ZnO, TiO₂, ZrO, Mg stearate, and Zn Stearate.

7. A primary particle according to claim 1, wherein said additive is a primary particle capping agent.

8. A primary particle according to claim 7, wherein said 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 primary particle according to claim 1, wherein said additive is a reducing agent.

10. A primary particle according to claim 9, wherein said additive is selected from the group consisting of ascorbic acid palmitate, alpha tocopherol, octane thiol, butylated hydroxyanisole, butylated hydroxytoluene, a gallate ester, and a metabisulfite.

11. A primary particle according to claim 1, wherein said additive is a free radical scavenger.

12. A primary particle according to claim 11, wherein said additive is a benzophenone.

13. A primary particle according to claim 1, wherein said additive is a hydride reactive agent.

14. A primary particle according to claim 13, wherein said additive is selected from the group consisting of 1,4-butandiol, 2-hydroxyethyl methacrylate, allyl methacrylate, 1,6 heptadiene-4-ol, 1,7 octadiene, and 1,4 butadiene.

15. A primary particle according to claim 1, wherein the primary particle is provided with a layer of a surface-coating material.

16. A primary particle according to claim 15, wherein said surface-coating material 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 primary matrix material to the semiconductor nanoparticles.

17. A primary particle according to claim 15, wherein the surface-coating material is a barrier that hinders or prevents the passage of oxygen or an oxidising agent through the primary matrix material.

18. A primary particle according to claim 15, wherein the surface-coating material is a barrier that hinders or prevents the passage of free radical species through the primary matrix material.

19. A primary particle according to claim 15, wherein the surface-coating material is a barrier that hinders or prevents moisture passing through the primary matrix material.

20. A primary particle according to claim 15, wherein the surface-coating material has a thickness of up to around 500 nm.

21. A primary particle according to claim 20, wherein the thickness of the surface-coating material is selected from the range of around 5 to 100 nm.

22. A primary particle according to claim 15, wherein the surface-coating material comprises an inorganic material.

23. A primary particle according to claim 22, wherein the inorganic material is selected from the group consisting of a dielectric, a metal oxide, a metal nitride, and a silica-based material.

24. A primary particle according to claim 15, wherein the surface-coating material comprises a polymeric material.

25. A primary particle according to claim 24, 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.

26. A primary particle 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.

27. A composite material incorporating a plurality of primary particles according to claim 1 dispersed within a secondary matrix material.

28. A composite material according to claim 27, 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.

29. A composite material according to claim 27, wherein said secondary matrix material is in the form of one or more secondary particles and the or each secondary particle contains one or more additives to enhance the physical, chemical and/or photo-stability of the semiconductor nanoparticles.

30. A light-emitting device including a primary light source in optical communication with a formulation comprising a plurality of primary particles according to claim 1 embedded in a host light-emitting diode encapsulation medium.

31. A light-emitting device including a primary light source in optical communication with a formulation comprising a composite material according to claim 27 embedded in a host light-emitting diode encapsulation medium.

32. A method for preparing a primary particle comprising a primary matrix material, a population of semiconductor nanoparticles and an additive to enhance the physical, chemical and/or photo-stability of the semiconductor nanoparticles, the method comprising:

combining said semiconductor nanoparticles, primary matrix material and additive under conditions suitable to produce said primary particle.

33. A method according to claim 32, wherein the additive is combined with semiconductor nanoparticles and precursors to the primary matrix material during reaction of said precursors to produce the primary particle.

34. A method according to claim 33, wherein the semiconductor nanoparticles are contained within a matrix material prior to being combined with the primary matrix material precursors.

35. A method according to claim 32, 33 or 34, wherein the additive is added after the semiconductor nanoparticles have been entrapped within the primary matrix material.

36. A method according to claim 32, 33 or 34, wherein a surface coating is provided on a surface of the primary particle.

37. A method according to claim 36, wherein said surface coating is formed so as to possess a layer thickness of around 1 to 500 nm.

38. A method according to claim 36, where the surface coating is provided by atomic layer deposition.

39. A method according to claim 36, wherein the surface coating is produced in-situ on a surface of the primary particle.