Semiconductor nanoparticle-based light emitting materials

• US 10,644,207 B2
• Filed: 03/20/2019
• Issued: 05/05/2020
• Est. Priority Date: 09/23/2011
• Status: Active Grant

• Current Assignee: Nanoco Technologies Limited (Nanoco Group Plc)
• Original Assignee: Nanoco Technologies Limited (Nanoco Group Plc)
• Inventors: Naasani, Imad, Pickett, Nigel
• Primary Examiner(s): Gumedzoe, Peniel M
• Assistant Examiner(s): Johnson, Christopher A
• Application Number:
  US16/359,565
• Publication Number:
  US 20190267515A1
• Time in Patent Office: 412 Days
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• 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 11/883 with zinc or cadmium
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 2933/005 relating to encapsulations
• CPC Class Codes: H01L 33/06 within the light emitting region, e.g. quantum confinement structure or tunnel barrier
• 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 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H01L 33/52 Encapsulations

Abstract

A light emitting layer including a plurality of light emitting particles embedded within a host matrix material. Each of said light emitting particles includes a population of semiconductor nanoparticles embedded within a polymeric encapsulation medium. A method of fabricating a light emitting layer comprising a plurality of light emitting particles embedded within a host matrix material, each of said light emitting particles comprising a population of semiconductor nanoparticles embedded within a polymeric encapsulation medium. The method comprises providing a dispersion containing said light emitting particles, depositing said dispersion to form a film, and processing said film to produce said light emitting layer.

Claims

1. A method of fabricating a light emitting device incorporating a light emitting layer comprising a plurality of light emitting beads dispersed within a host matrix material, each of said light emitting beads comprising a population of semiconductor nanoparticles embedded within a polymeric encapsulation medium, the method comprising:

providing a dispersion containing said light emitting beads, an initiator, a cross-linker, a monomer, and polyisobutylene;

depositing said dispersion on a surface of a diffuser sheet to form a film thereon;

annealing said film to produce said light emitting layer on the surface of the diffuser sheet; and

placing the diffuser sheet over a light source such that the diffuser sheet is between the light source and the light emitting layer.

2. The method recited in claim 1 wherein the initiator is a photoinitiator.

3. The method recited in claim 2 wherein the photoinitiator is bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide.

4. The method recited in claim 1 wherein the cross-linker is trimethylol propane trimethacrylate (TMPTM).

5. The method recited in claim 1 wherein the cross-linker is divinyl benzene.

6. The method recited in claim 1 wherein the monomer is an acrylate monomer.

7. The method recited in claim 6 wherein the acrylate monomer is lauryl methacrylate.

8. The method recited in claim 1 wherein said dispersion possesses a viscosity suitable for deposition by printing or drop casting.

9. The method recited in claim 1 wherein depositing said dispersion on the surface of the diffuser sheet is by printing or drop casting.

10. The method recited in claim 1 wherein said film has a thickness less than about 250 nm.

11. The method recited in claim 1 wherein the host matrix material is a polystyrene resin.

12. The method recited in claim 1 wherein the dispersion further comprises a polystyrene resin and toluene, and wherein the host matrix material is the polystyrene resin.

13. The method recited in claim 1 wherein the host matrix material is a methacrylate.

14. The method recited in claim 1 wherein annealing comprises heating said film to a temperature of about 300°

C.

15. An ink composition, the ink comprising a dispersion containing:

light emitting beads;

an initiator;

a cross-linker;

a monomer; and

polyisobutylene.

16. The ink composition recited in claim 15 wherein the initiator is a photoinitiator.

17. The ink composition recited in claim 15 wherein the cross-linker is trimethylol propane trimethacrylate (TMPTM).

18. The ink composition recited in claim 15 wherein the monomer is an acrylate monomer.

19. The ink composition recited in claim 18 wherein the acrylate monomer is lauryl methacrylate.

20. The ink composition recited in claim 15 wherein the light emitting beads comprise semiconductor nanoparticles containing ions selected from groups 11, 12, 13, 15 and 16 of the periodic table.