Quantum dot and wavelength converting member, lighting member, back light unit, and display device using quantum dot, and method of producing quantum dot

Patent metadata

Field	Value
Publication number	US-11257981-B2
Application number	US-201816633010-A
Country	US
Kind code	B2
Filing date	Jul 27, 2018
Priority date	Jul 27, 2017
Publication date	Feb 22, 2022
Grant date	Feb 22, 2022

Abstract

The present invention seeks to provide cadmium-free quantum dots with a narrow fluorescence FWHM. The quantum dot does not contain cadmium and its fluorescence FWHM is 30 nm or less. The quantum dot is preferably a nanocrystal containing zinc and tellurium or zinc and tellurium and sulfur or zinc and tellurium and selenium and sulfur. Further, the quantum dot preferably has a core-shell structure in which the nanocrystal serves as a core and the surface of the core is coated with a shell.

First claim

The invention claimed is:

1. A method of producing a quantum dot, the method comprising:
synthesizing copper chalcogenide, as a precursor, from an organic copper compound or an inorganic copper compound, and an organic chalcogen compound; and
synthesizing a quantum dot using the precursor,
wherein the quantum dot is free of cadmium and contains: zinc and tellurium; zinc, tellurium, and sulfur; or zinc, tellurium, selenium, and sulfur, and
a fluorescence FWHM of the quantum dot is 40 nm or less.

2. The method according to claim 1 , wherein metal exchange is performed between copper in the precursor made of the copper chalcogenide and zinc.

3. The method according to claim 2 , wherein the metal exchange reaction is performed within a temperature range of temperature between 180° C. and 280° C.

4. The method according to claim 1 , wherein the copper chalcogenide is synthesized within a range of a reaction temperature between 160° C. and 250° C.

5. The method according to claim 1 , wherein the fluorescence FWHM is 30 nm or less.

6. The method according to claim 1 , wherein the fluorescence FWHM is 25 nm or less.

7. The method according to claim 1 , wherein the quantum dot is a nanocrystal.

8. The method according to claim 1 , wherein the quantum dot has a core-shell structure in which a nanocrystal serves as a core and a surface of the core is coated with a shell.

9. The method according to claim 1 , wherein a fluorescence wavelength of the quantum dot is 400 nm or more and 650 nm or less.

10. The method according to claim 1 , wherein ligands are placed on a surface of the quantum dot.

11. The method according to claim 10 , wherein the ligands are comprised of at least one selected from aliphatic amine-based compounds, phosphine-based compounds, and aliphatic carboxylic acid-based compounds.

Assignees

• Ns Mat Inc

Inventors

• Iida Kazunori
• Tsutsumi Emi
• Ogura Yuko
• Tanaka Masanori
• Nikata Soichiro
• Takamizuma Yuka

Classifications

• H10H20/851

  Wavelength conversion means · CPC title

• H10H20/8513

  having two or more wavelength conversion materials · CPC title

• H10H20/812 Primary

  within the light-emitting regions, e.g. having quantum confinement structures · CPC title

• B82Y15/00

  Nanotechnology for interacting, sensing or actuating, e.g. quantum dots as markers in protein assays or molecular motors · CPC title

• F21S2/00

  Systems of lighting devices, not provided for in main groups F21S4/00 - F21S10/00 or F21S19/00, e.g. of modular construction · CPC title