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

Patent metadata

Field	Value
Publication number	US-12391880-B2
Application number	US-202318386884-A
Country	US
Kind code	B2
Filing date	Nov 3, 2023
Priority date	Oct 12, 2017
Publication date	Aug 19, 2025
Grant date	Aug 19, 2025

Abstract

A Cd-free blue fluorescent quantum dot with a narrow fluorescence FWHM. The quantum dot does not contain cadmium and its fluorescence FWHM is 25 nm or less. The quantum dot is preferably a nanocrystal containing zinc and selenium or zinc 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 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 free of cadmium using the copper chalcogenide precursor,
wherein the quantum dot contains zinc and selenium, or zinc and selenium and sulfur,
wherein the quantum dot has a core-shell structure containing a nanocrystal core and a shell that covers a surface of the nanocrystal core,
wherein ligands are placed on a surface of the quantum dot, and
wherein the quantum dot has a fluorescence FWHM of 25 nm or less and has a fluorescence quantum yield of 50% or more.

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

3. The method of producing a quantum dot, according to claim 2 , wherein the metal exchange reaction is performed at 180° C. or more and 280° C. or less.

4. The method of producing a quantum dot according to claim 1 , wherein the copper chalcogenide is synthesized at a reaction temperature of 140° C. or more and 250° C. or less.

5. A quantum dot
wherein the quantum dot does not contain cadmium, and has a fluorescence quantum yield of 50% or more,
wherein a residual amount of Cu is more than 0 ppm and 100 ppm or less, and
wherein a fluorescence wavelength of the quantum dot is 410 nm or more and 470 nm or less.

6. The quantum dot according to claim 5 , wherein the quantum dot has a fluorescence FWHM of 25 nm or less.

7. The quantum dot according to claim 5 , wherein the quantum dot comprises a nanocrystal containing zinc and selenium, or zinc and selenium and sulfur.

8. The quantum dot according to claim 5 , wherein the quantum dot includes ligands placed on a surface of the quantum dot.

9. The quantum dot according to claim 8 , wherein the ligands are comprised of at least one selected from a phosphorus-based ligand, an amine-based ligand, and a thiol-based ligand.

10. The quantum dot according to claim 5 , wherein the quantum dot is produced by synthesizing copper chalcogenide as a precursor from an organic copper compound or an inorganic copper compound, and an organic chalcogen compound, wherein a metal change is performed between copper in the copper chalcogenide and zinc.

Assignees

• Ns Mat Inc
• Toppan Inc

Inventors

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

Classifications

• C09K11/025

  non-luminescent particle coatings or suspension media · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• B82Y20/00

  Nanooptics, e.g. quantum optics or photonic crystals · CPC title

• F21V9/30

  Elements containing photoluminescent material distinct from or spaced from the light source (shades F21V1/17; globes, bowls or cover glasses F21V3/08, F21V3/12; refractors F21V5/10; reflectors F21V7/26, F21V7/30; elements with provision for controlling the spectral properties or intensity F21V9/40) · CPC title

• H10H20/851

  Wavelength conversion means · CPC title