Cadmium free quantum dots

Patent metadata

Field	Value
Publication number	US-11142685-B2
Application number	US-201916245544-A
Country	US
Kind code	B2
Filing date	Jan 11, 2019
Priority date	Jan 11, 2018
Publication date	Oct 12, 2021
Grant date	Oct 12, 2021

Abstract

A cadmium free quantum dot not including cadmium and including: a semiconductor nanocrystal core comprising indium and phosphorous, a first semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core and comprising zinc and selenium, and a second semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal shell and comprising zinc and sulfur, a composition and composite including the same, and an electronic device.

First claim

What is claimed is:

1. A cadmium free quantum dot comprising:
a semiconductor nanocrystal core comprising indium and phosphorous,
a first semiconductor nanocrystal shell disposed on the semiconductor nanocrystal core and comprising zinc and selenium, and
a second semiconductor nanocrystal shell disposed on the first semiconductor nanocrystal shell and comprising zinc and sulfur,
wherein the cadmium free quantum dot does not comprise cadmium, and
wherein the cadmium free quantum dot has a quantum yield of greater than about 80%, and
wherein when the cadmium free quantum dot has a photoluminescent peak wavelength in a range from about 600 nanometers to about 650 nanometers, a molar ratio of indium to a sum of sulfur and selenium is greater than or equal to about 0.06:1 and less than or equal to about 0.3:1, or
wherein when the cadmium free quantum dot has a photoluminescent peak wavelength in a range from about 500 nanometers to about 550 nanometers, a molar ratio of indium to a sum of sulfur and selenium is greater than or equal to about 0.027:1 and less than or equal to about 0.1:1.

2. The cadmium free quantum dot of claim 1 , wherein in an ultraviolet-visible absorption spectrum of the cadmium free quantum dot, a ratio of an intensity of 450 nanometers to that of the first absorption peak wavelength is greater than or equal to about 1.1:1.

3. The cadmium free quantum dot of claim 1 , wherein the semiconductor nanocrystal core further comprises zinc.

4. The cadmium free quantum dot of claim 1 , wherein the first semiconductor nanocrystal shell does not comprise sulfur.

5. The cadmium free quantum dot of claim 1 , wherein the first semiconductor nanocrystal shell is disposed directly on a surface of the semiconductor nanocrystal core.

6. The cadmium free quantum dot of claim 1 , wherein a thickness of the first semiconductor nanocrystal shell is greater than or equal to about 3 monolayers and less than or equal to about 10 monolayers.

7. The cadmium free quantum dot of claim 1 , wherein the second semiconductor nanocrystal shell is an outermost layer of the cadmium free quantum dot.

8. The cadmium free quantum dot of claim 1 , wherein the second semiconductor nanocrystal shell is disposed directly on a surface of the first semiconductor nanocrystal shell.

9. The cadmium free quantum dot of claim 1 , wherein the cadmium free quantum dot has a photoluminescent peak wavelength in a range from about 600 nanometers to about 650 nanometers and a molar ratio of indium to a sum of sulfur and selenium is greater than or equal to about 0.064:1 and less than or equal to about 0.25:1.

10. The cadmium free quantum dot of claim 1 , wherein the cadmium free quantum dot has a photoluminescent peak wavelength in a range from about 500 nanometers to about 550 nanometers and a molar ratio of indium to a sum of sulfur and selenium is greater than or equal to about 0.030:1 and less than or equal to about 0.065:1.

11. The cadmium free quantum dot of claim 1 , wherein in an ultraviolet-visible absorption spectrum of the cadmium free quantum dot, a ratio of an intensity of 450 nanometers to that of the first absorption peak wavelength is greater than or equal to about 1.5:1.

12. The cadmium free quantum dot of claim 1 , wherein a blue light absorption per one gram of the cadmium free quantum dot is greater than or equal to 1.

13. The cadmium free quantum dot of claim 1 , wherein the cadmium free quantum dot has a quantum yield of greater than about 85%.

14. The cadmium free quantum dot of claim 1 , wherein the first absorption peak wavelength of the cadmium free quantum dot is present within a range of greater than about 450 nanometers and less than a photoluminescent peak wavelength of the cadmium free quantum dot.

15. The cadmium free quantum dot of claim 1 , wherein a full width at half maximum of the cadmium free quantum dot is less than or equal to about 44 nanometers.

16. A method of producing the cadmium free quantum dot of claim 1 , the method comprising:
providing a first mixture comprising a first shell precursor containing zinc, an organic ligand, and an organic solvent;
optionally heating the first mixture;
preparing a second mixture by injecting to the optionally heated first mixture, a semiconductor nanocrystal core comprising indium and phosphorous, and a selenium containing precursor;
heating the second mixture to a first reaction temperature and maintaining the first reaction temperature for at least 40 minutes to obtain a third mixture comprising a particle having a first semiconductor nanocrystal shell comprising zinc and selenium formed on the semiconductor nanocrystal core;
adding a sulfur containing precursor to the third mixture at the first reaction temperature to form a second semiconductor nanocrystal shell containing zinc and sulfur on the first semiconductor nanocrystal shell, thereby obtaining the cadmium free quantum dot,
wherein amounts of the selenium containing precursor and the sulfur containing precursor with respect to the indium in the second and third mixtures are controlled such that
when the cadmium free quantum dot has a photoluminescent peak wavelength in a range from about 600 nanometers to about 650 nanometers, a molar ratio of indium to a sum of sulfur and selenium is greater than or equal to about 0.06:1 and less than or equal to about 0.3:1, and or
when the cadmium free quantum dot has a photoluminescent peak wavelength in a range from about 500 nanometers to about 550 nanometers, a molar ratio of indium to a sum of sulfur and selenium is greater than or equal to about 0.027:1 and less than or equal to about 0.1:1.

17. The method of claim 16 , wherein the method does not comprise lowering a temperature of the third mixture to a temperature of less than or equal to about 100° C.

18. A composition comprising:
the cadmium free quantum dot of claim 1 ;
a carboxylic acid group-containing binder;
a polymerizable monomer comprising a carbon-carbon double bond; and
an initiator.

19. The composition of claim 18 , wherein the carboxylic acid group-containing binder comprises
a copolymer of a monomer combination comprising a first monomer, a second monomer, and optionally a third monomer, the first monomer comprising a carboxylic acid group and a carbon-carbon double bond, the second monomer comprising a carbon-carbon double bond and a hydrophobic moiety and not comprising a carboxylic acid group, and the third monomer comprising a carbon-carbon double bond and a hydrophilic moiety and not comprising a carboxylic acid group;
a multi-aromatic ring-containing polymer comprising a carboxylic acid group and a backbone structure in a main chain, wherein the backbone structure comprises a cyclic group comprising a quaternary carbon atom, and two aromatic rings bound to the quaternary carbon atom; or
a combination thereof.

20. The composition of claim 18 , wherein the carboxylic acid group-containing binder has an acid value of greater than or equal to about 50 milligrams of KOH per gram and less than or equal to about 240 milligrams of KOH per gram.

21. The composition of claim 18 , wherein the composition further comprises a thiol compound comprising a thiol group at a terminal end thereof, a metal oxide particle, or a combination thereof.

22. The composition of claim 21 , wherein the metal oxide particle comprises TiO 2 , SiO 2 , BaTiO 3 , Ba 2 TiO 4 , ZnO, or a combination thereof, and
wherein the thiol compound comprises a compound represented b

Assignees

• Samsung Electronics Co Ltd

Inventors

• Won Yuho
• Won Nayoun
• Hwang Sungwoo
• Jang Eun Joo
• Kwon Soo Kyung
• Kim Yong Wook
• MIN Jihyun
• Park Garam
• Park Shang Hyeun
• Jang Hyo Sook
• Jun Shin Ae
• Han Yong Seok

Classifications

• B82Y20/00 Primary

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

• H10H20/8512

  Wavelength conversion materials · CPC title

• C09K11/883 Primary

  with zinc or cadmium · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• C09K11/0883 Primary

  Arsenides; Nitrides; Phosphides · CPC title