Core/shell nanocrystals with copper sulfide cores and lead sulfide shells

Patent metadata

Field	Value
Publication number	US-11732186-B2
Application number	US-202117238265-A
Country	US
Kind code	B2
Filing date	Apr 23, 2021
Priority date	Apr 24, 2020
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

A process for synthesizing Cu2-xS/PbS core/shell nanocrystals. Pb-oleate is mixed with 1-octadecene and heated to 60° C. Cu2-xS core solution and bis(trimethylsilyl)sulfide stock solution are added and the mixture is stirred at 60° C. for 6 minutes to form the PbS shell around the Cu2-xS nanocrystal cores. The flask is cooled and acetonitrile and toluene is added and the mixture is centrifuged to precipitate and remove the Cu2-xS/PbS core/shell nanocrystals from the reaction mixture. The reaction also produces homogeneously nucleated PbS nanocrystals, which are removed from the Cu2-xS/PbS core/shell reaction mixture via size-selective precipitation. By tailoring the amounts of Pb-oleate and bis(trimethylsilyl)sulfide stock solution in the reaction vessel, while maintaining their molar ratio of 1.5:1 and the number of Cu2-xS cores in the reaction, Cu2-xS/PbS core/shell nanocrystals having a predetermined shell thickness of PbS, and thus a predetermined level of chemical stability, can be obtained.

First claim

What is claimed is:

1. A process for synthesizing core/shell nanocrystals, wherein each of the core/shell nanocrystals includes a respective copper sulfide core and a respective lead sulfide shell, the process comprising:
mixing an amount of Pb-oleate with 1-octadecene reaction flask within an N 2 glovebox to form a Pb-oleate mixture;
removing the flask from the glovebox and heating the Pb-oleate mixture under an argon atmosphere to 60° C.;
while maintaining the temperature of the Pb-oleate mixture at 60° C., adding an amount of copper sulfide core hexane solution and an amount of bis(trimethylsilyl)sulfide stock solution to the Pb-oleate mixture to form a reaction mixture, the amount of Pb-oleate and the amount of bis(trimethylsilyl)sulfide stock solution being maintained at a Pb-oleate:bis(trimethylsilyl)sulfide molar ratio of 1.5:1;
rapidly stirring the reaction mixture for 6 minutes to form the core/shell nanocrystals from the reaction mixture, wherein each the core/shell nanocrystals includes the respective copper sulfide core and the respective lead sulfide shell;
cooling the flask to room temperature;
returning the flask to the N 2 glovebox and adding toluene and acetonitrile to the flask in the N 2 glovebox;
removing the reaction mixture from the flask and placing it in a centrifuge tube; and
centrifuging the reaction mixture to precipitate and remove the core/shell nanocrystals from the reaction mixture;
wherein the amount of Pb-oleate and the amount of bis(trimethylsilyl)sulfide stock solution are configured to produce number of lead sulfide monolayers on each of the copper sulfide cores.

2. The process according to claim 1 , further comprising adding toluene and acetonitrile to the reaction mixture and centrifuging the reaction mixture to precipitate out homogeneously nucleated lead sulfide nanocrystals from the reaction mixture via size-selective precipitation.

3. The process according to claim 1 , wherein the reaction mixture comprises a 15 milllimolar (mM) concentration of Pb-oleate and a 10 mM concentration of bis(trimethylsilyl)sulfide.

4. The process according to claim 1 , wherein the reaction mixture comprises a 61 milllimolar (mM) concentration of Pb-oleate and a 41 mM concentration of bis(trimethylsilyl)sulfide.

5. The process according to claim 1 , wherein the reaction mixture comprises a 127 milllimolar (mM) concentration of Pb-oleate and a 85 mM concentration of bis(trimethylsilyl)sulfide.

6. A core/shell nanocrystal produced by the process of claim 1 .

7. A core/shell nanocrystal comprising a copper sulfide core with a lead sulfide shell.

8. The core/shell nanocrystal according to claim 7 , further comprising an SiO 2 shell.

9. The core/shell nanocrystal according to claim 8 , wherein the lead sulfide shell surrounds the copper sulfide core, and wherein the SiO 2 shell surrounds the lead sulfide shell.

10. The core/shell nanocrystal according to claim 7 , wherein the core/shell nanocrystal has a diameter in the range of about 5.9 nm to about 7.7 nm.

11. A dimer comprising:
a core/shell/shell nanocrystal having a copper sulfide core, a lead sulfide shell on the copper sulfide core, and a first SiO 2 shell on the lead sulfide shell; and
a core/shell nanocrystal comprising a lead sulfide core having a second SiO 2 shell formed on the lead sulfide core;
wherein the first and second SiO 2 shells are configured to provide a distance between the copper sulfide core and the lead sulfide core defined by thicknesses of the first and second SiO 2 shells.

12. A superlattice comprising:
a plurality of core/shell nanocrystals, wherein each of the core/shell nanocrystals includes a copper sulfide core and a lead sulfide shell; and
a plurality of lead sulfide nanocrystals;
wherein the core/shell nanocrystals and the lead sulfide nanocrystals are arranged in a lattice structure.

13. The superlattice according to claim 12 , wherein the lattice structure is analogous to the lattice structure in an A1B 2 superlattice.

14. The superlattice according to claim 12 , wherein the lattice structure is analogous to the lattice structure in a CuAu superlattice.

15. The superlattice according to claim 12 , wherein the lattice structure is analogous to the lattice structure in a Cu 3 Au superlattice.

16. The superlattice according to claim 12 , wherein the lattice structure is analogous to the lattice structure in a NaZn 13 superlattice.

17. The superlattice according to claim 12 , wherein each of the core/shell nanocrystals further includes an SiO 2 shell on the lead sulfide shell.

18. The superlattice according to claim 17 , wherein each of the copper sulfide cores is surrounded by the respective lead sulfide shell, and wherein each of the lead sulfide shells is surrounded by the respective SiO 2 shell.

19. The superlattice according to claim 12 , wherein each of the lead sulfide nanocrystals has an SiO 2 shell thereon.

20. The superlattice according to claim 19 , wherein each of the lead sulfide nanocrystals is surrounded by the respective SiO 2 shell thereon.

Assignees

• Us Gov Sec Navy

Inventors

• Boercker Janice E
• Brittman Sarah F
• Tischler Joseph G
• Yee Patrick Y
• Ellis Chase T
• Cunningham Paul D
• Stroud Rhonda M
• Stewart Michael H
• Erwin Steven C

Classifications

• C09K11/56 Primary

  containing sulfur · CPC title

• C09K11/582

  Chalcogenides · CPC title

• C09K11/661

  Chalcogenides · CPC title

• B82Y20/00

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

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title