Post-deposition encapsulation of nanostructures: compositions, devices and systems incorporating same
Ligand compositions for use in preparing discrete coated nanostructures are provided, as well as the coated nanostructures themselves and devices incorporating same. Methods for post-deposition shell formation on a nanostructure and for reversibly modifying nanostructures are also provided. The ligands and coated nanostructures of the present invention are particularly useful for close packed nanostructure compositions, which can have improved quantum confinement and/or reduced cross-talk between nanostructures.
1. A charge storage device or memory device comprising a plurality of discrete nanostructures comprising metal cores and SiO 2 shells, wherein a diameter of a member nanostructure with its shell is less than or equal to 50 nm, and wherein the member nanostructures are arranged in a monolayer array and present at a density greater than 1×10 12 /cm 2 .
2. The charge storage device or memory device of claim 1 , wherein the diameter of a member nanostructure with its shell is less than or equal to 20 nm.
3. The charge storage device or memory device of claim 1 , wherein the diameter of a member nanostructure with its shell is less than about 10 nm.
4. The charge storage device or memory device of claim 1 , wherein the metal cores are palladium, platinum, iridium, gold, silver, nickel, iron, tin, zinc, titanium, or cobalt cores.
5. A discrete coated nanostructure comprising:
an individual nanostructure coated with a first coating; wherein the first coating comprises a silsesquioxane and one or more amine moieties that bind to the nanostructure, each of which amine moieties is coupled to the silsesquioxane.
6. A plurality of the coated nanostructures of claim 5 present at a density of greater than about 1×10 12 /cm 2 on a surface of a substrate.
7. The coated nanostructure of claim 5 , wherein the first coating encapsulates the nanostructure.
8. The coated nanostructure of claim 5 , wherein the nanostructure is a metal nanostructure.
9. The coated nanostructure of claim 5 , wherein each of the amine moieties is independently coupled to the silsesquioxane.
10. A coated nanostructure-containing composition comprising:
a plurality of nanostructures; and
a coating separating each member nanostructure, wherein the coating comprises silicon, and wherein the coating comprises a plurality of amine moieties that bind to a surface of the individual member nanostructure;
wherein the coating is convertible to a silicon oxide shell after deposition of the coating and binding of the moieties to the surface of the member nanostructure.
11. The coated nanostructure of claim 10 , wherein the coating comprises a silsesquioxane.
12. A method for post-deposition shell formation on a nanostructure, the method comprising:
providing one or more nanostructures having a ligand composition coating a surface of the nanostructure and thereby forming a first coating on the nanostructure, which first coating is curable to a rigid shell, and which ligand composition comprises a silsesquioxane and one or more moieties that bind to the nanostructure and that are coupled to the silsesquioxane; and
curing the first coating and generating the rigid shell on the surface of the nanostructure, thereby forming the shell post-deposition.
13. The method of claim 12 , wherein the ligand composition is selected from the group consisting of:
where R is an organic group or a hydrogen atom.
14. The method of claim 13 , wherein R is a hydrocarbon group.
15. The method of claim 13 , wherein R is an alkyl group, a cyclic alkyl group, an aryl group, or an alkylaryl group.
16. The method of claim 15 , wherein R is an isobutyl group, a methyl group, a hexyl group, a cyclopentyl group, or a cyclohexyl group.
17. The method of claim 12 , wherein the ligand composition is selected from the group consisting of:
where R is an alkyl group, a heteroatom, or an electron withdrawing group; and
where R is a halide.
18. The method of claim 12 , wherein the one or more moieties that bind to the nanostructure and that are coupled to the silsesquioxane are amine moieties.
19. The method of claim 12 , wherein the one or more nanostructures are metal nanostructures.
20. The method of claim 12 , wherein providing the one or more nanostructures comprises coupling the nanostructures to a substrate.
21. The method of claim 20 , wherein the substrate comprises a silicon substrate.
22. The method of claim 20 , wherein coupling the nanostructures to a substrate comprises spin-coating the nanostructures onto a surface of the substrate.
23. The method of claim 22 , wherein the substrate comprises a memory device substrate.
24. The method of claim 23 , wherein said spin-coating the nanostructures onto a memory device substrate comprises coating them onto the surface of the substrate at a density of greater than about 1×10 12 /cm 2 .
25. The method of claim 12 , wherein curing the first coating comprises heating the one or more nanostructures having the ligand composition coating the surface.