Claims
- 1. A method for producing silicon nanocrystals comprising the steps of:
contacting a silicon halide and a first reducing agent in a first organic solvent to produce halide-terminated silicon nanocrystals; and contacting the halide-terminated silicon nanocrystals and a second reducing agent along with a preselected termination group in a second organic solvent to produce silicon nanocrystals terminated with the preselected termination group.
- 2. The method of claim 1 wherein the silicon halide is SiX4, a mixed silicon halide, RnSiX(4-n), or a mixture thereof, wherein X is a halide, R is an alkyl group, and n=0, 1, 2, or 3.
- 3. The method of claim 1 wherein at least one of the first and the second reducing agents is an elemental metal having an oxidation potential greater than 0.24V.
- 4. The method of claim 3 wherein the elemental metal is in bulk form.
- 5. The method of claim 3 wherein the elemental metal is in finely divided form.
- 6. The method of claim 3 wherein the elemental metal is selected from the group consisting of Li, Na, K, Rb, Cs Mg, Ca, Zn, and Al.
- 7. The method of claim 1 wherein at least one of the first and the second reducing agents comprises a liquid alloy comprising one metal component that has an oxidation potential greater than 0.24V.
- 8. The method of claim 7 wherein at least one of the first and the second reducing agents comprises an agent selected from the group consisting of a liquid alloy of Na/K, Hg/Na, Hg/K, Hg/Li, Hg/Zn, and Hg/Al.
- 9. The method of claim 1 wherein at least one of the first and the second reducing agents comprises a mixture of an alkali metal and a phase transfer catalyst.
- 10. The method of claim 1 wherein the phase-transfer catalyst is a crown ether.
- 11. The method of claim 1 wherein at least one of the first and the second reducing agents comprises an aromatic anion, an alkyl metal compound, or a metal hydride of an metal selected from the group consisting of Li, Na, K, Mg, Ca, Zn, and Al.
- 12. The method of claim 1 wherein at least one of the first and the second reducing agents comprises an activated magnesium reagent.
- 13. The method of claim 1 wherein the first and the second reducing agents are the same.
- 14. The method of claim 1 wherein at least one of the first and second organic solvents comprises a polyether having the formula of MeO(CH2CH2O)nMe.
- 15. The method of claim 14 wherein the polyether is selected from the group consisting of 1,2-dimethoxyethane (glyme), 2-methoxyethylether (diglyme), and triethyleneglycoldimethylether (triglyme).
- 16. The method of claim 1 wherein at least one of the first and second organic solvents comprises tetrahydrofiran, 1,4-dioxane, benzene, toluene, or hexane.
- 17. The method of claim 1 wherein the first and second organic solvents are the same.
- 18. The method of claim 1 wherein the preselected termination group comprises an alkyl termination group, a hydride termination group, an alkoxy termination group, an amino termination group, or a mixture thereof.
- 19. The method of claim 18 wherein the preselected termination group is an oligomeric or polymeric group.
- 20. The method of claim 1 wherein at least 95% of the silicon nanocrystals are between about 1 nm to about 80 nm and at least 80% of the silicon nanocrystals are between about 1 nm to about 70 nm.
- 21. The method of claim 1 wherein at least 95% of the silicon nanocrystals are between about 40 nm to about 80 nm and at least 80% of the silicon nanocrystals are between about 50 nm to about 70 nm.
- 22. The method of claim 1 wherein at least 80% of the silicon nanocrystals are between about 1 nm to about 50 nm.
- 23. The method of claim 1 wherein at least 80% of the silicon nanocrystals are between about 1 nm to about 10 nm.
- 24. The method of claim 1 wherein at least one of the steps of contacting a silicon halide and a first reducing agent in a first organic solvent and contacting the halide-terminated silicon nanocrystals and a second reducing agent along with a preselected termination group is carried out at ambient temperature and pressure.
- 25. The method of claim 1 wherein both steps of contacting a silicon halide and a first reducing agent in a first organic solvent and contacting the halide-terminated silicon nanocrystals and a second reducing agent along with a preselected termination group are carried out at ambient temperature and pressure.
- 26. The method of claim 1 wherein the steps of contacting a silicon halide and a first reducing agent in a first organic solvent and contacting the halide-terminated silicon nanocrystals and a second reducing agent along with a preselected termination group are carried out concurrently in one reaction.
- 27. The method of claim 1 wherein the yield of silicon nanocrystals is greater than 90% by weight of silicon in the staring silicon halide.
- 28. The method of claim 1 wherein the second reducing agent provides the preselected termination group.
- 29. The method of claim 28 wherein the second reducing agent is alkyllithium and the preselected termination group is an alkyl group.
- 30. The method of claim 29 wherein the alkyllithium is n-butyllithium.
- 31. The method of claim 28 wherein the second reducing agent comprises a metal alkoxide, an anionic amine, or a metal hydride.
- 32. Silicon nanocrystals having a size distribution wherein at least 95% of the silicon nanocrystals are between about 40 nm to about 80 nm and at least 80% of the silicon nanocrystals are between about 50 nm to about 70 nm.
- 33. The silicon nanocrystals of claim 32 wherein at least 80% of the silicon nanocrystals are between about 50 nm to about 60 nm.
- 34. The silicon nanocrystals of claim 32 wherein substantially all the silicon nanocrystals are tetrahedral shaped.
- 35. The silicon nanocrystals of claim 32 having surface termination in the form of an alkyl termination group, an alkoxy termination group, an amino termination group, a hydride terminating group or a mixture thereof.
- 36. A method for producing silicon nanocrystals in high yield comprising the step of reducing a silicon halide with a reducing agent in an organic solvent to produce halide-terminated silicon nanocrystals.
- 37. The method of claim 36 further comprising the step of reacting the halide-terminated silicon nanocrystals with a preselected termination group to form silicon nanocrystals terminated with the preselected termination group.
- 38. The method of claim 37 wherein the step of reacting the halide-terminated silicon nanocrystals with a preselected termination group comprises contacting the halide-terminated silicon nanocrystals and a reducing agent along with a reagent containing the preselected termination group in an organic solvent.
- 39. The method of claim 37 wherein the preselected termination group is an alkyl group, an alkoxy group, an amino group, a hydride group, or a mixture thereof.
- 40. The method of claim 36 wherein the silicon halide comprises RnSiX(4-n) and SiX4, wherein R is an alkyl group, X is a halide, and n is 0, 1, 2, or 3.
- 41. The method of claim 40 wherein R is t-butyl, X is Cl, and n=1.
RELATED APPLICATIONS
[0001] This application claims the benefit of the filing date of U.S. Provisional Patent Application Serial No. 60/323,285, filed on Sep. 19, 2001, entitled “HIGH YIELD METHOD FOR PREPARING SILICON NANOCRYSTALS WITH CHEMICALLY ACCESSIBLE SURFACES” by Kauzlarich et al, the entirety of which is incorporated herein by reference.
GOVERNMENT RIGHTS
[0002] The subject matter described herein was supported in part by NIST Advanced Technology Program, Contract No. 70 NANBOH3028. The U.S. Government has certain rights in this invention.
Provisional Applications (1)
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Number |
Date |
Country |
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60323285 |
Sep 2001 |
US |