Nanocrystal synthesis
A method of preparing monodisperse MX semiconductor nanocrystals can include contacting an M-containing precursor with an X donor to form a mixture, where the molar ratio between the M containing precursor and the X donor is large. Alternatively, if additional X donor is added during the reaction, a smaller ratio between the M containing precursor and the X donor can be used to prepare monodisperse MX semiconductor nanocrystals.
1. A method of preparing semiconductor nanocrystals, comprising:
contacting an M-containing precursor with an X donor to form a mixture; and
heating the mixture in the presence of a coordinating solvent to form nanocrystals,
wherein the molar ratio between the M containing precursor and the X donor is more than 15.
2. The method of claim 1 , wherein M is selected from the group consisting of Cd, Pb, Zn, Mg, Hg, Al, Ga, In, and Tl.
3. The method of claim 1 , wherein X is selected from the group consisting of O, S, Se, Te, N, P, As, and Sb.
4. The method of claim 1 , wherein M is Pb.
5. The method of claim 1 , wherein X is S.
6. The method of claim 1 , wherein X is Se.
7. The method of claim 1 , wherein the molar ratio between the M containing precursor and the X donor is between 20:1 and 30:1.
8. The method of claim 1 , wherein the molar ratio between the M containing precursor and the X donor is between 23:1 and 25:1.
9. The method of claim 1 , wherein the molar ratio between the M containing precursor and the X donor is 24:1.
10. The method of claim 1 , wherein the formed nanocrystals are monodisperse.
11. The method of claim 1 , wherein the dispersity of the nanocrystals is less than 5%.
12. The method of claim 1 , wherein the dispersity of the nanocrystals is less than 4%.
13. The method of claim 1 , wherein the nanocrystals have a HWHM of less than 30 meV.
14. The method of claim 1 , wherein the peak absorption of the nanocrystals is between 1000 nm and 1800 nm.
15. The method of claim 1 , further comprising heating the mixture at a temperature of less than 150° C.
16. The method of claim 1 , further comprising heating the mixture at a temperature of less than 100° C.
17. The method of claim 1 , further comprising heating the mixture at a temperature of less than 50° C.
18. The method of claim 1 , wherein the quantum yield of the nanocrystals is more than 30%.
19. The method of claim 1 , wherein the quantum yield of the nanocrystals is more than 50%.
20. The method of claim 1 , further comprising purifying the nanocrystals.
21. The method of claim 1 , further comprising purifying the nanocrystals with an alcohol.
22. The method of claim 1 , further comprising purifying the nanocrystals with oleic acid.
23. A method of preparing semiconductor nanocrystals, comprising:
contacting an M-containing precursor with an X donor to form a mixture, wherein the molar ratio between the M containing precursor and the X donor is more than 4;
heating the mixture in the presence of a coordinating solvent to form nanocrystals; and
adding additional X donor to the mixture during the heating.
24. The method of claim 23 , wherein the dispersity of the nanocrystals is less than 5%.
25. The method of claim 23 , wherein the dispersity of the nanocrystals is less than 4%.
26. The method of claim 23 , wherein the additional X donor is added slowly to the mixture.