Facile synthesis of magic-sized CdSe and CdTe nanocrystals with tunable existence periods

A facile and reproducible approach for the synthesis of magic-sized CdSe and CdTe nanocrystals is established. The as-synthesized CdSe nanocrystals exhibit strong and fixed absorption features with unusually narrow emission spectra. White-light emission can be achieved by two different routes. One is to mix colours emitted from both the magic-sized nanocrystals and the subsequently transformed regular-sized nanocrystals; the other is to expose the magic-sized nanocrystals to ambient conditions. A systematic study of the nanocrystal formation process shows that monomer activity and injection/growth temperatures are important parameters to the growth kinetics of magic-sized nanocrystals. Variation of these parameters provides tunable existence periods in the hot solution.