Ag and Cu doped colloidal CdSe nanocrystals: partial cation exchange and luminescence

Partial cation exchange was employed to dope pre-formed colloidal CdSe nanocrystals with Ag+ and Cu2+ ions. Unusual photoluminescence (PL) properties were observed after these partial cation exchange reactions. Intensity of excitonic PL increases by similar to 4 times at low level of doping (1.3 dopant per nanocrystal). However, systematic study shows that the dopant ions do not enhance the excitonic emission. Instead, better surface passivation by trioctylphosphine used during the cation exchange is responsible for enhancement of excitonic PL. As doping concentration increases, intensity of excitonic PL decreases, and a new dopant-related emission emerges.