Enhancement of the photoluminescence of CdSe nanocrystals dispersed in CHCl3 by oxygen passivation of surface states

An unusual enhancement of photoluminescence from CdSe nanocrystals (NCs) dispersed in air-saturated CHCl3 was observed as a function of time. Within two weeks, for samples kept in the dark, the photoluminescence intensity increased by as much as a factor of 6, based on the peak height, with no change in peak position or width. This enhancement can be attributed to the reaction of nanocrystals with dissolved oxygen, which results in surface passivation. CdSe NCs kept in the growth solution (TOP/TOPO) showed no photoluminescence increase.