Preparation of highly luminescent CdSe quantum dots by reverse micelles

Abstract

CdSe quantum dots (QDs) with relatively high photoluminescence (PL) quantum yield (QY) (about 30%) were prepared by a safe, low-cost, and simple synthesis method, utilizing a sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/water/cyclohexane microemulsion system. Cadmium chloride (CdCl2) and selenium powder were used as the cadmium and selenium sources, respectively. Size-tunable CdSe nanoparticles were obtained at various water-to-surfactant ratios, W ([H2O]/[surfactant]). The size of the CdSe nanoparticles increased, and the UV-vis absorption and PL peaks shifted towards the red region as W increased. Interestingly, the redshift also occurred when the ratio of Cd to Se increased. The highest PL efficiency was obtained at W of 5 and a Cd/Se ratio of 2 : 1. In addition, the CdSe nanoparticles with higher Cd to Se molar ratio (3/1) showed a higher stability against photooxidation. (C) 2014 The Japan Society of Applied Physics