Characterization of nucleation and growth kinetics of the formation of water-soluble CdSe quantum dots by their optical properties

The nucleation and growth kinetics of the formation of water-soluble CdSe quantum dots (QDs) was characterized by measurements of their optical properties of ultraviolet-visible and fluorescence spectra. The QDs were synthesized using thioglycolic acid as a capping agent. Two kinetic parameters, reaction temperature and time, were varied over wide ranges 20-90 degrees C and 0-12 h, respectively. Our results showed that a low reaction temperature was preferable for the nucleation process, resulting in relatively small particles and a narrow size distribution. The subsequent grain growth was mainly achieved within 1 h. The reaction temperature virtually affected the kinetic features of the QDs. The fluorescence measurements revealed largest variations of the fluorescence features for the 70 degrees C samples. From a viewpoint of controls of fluorescence colour and intensity over a wide range, a reaction temperature of 70 degrees C was appropriate for the CdSe QD synthesis.