Synthesis and characterization of CdS nanoclusters in a quarternary microemulsion: The role of the cosurfactant

Nanostructured semiconductor particles are currently under intense investigation because of their interesting photophysical and photochemical properties. Several preparation methods have been exploited for this class of materials; among them, the use of reverse micelles or "water-in-oil" microemulsions is a simple and successful preparative route. In this paper, a novel synthetic medium has been exploited, consisting of a quaternary CTAB/n-pentanol/n-hexane/water microemulsion. The presence of cosurfactant (n-pentanol), in addition to water, allows the simultaneous modulation of the water droplets dimensions and their exchange dynamics. Nanoparticles were characterized by UV-vis and photoluminescence spectroscopy, High-Resolution Transmission Electron Microscopy, and Raman spectroscopy. All measurements showed that the mean size of the nanoparticles is governed by the pentanol content of the system. They also possess a narrow size distribution and a good degree of crystallinity. Moreover, pentanol has an influence on the stability of CdS clusters, behaving as a capping agent at high concentrations. Stopped-flow measurements elucidated the influence of the cosurfactant in the kinetics of nucleation and growth.