FORMATION OF II–VI SEMICONDUCTOR NANOCRYSTALS WITH TUNABLE VISIBLE EMISSION IN AQUEOUS SOLUTION PROMOTED BY HYDRAZINE

Abstract

II–VI Semiconductor nanocrystals (NCs) with tunable visible emission, such as CdS , CdSe and CdTe , were synthesized in aqueous solution using thiols as capping molecules. Hydrazine was found to promote the growth of NCs through a special mechanism. In only a few hours, the synthesis process was completed at room temperature. Under moderate conditions, the capping molecules not only changed the growth rate of NCs simply by varying the concentration, but also altered the spectral properties of NCs. The capping molecules with amino groups were propitious to the growth of CdS NCs, whereas the kinetic growth of CdS NCs was more affected by the surface passivation efficiency of NCs than by steric hindrance in the system. The fastest growth of the CdS NCs was achieved when glutathione was used as a capping molecule, while the emission of CdS and CdSe NCs were shown to remain steady and tunable using the same capping molecule. The growth rate of 3-mercaptopropionic acid-capped CdS and CdSe NCs slowed down significantly, while CdTe NCs were obtained with excellent emission properties when capped with the same molecule. Furthermore, our approach will also be useful for the study of the kinetic growth of NCs in aqueous solution.