The evolution of optical properties during hydrothermal coarsening of ZnS nanoparticles

Nearly monodisperse 3-nm ZnS nanoparticles capped with the mercaptoethanol were prepared in aqueous solution. During hydrothermal coarsening of ZnS nanoparticles, the evolution of optical properties and growth kinetics were investigated. As the particle size increased, the absorbance spectrum continued a size-dependent shift to long wavelength. A significant enhancement in photoluminescence was obtained during the growth, indicating the decrease of defects and the increase of ZnS crystallinity. The average particle size and size distribution were calculated from the absorption spectra, which revealed two-stage growth kinetics of ZnS nanoparticles.