Structural and optical properties of ZnS nanoparticles

Abstract

In this work we report on the growth of ZnS semiconductor nanocrystals embedded in a polymeric matrix (Polyvinyl alcohol) were synthesized by a chemical route. The as-obtained films were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-VIS absorption, and photoluminescence (PL) spectra. X-ray diffraction (XRD) study confirmed the formation of cubic phase of ZnS nanocrystals into the polymer matrix. The particle size variations were achieved by varying the pH in the starting solution. Transmission electron microscopic image as well as XRD studies confirmed the nanometer size particles formation within the polymer matrix. The average particle size was found to lie in the range of 5-7 nm. A UV-VIS optical spectroscopy study was carried out to determine the band gap of the nanocrystalline ZnS thin film and it showed a blue shift with respect to the bulk value. The room temperature photoluminescence spectra of the films showed two peaks centered around 315nm, and 425 nm. We assigned the first peak due to band gap transitions while the latter was due to sulfur vacancy in the films.