Characterization of Chemically Synthesized Nanofilms

In this work, a chemical bath deposition (CBD) method was employed for the synthesis of ZnS nanofilms. These ZnS nanofilms were grown two dimensionally on a silica glass substrate immersed in a colloidal solution of ZnS nanopartilces. These colloidal ZnS nanoparticles were prepared by mixing equivolume and equimolar (0.5M) solution of zinc sulphate dehydrate and thiourea in the presence of ammonia at room temperature and 3 % solution of Poly-Vinyl Alcohol (PVA) was added to it as capping agent. In TEM analyses, the formation of the different size of ZnS nanofilms was observed. XRD analysis showed that sample prepared were the cubic Zinc blende structure with particles size in the ranges 5nm -12nm and the measured spacing of crystallographic plane is about 0.27nm. Room-temperature optical absorption spectroscopy exhibits the presence of two separate excitonic characters inferring that the as-prepared ZnS nanostructures have some crystal defects. Due to the simplicity of this synthesis method, it has a great potential for a rapid and cost-effective preparation of high-quality ZnS nanofilms for use in photovoltaic or photocatalytics applications