Synthesis and study of optical and thermal properties of multi layers coated CdS core-shell nanocomposites

Novel CdS/ZnS/ZnO (0.1-0.5 M, mole concentration of the precursors) nanocomposites were successfully synthesized by the chemical precipitation method in air and studied for their excellent optical properties. Water-ethanol matrix was used as solvent. The crystal structure, morphology and photoluminescence properties of as-prepared nanocomposites were investigated in detail. XRD patterns show that the obtained CdS/ZnS/ZnO nanocomposites exhibit cubic and hexagonal mixed structures. Peak positions of the uncoated materials (CdS, ZnS and ZnO) were tuned into a single and strong emission in the visible region by synthesis of core-shell CdS/ZnS/ZnO nanocomposites. It was found that the multi shells coating passivates reduce the surface defects largely, thus the green and yellow emission is improved significantly.