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.