Synthesis and optical properties of CdS/ZnS coreshell nanoparticles

Synthesis and optical properties of manganese (Mn2+)-doped, polyvinyl pyrrolidone (PVP)–capped cadmium sulphide (CdS) nanoparticles coated with zinc sulphide (ZnS) are reported. Colloidal solution of Mn2+-doped CdS nanoparticles capped with PVP is synthesized using methanol as solvent. PVP is used to control the particle size and to prevent agglomeration. Mn2+ doping is expected to help in increasing the CdS band edge photoluminescence (PL) emission. Addition of zinc nitrate and sodium sulphide alternately to the Mn2+-doped, PVP-stabilized CdS colloid led to the formation of ZnS-coated CdS coreshell nanoparticles. Photoluminescence emission spectra recorded for (CdS–PVP)Mn nanoparticles showed two emission peaks, one at 416 nm and the other weaker peak at 586 nm which is attributed to Mn2+ emission. Intensity of Mn2+ peak increased with increase in the Mn2+ content. Mn2+ emission disappears when ZnS is coated over the CdS core, resulting in pure CdS band edge emission.