Optical properties of poly-vinyl pyrrolidone encapsulated PbS/CdS coreshell quantum dots

Abstract

PbS/CdS core-shell quantum dots have been synthesized through chemical route. PbS shows polycrystalline cubic structure and CdS shows hexagonal structure. The photoluminescence study shows a blue shift of near band gap emission of core PbS when coated with shell CdS. PbS shows a band gap of 2.2 eV and CdS shows 2.7 eV whereas the PbS/CdS nanocomposite shows a reduction of band gap 1.5 eV. The observed optical properties are clearly carrying evidences of cationic exchange between the lead and cadmium ion complexes. The quantum yield of the composite is greatly enhanced implying its potential for application in optoelectronic devices.

Keywords

• PbS/CdS core-shell quantum dot
• cationic exchange
• blue shift
• PVP.