Synthesis, Nonlinear Optical Properties of PVP Encapsulated CdS Quantum Dots and Nanocomposites

Three kinds of CdS Nanocomposites _CdS, CdS:Cu and CdS/PMMA (core/shell)_ using polyvinylpyrrolidone (PVP) as the capping agent were synthesized by chemical coprecipitation method.In the presence of PVP,cubic phase with small grain size of CdS were observed in X-Ray diffraction. The crystallite size of the synthesizedCdS quantum dots (QDs) and nanocomposites were less than 2nm calculated by considering FWHM from the (111)plane of XRD pattern in Debye-Scherrer method. From the UV-VIS analysis, increasing in the band gap withdecreasing in the particles size were observed, which confirms the quantum confinement effects. These nanomaterialshave shown highly nonlinear optical properties after using z-scan techniques.

کلیدواژه ها:

PVP ، coprecipitation ، quantum dots (QDs) ، FWHM ، quantum confinement