Effects of cadmium ion concentration on the optical and photo-response properties of CdSe/PVP nanocomposites for white light sensing application

Abstract

Cadmium selenide (CdSe) nanoparticles dispersed in the PVP matrix with varying concentrations of cadmium (Cd) ion complex have been synthesized through a low-cost chemical bath deposition technique to investigate the effects of cadmium ion concentration on its optical and photo-response characteristics. To confirm the formation of pure, stable, well dispersed, and highly crystalline spherical CdSe nanocomposites different characterization techniques such as X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and Fourier transform infrared spectroscopy have been used. The optical band gaps and sizes of the nanocomposites are determined from the UV–Vis data while the surface-related emission properties of the CdSe nanocomposites are obtained from the PL data. The quantum confinement on the CdSe nanocomposites increases with the decrease of Cd ion concentration. I–V characteristics measurements have been done on the samples to investigate the photo-response properties of the samples. Various optical properties such as bandgap, near bandgap emission, and impurity emission are correlated with the photo-response properties of the samples. The photoresponse properties are found to become more suitable for application in white light photosensor with the increase of quantum confinement. Mechanisms related to the enhancement of photocurrent with respect to quantum confinement are also discussed in this paper.