Gamma Ray-Induced Changes in Polyvinyl Alcohol/Carboxymethyl Cellulose/Cadmium Selenide Nanocomposite Films: Optical Analysis for Optoelectronic Devices

Abstract

In order to create nanocomposite films (NC) of polyvinyl alcohol, carboxymethyl cellulose and cadmium selenide nanoparticles (PVA/CMC/CdSe), thermolysis and ex-situ casting techniques were used. The microstructure and shape of the CdSe nanoparticles (NP) were characterized with the Rietveld method and transmission electron microscopy (TEM). Rietveld refinement of the x-ray data showed that the prepared CdSe NP had the cubic zinc blend structure with a lattice parameter 6.057 Å. The TEM showed the formation of the dotted shape of CdSe with a particle size around 2 nm, confirming the quantum dot size of the mother phase CdSe. Samples from the prepared PVA/CMC/CdSe films were irradiated with γ radiation doses of 20−150 kGy. The resultant effects of the γ ray irradiation on the optical and color properties of the prepared films were investigated using UV–vis spectroscopy and the International Commission on Illumination (CIE) color difference technique. When the γ dose was increased to 150 kGy, the maximum dose used, the direct and indirect optical band gaps (Eg) decreased. We attribute this decrease to the domination of crosslinking that destroyed the ordered structure and thus increased the amorphous regions. In addition, we used the optical dielectric loss (ε”) to identify the type of microelectronic transition for the PVA/CMC/CdSe NC samples, which was found to be a direct allowed transition. The effect of γ ray irradiation on the absorbance, extinction coefficient, refractive index, dielectric parameters and optical conductivity of the NC samples were studied. The enhancement in the optical properties indicated that the γ radiation is a useful tool that allows the use of the resulting PVA/CMC/CdSe NC in optoelectronic devices. Finally, the color differences between the pristine and irradiated films were estimated. The irradiated PVA/CMC/CdSe NC film exhibited significant color differences relative to the pristine films.