Synergic Effect of CdS Nano Additives and UV Exposure on Properties of PVA/CdS Nanocomposite

PVA/CdS nanocomposites with varying amounts of CdS NPs in PVA were synthesized by chemical reduction method and these were UV irradiation for different time. Absorption peak around 450 nm observed in these films indicates presence of CdS NPs in PVA. UV irradiation causes red shift in wavelength in absorption spectra which suggests increase of particle size after UV exposure. Decrease in transmittance of PVA after embedding NPs and further with UV exposure suggests that these can be used for UV-blocking devices. Band gap of PVA was noticed to decrease with increase in amount of NPs and UV exposure time. Increase in refractive index of PVA after embedding CdS NPs was observed which further increases with increasing concentration of NPs and with increase of UV exposure. Structural induced changes in PVA after embedding NPs and with UV exposure were analyzed by FTIR. FE-SEM and EDS analysis confirmed presence and distribution of NPs. Photoluminescence spectrum exhibits quantum confinement effect of CdS NPs embedded in polymer matrix. Thermal nature of nanocomposite films was investigated by DSC and TG. Dependence of electrical parameters on concentration of NPs and UV exposure time were studied and explained on the basis of formation charge-transfer complexes inside matrix.