Optical, phonon properties of ZnO–PVA, ZnO–GO–PVA nanocomposite free standing polymer films for UV sensing

In order to study the response of poly(vinyl alcohol) based composite films under UV radiations, polymer-based films of ZnO, GO and ZnO/rGO powders were prepared by solution casting technique at room temperature. The prepared samples were characterized by powder X-ray diffraction, UV–Visible absorption spectroscopy, atomic force microscopy and Raman spectroscopic technique. The photo-sensitivity of the films towards UV radiation were studied by current–voltage measurements (IV) under visible and UV irradiation. The electric field produced by the UV radiation can pull the holes to the surface while at the surface the adsorbed oxygen ions will trap the photo-generated holes by the recombination of surface electrons and holes, which results in the increase of photocurrent gain. A better response was observed for the ZnO/rGO polymer composite film due to large surface roughness and localized electrons in the GO sheet.