Photosensitization of optical band gap modified polyvinyl alcohol films with hybrid AgAlO₂ nanoparticles

Silver doped aluminium oxide (AgAlO₂) nanoparticles (NPs) have been synthesized by sol gel combustion method. The size and morphology of the synthesized NPs have been confirmed by high-resolution transition electron microscopy (HRTEM), and results indicate the size of the particles is around 8–14 nm with spherical in shape. A series of polyvinyl alcohol (PVA) nanocomposites (NCs) have been fabricated with varying amounts viz., 0.5, 1.0, 1.5, 2.0 and 2.5 wt% of AgAlO₂ NPs using solvent intercalation technique. The intensity of crystalline peaks of NC films was reduced, and a slight shift in the peak position was observed in XRD profiles, which depicts the changes in microcrystalline behaviors of the NCs. The morphological behaviors of PVA/AgAlO₂ films have been established by scanning electron microscope and atomic force microscopy. The physical interactions between the components in NCs have been evaluated by Fourier transfer infrared spectroscopy. Differential scanning calorimeter data showed a reduction in glass transition temperature (T_g) from 72 °C for PVA to 64 °C for PVA/2.5 wt% NPs. The optical constants of NCs have been evaluated from UV–Visible spectra. The obtained results reveal that band gap energy (E_g) reduces from 4.9 to 2.8 eV and refractive index increases from 1.5 to 2.4 with an increase in AgAlO₂ NPs content from 0 to 2.5 wt% in PVA matrix respectively. The current–voltage (I–V) data exhibit non-ohmic behaviors at higher potential voltage region (> 6 V) for NC films.