An Investigation into the Influence of Silver Nanoparticles on the Refractive Index of AgNO₃-Doped PVP/PVA Nanocomposites via the Refractive Index-Band Gap Energy Paradigm

A nanocomposite consisting of a Polyvinylpyrrolidone (PVP) and polyvinyl alcohol (PVA) blend doped with silver nitrate (AgNO₃) was prepared using a combination of chemical reduction and solution casting, with varying silver nanoparticle (Ag-NP) contents. Polymer nanocomposites were prepared by adding AgNO3 (0, 10, 20, and 30 wt.%) to a PVP/PVA host polymeric matrix with a weight ratio containing 60% of (PVP) and 40% of (PVA). The UV-Vis-NIR absorption spectroscopy was employed to examine the optical properties of the prepared films. The impact of various AgNO3 concentrations on the direct and indirect band gap energies was obtained from Tauc's plots, and the refractive index was determined using the optimal formula, as reported in previous studies, which provides an accurate correlation between refractive index and band gap energy. The structural and crystallinity degree were examined by XRD analysis. SEM images showed the nanoparticle formations. The discussion focused on the discovery that the refractive index change increased substantially with increasing salt concentration, consistent with the formation of silver nanoparticles.