In the current study, the film fabrication of polystyrene (PS) based polymer nanocomposites (NCs) with tuned refractive index and absorption edge was carried out using the solution cast method. X-ray diffraction (XRD) and ultraviolet-visible (UV-Vis) light characterization techniques were performed. The structural and optical properties of the prepared films were specified. The hump of PS decreased significantly when SnTiO₃ nanoparticles (NPs) were introduced. Sharp and high intense peaks of SnTiO₃ NPs at a high filler ratio were observed. The crystalline size was determined for SnTiO₃ NPs from the sharp crystalline peaks using Debye-Scherrer’s equation and was found to be 25.179 nm, which is close enough to that described by the supplier. Several optical parameters, such as absorption coefficient (α), refractive index (n), and optical dielectric properties, were investigated. The absorption spectra were tuned with increasing SnTiO₃NPs. Upon the addition of the NPs to the PS host polymer, the absorption edge undergoes shifting to lesser photon energy sides. The optical dielectric constant (ε′) was correlated to the refractive index. The study of the optical band gap was conducted in detail using both Tauc’s model and the optical dielectric loss (ε″) parameter. The results showed that the ε″ parameter is noteworthy to be measured in the optical band gap study of materials.

The current study employed a novel approach to design polymer composites with modified structural and declined optical band gaps.

The structure and optical properties of polyethylene oxide (PEO) doped with tin titanate (SnTiO₃) nano-filler were studied by X-ray diffraction (XRD) and UV-Vis spectroscopy as non-destructive techniques. PEO-based composed polymer electrolytes inserted with SnTiO₃ nano-particles (NPs) were synthesized through the solution cast technique. The change from crystalline phase to amorphous phase of the host polymer was established by the lowering of the intensity and broadening of the crystalline peaks. The optical constants of PEO/SnTiO₃ nano-composite (NC), such as, refractive index (n), optical absorption coefficient (α), dielectric loss (ε_i), as well as dielectric constant (ε_r) were determined for pure PEO and PEO/SnTiO₃ NC. From these findings, the value of n of PEO altered from 2.13 to 2.47 upon the addition of 4 wt.% SnTiO₃NPs. The value of ε_r also increased from 4.5 to 6.3, with addition of 4 wt.% SnTiO₃. The fundamental optical absorption edge of the PEO shifted toward lower photon energy upon the addition of the SnTiO₃ NPs, confirming a decrement in the optical band gap energy of PEO. The band gap shifted from 4.78 eV to 4.612 eV for PEO-doped with 4 wt.% SnTiO₃. The nature of electronic transitions in the pure and the composite material were studied on the basis of Tauc’s model, while optical ε_i examination was also carried out to calculate the optical band gap.