PVA/Bi2WO6 Nanocomposites: Evaluation of Bi2WO6 Filler Composition on Thermal, Optical, Electrical and Photoluminescence Characteristics

Herein, bismuth tungstate (Bi₂WO₆) nanoparticles (NPs) were synthesized employing solution combustion approach using lemon juice as fuel. The successful synthesis of Bi₂WO₆ NPs was confirmed by X-ray diffraction (XRD) and High resolution transmission electron microscopy (HR-TEM) methods which revealed the formation of nanoparticles with particles size 90–100 nm having a spherical geometry. A series of polyvinyl alcohol (PVA) nanocomposites (NCs) with varying Bi₂WO₆ NPs filler compositions viz. 0, 1, 2, 4, and 8 wt % were fabricated using an eco-friendly solvent intercalation process. X-ray diffraction analysis of the PVA/Bi₂WO₆ NCs revealed microcrystalline changes, providing evidence of the existence of Van der Waals interactions between Bi₂WO₆ NPs and the PVA matrix. Differential scanning calorimetry (DSC) analysis shows that incorporation of the Bi₂WO₆ NPs into the PVA matrix increases the glass transition temperature (Tg) of PVA from 97.5 °C to 108.16 °C and melting temperature (T_m) of plain shows a slight increase, rising from 188 to 190.7^º C. The optical characteristics of different PVA/Bi₂WO₆ NC films carried out using UV-visible spectroscopy confirmed a strong Bi₂WO₆ filler concentration dependent UV-absorption in the wavelength range of 210–290 nm thereby demonstrating an excellent UV-protection behavior. The transmittance, refractive index, absorption coefficient, optical band gap and Urbach energy of NCs determined from absorption spectral data also supported these findings. The band gap and Urbach energy showed a Bi₂WO₆ NPs concentration-dependent decrease for different NCs suggesting the formation of localized states in the forbidden band regions. Dc current measurements were performed on NC films to develop current-voltage (I-V) characteristics to understand the effect of Bi₂WO₆ NPs dose on electrical behavior of PVA NC films. The I-V characteristics revealed enhancement in electrical conductivity with increasing Bi₂WO₆ NPs concentration. Based on the above results, it is concluded that PVA/ Bi₂WO₆ NCs exhibit excellent Bi₂WO₆ NPs concentration-dependent optical and electrical properties, making them potential materials for optoelectric and optoelectronic devices applications.