Examining the Conductivity and Bandgap Engineering in PVA-TiO2 Nanocomposites for Enhanced Optoelectronic Device Performance

The utilization of materials and devices at the nanoscale and the application of diverse methodologies constitute a fundamental element of contemporary nanotechnology, which is currently being implemented across numerous scientific fields. This study investigates the structural, electrical, and optical properties of polyvinyl alcohol (PVA) and Titanium Dioxide(TiO2) NC films. The PVA-TiO2 NC films were prepared using a simple solution casting method, with varying concentrations of TiO2 nanoparticles. The structural analysis revealed the incorporation of TiO2 nanoparticles into the PVA matrix, resulting in a uniform dispersion and improved crystallinity. SEM micrographs demonstrated the uniform dispersion of TiO2 nanoparticles in the PVA matrix. FTIR spectroscopy indicated the interaction between TiO2 nanoparticles and the PVA matrix through -OH functional groups. The electrical properties were assessed through DC electrical conductivity studies, which showed an increase in conductivity with increasing TiO2 concentration. The optical properties were characterized using UV-Vis spectroscopy, indicating a significant enhancement in the absorption and transmittance properties of the films with the incorporation of TiO2 nanoparticles. A significant peak of absorption was observed at a wavelength of 225 nm for the nanocomposite films incorporating 8.0 wt.% TiO2 into PVA. The incorporation of 8.0 wt.% TiO2 NPs in PVA polymer led to notable alterations in the direct bandgap, with a decrease from 6.09 eV to 5.28 eV, as well as in the indirect bandgap, with a decrease from 5.53 eV to 4.64 eV. Additionally, the Urbach energy decreased from 0.82 eV to 0.548 eV. Among the samples, the one with 8.0 wt.% TiO2 exhibited the highest DC electrical conductivity at 338 K, measuring 5.59x10-13 Scm-1, and at 393 K, measuring 4.01x10-8 Scm-1. The PVA-TiO2 NC films exhibited excellent potential for applications in optoelectronic devices due to their enhanced electrical and optical properties. UV-Vis spectroscopic studies revealed that these nanocomposites can be utilized in UV-shielding and optoelectronics devices. There is significant room for further study of these materials for potential applications. These findings indicate that the fabricated PVA-TiO2 nanocomposite films have potential applications in UV-shielding devices, photo sensors, tunable bandgap devices, refractive index-controlled optical devices, and flexible optoelectronic devices.