Exploring the Optical and Electrical Properties of α-Fe2O3 Nanoparticle-Enhanced PVA/Cs Polymer Nanocomposites for Flexible Optoelectronic Devices

Abstract

This study investigates polymer nanodielectrics, a class of nanoceramic filler polymer hybrids known for their tunable optical and electrical properties. These materials hold promise for applications in flexible optoelectronic and organoelectronic devices. High-purity iron(III) oxide (α-Fe₂O₃) nanoparticles were synthesized using a simple sol–gel method. These nanoparticles were incorporated, at varying weight percentages (1, 4, 8, and 16 wt%), into a polyvinyl alcohol/chitosan (PVA/Cs) blend using solution casting. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) analyses revealed changes in the amorphous nature of the PVA/Cs matrix and suggested interactions between the polymer and nanoparticles upon filler incorporation. UV–visible spectroscopy was employed to investigate the optical absorption properties and determine the bandgap of the nanocomposite films. The UV–Vis spectra revealed the presence of both direct and indirect bandgap transitions. The direct bandgap ranged from 5.76 to 4.68 eV, while the indirect bandgap ranged from 5.03 to 3.34 eV. The AC conductivity and dielectric permittivity of the prepared samples were found to be dependent on the α-Fe₂O₃ wt% across a frequency range of 10^–1 Hz to 10⁷ MHz. The relaxation process and interfacial polarization effects were explored to explain the observed behavior. Notably, at 10 Hz, the dielectric constant increased from 105 to 2656, and the \({\upsigma }_{\text{ac}}\) rose from 1.28 × 10⁻¹¹ to 1.02 × 10⁻⁹ S/m upon loading with 16 wt% α-Fe₂O₃ nanoparticles. These findings suggest the potential multifunctionality of PVA/Cs-α-Fe₂O₃ nanocomposite for various applications, including UV blockers, optical coatings in advanced organoelectronic/optoelectronic devices, and high-permittivity tunable nanodielectric substrates for next-generation high-performance energy storage devices.