Structural, optical, and electrical Studies of cobalt oxide incorporated chitosan/poly(vinyl alcohol) composite films

Abstract

Flexible, lightweight, and low-cost polymer-based materials are increasingly important for emerging electronic and optoelectronic technologies with reduced environmental impact. In this study, chitosan/poly(vinyl alcohol) (Cs/PVA) composite films incorporating different concentrations of cobalt oxide (Co₃O₄) were fabricated. The novelty of this work lies in the systematic correlation between Co₃O₄ content and the combined structural, optical, dielectric, electric modulus, and electrical conductivity responses of Cs/PVA composite films. Structural and morphological features were analyzed using XRD, FTIR, and SEM, confirming the successful incorporation of Co₃O₄ within the polymer matrix. Optical measurements revealed a gradual reduction in the indirect band gap and an increase in the Urbach energy with increasing Co₃O₄ content, indicating the formation of localized states and enhanced light absorption. Dielectric studies demonstrated a significant enhancement in permittivity and dielectric loss at low frequencies due to interfacial and space-charge polarization, while electric modulus analysis revealed concentration-dependent relaxation behavior. In addition, electrical conductivity increased progressively with increasing Co₃O₄ loading, reflecting improved charge-transport pathways. These findings demonstrate that Co₃O₄-loaded Cs/PVA composite films are promising candidates for flexible dielectric devices, charge-storage components, sensors, and lightweight electronic systems.