Enhanced dielectric and optical characteristics of NiO/Co₃O₄-filled poly(vinyl alcohol)/poly(vinyl pyrrolidone) blend films for potential optoelectronic applications

Polymer blend nanocomposites with synergistically enhanced functional properties are highly desirable for next-generation optoelectronic and energy-related devices. In this Study, a novel hybrid system based on poly(vinyl alcohol)/poly(vinyl pyrrolidone) (PVOH/PVP) blend films reinforced with dual-phase NiO/Co₃O₄ nanoparticles (0.5–2.0 wt%) was fabricated via a simple, eco-friendly solution-casting route. Structural analysis confirmed the effective dispersion of the hybrid nanofillers within the polymer matrix, accompanied by a pronounced reduction in crystallite size from 4.01 to 2.64 nm, evidencing enhanced amorphization induced by the synergistic NiO/Co₃O₄ interaction. FTIR results revealed strong interfacial bonding between the polymer chains and the metal oxides, which plays a key role in tuning the system’s physical properties. Optical measurements demonstrated controlled modulation of the electronic structure, with the direct and indirect optical band gaps reduced from 5.27 to 4.96 eV and from 4.95 to 3.86 eV, respectively, and an increase in the Urbach energy (0.317–0.504 eV), indicating the formation of localized states. Impedance analysis revealed a remarkable improvement in the electrical performance of the nanocomposites, with the bulk resistance decreasing from 3.21 × 10⁹ Ω for the pristine PVOH/PVP blend to 1.34 × 10⁸ Ω at 2.0 wt% NiO/Co₃O₄, accompanied by a substantial increase in interfacial polarization, indicating enhanced charge transport. Mechanical measurements revealed an increase in tensile strength from 0.0338 ± 0.001 to 0.0407 ± 0.002 MPa, accompanied by an improvement in elongation at break from 31.1 ± 0.8% to 35.8 ± 0.8%, confirming the reinforcing effect of the hybrid NiO/Co₃O₄ nanofillers. The observed synergistic Enhancement in the optical and dielectric responses highlights the novelty of employing hybrid NiO/Co₃O₄ nanofillers in PVOH/PVP blends, positioning these nanocomposites as promising candidates for advanced optoelectronic and energy-storage applications.