Enhancement of Optical, Dielectric and Electrical Transport Properties in CoCl2-Doped PEO Polymer Electrolyte Films by Gamma Irradiation for Optoelectronic Applications

Abstract

Objectives: This study investigates physical properties such as structural, optical, dielectric, and electrical properties of cobaltous chloride (CoCl₂)-doped polyethylene oxide (PEO) Polymer Electrolyte Films for optoelectronic applications upon γ-irradiation. Method: PEO–CoCl₂ films with varying dopant concentrations were prepared using the solution casting technique. Among these selected samples were exposed to different doses of γ-irradiation to induce controlled modifications. Structural properties modifications were analyzed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Optical properties were evaluated using UV–Visible spectroscopy, while dielectric and electrical properties were studied through dielectric and AC conductivity measurements. Findings: Structural properties modifications were analyzed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy data with slight shift in 2θ along with slightly decreased in peak width from 0.307 to 0.049 and reduced crystallinity confirming a transition toward an amorphous phase along with chain scission and cross-linking irradiation as a result of γ-irradiation. The incorporation of CoCl₂ transformed semicrystalline, PEO into a more amorphous phase due to coordination between Co²⁺ ions and polymer chains, which was further enhanced by γ-irradiation through chain scission and cross-linking. Optical analysis revealed a significant reduction in the direct band gap reaching 1.30 eV for irradiated films, indicating improved optical conductivity along with shift in the peak to red region. Dielectric studies showed increased polarization and reduced relaxation time, while AC conductivity results confirmed enhanced charge carrier mobility. These improvements are attributed to the dissociation of CoCl₂ into mobile ions, facilitating hopping conduction within the polymer matrix. Novelty: This work provides quantitative evidences, the combined effect of CoCl₂ doping and γ-irradiation significantly enhances ion transport and electrical performance of PEO-based composites. The developed films demonstrate shows strong potential for use in flexible electrodes and low-energy optoelectronic devices. Keywords: Polymer electrolyte films, Gamma-irradiation, AC conductivity, optical band gap, dielectric properties