Development of Sustainable PEO/HPMC-CuO Nanocomposite Polymer Electrolytes for Advanced Dielectric Capacitors and Energy Storage Applications

This study focuses on the development and characterization of novel PEO/HPMC-based nanocomposites incorporating copper oxide (CuO) to enhance their physiochemical properties for optoelectronic applications. X-ray diffraction analysis verified the effective incorporation of nanoparticles and indicated a reduction in the degree of crystallinity, declining from 28.24% in the pristine PEO/HPMC to 17.29% in the PEO/HPMC containing 9%CuO. This increase in amorphous character is beneficial for charge mobility. Fourier-transform infrared spectroscopy showed characteristic functional groups of the components with no major chemical structural changes, indicating good compatibility. Optical band gap analysis using Tauc’s method revealed a significant reduction in both direct and indirect band gaps. The direct band gap decreased from 5.19 eV (pure PEO/HPMC) to 4.48 eV (PEO/HPMC containing 9%CuO), reflecting the formation of localized states and stronger interfacial interactions. Electrical conductivity ( σ ac ) improved with both filler content and frequency, indicating enhanced ionic mobility and conductive network formation. Dielectric studies showed increased dielectric constant ( ε ′) and loss ( ε ″), especially at low frequencies, due to space charge and interfacial polarization. These results confirm the promising multifunctional behavior of the nanocomposites, making them strong candidates for flexible electronic and optoelectronic device applications.