Tunable structural, optical, and electrical performance of PEMA/PMMA–CoCl₂ composites for advanced optoelectronics and energy storage applications

This work investigates the effects of CoCl₂ doping on the structural, optical, and impedance characteristics of PEMA/PMMA blends for the advancement of sophisticated polymeric multifunctional materials. Composite films containing CoCl₂ were prepared using the solution-casting method and characterized by various analytical techniques. XRD and FTIR analysis revealed reduced crystallinity with significant interactions in the doped samples, SEM revealed a homogeneous morphology with slight porosity as a result of filler incorporation. UV-Vis spectra have demonstrated a systematic decrease of both direct and indirect band gaps, which evidences an effective tuning of the electronic structure via controlled doping. Electrical studies have demonstrated a significant increase of ionic conductivity at higher CoCl₂ content, which was further supported by impedance spectra that have revealed a lower bulk resistance and better charge transport. Conducing equivalent-circuit models further confirmed and quantified these improvements in conductivity. This is a dual-polymeric (PEMA/PMMA) matrix doped with CoCl₂, hence attaining the simultaneous control of structural order, optical properties, and ionic transport each rarely observable in convention polymer films. The optimized 5.0 wt.% composite exhibits an excellent balance between the conductivity and structural stability and, hence, is considered a promising candidate for tunable optoelectronic and energy storage applications.