Effect of TiO₂ nanofiller morphology on the electrochemical properties of chitosan/PMMA/PANI-based gel polymer electrolyte for dye-sensitized solar cells

Gel polymer electrolytes (GPEs) have been widely recognized as a viable alternative due to their improved safety, flexibility, and electrochemical stability, addressing the major drawbacks of liquid electrolytes for DSSCs, including leakage, volatility, and long-term stability. In this study, a ternary blend of chitosan, poly(methyl methacrylate) (PMMA), and polyaniline (PANI) (chitosan/PMMA/PANI) was used as the host matrix to prepare GPEs incorporating titanium dioxide (TiO₂) nanofillers with various morphologies. The combination of those three polymers is expected to produce a synergistic effect that enhances the electrolyte's overall electrochemical performance. TiO₂ was synthesized in three distinct morphologies: nanospheres, nanoflowers, and nanofibers. The gel polymer electrolytes were then characterized using XRD, FT-IR spectroscopy, and cyclic voltammetry (CV), including the electrochemical stability under light irradiation. The incorporation of TiO₂ nanofillers improved the structural and electrochemical properties of the gel polymer electrolyte, with TiO₂ nanospheres incorporated into the polymer matrix yielding the highest anodic and cathodic current peaks of 1.172 mA and −1.586 mA, respectively. This improvement may be attributed to the formation of additional ion transport pathways. Furthermore, the TiO 2 nanosphere-based GPE maintained electrochemical stability after irradiation, indicating its potential for DSSC application. These findings highlight the role of TiO 2 morphology in enhancing the electrochemical properties of chitosan/PMMA/PANI-based gel polymer electrolytes, providing insight for the development of DSSC.