Enhancing the Performance of Nanocrystalline TiO₂ Dye-Sensitized Solar Cells with Phenothiazine-Doped Blended Solid Polymer Electrolyte

Herein, we present a novel blended solid polymer electrolyte system composed of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-co-HFP) and polymethyl methacrylate (PMMA) with the addition of phenothiazine (PZ) as an additive and iodide/triiodide (I^-/I₃^-) as a redox couple in nanocrystalline TiO₂ dye-sensitized solar cells (DSSCs). The characterization of the blended solid polymer electrolyte was conducted using techniques such as XRD, FTIR, SEM, and current-voltage (I-V) measurements. Our analyses revealed a decrease in the degree of crystallinity in PVDF-co-HFP/PMMA-based blended solid polymer electrolytes due to the incorporation of PZ, as observed through XRD, FTIR, and SEM. The electrical conductivity of the optimized solid polymer electrolyte film was determined using complex impedance spectroscopy, showing a maximum ionic conductivity value of 3.2 × 10^-7 Scm^-1 at ambient temperature (298 K). DSSCs based on nanocrystalline TiO₂ were fabricated, and the cell parameters, including short-circuit current density (J_sc), open-circuit voltage (V_oc), fill factor (ff), and photovoltaic energy conversion efficiency (η), were evaluated. The DSSC fabricated with the polymer electrolyte exhibited values of 9.3 mA/cm², 800 mV, 0.56, and 5.2% for J_sc, Voc, ff, and η, respectively, under 80 mW/cm² at AM 1.5 simulated solar irradiation.