PEO/PVdF–HFP electrolytes for natural dye sensitized solar cell applications: effect of modified nano-TiO₂ on electrochemical and photovoltaic performance

Poly ethylene oxide (PEO) and Polyvinylidene fluoride-co-hexaflouropropylene (PVdF–HFP) blend electrolytes filled with surface modified TiO₂ nanofillers were prepared by solvent casting method. The ionic conductivity is increased about 7.02 × 10⁻⁴ S/cm with the incorporation of surface modified TiO₂ nanoparticles upto 7 wt %, where the ionic conductivity was about 7.94 × 10⁻⁵ S/cm with the addition of unmodified counterpart as the filler within PEO/PVdF–HFP blends. Similarly, ionic mobility, charge carrier concentration, ion diffusion coefficient also found to increase with the addition of surface modified TiO₂ nanoparticles. XRD results showed the change in the crystalline phase of PEO/PVdF–HFP blend electrolyte with the addition of surface modified TiO₂. The effect of the TiO₂ nanoparticles surface functionality on the degree of crystallinity of the polymer matrix was analyzed using DSC. The distribution of nanoparticles within the PEO/PVdF–HFP was studied by SEM. The solid state dye sensitized solar cell has been fabricated by using silane modified TiO₂/PEO/PVdF–HFP polymer nanocomposites electrolyte and natural dye extracted from gross as a sensitizer. The current–voltage characteristics of solar cells showed an enhancement of open circuit voltage (V_oc) from 0.31 to 0.47 V and the best fill factor achieved about 64 %, when silane modified TiO₂ is added.