TiO2 flowers and spheres for ionic liquid electrolytes based dye-sensitized solar cells

Micro-sized 3D branched flower like and sphere TiO2 have been synthesized through a controlled hydrolysis followed by hydrothermal process. The resultant flower and sphere TiO2 were characterized by SEM, XRD, BET and light scattering measurements. Overwhelming anatase and strong light scattering were exhibited for the flower sample. Pure sphere and flower and sphere-mixed (flower/sphere) films were formed and applied as photoelectrodes for dye-sensitized solar cells (DSCs) with both ionic liquid and gelled ionic liquid electrolytes. The devices exhibited considerably enhanced overall energy conversion efficiency in comparison with that of those derived from TiO2 nanoparticles. The superior performances were attributed to their fast electrolyte diffusion and good interfacial contact of TiO2/electrolyte as validated by EIS investigations as well as light scattering. The participation of flowers with the sphere films further improved the electrolyte penetration and light scattering, making the flower/sphere device the most efficient with a low dye loading.

► Micro-sized 3D flower and sphere like anatase TiO2 were hydrothermal synthesized.
► Flower and sphere were applied as DSCs photoanodes in comparison with nanoparticles.
► Higher efficiencies were achieved and flower/sphere device proved most efficient.
► The performance resulted from efficient electrolyte diffusion and light scattering.