Controllable synthesis of anatase TiO2 crystals for high-performance dye-sensitized solar cells

TiO2 sub-micrometer spheres and size-tunable TiO2 rods with pure anatase phases have been prepared through a combined hydrolysis and hydrothermal process by simply controlling the reaction composition. The TiO2 spheres are highly porous structures possessing a large surface area, whereas TiO2 rods are single crystalline demonstrating excellent electron transfer and light scattering abilities. The product materials were utilized to form a bilayer structured photoanode incorporated in a dye-sensitized solar cell (DSSC). Under global AM 1.5 solar irradiation, a high overall solar energy conversion efficiency of 9.23% was achieved for the resultant DSSC, significantly higher than those cells derived from both TiO2 spheres (7.29%) and P25 particles (6.52%). The large improvement in cell performance is ascribed to the enhanced light harvesting and charge collecting capability along with the lowered charge recombination, resulting from the synergetic effect of TiO2 rods and spheres.