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

Abstract

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.