Morphology control of mesoporous TiO2 nanocrystalline films for performance of dye-sensitized solar cells

Pure anatase TiO2 nanocrystallites were prepared by hydrolysis of TiCl4 aqueous solution, and TiO2 mesoporous films with precisely controlled morphology were prepared using the TiO2 nanocrystallites. The correlation between morphology of the films and photoelectrochemical characteristics of dye-sensitized solar cells fabricated from these films was investigated. The amount of the adsorbed dye (Adye) on the film and photocurrent of the cell were proportional to the roughness factor (rf) of the films, but did not depend on the particle size and pore size of the films under rf<1400. The photocurrent of the cell was linearly increased with the increase of irradiated light intensity up to 3 Sun. These results showed that the lowering of the photocurrent due to the diffusion limit of electrolyte was rarely appeared under solar light (1 Sun) irradiance when average pore size of the film was over 14 nm. However, small pores prevented the penetration and adsorption of the dye molecule, leading to the decrease of the cell performance.