Ta-doped hierarchical TiO2 spheres for dye-sensitized solar cells

Ta-doped hierarchical TiO2 spheres were prepared by a general hydrothermal method and the morphology and structure were characterized by SEM, XRD and XPS. The photovoltaic performance of the quasi-solid-state dye-sensitized solar cells (DSSC) based on the Ta-doped TiO2 hierarchical spheres was investigated. The results show that the Ta-doped hierarchical TiO2 spheres photoelectrode shows a maximum conversion efficiency of 7.10%, which is 29% higher than that of the undoped TiO2 spheres (5.42%) due to the increase of both short-circuit current density and the open-circuit voltage. The obviously enhancement in the conversion efficiency of the Ta-doped TiO2 hierarchical spheres electrode-based DSSCs can be ascribed to the negatively shift of the flat band potential and increase of the electron concentration of the TiO2 electrode, the reduction of electron recombination and the enhancement of electron transport in the TiO2 film by Ta doping.