Enhanced conversion efficiency of dye-sensitized titanium dioxide solar cells by Ca-doping

Abstract Ca salts [CaSO 4 ]-doped TiO 2 electrodes prepared with well-optimized condition by the hydrothermal method show an increase in short-circuit (J SC ), resulting in a power conversion efficiency (PCE) of 8.35%, which is higher than that of the undoped TiO 2 thin film (7.33%). The doping of Ca shifts the flat band potential of TiO 2 photoanode positively and increases the electron density indicated by the Mott–Schottky plot. The driving force of injecting electrons from the LUMO of the dye to the conduct band of TiO 2 improves apparently because of the positive shift of the flat band potential. The intensity-modulated photocurrent spectroscopy measurement confirms that increased electron density accelerates the electrons transfer rate in the Ca-doped TiO 2 thin films by comparison to undoped films.