enhanced efficiency of dye-sensitized solar cells by trace amount ca-doping in tio2 photoelectrodes

Trace amount Ca-doped TiO2 films were synthesized by the hydrothermal method and applied as photoanodes of dye-sensitized solar cells (DSSCs). To prepare Ca-doped TiO2 film electrodes, several milliliters of Ca(NO3)2 solution was added in TiO2 solution during the hydrolysis process. The improvements of DSSCs were confirmed by photocurrent density-voltage (J-V) characteristics, electrochemical impedance spectroscopy (EIS) measurements. Owing to the doping effect of Ca, the Ca-doped TiO2 thin film shows power conversion efficiency of 7.45% for 50 ppm Ca-doped TiO2 electrode, which is higher than that of the undoped TiO2 film (6.78%) and the short-circuit photocurrent density (Jsc) increases from 13.68 to 15.42 mA·cm−2. The energy conversion efficiency and short-circuit current density (Jsc) of DSSCs were increased due to the faster electron transport in the Ca-doped TiO2 film. When Ca was incorporated into TiO2 films, the electrons transport faster and the charge collection efficiency ηcc is higher than that in the undoped TiO2 films.