The effect of applying lead ion to the surface of TiO2 on dye-adsorption rate and photovoltaic properties of solar cells

Lead ion was incorporated into TiO layers prepared on an F-doped tin oxide (FTO) substrate. The resulting electrodes (Pb-TiO/FTO) were sensitized with N719 dye and put to use in dye-sensitized solar cells (DSCs). Owing to the electrostatic attraction between the positively charged TiO and the carboxylate anions (–COO) in the N719 dye, more dye was adsorbed into the Pb-TiO/FTO, which required only 2 h for sensitization, than in a reference TiO/FTO electrode that was sensitized for 8 h. The power conversion efficiency of a DSC with the Pb-TiO/FTO rose to 10.01 % over the efficiency (9.29 %) of the reference device. It was found that the increased dye adsorption in the Pb-TiO/FTO allowed the cells to more efficiently harvest light and collect electrons, resulting in a higher short-circuit current in the DSC. The larger amount of dye also induced a higher open-circuit voltage in the cell by increasing the total number of photoinjected electrons and prolonging their lifetime.