Photoelectrochemical properties of WO3-modified anatase TiO2 photoanodes and application for dye-sensitized solar cells

TiO2 electrodes were modified with different WO3 loadings and photoelectrochemical characterization revealed an increase in photocurrent density and decrease in interface charge transfer resistance with increasing amount of WO3. A decrease in green PL was observed with WO3 addition indicating more mobility of charges and therefore less probability of recombination. A series of TiO2 photoanodes modified by WO3 were designed with different geometrical configurations for dye-sensitized solar cell (DSSC) applications, WO3 was introduced successively in the screen-printed paste, as an undercoat and in the TiCl4 pretreatment bath. The results indicated a decrease in photovoltaic performance of all devices modified by WO3 compared to TiO2 reference cell. The highest conversion efficiency of the modified cells was observed for the configuration of WO3 introduced into the TiCl4 pretreatment bath. In this case, the optimized contact between the coupled semiconductors improved the charge transfer, also the direct contact of WO3 with the FTO substrate decreased the loss of electrons by confinement and recombination.