Sn-Doped TiO₂ Photoanode for Dye-Sensitized Solar Cells

A series of Sn-doped TiO 2 with Sn content ranging from 0.25 to 1 mol % were successfully synthesized by the hydrothermal method, and its performance as the photoanode of dye-sensitized solar cells (DSSCs) was investigated. TEM and XRD results indicate that the doping has no effect on the morphology and the crystal form of TiO 2 . The shift of XRD peaks observed at higher angle and the XPS results indicate Sn 4+ ions incorporation into the TiO 2 lattice. The flatband potential of Sn-TiO 2 films shifts from −0.505 V (vs SCE) to −0.55 V with increasing Sn content from 0 to 1 mol at. %, which is beneficial to the increase of V oc . The higher transfer rate of electrons in the Sn-doped TiO 2 films than in the undoped TiO 2 films is confirmed by IMPS measurements, which is favorable to the higher J sc . IMVS and EIS measurements indicate that the charge recombination increases with increasing Sn doping content. Taking these factors, the optimum efficiency of 8.31% was found at 0.5 mol % Sn-doped TiO 2 based DSSCs, which gave an efficiency improved by 12.1% compared with that of the cells based on pure TiO 2 (7.45%). This work shows that Sn-doped TiO 2 is a most interesting material and has good potential for application in photoenergy conversion devices.