Improving photovoltaic performance of dye-sensitized solar cells by doping SnO2 compact layer with potassium

• K-doped SnO 2 film is fabricated by spin-coating technique. • The electrical properties of SnO 2 film are improved by introducing potassium. • The recombination effect between FTO and electrolyte is effectively suppressed. • The champion PCE of devices is improved from 7.02% to 7.84%. SnO 2 film doped with potassium has been fabricated by spin-coating technique on fluorine-doped tin oxide (FTO) glass. The electrical properties of the SnO 2 film are improved by introducing potassium, which is in favor of electrons transfer from TiO 2 film to FTO glass. Meanwhile, the K-doped SnO 2 compact layer is beneficial in suppressing the recombination effect between the FTO glass and the electrolyte. As a result, the short-circuit current density of dye-sensitized solar cells (DSSCs) is enhanced from 15.20 mA cm −2 to 17.48 mA cm −2 . Then, the highest power conversion efficiency is 7.84 % for the optimized DSSC based on the K-doped SnO 2 /TiO 2 film, which is larger than those of the DSSCs based on TiO 2 film (7.02 %) and non-doped SnO 2 /TiO 2 film (7.18 %).