The effect of RF-sputtered TiO ₂ passivating layer on the performance of dye sensitized solar cells

The aim of this work is to prevent the back transfer of electrons due to direct contact between the electrolyte and the conductive substrate by using TiO ₂ passivation. A thin TiO ₂ passivating layer was deposited on fluorine-doped tin oxide (SnO ₂:F, denoted FTO) glass by radio frequency (denoted RF) magnetron sputtering using different working pressures. The thickness and the crystalline structure were adjusted by applying various working conditions. The TiO ₂ films calcinated at low working pressure had an anatase phase, and they grew into a rutile phase with a decrease of the working pressure. The dye-sensitized solar cell using TiO ₂ passivating layer prepared at 0.5 mTorr was measured the maximum conversion efficiency of 4.6% due to effective prevention of the electron recombination to electrolyte. It was found that the conversion efficiency of the dye sensitized solar cell (denoted DSSC) was highly affected by the crystalline structure of the passivating layer.