Thickness effect of RF sputtered TiO₂ passivating layer on the performance of dye-sensitized solar cells

We report on the characteristics of a TiO₂ passivating layer grown by radio frequency (RF) magnetron sputtering on F-doped SnO₂ (FTO) electrodes as a function of its thickness. The optical transparency, surface roughness and passivation properties of the TiO₂ layer passivating the FTO electrode depend on the thickness of the TiO₂ passivating layer. In addition, it was found that the power conversion efficiency of the dye-sensitized solar cells (DSSCs) is critically dependent on the thickness of RF sputtered TiO₂ layer inserted between FTO electrode and nanoporous TiO₂ layer. The DSSC fabricated on 50 nm thick TiO₂ passivating FTO electrode showed the maximum power conversion efficiency of 4.42% due to effective prevention of the electron transfer to electrolyte. This indicates that the thickness optimization of the TiO₂ passivating layer is one of the important parameter to obtain high performance DSSCs.