Increase in photovoltaic performances of dye-sensitized solar cells—Modification of interface between TiO2 nano-porous layers and F-doped SnO2 layers

In order to improve the physical and chemical contacts between a porous TiO2 layer and an F-doped SnO2 transparent conductive layer (FTO), the surface of the FTO layer is polished. After polishing, the surface roughness decreased. However, light transmittance and sheet resistance did not vary largely. The short circuit current (Jsc) and efficiencies increased after the FTO was polished. It was found that the interfacial charge transfer between a TiO2 layer and an FTO layer decreased by impedance measurement, which suggests that contacts between an FTO and a TiO2 layer are improved because of the flatted surfaces or removal of electrical impurities. We propose one of the industrially important phenomena that surface polishing of FTO is one of the ways to increase photovoltaic performances for DSCs.