Sodium poly[2-(3-thienyl)-ethoxy-4-butylsulfonate] or PTEBS has been explored previously for use in the fabrication of photovoltaic cells. PTEBS is a water-soluble polythiophene and the use of this polymer would allow safe, environmentally friendly processing as well improved reproducibility. In this study, solar cells based on layered PTEBS and TiO2 nanocrystalline films were investigated. The variation of the TiO2 thickness on the spin coating speed and suspension concentration was studied. Multiple spin coatings were used to make layers thicker than 3.5 μm. The photovoltaic samples with the TiO2 thickness in the range of 180 nm ∼ 8.08 μm have been fabricated to investigate the dependence of the efficiency and open circuit voltage on the TiO2 thickness. The optimum TiO 2 thickness was found to be around 4 - 4.5 μm. The maximum efficiency of 0.15% was obtained at the TiO2 thickness of 4.17 urn in this experiment. The initial investigation of dependence of the device characteristics on the PTEBS thickness was also explored. copyright The Electrochemical Society.