Tungsten doped titanium dioxide as a photoanode for dye sensitized solar cells

Tungsten doped titanium dioxide photoanodes were prepared using room temperature solid-state method with different doping ratios of 10, 15 and 20 mol%. This process is a convenient, inexpensive and efficient preparation of tungsten doped titanium dioxide with desired properties. The prepared tungsten doped titanium dioxide photoanodes were characterized by X-ray diffraction, UV–Vis absorption spectroscopy, photoluminescence spectra, scanning electron microscopy and transmission electron spectroscopy. Electrochemical properties were examined by electrochemical studies. Electrochemical impedance spectroscopy proposed that 20 mol% of tungsten doped titanium dioxide photoanode showed the highest ionic conductivity of 0.37 × 10⁻³ S/cm. The lower value of grain resistance was a possible to obtain high ionic conductivity, but the grain boundary resistance limits the total ionic conductivity of the photoanodes. The high ionic conductivity suggests that the tungsten is a favorable dopant to form titanium dioxide based photoanodes. The resulting photoanodes exhibits well-defined redox responses with the formal potential analyzed from cyclic voltammetry. The electrochemical stability of tungsten doped titanium dioxide photoanodes were determined by chronoamperometric studies. The dye-sensitized solar cells fabricated with 20 mol% W doped TiO₂ photoanode and phthaloylchitosan based polymer electrolyte was achieved a power conversion efficiency of 2.47%, which is higher than the pure TiO₂ photoelectrode (1.03%). The obtained results of this work should prove the selection of tungsten doped titanium dioxide photoanodes depicts a wide range of applications in the field of dye-sensitized solar cells.