Effect of TiO2 electrode thickness on photovoltaic properties of dye sensitized solar cell based on randomly oriented Titania nanotubes

Anatase titania nanotubes (TNTs) have been synthesized from P25 TiO2 powder by alkali hydrothermal method followed by post annealing. The microstructure analysis by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) revealed the formation of anatase nanotubes with a diameter of 9–10 nm. These NTs are used to make photo anode in dye-sensitized solar cells (DSSCs). Layer by layer deposition with curing of each layer at 350 °C is employed to realize films of desired thickness. The performance of these cells is studied using photovoltaic measurements. Electrochemical impedance spectroscopy (EIS) is used to quantitatively analyze the effect of thickness on the performance of these cells. These studies revealed that the thickness of TiO2 has a pronounced impact on the cell performance and the optimum thickness lies in the range of 10–14 μm. In comparison to dye solar cells made of P25, TNTs based cells exhibit an improved open circuit voltage and fill factor (FF) due to an increased electron lifetime, as revealed by EIS analysis.