Multistep electrophoretic deposition of TiO2 film and its surface modification for dye sensitized solar cells

TiO2 is a wide bandgap semiconductor commonly used as a photoanode material in dye sensitized solar cells (DSSCs). However, low absorption of TiO2 in visible range of solar spectrum limits its performance in DSSCs. A multistep electrophoretic deposition (EPD) process was used to improve the morphology of the mesoporous films and high quality TiO2 films were fabricated. Meanwhile, the optical absorbance was enhanced by a convenient and simple surface modification method using tin (Sn). The prepared films were subjected to morphological, optical, elemental, and phase analyses. It was observed that multistep EPD produced high quality films at various electric fields. Moreover, the surface modification was achieved using sonochemical deposition of Sn+ on the film which enhanced its photo-absorption. The current density (J) versus voltage (V) characteristics of Sn/TiO2 film deposited at 20 V based DSSC showed approximately twofold increase in the efficiency of the solar cells. Improved open-circuit voltage (Voc), short-circuit current density (Jsc) and efficiency (η) of the DSSCs as well as significantly high fill factor indicated that the surface modified EPD film is a potential candidate as a photoanode film in DSSCs.