Effect of TiO2 sol on the conversion efficiency of TiO2 based dye-sensitized solar cell

Many approaches such as coupling with narrow bandgap semiconductors, doping with metals, using TiO2/graphene/TiO2 sandwich structure and TiCl4 treatment have been taken to improve TiO2 based dye-sensitized solar cell (DSSC). In this work, the effect of mixing TiO2 sol on the performance of TiO2 based DSSC, as compared mixing with pure anatase TiO2 particles was systematically studied. TiO2 sol has smaller particles (1 nm–1 µm) that could fill up the voids between large TiO2 particles in the TiO2 layer. The mixture was deposited on the working electrodes via simple casting method, followed by TiCl4 treatment and annealing in order to form TiO2 layers. The study showed that P III layer, prepared using mixture of TiO2 sol and P25 TiO2 particles, gave the best photoelectric conversion performance of DSSC (3.31%). The TiO2 sol improved the compactness and crystallinity of TiO2 layer (P III layer) in heat treatment, providing the lowest resistance path for more effective charge carrier transportation as verified by the electrochemical impedance spectroscope (EIS) measurement. Thus, all these factors contributed to the performance of DSSC fabricated by P III layer.