Preparation of hierarchical tin oxide microspheres and their application in dye-sensitized solar cells

Three-dimensional hierarchical tin oxide microspheres (HM-SnO2) are successfully synthesized by hydrothermal treatment. The SnO2 microspheres with diameter of 1–4 μm are pure rutile phase and consist of nanosheets. The two-dimensional nanosheets ensure fast electron transport and slow charge carrier recombination. Due to their large particle size, the HM-SnO2 films can scatter light efficiently and enhance light harvesting. Because of the above advantages, a dye-sensitized solar cell (DSSC) based on the HM-SnO2 photoanode shows an energy conversion efficiency of 4.55%, which indicates a 12.6% improvement compared to the DSSC based on a current SnO2 nanoparticle photoanode prepared under the same conditions. Moreover, the photovoltaic performance of the DSSC can be improved by modifying the photoanode with a TiO2 blocking layer and TiCl4 post-treatment.