Growth of single-crystalline rutile TiO2 nanowire array on titanate nanosheet film for dye-sensitized solar cells

A titanate nanosheet (TN) film is employed as a seed layer for the hydrothermal growth of a single-crystalline rutile TiO2 nanowire array on SnO2:F (FTO) conductive glass for dye-sensitized solar cell (DSSC) applications. TiO2 nanowires grown on a TN film appear to be thinner, more uniform, and well separated from each other, compared with those grown directly on FTO conductive glass. Besides FTO conductive glass, TiO2 nanowires can also be grown on silicon wafers and glass slides when a TN film is involved. Scanning electron microscope observations showed that the TN film underwent surface coarsening and thinning during the nucleation and growth of the TiO2 nanowires, suggesting that the film may act as a sacrificial seed layer. When applied in a DSSC, the nanowire photoanode with a TN film involved is significantly superior to that without the film in terms of all cell parameters, and gave an overall solar energy conversion efficiency of over 3% under AM 1.5G solar irradiation, about 3.4 times greater than that without the TN film. The combination of increased dye loading amount and reduced charge recombination at the FTO glass/electrolyte interface due to the involvement of the TN film should contribute to the significant improvement in cell performance.