Growth of single-crystalline rutile TiO2nanowire array on titanate nanosheet film for dye-sensitized solar cells

Abstract

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.