Influence of a solution-deposited rutile layer on the morphology of TiO2 nanorod arrays and the performance of nanorod-based dye-sensitized solar cells

The morphology of TiO2 one-dimensional structures plays an important role in improving the photovoltaic performance of nanostructured solar cells. Herein we utilized a low-temperature solution-deposited rutile layer to adjust the morphology of TiO2 nanorod (NR) arrays on SnO2:F (FTO) conductive glass. A higher concentration of the TiCl4 precursor solution for the deposition of the seed layer can generate more nucleation sites for the growth of the TiO2 NRs, which raises the density of the TiO2 NR arrays and further restrains the growth of TiO2 in the transverse direction. The obtained TiO2 NR arrays were successfully incorporated into dye-sensitized solar cells (DSSCs) as the photoanodes. The denser TiO2 NR arrays, resulting from the TiCl4 precursor solution with a higher concentration, provided a larger surface for the adsorption of dyes, and thus improved the light harvesting of solar cells. More importantly, the seed layers were proven to present an effective blocking effect in preventing electron recombination at the FTO/electrolyte interface, which increased the open-circuit voltage of the DSSCs by ∼110 mV. This is a convenient method to control the morphology of the TiO2 NR photoanode and back electron reaction via seed layers, which could be used in other nanostructured photoelectrochemical devices.