Electron transport and recombination in polycrystalline TiO₂ nanowire dye-sensitized solar cells

Electron transport and recombination time constants in dye-sensitized solar cells made from TiO2 nanowires were determined using transient photocurrent and photovoltage measurements. The magnitude of the electron transport time (10-2 to 10-3 s) and its dependence on the illumination intensity were similar to those reported for dye-sensitized solar cells made from TiO2 nanoparticles indicating that electron capture and release by surface traps determine transport times even in nanowires. However, the ratio of the electron recombination time to the electron collection time in nanowire solar cells was ∼150, larger than those observed in nanoparticle dye-sensitized solar cells.