Study on dynamic properties of the photoexcited charge carriers at anatase TiO2 nanowires/fluorine doped tin oxide interface.

The photoexcited electrons transfer dynamics at the TiO 2 film/fluorine doped tin oxide (FTO) interface of anatase TiO 2 nanowire arrays (NWAs) and QD-sensitized TiO 2 NWAs films have been studied by using surface photovoltage (SPV) and transient photovoltage (TPV) techniques. Various SPV and TPV responses were obtained when the laser beam was incident from the front side illumination and back side illumination. Based on the work function values of anatase TiO 2 NWAs and FTO, the results indicate that diffusion is the major way for the separation and transfer of the photoexcited charge in the both anatase TiO 2 NWAs and QD-sensitized TiO 2 NWAs films under front side illumination. And the photoexcited charge were separated by drift under the built-in electric field at the TiO 2 film/FTO interface for anatase TiO 2 NWAs and QD-sensitized TiO 2 NWAs films under back side illumination. In addition, under back side illumination the built-in electric field and band structure of CdS/CdSe QDs and anatase TiO 2 NWAs lead to the separation and transfer of the photoexcited charge for CdS/CdSe QDs sensitized TiO 2 NWAs/FTO film. As the intensity of illumination increases, the effect of built-in electric field on the separation and transfer of the photoexcited charge in the QD-sensitized TiO 2 NWAs film decreases. [ABSTRACT FROM AUTHOR]