Synthesis of Zn-doped TiO2 microspheres with enhanced photovoltaic performance and application for dye-sensitized solar cells

Zn-doped TiO2 microspheres have been synthesized by introducing a trace amount of zinc nitrate hexahydrate to the reaction system. Scanning electron microscope (SEM), field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) have been utilized to characterize the samples. Both surface photovoltage spectroscopy (SPS) technique based on lock-in amplifier and transient photovoltage (TPV) measurement reveal that the slight doping of Zn can promote the separation of photo-generated charges as well as restrain the recombination due to the strong interface built-in electric field and the decreasing of surface trap states. The photovoltaic parameters of dye-sensitized solar cells (DSSCs) based on Zn-doped TiO2 are significantly better, compared to that of a cell based on undoped TiO2. The relation between the performance of DSSCs and their photovoltaic properties is also discussed.

► Near-monodisperse Zn-doped TiO2 microspheres have been synthesized.
► The photovoltaic properties of the samples were examined by SPS, FISPS and TPV measurements.
► Surface photovoltage results revealed Zn doping can promote charge transfer in TiO2 film electrode.