Effect of precipitating agent NaOH on the synthesis of SrTiO3/TiO2 heterostructure for dye-sensitized solar cells

In this work, the effect of precipitating agent NaOH on the growth of SrTiO3 blocking layer to serve as the charge recombination barrier for DSSC based TiO2 were investigated. The SrTiO3/TiO2 heterostructure was synthesized by the hydrothermal method. The structure and surface morphology of SrTiO3/TiO2 heterostructure were carried out by SEM, TEM and XRD characterization techniques. The optical band gap of TiO2 NR and SrTiO3/TiO2 heterostructure were studied by the UV–visible spectrophotometer. The estimated band gap of TiO2 nanorod and SrTiO3/TiO2 heterostructure were typically 3.0–3.1 eV. At the best condition for fabrication (0.001 M NaOH), the SrTiO3/TiO2 heterostructure photoanode achieves the highest photo-conversion efficiency of 2.68%, which is 38% higher than the bare TiO2 nanorod photoanode (1.93%). By further analysis with the EIS, the results reveals that the added SrTiO3 blocking layer is enhanced the DSSCs performance by prolonging the charge recombination and also improve the charge transfer resistance in the photoanode.