A novel sulfur source for biosynthesis of (Ag, S)-modified TiO2 photoanodes in DSSC

• (Ag, S)-modified TiO2 photoanodes were prepared using natural garlic as a sulfur source.
• Modification widened light absorption in UV–vis light and promoted electron transport.
• Modification can improve the efficiency of the DSSC.

The (Ag, S)-modified TiO2 photoanodes were prepared using novel garlic (Allium sativum) as a sulfur source. X-ray photoelectron spectroscopy (XPS) confirmed more sulfur adsorption and the modification of TiO2 by interactions between Ag and S. UV–vis spectral analysis and Electrochemical Impedance Spectroscopy (EIS) measurements showed that (Ag, S)-modified TiO2 photoanodes exhibited a strongly enhanced absorption in the UV–vis region and a clear reduction in charge transport resistance, indicating a higher light-harvesting capacity and more efficient charge transport. Therefore, the photoelectric conversion efficiency of dye-sensitized solar cells (DSSCs) was improved. At the optimal Ag loading of 0.5 wt%, (Ag, S)-modified DSSC gave the best performance.