Effects of Post-Synthesis Treatments on the Optical Properties of SnO₂Aerogel

This study investigates the effects of post-synthesis annealing and peroxide treatment on the optical properties of semiconducting tin oxide (SnO₂) aerogel synthesized using an epoxide-assisted technique. Characterization using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and UV-Visible spectroscopy revealed that while bulk SnO₂ exhibits an optical bandgap of around 3.6 eV, SnO₂ aerogel displays a larger apparent bandgap of approximately 4.6 eV, attributed to defects occupying the bottom of the conduction band. To minimize these defects, we explored the effects of annealing in ambient environments and the use of hydrogen peroxide (H₂O₂) as a surface treatment. Our results demonstrate that annealing induces a partial phase change from SnO₂ to SnO but it is ineffective in removing defects. Conversely, peroxide surface treatment significantly improves the optical characteristics by passivating dangling bonds. These findings offer valuable insights for optimizing the optical properties of SnO₂ for applications such as solar cells.