Correlation between Photophysical and Structural-Properties in Guanidinium-Iodide Treated Perovskite Solar Cells

The thesis investigates the impact of a Guanidinium iodide (GAI) surface treatment on the structural and photophysical properties of triple-cation CsMAFA perovskite films. The results suggest that a low-concentration treatment with GAI enhances the CsMAFA perovskite crystallinity, homogenizes the PL intensity, and improves the device performance. While, on the other hand, excess GAI yields low degree of crystallization leading to poor device performance. The results show that controlling the concentration of surface treatment agents is important for the homogenization of perovskite optoelectronic properties and hence eliminating performance losses and instabilities.