Cation Engineering for Effective Defect Passivation to Improve Efficiency and Stability of FA0.5MA0.5PbI3Perovskite Solar Cells

Large organic cations have been widely employed to passivate defects in perovskite solar cells (PSCs). In this research, we study how double ions influence PSC developments. Four additives, namely, BAI, BACl, PEAI, and PEACl, were introduced into the precursor solution during the hybrid PSC preparation, and it is found that they not only improve the crystallization of the perovskite films but also passivate the surface and grain boundary defects, leading to improved PSC performance. BACl is found to be the best among this group of additives, giving the highest solar cell efficiency and the best stability. This work provides insights and guidelines as to how amine additives influence perovskite film formation as well as device performance, which is badly needed for PSC advancement.