Lock FA/MA Cations by Constructing Multiple Hydrogen Bonds for Efficient and Stable 2D/3D Perovskite Solar Cells

Abstract The inevitable ion migration in organic–inorganic hybrid perovskites can trigger their own chemical reactions and photolysis, posing significant challenges to the operational stability of perovskite solar cells. This is particularly evident in the case of organic cations that become separated from the perovskite lattice, making them more susceptible to deprotonation and leading to material degradation. Herein, the issue of organic cations migration is aimed to address by constructing multiple hydrogen bonds in the L‐arginine (L‐Arg) 2D/3D perovskite. Theoretical calculations reveal that the introduction of L‐Arg dramatically increases the energy barrier for FA + /MA + at each migration step, effectively immobilizing FA + /MA + . Immersion experiments using isopropyl alcohol (IPA) further confirm that L‐Arg plays a convincing role in hindering the migration of FA + /MA + within the perovskite, as observed from both macroscopic and microscopic perspectives. Additionally, due to the strong interaction between L‐Arg and the perovskite, L‐Arg acts as a nucleation center, slowing down the growth rate of perovskite crystals and promoting the formation of high‐quality perovskite films. Finally, L‐Arg‐based devices achieve an impressive efficiency of 24.62% with reduced hysteresis, as well as exceptional stability in humidity and heat aging tests, attributing to the inhibited ion migration and the low‐defect, high‐quality 2D/3D perovskite film.