Clonidine Improves the Efficiency and Stability of Perovskite Solar Cells

Abstract Uncontrolled crystallization processes in perovskite films generate substantial defects, particularly at the top and bottom interfaces, which induce interfacial recombination and critically compromise both efficiency and long‐term stability. In this study, a multifunctional imidazole derivative, 2‐[(2,6‐dichlorophenyl)imino]imidazolidine (Clonidine) is introduced into the perovskite precursor solution. Clonidine enables dual‐interface passivation and crystallization modulation through its multi‐site functionality: the electron‐rich ─NH groups coordinate with undercoordinated Pb 2 ⁺ ions, while the electron‐deficient ─C═N moiety forms hydrogen bonds with unbound I 3 − . Concurrently, the two ─Cl substituents stabilize I 3 − ions, effectively passivating Pb─I antisite defects. This synergistic mechanism suppresses non‐radiative recombination, stabilizes the perovskite lattice, and enhances crystallinity. The dual‐interface passivation further mitigates ion migration and elevates carrier transport efficiency. Consequently, Clonidine‐modified PSCs achieve a champion power conversion efficiency (PCE) of 25.33% with an open‐circuit voltage (V OC ) of 1.16 V. Additionally, Clonidine enhances moisture resistance and device stability, retaining over 90% of the initial PCE after 1500 h of continuous illumination in ambient nitrogen.