Enhancing the Performance of Perovskite Solar Cells by 4‐Chloro‐1,8‐Naphthalic Anhydride for Surface Passivation

Abstract On the surface and grain boundary of perovskite films there are large quantities defects, which leads to photogenerated carrier nonradiative recombination and degrades the performance of the perovskite solar cells (PSCs). Surface passivation can suppress the detrimental effects of defect and improve the performance of PSCs. Here, an organic molecule, 4‐chloro‐1,8‐naphthalic anhydride (ALS), is adopted to passivate the defects on the surface and grain boundary of (FAPbI₃)_0.95(MAPbBr₃)_0.05 perovskite films. The oxygen of carbonyl group in the ALS provides lone pair electron to the undercoordinated Pb²⁺ and passivated this defect. The ALS passivated perovskite films have lower trap state density and longer carrier lifetime. As a result, the photoelectric conversion efficiency (PCE) of the PSCs was improved from 21.52% to 23.72%. Furthermore, the ALS passivated PSC show good stability, and it could maintain 88% of its initial efficiency after 1200 h storage in ambient atmosphere without encapsulation.