Observing Defect Passivation of the Grain Boundary with 2‐Aminoterephthalic Acid for Efficient and Stable Perovskite Solar Cells

Abstract Metal halide perovskite solar cells (PSCs), with their exceptional properties, show promise as photoelectric converters. However, defects in the perovskite layer, particularly at the grain boundaries (GBs), seriously restrict the performance and stability of PSCs. Now, a simple post‐treatment procedure involves applying 2‐aminoterephthalic acid to the perovskite to produce efficient and stable PSCs. By optimizing the post‐treatment conditions, we created a device that achieved a remarkable power conversion efficiency (PCE) of 21.09 % and demonstrated improved stability. This improvement was attributed to the fact that the 2‐aminoterephthalic acid acted as a cross‐linking agent that inhibited the migration of ions and passivated the trap states at GBs. These findings provide a potential strategy for designing efficient and stable PSCs regarding the aspects of defect passivation and crystal growth.