Achieving High Efficiency and Stability by Blocking Moisture‐Oxygen Permeation Paths on Perovskite Surfaces Using the Curing Agent 4‐(2‐Carboxyvinyl) Benzoic Acid

Organic–inorganic hybrid perovskite solar cells (PSCs) are ideal candidates for the new generation of photovoltaics (PV) due to their excellent physical and chemical properties. However, the active layer of perovskite may have many defects such as vacancies, interstitials, and substitutions during the solution method preparation process. The defects in films can become fast channels for moisture‐oxygen penetration, which promotes the interaction of moisture and oxygen with the defects and accelerates the degradation of PV in air, significantly limiting the efficiency and stability of PSCs. Herein, the curing agent 4‐(2‐carboxyvinyl) benzoic acid is added to the perovskite precursor solution to enhance the device stability by forming a moisture‐oxygen‐blocking barrier at the grain boundaries, at the same time, the Lewis base property of the molecule plays a key role to realize the preferred crystal orientation of perovskite films, passivate the defects and enhance the PV performance, which can significantly improve the devices efficiency. The final optimized PSCs achieve an outstanding power conversion efficiency of 20.28% and show excellent stability, with the unencapsulated device maintaining 78% of its initial efficiency after 1000 h of under ambient environment.