The fabrication of perovskite solar cells (PSCs) in ambient air can accelerate their industrialization. However, moisture induces severe decomposition of the perovskite layer, limiting the device efficiency. Here we show that sites near vacancy defects absorb water molecules and trigger the hydration of the perovskite, eventually leading to the degradation of the material. We demonstrate that guanabenz acetate salt eliminates both cation and anion vacancies, blocking the perovskite hydration and allowing the crystallization of a high-quality film in ambient air. With guanabenz acetate salt, we prepare PSCs in ambient air with a certified efficiency of 25.08%. The PSCs without encapsulation maintain around 96% of their initial efficiency after 2,000 hours of ageing in ambient air and after 500 hours of operating at the maximum power point under simulated air mass (AM) 1.5 G solar light in a N₂ atmosphere. The encapsulated devices retained 85% of their initial efficiency after 300 hours under damp heat conditions (85 °C and 85% relative humidity).

在环境空气中制造钙钛矿太阳能电池（PSC）可以加速其工业化。然而，水分会引起钙钛矿层的严重分解，限制了器件的效率。在这里，我们发现空位缺陷附近的位点吸收水分子并引发钙钛矿的水合作用，最终导致材料的降解。我们证明，胍苯乙酸盐可以消除阳离子和阴离子空位，阻止钙钛矿水合作用，并允许在环境空气中结晶出高质量的薄膜。我们使用胍那醋酸盐在环境空气中制备 PSC，经认证效率为 25.08%。没有封装的 PSC 在 2 年后仍保持其初始效率的 96% 左右，_2个气氛。在湿热条件（85°C 和 85% 相对湿度）下 300 小时后，封装器件仍保持其初始效率的 85%。