Suppressing the Oxygen/Moisture Effect with 9‐Fluorenylmethyl Carbazate to Facilitate Ambient‐Fabrication of Stable Perovskite Solar Cells

ABSTRACT The fabrication of perovskite solar cells (PSCs) in ambient air offers a promising route to reduce production cost for up‐scaling. However, the oxygen/moisture effects always compromise the efficiency and stability of PSCs. To address this, we introduced 9‐fluorenylmethyl carbazate (9FC) molecule in lead iodide (PbI 2 ) precursor to suppress the oxygen/moisture effect and facilitate ambient‐fabrication. Featured with functional groups‐carbonyl (C═O) and hydrazino (─NHNH 2 ), 9FC forms multidentate chelation bonds with perovskite components and slows down crystallization kinetics. Thus, the perovskite film has larger grain size, preferred crystal orientation, and reduced defect density. Quartz crystal microbalance (QCM) measurements indicate that the 9FC‐doped perovskite film exhibits improved humidity tolerance under humid conditions. Moreover, the ─NHNH 2 moiety of 9FC suppresses the oxidation process of I − to I 2 . As a result, the 9FC‐doped PSCs achieved power conversion efficiency of 24.83%. Furthermore, the enhanced hydrophobicity of the 9FC‐doped perovskite surface enabled the unencapsulated 9FC‐doped PSCs retained 78% after 2280 h in ambient air with 20%–40% relative humidity, which is significantly higher than the 57% retention observed in control PSCs.