Dipolar Cation Chemically Bonded Tin Oxide and Bridged Buried Interface for Air‐Processed Operationally Stable n‐i‐p Perovskite Solar Cells

The unstable electron transport layer (ETL) and buried interface, resulting from defects and weak adhesive strength, hampers the advancement of regular (n-i-p) perovskite solar cells (PSCs). Here, multisite dipolar molecules, namely 3,5-bis(trifluoromethyl)benzamidine hydrochloride (BTBACl), are employed to manipulate and stabilize SnO2 ETL and buried interface for high-performance n-i-p PSCs. Due to its multiple active sites, BTBA+ can effectively chemically bonded SnO2 nanoparticles and passivate various defects mainly including undercoordinated Pb2+/Sn4+ and I/O vacancies, thereby suppressing agglomeration of SnO2 nanoparticles, homogenizing buried interface and reducing interface non-radiative recombination losses. Benefiting from the incorporation of two strong electron-withdrawing trifluoromethyl groups, the BTBA+ with large dipole moment enables efficient electron transfer and extraction at the buried interface. Ultimately, the BTBACl-modified n-i-p PSCs achieve a champion power conversion efficiency (PCE) of 26.20%, which is among the highest PCEs for air-processed PSCs. The significantly improved ETL and buried interface stabilities are translated into exceptional operational stability, maintaining 90.2% of its initial PCE after maximum power point tracking for 1000 h. This study offers a novel route to simultaneously stabilize ETL and buried interface from the perspective of functional group and dipole engineering, which promotes the development of n-i-p PSCs.