Regulating the chain length of phenylalkylaminium iodides to passivate inorganic perovskites

Inverted inorganic perovskite solar cells (IIPSCs) have great application potential in thin-film photovoltaic fields. However, their performance is largely limited by the high trap density at the interface between perovskites and electron transport layers (ETLs). Theoretical analysis reveal that among normal phenylalkylamine passivators, phenylbutylamine (PBA) has a proper chain length to interacts the most strongly with under-coordinated lead defects on CsPbI3. Besides, PBAI is observed to form 2D-phase perovskites with n = 2 on 3D-phase CsPbI3, modifying the interface energy level arrangement to be conducive to interfacial charge transfer. After PBAI passivation, the defect concentration is greatly reduced, and the device efficiency significantly is improved from 15.05% to 18.14%, with greatly enhanced environmental stability.