Surface optimization by poly(α-methylstyrene) as additive in the antisolution to enhance lead-free Sn-based perovskite solar cells

摘要： Surface quality of the perovskite layer plays an important role in the determination of the device performance. This study presents an e?ective method to optimize the surface morphology for the lead-free formamidinium tin iodide (FASnI3) perovskite solar cells. Poly(α-methylstyrene) (PAMS) was applied as polymer additive into the diethyl ether at di?erent blend concentration. The addition of PAMS can apparently reduce the pinholes at the surface of the FASnI3 ?lm without ruining the interior crystallinity of the bulk FASnI3 layer. Therefore the non-radiative carrier traps can be e?ectively suppressed. The surface of the FAsnI3 ?lm becomes more hydrophobic which facilitates the consequent spin-coating of the acceptor material solution. The modi?cation of FASnI3 ?lm’s wettability is favorable of the photo-induced carriers’ extraction and transportation. As a result, the power conversion e?ciency of the PAMS-modi?ed devices is greatly improved.