摘要
Formamidinium(FA)-based Sn-Pb perovskite solar cells(FAPb_(0.5)Sn_(0.5)I_(3) PSCs)with ideal bandgap and impressive thermal stability have caught enormous attention recently.However,it still suffers from the challenge of realizing high efficiency due to the surface imperfections of the transport materials and the energy-level mismatch between functional contacts.Herein,it is demonstrated that the modification on buried interface with alkali metal salts is a viable strategy to alleviate these issues.We systematically investigate the role of three alkali metal bromide salts(NaBr,KBr,CsBr)by burying them between the NiOx hole transport layer(HTL)and the perovskite light-absorbing layer,which can effectively passivate interface defects,improve energy-level matching and release the internal residual strain in perovskite layers.The device with CsBr buffer layer exhibits the best power conversion efficiency(PCE)approaching 20%,which is one of the highest efficiencies for FA-based Sn-Pb PSCs employing NiO_(x) HTLs.Impressively,the long-term storage stability of the unencapsulated device is also greatly boosted.Our work provides an efficient strategy to prepare desired FA-based ideal-bandgap Sn-Pb PSCs which could be applied in tandem solar cells.
基金
support from the National Natural Science Foundation of China(No.61974106)
the Core Facility of Wuhan University。
