NH_(4)PF_6 assisted buried interface defect passivation for planar perovskite solar cells with efficiency exceeding 21

摘要

The buried interface defects severely affect the further enhancements of efficiency and stability of SnO_(2)-based planar perovskite solar cells(PSCs).To well tackle this problem,we propose a passivation strategy employing NH_(4)PF_6 to modify the buried interface of perovskite layer((FAPbI_(3))_(0.85)(MAPbBr_(3))_(0.15) composition) in planar PSCs.After introducing NH_(4)PF_6,the oxygen defects on the surface of SnO_(2) film are greatly restricted due to the coordinate interaction between fluorine atoms(F) in PF_6~-and undercoordinated Sn^(4+).Meanwhile,the hydrogen bonding interaction(N-H…I) between NH_(4)PF_6 and PbI_(2) can passivate the non-radiative charge recombination sites,significantly optimizing the quality of perovskite film,as well as the charge transfer process at the SnO_(2)/perovskite interface.As a result,the NH_(4)PF_(6-mo)dified PSC obtains a champion power conversion efficiency(PCE) of 21.11%superior to the reference device(18.46%),and the device with an active area of 1 cm~2 achieves a PCE as high as17.38%.Furthermore,the unencapsulated NH_(4)PF_6-modified PSCs show good humidity stability and retain about80% of the initial PCE after 1080 h aging at the relative humidity(RH) of 35% ± 5%.