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Surface Reconstruction Engineering with Synergistic Effect of Mixed‐Salt Passivation Treatment toward Efficient and Stable Perovskite Solar Cells
Author(s) -
Suo Jiajia,
Yang Bowen,
Mosconi Edoardo,
Choi HyeonSeo,
Kim YeonJu,
Zakeeruddin Shaik M.,
De Angelis Filippo,
Grätzel Michael,
Kim HuiSeon,
Hagfeldt Anders
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202102902
Subject(s) - passivation , perovskite (structure) , materials science , formamidinium , iodide , halide , photovoltaics , carrier lifetime , salt (chemistry) , alkyl , inorganic chemistry , chemical engineering , nanotechnology , chemistry , organic chemistry , silicon , metallurgy , layer (electronics) , photovoltaic system , ecology , biology , engineering
Surface passivation treatment is a widely used strategy to resolve trap‐mediated nonradiative recombination toward high‐efficiency metal‐halide perovskite photovoltaics. However, a lack of passivation with mixture treatment has been investigated, as well as an in‐depth understanding of its passivation mechanism. Here, a systematic study on a mixed‐salt passivation strategy of formamidinium bromide (FABr) coupled with different F‐substituted alkyl lengths of ammonium iodide is demonstrated. It is obtained better device performance with decreasing chain length of the F‐substituted alkyl ammonium iodide in the presence of FABr. Moreover, they unraveled a synergistic passivation mechanism of the mixed‐salt treatment through surface reconstruction engineering, where FABr dominates the reformation of the perovskite surface via reacting with the excess PbI 2 . Meanwhile, ammonium iodide passivates the perovskite grain boundaries both on the surface and top perovskite bulk through penetration. This synergistic passivation engineer results in a high‐quality perovskite surface with fewer defects and suppressed ion migration, leading to a champion efficiency of 23.5% with mixed‐salt treatment. In addition, the introduction of the moisture resisted F‐substituted groups presents a more hydrophobic perovskite surface, thus enabling the decorated devices with excellent long‐term stability under a high humid atmosphere as well as operational conditions.