The buried interface defects severely affect the further enhancements of efficiency and stability of SnO₂-based planar perovskite solar cells (PSCs). To well tackle this problem, we propose a passivation strategy employing NH₄PF₆ to modify the buried interface of perovskite layer ((FAPbI₃)_0.85(MAPbBr₃)_0.15 composition) in planar PSCs. After introducing NH₄PF₆, the oxygen defects on the surface of SnO₂ film are greatly restricted due to the coordinate interaction between fluorine atoms (F) in PF₆⁻ and undercoordinated Sn⁴⁺. Meanwhile, the hydrogen bonding interaction (N–H⋯I) between NH₄PF₆ and PbI₂ can passivate the non-radiative charge recombination sites, significantly optimizing the quality of perovskite film, as well as the charge transfer process at the SnO₂/perovskite interface. As a result, the NH₄PF₆-modified 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 cm² achieves a PCE as high as 17.38%. Furthermore, the unencapsulated NH₄PF₆-modified PSCs show good humidity stability and retain about 80% of the initial PCE after 1080 h aging at the relative humidity (RH) of 35% ± 5%.

Graphical abstract

中文翻译：

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NH4PF6辅助埋入界面缺陷钝化平面钙钛矿太阳能电池效率超过21%

掩埋界面缺陷严重影响SnO ₂基平面钙钛矿太阳能电池（PSC）效率和稳定性的进一步提高。为了很好地解决这个问题，我们提出了一种钝化策略，采用NH ₄ PF ₆来修改平面PSC中钙钛矿层（(FAPbI ₃ ) _0.85 (MAPbBr ₃ ) _{0.15成分）的埋入界面。}引入NH ₄ PF ₆后，由于PF ₆ ^-中的氟原子(F)与欠配位的Sn ^{4+之间的配位相互作用，SnO} ₂薄膜表面的氧缺陷得到了极大的限制。。_{同时，NH 4} PF ₆和PbI ₂之间的氢键相互作用（N–H⋯I）可以钝化非辐射电荷复合位点，显着优化钙钛矿薄膜的质量以及SnO 2 上的电荷转移过程_。 /钙钛矿界面。结果，NH ₄ PF ₆修饰的PSC获得了优于参考器件（18.46％）的21.11％的冠军功率转换效率（PCE），并且有源面积为1 cm ²的器件实现了与参考器件一样高的PCE。为 17.38%。此外，未封装的NH ₄ PF ₆改性PSC表现出良好的湿度稳定性，在35%±5%的相对湿度（RH）下老化1080小时后，保留了约80%的初始PCE。

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