The practical applications of perovskite solar cells (PSCs) are limited by further improvement of their stability and performance. Additive engineering and interface engineering are promising medicine to cure this stubborn disease. Herein, an alkali metal fluoride as an additive is introduced into the tin oxide (SnO₂) electron transport layer (ETL). The formation of coordination bonds of F^– ions with the oxygen vacancy of Sn⁴⁺ ions decreases the trap-state density and improves the electron mobility; the hydrogen bond interaction between the F ion and amine group (FA⁺) of perovskite inhibits the diffusion of organic cations and promotes perovskite (PVK) stability. Meanwhile, the alkali metal ions (K⁺, Rb⁺, and Cs⁺) permeated into PVK fill the organic cation vacancies and ameliorate the crystal quality of PVK films. Consequently, a SnO₂-based planar PSC exhibits a power conversion efficiency (PCE) of 20.24%, while the PSC modified by CsF achieves a PCE of 22.51%, accompanied by effective enhancement of stability and negligible hysteresis. The research results provide a typical example for low-cost and multifunctional additives in high-performance PSCs.

中文翻译：

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用于 n-i-p 平面钙钛矿太阳能电池的碱金属氟化物改性氧化锡

钙钛矿太阳能电池（PSC）的实际应用受到稳定性和性能进一步提高的限制。增材工程和界面工程是治愈这种顽固疾病的有前途的药物。在此，将碱金属氟化物作为添加剂引入氧化锡(SnO ₂ )电子传输层(ETL)。F ^-离子与Sn ⁴⁺离子的氧空位形成配位键，降低了陷阱态密度，提高了电子迁移率；F离子与钙钛矿的胺基（FA ⁺）之间的氢键相互作用抑制了有机阳离子的扩散并促进了钙钛矿（PVK）的稳定性。同时，碱金属离子（K ⁺、Rb⁺ , 和 Cs ⁺ ) 渗透到 PVK 中，填补了有机阳离子空位，改善了 PVK 薄膜的晶体质量。因此，基于 SnO ₂的平面 PSC 表现出 20.24% 的功率转换效率 (PCE)，而由 CsF 改性的 PSC 实现了 22.51% 的 PCE，同时有效增强了稳定性和可忽略的滞后。研究结果为高性能 PSC 中的低成本和多功能添加剂提供了典型示例。