Pseudo-halide anion formate (HCOO⁻) in halide perovskite has been widely employed to improve film quality without altering the band gap. However, there is a lack of understanding regarding the effect on perovskite films depending on the chemical bonding state of formate. Herein, we demonstrated the distinguishable crystallization behavior of FAPbI₃ film by comparing the formate salts with different bonding states. Furthermore, we found that distinct passivation mechanisms depended on the cations of formate salts, which resulted in the differences in device performance. Notably, sodium-based formate exhibited simultaneous bi-directional behavior of cation and anion, distinguishing it from other formate salts. Consequently, the device exhibited an enhanced power conversion efficiency (PCE) of 25.6% with a significantly high open-circuit voltage (V_oc) of 1.18 V. This work provides insights into the effect on the chemical bonding state of formate, as well as different passivation mechanisms depending on the cations of formate salts.

中文翻译：

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设计了钙钛矿太阳能电池的双向阳离子/阴离子界面分布


卤化物钙钛矿中的伪卤化物甲酸阴离子 （HCOO⁻） 已被广泛用于在不改变带隙的情况下提高薄膜质量。然而，对于取决于甲酸盐的化学键合状态对钙钛矿薄膜的影响，目前还缺乏了解。在此，我们通过比较不同键合态的甲酸盐证明了 FAPbI₃ 膜的可区分结晶行为。此外，我们发现不同的钝化机制取决于甲酸盐的阳离子，这导致了器件性能的差异。值得注意的是，钠基甲酸盐表现出阳离子和阴离子的同时双向行为，将其与其他甲酸盐区分开来。因此，该器件表现出 25.6% 的增强功率转换效率 （PCE） 和 1.18 V 的明显高开路电压 （V_oc）。这项工作深入了解了对甲酸盐化学键合状态的影响，以及取决于甲酸盐阳离子的不同钝化机制。