All-inorganic perovskites are emerging as excellent photovoltaic candidates for single-junction or tandem solar cells. However, large energy loss due to non-radiative recombination is the main constraint for performance enhancement. Accordingly, we developed a surface in situ reconstruction (SISR) strategy for inorganic perovskite by CsF treatment, which can suppress non-radiative recombination and promote hole extraction simultaneously. Surface defects can be effectively passivated by the introduced fluorine, and carrier lifetime was prolonged from 11.5 ns to 737.2 ns. In addition, a wider-bandgap perovskite layer can be generated as a graded heterojunction to facilitate hole extraction. The SISR reaction mechanism was also verified from both kinetic calculations and experiments. As a result, CsPbI_xBr_3−x solar cell with SISR achieved an efficiency of 21.02% with a high open-circuit voltage of 1.27 V and fill factor of 85.3%. This work provides an effective approach to modulate inorganic perovskite surfaces for the design of efficient solar cells.

全无机钙钛矿正在成为单结或串联太阳能电池的优秀光伏候选材料。然而，非辐射复合导致的大量能量损失是性能提升的主要制约因素。因此，我们开发了一种通过 CsF 处理的无机钙钛矿表面原位重建 (SISR) 策略，该策略可以抑制非辐射复合并同时促进空穴提取。引入的氟可以有效钝化表面缺陷，载流子寿命从11.5 ns延长至737.2 ns。此外，可以生成更宽带隙的钙钛矿层作为渐变异质结，以促进空穴提取。SISR反应机理也得到了动力学计算和实验的验证。因此，CsPbI _x Br_{具有 SISR 的3− x}太阳能电池实现了 21.02% 的效率，具有 1.27 V 的高开路电压和 85.3% 的填充因子。这项工作为调制无机钙钛矿表面以设计高效太阳能电池提供了一种有效的方法。