Development of inorganic metal halide perovskites solar cells (PSCs) has been hampered by the inherent phase instability of inorganic perovskites. Herein, an ionic liquid of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF₄) is proposed to stabilize the CsPbI₂Br phase and reduce the surface defect density. From experimental analyzes and density functional theory calculations, the BMIMBF₄ interlayer could reduce the energy loss and stabilize the cubic -phase of CsPbI₂Br. The interaction between BMIMBF₄ and CsPbI₂Br could improve the perovskite film quality and the interfacial charge transport. Accordingly, the BMIMBF₄-modified device enables a 37.18% and 18.89% improvement in the power conversion efficiency and open-circuit voltage compared to the control CsPbI₂Br device, along with an 86.9% retaining of its initial performance over 1000 h storage in N₂ atmosphere, while the control device drops to zero in 200 h. The work provides a novel cogitation for the defect passivation and energy loss reduction to improve both the stability and efficiency of inorganic perovskite solar cells.

无机金属卤化物钙钛矿太阳能电池（PSC）的开发已被无机钙钛矿的固有相不稳定性所阻碍。此处，提出了一种四氟硼酸1-丁基-3-甲基咪唑鎓盐（BMIMBF ₄）的离子液体，以稳定CsPbI ₂ Br相并降低表面缺陷密度。通过实验分析和密度泛函理论计算，BMIMBF ₄中间层可以减少能量损失并稳定CsPbI ₂ Br的立方相。BMIMBF ₄和CsPbI ₂ Br之间的相互作用可以改善钙钛矿薄膜的质量和界面电荷传输。因此，BMIMBF ₄改进的器件与CsPbI ₂ Br对照器件相比，能够在功率转换效率和开路电压方面分别提高37.18％和18.89％，并且在N ₂气氛中存储1000 h时仍能保持86.9％的初始性能，而控制设备在200小时内降至零。这项工作为缺陷钝化和减少能量损失提供了新的思路，以提高无机钙钛矿太阳能电池的稳定性和效率。