Mixed-halide alloying inorganic perovskite CsPbI₂Br with prominent thermal stability has been considered as a promising candidate for wide-bandgap solar cells. However, the thermally driving coordination configuration evolution and phase transition during the crystallization of the perovskite CsPbI₂Br were still not understood in depth, which was not conducive to the controllable preparation of high-quality CsPbI₂Br thin films and the enhancement of photovoltaic performance. In this study, the phase segregation and unfavorable phase transition during the crystallization of CsPbI₂Br that lead to the low quality of the perovskite thin films were investigated systematically. Moreover, the existing issue was overcome through intermediate engineering by introducing volatile organic amine acetates. Specially, the introduction of 0.5 equiv. of formamidine acetate (FAAc) in the precursor of CsPbI₂Br generated a phase-pure intermediate, which facilitated the crystallization of high-quality CsPbI₂Br perovskite thin films, and thus improved the device performance. As a result, the champion device achieved a power conversion efficiency (PCE) of 16.36%.

具有突出热稳定性的混合卤化物合金无机钙钛矿 CsPbI ₂ Br 被认为是宽带隙太阳能电池的有前途的候选者。然而，钙钛矿CsPbI ₂ Br结晶过程中的热驱动配位构型演变和相变仍未深入了解，不利于高质量CsPbI ₂ Br薄膜的可控制备和光伏性能的提升. 在这项研究中，CsPbI _{2结晶过程中的相分离和不利的相变}系统地研究了导致钙钛矿薄膜质量低下的 Br。此外，通过引入挥发性有机胺乙酸盐通过中间工程克服了现有问题。特别是，引入 0.5 当量。CsPbI ₂ Br 前驱体中乙酸甲脒 (FAAc) 生成相纯的中间体，促进了高质量 CsPbI ₂ Br 钙钛矿薄膜的结晶，从而提高了器件性能。结果，冠军设备实现了 16.36% 的功率转换效率 (PCE)。