Ke Zhao, Libing Yao, Caner Değer, Xu Zhang, Jiahui Shen, Xiaohe Miao, Pengju Shi, Yixin Luo, Donger Jin, Yuan Tian, Jiazhe Xu, Shaochen Zhang, Qingqing Liu, Shenglong Chu, Xiaonan Wang, Liuwen Tian, İlhan Yavuz, Jingjing Xue, Rui Wang
Perovskite solar cells (PSCs) based on formamidinium lead iodide (FAPbI₃) demonstrate near-ideal bandgaps approaching the Shockley-Queisser efficiency limit, yet residual MA⁺ from methylammonium chloride (MACl) additives compromises their operational stability under thermal/light stress. Therefore, we developed an α-phase-assisted antisolvent method employing MACl-free precursors to fabricate α-FAPbI3 films. These films exhibit enhanced thermal stability and structural integrity, which were comprehensively characterized using multiple techniques. The optimized devices achieved a 26.1% power conversion efficiency (PCE), ranking among one of the highest reported values for FAPbI3-based inverted PSCs, and exhibit sustained stability under accelerated aging conditions. This strategy resolves the MA⁺-induced degradation bottleneck, paving the way for commercially viable high-performance PSCs. The residual methylammonium cation from additives compromises the operational stability of formamidinium lead iodide-based solar cells under thermal/light stress. Here, authors introduce MASCN to enhance film formation in ethyl acetate antisolvent and achieve efficiency of 26.1% for stable devices.