Ruixuan Jiang, Yikai Yun, Kexuan Sun, Xinyue Cui, Qi Zhang, C HU, Chengkai Jin, Qiumin Kong, Yuqiang Liu, Junbo Gong, Sisi He, Longbin Qiu, Chang Liu, Sai Bai, C. Li, Zhishan Bo, Fuzhi Huang, Yi‐Bing Cheng, Tongle Bu
Wide-bandgap (WBG) perovskites with bandgaps exceeding 1.8 eV are suitable for perovskite/organic or multi-junction tandem solar cell (TSC) applications. However, their complex components easily induce hardly controlled phase heterogeneity and defects during the crystallization process. Herein, we propose a multifunctional additive, DL-methionine methylsulfonium chloride, with a unique combination of functional groups to regulate the crystallization thermodynamics and passivate defects of WBG perovskites. Our comprehensive experimental and computational results reveal that the additive synergistically promotes the nucleation kinetics and improves phase homogeneity during the crystallization process, thereby achieving uniform and low-defect perovskite films, significantly suppressing the non-radiative recombination and phase segregation. Consequently, the single-junction 1.83 eV-WBG perovskite solar cells demonstrate a champion power conversion efficiency (PCE) of 20.4% and notably enhanced operational stability. Furthermore, impressive PCEs of 26.0% and 22.1% are achieved for rigid and flexible perovskite/organic TSCs, respectively, showing great promise for pursuing flexible tandem applications. Defect formation and phase instability remain critical challenges for perovskite/organic tandem solar cells. Jiang et al. address this by designing an additive to modulate the crystallization thermodynamics of wide-bandgap perovskite, achieving a record efficiency of 22.1% in a flexible cell.