Synergistic Optimization of n‐i‐p Structured Monolithic All‐Inorganic Perovskite/Organic Tandem Solar Cells Achieving Efficiency over 24%

Abstract CsPbI ₂ Br‐based perovskite solar cells (PSCs) garner significant attention in recent years due to their superior thermal stability compared to the organic–inorganic hybrid counterparts. Besides, with a bandgap of 1.92 eV making CsPbI ₂ Br ideal candidates for combining with organic semiconductors to construct perovskite/organic tandem solar cells (TSCs), which achieve complementary absorption and high power conversion efficiency (PCE). However, the severe voltage loss at the interconnection layer (ICL) and unbalanced current of the subcells restrict the efficiency improvement of perovskite/organic TSCs. Herein, n‐i‐p structured monolithic all‐inorganic perovskite/organic TSC is constructed with structure of ITO/Cl@MZO/CsPbI ₂ Br/PM6/MoO ₃ /Ag/PFN‐Br/PM6:BTP‐BO‐4Cl:PC ₇₁ BM/MoO ₃ /Ag. The thickness of the CsPbI ₂ Br layer in the front subcell and the ratio of PM6:BTP‐BO‐4Cl:PC ₇₁ BM in the rear subcell are optimized to simultaneously achieve higher J _sc . Instead of unstable Spiro‐OMeTAD, PM6 is employed as the hole transport material (HTM), and the ICL is fine‐tuned to ensure a high fill factor (FF) and small open‐circuit voltage ( V _oc ) loss in the TSC. As a result, a remarkable PCE of 24.10%, along with a high J _sc of 13.90 mA cm ⁻² and an FF of 80.97% are achieved, among the best performance for CsPbI ₂ Br‐based n‐i‐p structured TSCs. Furthermore, the TSC exhibits outstanding stability under atmospheric conditions.