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

CsPbI₂Br-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 CsPbI₂Br 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/CsPbI₂Br/PM6/MoO₃/Ag/PFN-Br/PM6:BTP-BO-4Cl:PC₇₁BM/MoO₃ /Ag. The thickness of the CsPbI₂Br layer in the front subcell and the ratio of PM6:BTP-BO-4Cl:PC₇₁ 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 CsPbI₂Br-based n-i-p structured TSCs. Furthermore, the TSC exhibits outstanding stability under atmospheric conditions.