High‐Efficiency Perovskite‐Organic Tandem Solar Cells Enabled by Perovskite Crystallization Optimization and Metal‐Free Interconnecting Layer

Perovskite‐organic tandem solar cells (PO‐TSCs) offer a promising route toward high‐efficiency and cost‐effective photovoltaics by combining wide‐bandgap (WBG) perovskite solar cells (PSCs) with narrow‐bandgap organic solar cells. Nevertheless, achieving high‐performance PO‐TSCs still faces key challenges: open‐circuit voltage ( V OC ) loss in the WBG perovskite sub‐cell and optoelectrical loss at the interconnecting layer (ICL). Here, we incorporate 4‐nitrophenethylamine hydrochloride (4N‐PEACl), a functional additive bearing a strong electron‐withdrawing group (‐NO 2 ), into the WBG perovskite precursor solution to modulate crystallization kinetics and passivate bulk defects. This additive significantly improves crystallinity and phase stability, suppresses non‐radiative recombination and enhances charge extraction and transport. Consequently, the optimized 1.85 eV WBG single‐junction PSC achieves a champion efficiency of 19.79%, with V OC increasing from 1.349 to 1.388 V. Furthermore, the optimal PO‐TSC achieves an efficiency of 27.10% with an ICL of PCBM/AZO/SnO 2 /PEDOT:PSS/Ph‐4PACz. This work highlights the efficacy of ‐NO 2 ‐functionalized molecules in improving WBG perovskite film quality and provides new design strategy for low‐cost but effective ICLs in PO‐TSCs.