A Bimolecular Co‐Anchoring Strategy for Constructing Hydrogen Networks to Stabilize Perovskite Solar Cells

ABSTRACT Recent advances in formamidinium lead triiodide (FAPbI 3 ) solar cells have significantly improved their photoelectric conversion efficiency, positioning them as a leading candidate in third‐generation photovoltaics. However, their thermodynamic metastability—driven by phase transitions from photoactive α‐FAPbI 3 to inactive δ‐FAPbI 3 —causes efficiency decay, hindering long‐term stability and industrialization. This study introduces a bimolecular synergistic anchoring strategy to address these challenges: a multiscale molecular interlocking network is constructed using 4‐[3‐(trifluoromethyl)‐3H‐diazirin‐3‐yl]benzoic acid (HDA) and 2‐benzamidinyl‐5‐guanidinopentanoic acid (GS). HDA stabilizes formamidinium iodide (FAI) via carbene reactions, suppressing FA⁺ thermal escape, while GS binds under‐coordinated Pb 2 ⁺ through its high dipole moment, minimizing lead leakage. Leveraging structural homology, these dual passivators synergistically stabilize A‐site (FA⁺) and B‐site (Pb 2 ⁺) ions, forming a hydrogen‐bond network that optimizes crystal growth and enhances α‐FAPbI 3 phase stability and photothermal resilience. Perovskite solar cells (PSCs) optimized with HDA‐GS achieve a record power conversion efficiency of 26.07%, along with exceptional operational stability: unencapsulated devices retain 95% of initial efficiency after 1300 h at 85°C under nitrogen (thermal stability) and 91% after 1500 h of continuous light exposure (light stability). This work demonstrates that a multi‐scale molecular interlocking network effectively overcomes perovskite inherent instability, offering a scalable pathway to high‐performance, durable PSCs.