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

Recent advances in formamidinium lead triiodide (FAPbI₃) 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-FAPbI₃ to inactive δ-FAPbI₃—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 Pb²⁺ through its high dipole moment, minimizing lead leakage. Leveraging structural homology, these dual passivators synergistically stabilize A-site (FA⁺) and B-site (Pb²⁺) ions, forming a hydrogen-bond network that optimizes crystal growth and enhances α-FAPbI₃ 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. © 2026 Wiley-VCH GmbH.