Abstract Suppressing formamidinium (FA) loss and perovskite phase degradation is very crucial for achieving highly efficient and long-term stable perovskite solar cells (PSCs). Herein, we designed and synthesized a novel multifunctional additive (ZL1) to stabilize α -FAPbI 3 perovskite phase through synergistic multisite interactions: i its F atoms form F···H–N hydrogen bonds with FA + , (ii) its phenyl rings participate in cation–π interactions with FA + , (iii) the C=O and S groups coordinate Pb 2+ through Lewis acid–base interactions, and (iv) the NH groups engage I − anions through N–H···I hydrogen bonding. Consequently, ZL1 molecule can effectively suppress FA loss and optimizes perovskite crystallization kinetics, yielding high-quality and stable α -FAPbI 3 perovskite films with enlarged grain sizes and reduced defect density. Meanwhile, ZL1 treatment promotes exciton dissociation, facilitates hole extraction from the perovskite layer into the hole transport layer, and reduces charge carrier recombination in device. The ZL1-modified device achieves a power conversion efficiency of 26.13%, significantly outperforming the control device (24.20%). A similar improvement is observed in wide-bandgap PSCs, with efficiency increasing from 18.44% to 20.53% after ZL1 treatment. Notably, the unencapsulated ZL1-based devices exhibit exceptional operational stability under both illumination and thermal conditions.
Zheng et al. (2026) studied this question.