Molecular Chelating‐Clamp Strategy Using Dithiol Antidotes Enables Efficient and Stable Inorganic Perovskite Solar Cells

ABSTRACT

The photovoltaic performance and stability of all‐inorganic perovskites are critically compromised by halide vacancy defects and concomitant ion migration, both arising from their intrinsically soft lattice and mixed ionic‐electronic character. To simultaneously address both issues, we introduce sodium 2,3‐dimercapto‐1‐propanesulfonate (DPS), a sulfonated thiol molecule that acts as a multifunctional chelating clamp. Unlike conventional monodentate passivators, DPS employs a bidentate chelation strategy: its two thiol groups coordinatively bind to undercoordinated Pb ²⁺ sites, forming a stable five‐membered ring. The flexible three‐carbon linker enables conformational adaptation to heterogeneous grain‐boundary microenvironments, while the sulfonate group provides electrostatic anchoring and spatial orientation, guiding the thiol moieties toward targeted defect sites. Moreover, DPS retards the crystallization kinetics during film annealing, resulting in enlarged grains, reduced residual strain, and enhanced film homogeneity. This synergistic integration of molecular adaptability, chelate‐based defect passivation, and crystallization regulation yields CsPbI _3‐x Br _x perovskite films with lower trap density, prolonged carrier lifetime, and favorable energy alignment. Consequently, solar cells incorporating DPS achieve a champion power conversion efficiency of 22.28%, among the highest for all‐inorganic perovskite devices, alongside substantially enhanced operational and environmental stability. The strategy underscores the potential of tailored molecular design for enabling efficient and stable perovskite photovoltaics with straightforward processability.