Chemical Passivation and Crystallization Kinetics Regulation for Enhancing Efficiency and Stability of Inverted Perovskite Solar Cells

ABSTRACT The performance and stability of perovskite solar cells (PSCs) are primarily dictated by the quality of the perovskite films. Additive engineering is a promising strategy for enhancing the performance of perovskite solar cells. However, further investigation on the mechanism during additives‐precursor interaction, as well as the effectiveness in enhancing device stability through additive engineering remain key challenges. Herein, we introduce a new multifunctional organic small molecule, 4‐(Methylsulfonyl)benzene‐carboximidamide hydrochloride (MSB), into the perovskite precursor solution. The sulfonyl with its strong electron‐withdrawing nature and the amidinium group with its high number of hydrogen atoms in MSB molecules can interact with perovskite precursor components to delay the crystallization process of the perovskite film. Meanwhile, the sulfonyl group serves as a Lewis base to interact with Pb ²⁺ , whereas the amidinium group exhibits greater resistance to deprotonation than the ammonium group, thereby achieving a multi‐site, long‐term passivation effect within the perovskite films. The optimized crystallization process and effective passivation thus lead to the released internal strain, suppressed defect density, and enlarged grain size. Benefiting from these synergies, the MSB‐based PSCs achieved a champion PCE of 25.17% with over 1000 h T90 operational stability in addition to enhanced thermal and humidity stability.