High‐Efficiency Sn‐Pb Perovskite Solar Cells via Nucleation and Crystallization Control

The rapid crystallization of mixed tin‐lead (Sn‐Pb) perovskites and their dependence on antisolvent processes limit the development of large‐area Sn‐Pb perovskite solar cells (PSCs). Vacuum‐flash‐assisted solution processing (VASP) has emerged as a promising technique for large‐scale fabrication. However, achieving consistent control over crystallization parameters remains a limitation. To address this, a pumping rate‐controllable strategy is introduced, fitted from cavity pressure and time, to control nucleation and crystallization in Sn‐Pb perovskite films. By tuning the pressure rate, the solvent volatilization rate of the perovskite wet film is optimized, enabling controlled nucleation and crystallization dynamics. This allows for the scalable fabrication of high‐quality FA 0.7 MA 0.3 Pb 0.5 Sn 0.5 I 3 films without additives to aid crystallization, achieving power conversion efficiencies (PCEs) exceeding 21% and 19% for Sn‐Pb PSCs at 0.08 cm 2 and 1 cm 2 , respectively, the additives‐free and antisolvent‐free highest records. This further demonstrates that the uniformity and reproducibility of pumping rate control on a large 6 × 6 cm 2 substrate. The approach is also applicable to wide bandgap PSCs, normal bandgap PSCs, and all‐perovskite tandem solar cells, delivering a PCE >27% for the antisolvent‐free and additive‐free tandem device. This work establishes a scalable and versatile approach for developing large‐area Sn‐Pb and all‐perovskite tandem devices, advancing the field toward practical applications.