Multifunctional Sulfalene additive regulates crystallization dynamics toward inverted perovskite solar cells with...

The uncontrolled rapid crystallization inherent in one-step solution process for perovskite films preparation often results in poor crystalline quality and compromised stability, presenting a major obstacle to achieving high-performance perovskite solar cells (PSCs). To overcome this challenge, we propose a multifunctional additive strategy employing Sulfalene (SL), a sulfonyl-based molecule with dual π-conjugated rings, to precisely regulate crystallization dynamics and produce a high-quality crystalline perovskite film. Experimental results show that the electron-rich oxygen atoms in SL form robust coordination bonds with undercoordinated Pb²⁺, effectively modulating crystallization dynamics and extending the crystallization process. This yields perovskite films with large grain sizes and reduced internal stress, thereby suppressing non-radiative carrier recombination. In addition, the π-conjugated architecture of SL significantly optimizes energy band alignment by elevating the Fermi level and enhancing surface contact potential. Consequently, inverted PSCs incorporating SL-treated perovskite light absorbers achieve a champion power conversion efficiency (PCE) of 24.91 % (vs. 23.85 % for control), and exhibit exceptional operational stability. This work not only elucidates the dual role of π-conjugated sulfonyl additives in crystallization modulation and energy-level engineering but also provides a paradigm for designing multifunctional molecules to advance perovskite optoelectronics.