Tailored perovskite crystallization by passivation molecule engineering for efficient light-emitting diodes

Additives are widely employed for defect passivation in perovskite light-emitting diodes (PeLEDs), yet their influence on crystallization dynamics during perovskite film formation remains unclear. Here, CsPbBr 3 films modified with sulfonic-acid-based additives are systematically investigated using in situ photoluminescence and grazing-incidence wide-/small-angle X-ray scattering techniques, revealing that additives not only passivate defects but also regulate perovskite nucleation and growth kinetics. In particular, the "- O -" bridge in hydroxylamine- O -sulfonic acid (HOS) promotes electronic redistribution, strengthening coordination with Pb 2+ and promoting uniform crystallite formation. By contrast, additives with "-C-" or "-C-C- O -" backbones exhibit weaker electronic polarization and yield larger crystallites. Consequently, perovskites treated with HOS exhibit markedly suppressed nonradiative recombination and improved device performance, with external quantum efficiency increasing from 13.9% to 23.7%. These findings establish a clear structure-property correlation between additive molecular configuration, electronic polarization, and perovskite crystallization dynamics, guiding additive design for high-efficiency PeLEDs.