ABSTRACT Crystallization of halide perovskites (HP) is strongly entangled with a meticulous equilibrium in precursor states. Molecular coordination with metal ions, via chelating additives, has emerged as an effective strategy to regulate this process, yet the details of their associated chemistry are rarely explored. Here, we explore the chelation behavior of the representative ethylenediaminetetraacetic acid (EDTA) toward Pb 2+ in HP precursors and show that the deprotonation state crucially alters the coordination scenario and the subsequent crystallization pathways of HP matrices. We found that the fully deprotonated EDTA 4− achieves a more rigorous chelation with Pb 2+ than the EDTA 2− counterpart, suppressing the iodoplumbate aggregates in solution responsible for local PbI 2 heterogeneity in the films. Furthermore, EDTA 4− incorporation promotes the nucleation of defect‐free and aligned HP lattices that manifest coherent lattice growth during crystallization, attributed to the chemical reconstruction of the cluttered lattice sites that eliminate surface HP defects. As a result, the EDTA 4− incorporated HP matrices exhibit improved structural and energetic homogeneity, resulting in improved solar cell performance. Our findings provide mechanistic insight into crystallization control and highlight that tuning precursor coordination through the deprotonation state of chelating additive enables molecular‐scale regulation of precursor chemistry to drive macroscopic improvements in device performance.
Kim et al. (Wed,) studied this question.