Ligand-Mediated Kinetic Control in Coprecipitation: Toward High-Performance Sb3+-Doped Cs2ZrCl6 for Single-Component White LEDs

Vacancy-ordered double perovskites have emerged as promising candidates for single-component white light-emitting diodes (WLEDs) owing to their intrinsic broadband emission, dopant-induced color tunability, and stable optoelectronic properties. However, their practical application is limited by the difficulty of obtaining high-quality crystals, as the typically rapid and poorly controlled crystallization processes tend to induce lattice disorder and defect formation. In this work, we report a 4-mercaptobenzoic acid (4MBA)-assisted coprecipitation strategy to synthesize high-quality 3%Sb 3+ -doped Cs 2 ZrCl 6 (CZC:3%Sb (4MBA)) microcrystals (MCs). Despite its non-coordinating nature with the crystal surface, 4MBA functions as an effective kinetic regulator that retards crystallization and enhances growth control, thereby suppressing lattice disorder and defect formation to improve crystal quality. As a result, the optimized CZC:3%Sb (4MBA) MCs achieve a photoluminescence quantum yield (PLQY) of 88%, twice that of the unmodified MCs, while concurrently ensuring excellent ambient and thermal stability. Fabricated WLEDs based on CZC:3%Sb (4MBA) MCs exhibit warm white emission with a high color rendering index (CRI) of 94 and maintain stable operation over 14 h. This work presents an effective strategy for regulating crystal growth to enhance the optical performance of lead-free vacancy-ordered double perovskites, paving the way for high-performance, single-component WLEDs.