Self-Driven Fate: Anion-Induced Decomposition of CsPbBr ₃ Perovskite Nanocrystals─Unusual Kinetic Dominance of Hydroxide Ions

The stability of lead halide perovskite nanocrystals remains a challenge for optoelectronic applications. In this study, we investigate the decomposition kinetics of CsPbBr 3 nanocrystals, focusing on surface charge effects. The positively charged nanocrystal surface attracts hydroxide ions, creating a localized region of elevated hydroxide concentration near the surface. Although lead ions typically form lead hydroxide under such conditions, this reaction is not observed. Instead, the high local concentration of hydroxide drives an alternative reaction pathway, highlighting the influence of surface charge-mediated ion redistribution. We also investigated the effects of sulfide, nitrate, carbonate, and sulfate ions. For these ions, the decomposition kinetics followed a trend which is inversely proportional to the solubility product of their corresponding lead compounds. Thermodynamic calculations confirm that the formation of plumbite complex is more favorable than lead hydroxide. These findings provide key insights into degradation mechanisms and suggest strategies for enhancing nanocrystal stability. Understanding this localized kinetic behavior provides important insights into degradation mechanisms and offers a basis for developing strategies to enhance the stability and performance of perovskite nanocrystals in optoelectronic applications.