Luminescence Variability of CsPbBr₃ Nanocrystals in Single-Particle Emitter Applications

Lead halide perovskite nanocrystals, particularly CsPbBr3, are promising materials for single-particle emitters due to their high quantum yield, intense luminescence, and ease of synthesis. However, challenges remain due to their inconsistencies in particle size, emission spectra, quantum yield, and stability, factors that hinder their use in single-particle emitters, as such variability can result in unpredictable optical behavior and complicate integration into reliable optoelectronic or quantum photonic systems. Here, we systematically evaluate the interbatch and intrabatch variability of nine CsPbBr3 nanocrystal batches synthesized across three independent days. Using single-particle spectroscopy, ensemble measurements, and multivariate statistical tools (principal component analysis (PCA) and permutational multivariate analysis of variance (PERMANOVA)), we show that batch-to-batch variability is significant and primarily driven by uncontrolled differences in aggregation and surface ligand coverage. Postsynthetic treatment with oleylamine increases emissive particle density and an ensemble quantum yield but does not immediately enhance the single-particle ON-time fraction (i.e., stability). Over a 30 day aging period (in dark ambient conditions), all samples, regardless of treatment, converge toward a stable nanocrystal population with a narrower size distribution, reduced spectral and blinking heterogeneity, and consistent photophysical behavior. This equilibrium state arises from the gradual elimination of small and large particles and slow surface passivation. This work clarifies the inconsistencies reported in CsPbBr3 nanocrystals and provides guidelines for producing CsPbBr3 nanocrystals for application to single-particle emitters.