Correlated Incorporation and Structural Variability in Au-CdSe/CdS Plasmon-Exciton Hybrid Microspheres

Structural distribution of semiconductor quantum dots (QDs) and plasmonic metal nanostructures in assemblies determines the emergent light-matter interactions and thus is extremely important. Here, we systematically investigate the structural aspects of self-assembly of thiol-capped Au nanoparticles and CdSe/CdS QDs into hybrid microspheres at various component ratios. Composition-dependent morphology of Au-QD hybrids is confirmed by transmission electron microscopy and energy-dispersive X-ray spectroscopy (EDS). Statistical analysis of the EDS data shows that the incorporation differs from Poisson statistics, consistent with chemical and structural effects guiding and controlling key aspects of the assembly process. In addition, the Gini index and Moran's I were used to measure the compositional heterogeneity and spatial clustering, respectively, revealing that Au is still uniformly dispersed while CdSe/CdS regions accumulate in more localized domains. This work offers a quantitative understanding of the statistical nature of nanocrystal incorporation and shows the routes to structural deterministic plasmon-exciton hybrid architectures.