Optimizing Interparticle Gaps in Large-Scale Gold Nanoparticle Supercrystals for Flexible Light-Matter Coupling

Abstract

Periodic arrangements of plasmonic nanoparticles, supercrystals, feature strong light–matter interaction. The light–matter coupling strength depends on the particle diameter and on the interparticle gaps, which provides a lever for controlling it. To facilitate material design, experimental data is analyzed with focus on how the reproducibility and tunability of the gap sizes change with the employed nanoparticles (particle size and molecular weight of the stabilizing organic ligands). A different behavior of the polystyrene-based ligands was found depending on their molecular weight with important consequences for the correlation of nanoparticle diameter and resulting gaps in the supercrystals. Commonly employed models to predict the resulting gaps for supercrystals of small nanoparticles (< 20 nm) are not as successful for larger ones, and an alternative volume-based approach is presented. The tested parameters cover the range of commonly available nanoparticles (diameters in the range of 10–80 nm). The presented data provides robust guidelines for the preparation of crystalline superstructures with gaps below 5 nm for maximized light–matter coupling.