SANS-Driven Insights into the Self-Assembly and Optimization of Metal-Based Superlattices

Recently, metal-nanocrystals (M-NCs) attracted significant attention due to their unique optical, electronic, and catalytic properties, making them valuable in various fields and industries. M-NCs Optimization has focused on manipulating shapes and dimensions to enhance surface energy, electronic structure, and environmental interactions. A novel approach involves creating three-dimensional nanoscale-ordered assemblies, altering the plasmonic band by forming ordered structures like face-centered or hexagonal phases. We analyzed the effects of solvent choice and surface coverage on gold, silver, and platinum NCs' self-assembly, upon functionalization with oleic acid (OA) in water, and optical properties. We highlighted that solvent dielectric constants impact the hydrodynamic radius of nanocrystals, emphasizing the environment's role in aggregation. Optical property analyses showed that oleylamine-nanocrystals exhibit shifts in absorption maxima (λmax) due to solvent refractive indices, demonstrating the interplay between the environment and nanocrystal behavior. OA-coated NCs assembled into different superlattices depending on the starting solvent and the oleylamine degree of coverage. Moreover, different superlattices display variations in λmax based on spatial organization, underscoring the influence of arrangement on optical properties. Moreover, through contrast matching SANS experiments we investigated the interdigitation of oleylamine capping layers within the superlattice shedding light on the oleylamine role in this self-assembly process.