Plasmonic response of complex nanoparticle assemblies

Optical properties of nanoparticle assemblies reflect the distinctive characteristics of their building blocks and their spatial organization, giving rise to emergent phenomena. Integrated experimental and computational studies have established design principles connecting structure to properties for assembled clusters and superlattices. However, conventional electromagnetic simulations are too computationally expensive to treat more complex assemblies. Here we establish a fast, materials agnostic method to simulate the optical response of large nanoparticle assemblies incorporating both structural and compositional complexity. This many-bodied, mutual polarization method resolves limitations of established approaches, achieving rapid, accurate convergence for configurations including thousands of nanoparticles, some overlapping. We demonstrate these capabilities by reproducing experimental trends and uncovering far- and near-field mechanisms governing the optical response of plasmonic semiconductor nanocrystal assemblies, including structurally complex gel networks and compositionally complex mixed binary superlattices. This broadly applicable framework will facilitate design of complex, hierarchically structured, and dynamic assemblies for desired optical characteristics.