From bioinspired structure formation to particle-based metamaterials
Institut für Polymerforschung Dresden and Technical University Dresden, Germany
Metallic nanoparticles offer a number of interesting optical and electronic effects. A prominent example is localized surface plasmon resonance (LSPR), which is due to resonance excitations of the free electron cloud vibrations of the particles by light. Due to LSPR, plasmonic nanoparticles provide excellent opportunities for controlling electromagnetic near-fields at optical frequencies, which has led to a wide range of applications in various fields such as surface-enhanced spectroscopy, light harvesting, or photonics.
While much of the research has been devoted to understanding nanoparticle synthesis and tailoring their LSPR at the single-particle level [1-3], the ordering of particles at different length scales opens another powerful route to optical and electronic functionality due to novel collective plasmonic excitations arising from plasmonic coupling effects.
We focus on achieving such ordered particle arrays through assembly approaches. Colloidal self-assembly can indeed achieve well-defined colloidal clusters  and surface arrays  where coupling effects can be controlled. In particular, large-scale assemblies are possible in combination with biomimetic surface patterning. We discuss the underlying physicochemical principles of the assembly process and the resulting plasmonic coupling effects [6,7]. Finally, we present perspectives on how this assembly principle can be applied to metasurfaces with high field enhancement and/or ultrahigh circular dichroism [6, 8].