Plasmon resonance coupling phenomena in self-assembled colloidal monolayers

Colloidal self-assembly merges the flexibility provided by (wet-chemical) colloid synthesis and the structural diversity offered by self-assembly. Using plasmonic nanocrystals as colloidal building blocks, this enables the fabrication of plasmonic superstructures that show optical response superior to the individual colloid properties. In this review, we highlight recent examples of colloidal monolayers featuring coupled plasmonic resonances. Depending on the average inter-particle distance and the structure of such monolayers, the discussed examples show either near-field or radiative coupling signatures depending on the critical interference length scale of the localized resonances. In addition, templated assembly is highlighted as a pathway for the preparation of monolayers that show anisotropic optical coupling. The collected works not only reflect the recent state of the art in plasmonic resonance engineering in self-assembled monolayers, but also point to future directions relevant for their use in nanophotonic applications such as plasmonic lasing.