Manipulating Light-Matter Interactions in Plasmonic Nanoparticle Lattices.

Rationally assembled nanostructures exhibit distinct physical and chemical properties beyond their individual units. Developments in nanofabrication techniques have enabled the patterning of a wide range of nanomaterial designs over macroscale (>in.) areas. Periodic metal nanostructures show long-range diffractive interactions when the lattice spacing is close to the wavelength of the incident light. The collective coupling between metal nanoparticles in a lattice introduces sharp and intense plasmonic surface lattice resonances, in contrast to the broad localized resonances from single nanoparticles. Plasmonic nanoparticle lattices exhibit strongly enhanced optical fields within the subwavelength vicinity of the nanoparticle unit cells that are 2 orders of magnitude higher than that of individual units. These intense electromagnetic fields can manipulate nanoscale processes such as photocatalysis, optical spectroscopy, nonlinear optics, and light harvesting. This Account focuses on advances in exciton-plasmon coupling and light-matter interactions with plasmonic nanoparticle lattices. First, we introduce the fundamentals of ultrasharp surface lattice resonances; these resonances arise from the coupling of the localized surface plasmons of a nanoparticle to the diffraction mode from the lattice. Second, we discuss how integrating dye molecules with plasmonic nanoparticle lattices can result in an architecture for nanoscale lasing at room temperature. The lasing emission wavelength can be tuned in real time by adjusting the refractive index environment or varying the lattice spacing. Third, we describe how manipulating either the shape of the unit cell or the lattice geometry can control the lasing emission properties. Low-symmetry plasmonic nanoparticle lattices can show polarization-dependent lasing responses, and multiscale plasmonic superlattices-finite patches of nanoparticles grouped into microscale arrays-can support multiple plasmon resonances for controlled multimodal nanolasing. Fourth, we discuss how the assembly of photoactive emitters on the nanocavity arrays behaves as a hybrid materials system with enhanced exciton-plasmon coupling. Positioning metal-organic framework materials around nanoparticles produces mixed photon modes with strongly enhanced photoluminescence at wavelengths determined by the lattice. Deterministic coupling of quantum emitters in two-dimensional materials to plasmonic lattices leads to preserved single-photon emission and reduced decay lifetimes. Finally, we highlight emerging applications of nanoparticle lattices from compact, fully reconfigurable imaging devices to solid-state emitter structures. Plasmonic nanoparticle lattices are a versatile, scalable platform for tunable flat optics, nontrivial topological photonics, and modified chemical reactivities.