Chemically Tailored Dielectric-to-Metal Transition for the Design of Metamaterials from Nanoimprinted Colloidal Nanocrystals

Abstract

We demonstrate optical metamaterial design using colloidal gold nanocrystal building blocks. In the solid state, chemically exchanging the nanocrystals' surface-capping molecules provides a tailorable dielectric-to-metal transition exhibiting a 10(10) range in DC conductivity and dielectric permittivity ranging from everywhere positive to everywhere negative throughout the visible-to-near-IR. Direct, wide-area nanoimprinting of subwavelength superstructures at room temperature, on plastic and glass substrates, affords plasmonic resonances ranging from 660 to 1070 nm, in agreement with numerical simulations.

Defect tolerance and the effect of structural inhomogeneity in plasmonic DNA-nanoparticle superlattices

“…Moreover, superlattices with higher metal volume fractions exhibit rich optical behavior (8)(9)(10)35). It is likely that the strong, nonlinear plasmonic coupling in these systems will increase the effect of randomness, disorder, and polydispersity on the optical response.…”

“…It is likely that further investigation of closely coupled plasmonic lattices will uncover unexpected and unusual plasmonic behavior (35). For example, numerous studies of closely coupled plasmonic nanoparticles have identified tunable reflection and dielectric behavior in addition to unique symmetrydependent properties (5,(8)(9)(10)13). These insights will lead to materials and devices that exhibit greater reproducibility including sensing, metamaterials, coatings, and optical electronics.…”

“…These efficient interactions with visible light are due to localized surface plasmon resonances (LSPRs), the collective oscillation of conduction electrons (1). Hierarchical arrangements of plasmonic nanoparticles have become the basis for colorimetric sensors (2,3), subdiffraction limited waveguides (4), visible light metamaterials (5), and nanoscale lasing devices (6,7), and the ability to adjust architecture in such materials has led to a wide variety of structures with tunable and unusual optical properties (8)(9)(10)(11)(12). Many of these technologies leverage the scalability and modularity of bottom-up assembly techniques, which use chemically synthesized colloidal nanoparticles as building blocks (13,14).…”

Large-Area Nanoimprinted Colloidal Au Nanocrystal-Based Nanoantennas for Ultrathin Polarizing Plasmonic Metasurfaces

“…Our group has shown previously that compact ligand exchange increases the coupling between Au NCs, inducing an insulator-to-metal transition in Au NC thin films. 33 Figure 1 (e) shows a representative scanning electron micrograph (SEM) of a Au NCbased nanorod array [Supporting Information Figure S1]. SEM images are taken from different regions of the sample to determine the uniformity in the nanorod dimensions across the array [Supporting Information Figure S2].…”

“…33 Since we fabricate anisotropic nanostructures as building blocks for metasurfaces, we probe their polarization control of incident light. The polarization-dependent transmittance spectra for the four samples in Figure 2 for (a) as the aspect ratio of the nanorods increases.…”