Large-Scale Plasmonic Pyramidal Supercrystals via Templated Self-Assembly of Monodisperse Gold Nanospheres

Abstract

Three-dimensional supercrystals of plasmonic nanoparticles are a novel class of materials with exciting applications in technologies such as light harvesting or metamaterials. However, their realization relies on extraordinarily regular colloidal building blocks and accurate self-assembly methods. We present here a simple and up-scalable protocol for the synthesis of smooth gold nanospheres with high monodispersity in size and sphericity. The synthesis involves rapid growth up to the desired size and subsequent removal of surface roughness via an efficient etching step, so that nanospheres with diameters ranging between 10 and 110 nm can be obtained in large quantities. Upon functionalization with thiolated polyethylene glycol and low surfactant concentration, Au nanospheres were employed as building blocks to produce uniform arrays of micron-sized 3D pyramidal supercrystals over large areas, by means of a template-assisted approach. Focused ion beam cutting and SEM characterization revealed a face-centered cubic lattice within individual pyramidal supercrystals.

Mechanotunable Plasmonic Properties of Colloidal Assemblies

“…Exchanging flat substrates for topographically structured templates gives access to particle arrays with a wide range of possible array geometries. In general, any nanostructured substrate—no matter whether fabricated via e‐beam‐, interference‐, or soft lithography—is applicable for TASA. A simple and lithography‐free method for creating templates is controlled surface wrinkling .…”

Plasmonic Detection of Carbohydrate‐Mediated Biological Events

“…In contrast, well-defined plasmonic substrates can also be prepared, typically through deposition on solid supports, [56,57] leading to maximized SERS signals, as well as uniform SERS enhancement factors across the entire surface, owing to their homogenous structure, so that the reproducibility of SERS analysis is greatly improved. In contrast, well-defined plasmonic substrates can also be prepared, typically through deposition on solid supports, [56,57] leading to maximized SERS signals, as well as uniform SERS enhancement factors across the entire surface, owing to their homogenous structure, so that the reproducibility of SERS analysis is greatly improved.…”

“…As shown above, random aggregation of NPs can be used to enhance SERS signals, however the poor control achieved over the size, geometry, and interparticle distance within these aggregates has a negative impact on reproducibility. In contrast, well-defined plasmonic substrates can also be prepared, typically through deposition on solid supports, [56,57] leading to maximized SERS signals, as well as uniform SERS enhancement factors across the entire surface, owing to their homogenous structure, so that the reproducibility of SERS analysis is greatly improved. [58] Such solid plasmonic substrates have been proposed for the long-term monitoring of target analytes in real biological systems.…”

Silver Particles with Rhombicuboctahedral Shape and Effective Isotropic Interactions with Light

“…4 Most of these applications rely on the plasmonic effects exhibited by the metallic nanoparticles. In recent years, the focus in this area has shifted significantly into the collective effects of plasmonic nanoparticles resulting in emergent properties, 5 e.g., complex coupling of particle assemblies, [6][7][8] collective interactions 9,10 and the interplay of plasmonics with classical photonic properties. 11 Well-defined nanoparticles as the building blocks in such complex systems are essential.…”

“…27 To overcome this limitation, additional etching processes such as oxidative etching have been reported to form high-index facets after the initial nanoparticle growth. 8,28,29 Most of these studies investigated the reshaping of anisotropic silver colloids using etching agents like copper or iron salts. 28,[30][31][32] Nevertheless, there is a lack of in-depth studies into the etching mechanism and especially, the formation of facets as a result of the etching mechanism.…”