Impurities in Polyvinylpyrrolidone: the key factor in the synthesis of gold nanostars

Control over the synthesis of anisotropic nanoparticles is crucial as slight differences in their size, shape, sharpness, or the number of tips in the case of gold nanostars, has an...

Lyotropic Liquid Crystalline Phases of Anisotropic Nanoparticles of Organic-Inorganic Metal Halide Perovskites: Photoluminescence from Self-Assembled Ordered Microstructures of Semiconductors

A simple method (could be completed within 60 minutes at 298 K) was developed to transform layered organic-inorganic metal halide perovskites into colloidal lyotropic liquid crystalline dispersions with microscopic structural...

Device-quality, reconfigurable metamaterials from shape-directed nanocrystal assembly

Anchoring nanoscale building blocks, regardless of their shape, into specific arrangements on surfaces presents a significant challenge for the fabrication of next-generation chip-based nanophotonic devices. Current methods to prepare nanocrystal arrays lack the precision, generalizability, and postsynthetic robustness required for the fabrication of device-quality, nanocrystal-based metamaterials [Q. Y. Lin et al. Nano Lett. 15, 4699–4703 (2015); V. Flauraud et al., Nat. Nanotechnol. 12, 73–80 (2017)]. To address this challenge, we have developed a synthetic strategy to precisely arrange any anisotropic colloidal nanoparticle onto a substrate using a shallow-template-assisted, DNA-mediated assembly approach. We show that anisotropic nanoparticles of virtually any shape can be anchored onto surfaces in any desired arrangement, with precise positional and orientational control. Importantly, the technique allows nanoparticles to be patterned over a large surface area, with interparticle distances as small as 4 nm, providing the opportunity to exploit light–matter interactions in an unprecedented manner. As a proof-of-concept, we have synthesized a nanocrystal-based, dynamically tunable metasurface (an anomalous reflector), demonstrating the potential of this nanoparticle-based metamaterial synthesis platform.