Nanoscale surface chemistry directs the tunable assembly of silver octahedra into three two-dimensional plasmonic superlattices

• Main Authors: Lee, Yih Hong, Shi, Wenxiong, Lee, Hiang Kwee, Jiang, Ruibin, Phang, In Yee, Cui, Yan, Isa, Lucio, Yang, Yijie, Wang, Jianfang, Li, Shuzhou, Ling, Xing Yi
• Other Authors: School of Materials Science & Engineering
• Format: Article
• Language: English
• Published: 2018
• Subjects: Nanoscience and Technology; Molecular Self-assembly; DRNTU::Science::Chemistry
• Online Access: https://hdl.handle.net/10356/89275; http://hdl.handle.net/10220/46149
• Institution: Nanyang Technological University

A major challenge in nanoparticle self-assembly is programming the large-area organization of a single type of anisotropic nanoparticle into distinct superlattices with tunable packing efficiencies. Here we utilize nanoscale surface chemistry to direct the self-assembly of silver octahedra into three distinct two-dimensional plasmonic superlattices at a liquid/liquid interface. Systematically tuning the surface wettability of silver octahedra leads to a continuous superlattice structural evolution, from close-packed to progressively open structures. Notably, silver octahedra standing on vertices arranged in a square lattice is observed using hydrophobic particles. Simulations reveal that this structural evolution arises from competing interfacial forces between the particles and both liquid phases. Structure-to-function characterizations reveal that the standing octahedra array generates plasmonic ‘hotstrips’, leading to nearly 10-fold more efficient surface-enhanced Raman scattering compared with the other more densely packed configurations. The ability to assemble these superlattices on the wafer scale over various platforms further widens their potential applications.