Soft plasmene helical nanostructures

Plasmene is recently defined as 2D arrays of plasmonic nanoparticles, which could be fabricated by the bottom-up self-assembly approach and demonstrated a wide range of applications in sensing, energy harvesting, nanophotonics and encryption. Here, this work further demonstrates a 3D helical plasmonic nanostructures that can be fabricated from 2D plasmene nanosheet. Inspired by chocolate curls-making process, a micro-spatula-based strategy is developed to selectively scrape substrate-supported plasmene to free space, which spontaneously folds the plasmene nanosheet into various complex helical nanostructures with controlled dimensions. 3D nanospirals can also be obtained by focus ion beam (FIB)-based lithography on free-standing plasmene. Helical plasmene structures are robust, exhibiting elastic mechanical properties and chiral optical response. This methodology represents a versatile fabrication route combining both bottom-up and top-down approaches to create soft plasmonic helical structures for potential applications in next-generation flexible nanophotonic devices.