• Energy Research

AbstractMetal nanostructures offer exciting ways to manage light at the nanoscale exploited in fields such as imaging, sensing, energy conversion, and information processing. The optical response of the metallic architectures can be engineered to exhibit photonic properties that span from plasmon resonances to more complex phenomena such as negative refractive index, optical chirality, artificial magnetism, and more. However, the latter optical properties are only observed in intricate architectures, which are highly demanding in terms of nanofabrication and hence less scalable and far away from device implementation. Here, a series of metasurfaces covering centimeter areas and operating in the visible spectrum are presented, which are produced from the combination of nanoimprinting lithography and oblique angle metal evaporation. The potential of this scalable approach is illustrated by easily fabricating metasurfaces engineered to exhibit artificial optical magnetism, tunable linear polarization dependent response, chirality with g‐factor of 0.2, and photoluminescence enhancement of 20 times over a 9 mm2 area.

Micro- and nanoscale patterned monolayers of plasmonic nanoparticles were fabricated by combining concepts from colloidal chemistry, self-assembly, and subtractive soft lithography. Leveraging chemical interactions between the capping ligands of pre-synthesized gold colloids and a polydimethylsiloxane stamp, we demonstrated patterning gold nanoparticles over centimeter-scale areas with a variety of micro- and nanoscale geometries, including islands, lines, and chiral structures (e.g., square spirals). By successfully achieving nanoscale manipulation over a wide range of substrates and patterns, we establish a powerful and straightforward strategy, nanoparticle chemical lift-off lithography (NP-CLL), for the economical and scalable fabrication of functional plasmonic materials with colloidal nanoparticles as building blocks, offering a transformative solution for designing next-generation plasmonic technologies.

Arrays of gold-covered inverted silicon pyramids exhibit strong light absorption in the near infrared and large field enhancements at hot spots, due to resonant excitation of surface-plasmon polaritons at the metal/dielectric interface.