Versatile Nanoring Fabrication Assisted by Hole-Mask Colloidal Lithography for Building Thermal Management

Nanomaterials shaped as rings are interesting nanostructures with control of the materials' properties at the nanoscale. Nanoring plasmonic resonators provide tunable optical resonances in the near-infrared with applications in sensing among others. Fabrication of nanorings can be carried out via top-down approaches based on electron beam lithography with high control of the ring size parameters but at a high cost. Alternatively, fabrication via self-assembly approaches has a higher speed/lower cost but at the cost of control of ring parameters. Current colloidal lithography approaches can provide nanoring fabrication over large areas but only of specific materials and a select set of rings (large ring diameters or small rings with ultrathin walls). We extend Hole-mask Colloidal Lithography to use ring-shaped holes, allow the deposition of arbitrary materials, and allow the independent tuning of ring-wall thickness over a large range of values. We present a generic approach for the fabrication of nanorings formed from a range of materials including low-cost (e.g., Cu, Al) and non-plasmonic (e.g., W) materials and with control of ring wall thickness and diameter allowing tuning of ring parameters and materials for applications in nanooptics and beyond.

In modern technology and industry, there is a pressing need for energy-saving materials, one of the major examples is advanced materials for windows. Regarding the mentioned application, the major goal is to design new materials capable of blocking infrared (IR) radiation while being optically transparent to visible light. These IR-blocking materials would allow to reduce the transfer of heat radioactivity inside of buildings, decreasing the consumption of active cooling systems. In the literature, there can be found several examples of passive and active solutions including low-emissivity materials, thermochromic materials, and gasochromic approaches. However, we believe that plasmonic metamaterials represent a feasible alternative and might lead to cost-effective solutions.

Windows play a crucial role in reducing heat loss, with double-paned windows already making a substantial difference compared to single panes. A notable passive smart glass technology under recent scrutiny is thermoplasmonics, a sub-field of plasmonics utilizing plasmonic materials sensitive to temperature changes. However, the application of thermoplasmonics in smart glass fabrication faces limitations, primarily due to challenges in upscaling plasmonic structures for commercial use. We aim to explore the plasmonic properties of metallic nanorings to fabricate a smart glass system based on thermoplasmonics with manipulable plasmonic properties through temperature changes. By subjecting the smart glass system to temperature variations, the plasmonic resonance peak could be shifted into or away from specific ranges, such as the Near-infrared (NIR) or visible range.