Scalable, ultra-resistant structural colors based on network metamaterials

TL;DR

This paper introduces a scalable, durable method for producing vibrant structural colors using network metamaterials that combine nanoscale dealloyed structures with ultra-thin dielectric coatings, suitable for practical large-scale applications.

Contribution

The authors develop a novel large-scale network metamaterial approach that achieves highly saturated, angle-independent structural colors with enhanced mechanical resistance.

Findings

Colors are efficiently generated at large angles up to 70 degrees.

The network architecture provides high mechanical durability.

The method is scalable for commercial applications.

Abstract

Structural colours have drawn wide attention for their potential as a future printing technology for various applications, ranging from biomimetic tissues to adaptive camouflage materials. However, an efficient approach to realise robust colours with a scalable fabrication technique is still lacking, hampering the realisation of practical applications with this platform. Here we develop a new approach based on large scale network metamaterials, which combine dealloyed subwavelength structures at the nanoscale with loss-less, ultra-thin dielectrics coatings. By using theory and experiments, we show how sub-wavelength dielectric coatings control a mechanism of resonant light coupling with epsilon-near-zero (ENZ) regions generated in the metallic network, manifesting the formation of highly saturated structural colours that cover a wide portion of the spectrum. Ellipsometry measurements report the efficient observation of these colours even at angles of $70$ degrees. The network-like architecture of these nanomaterials allows for high mechanical resistance, which is quantified in a series of nano-scratch tests. With such remarkable properties, these metastructures represent a robust design technology for real-world, large scale commercial applications.