Electrochromic Metamaterials of Metal-Dielectric Stacks for Multicolor Displays with High Color Purity.

Inorganic electrochromic (EC) materials with vibrant multicolor change that are compatible with large-scale processing have been at the forefront of EC technology and are crucial in a wide range of applications, such as displays and camouflage. However, limited strategies are available to realize such inorganic materials, and challenges such as low color purity are yet to be overcome. Here, we demonstrate multilayered metal-dielectric metamaterials (MMDMs) as a new family of inorganics-based EC materials to achieve dynamic alternation among multicolors with high contrast and high color purity, which are structurally realized by significantly enhancing the confinement of the incident light in specific optical frequencies. This multilayer structure renders high reflectivity (75%), high quality factor (7.4), and a full width at half-maximum of 60 nm before coloration and presents a color gamut at least 40% wider than that of previously reported metamaterials after coloration, indicating good color quality.