Multicolor Electrochromic Metamaterials Based on Mie Scatterer Nanospheres

Abstract Electrochromic materials (ECMs), the colors of which can be electrically modulated by small driving voltages with a unique open‐circuit memory effect, are in great demand in various application fields. However, traditional ECMs exhibit a narrow modulation range of color gamut under the electric stimulus, owing to the monotonous chemical coloration in an absorption manner. Multicolor ECMs with optical nanostructures can greatly extend the color gamut by incorporating complex optical interactions such as interference and diffraction. Mie scatterer nanospheres (MSNSs) are a kind of nanospheres with unique optical structures that can simply exhibit and change vivid structural colors by adjusting their diameters. Herein, this work reports multicolor ECMs based on MSNSs with polymer shells of poly‐3,4‐ethylenedioxythiophene (PEDOT) and poly‐pyrrole (PPY). They possess a superior optical modulation capability with a wide color gamut, a fast response rate, a visible‐angle‐independence, etc. Additionally, a nano‐dispersion strategy is used to prepare mixed electrochromic pigments with a nanoscale uniformity, further broadening the color gamut tunability. Simulations in wave optics and Mie scattering theory are conducted to unveil the multicolor modulation mechanism, demonstrating the interactions of MSNSs with incident lights. This work provides a feasible approach for fabricating multicolor ECMs with more application potential.