Tunable structural colors based on grayscale lithography and conformal coating of VO2

Abstract

Structural colors generated by optical micro-/nanostructures offer a notable advantage over traditional chemical pigments, including higher purity, greater brightness, resistance to fading, and enhanced environmental friendliness. However, achieving dynamically switchable color displays with high performances and without resorting to complex nanofabrication methods remain a challenge. Here, we present a simple method using grayscale lithography and conformal coating to create Salisbury screen (SS) cavities with variable resonant wavelengths, enabling the formation of tunable colorful patterns. The dynamic color display is achieved through the phase change of vanadium dioxide (VO2) nanostructures under electrothermal effects. At a low actuation voltage of 1.4 V, high performances of color switching such as high sensitivity, fast speed, high repeatability, and wide-view angle are achieved. The tunable structural colors, featuring a simple preparation process and high-speed switching, represent a promising alternative for applications such as thermal sensors, security information encryption, and dynamic full-color displays.