Reconfigurable, vivid reflective colors based on solution-processed Fabry–Perot absorber using thermochromic vanadium dioxide

Abstract

Artificial structural color generation has attracted much attention in developing ink-free color technology for applications such as security devices, reflective displays, and functionalized color decoration. An asymmetric Fabry–Pérot (F–P) cavity-based absorber can play this role because of its advantages of an ultra-thin structure, lithographic-free manufacturing, and applicability to a large area. However, the optical response of F–P absorbers, which is determined by the structural parameters and compositions of the individual layers, is fixed at a single frequency, and only a static color can be passively implemented. In this study, we propose a new active metamaterial-based F–P absorber that exhibits dynamically tunable optical responses with temperature change. An active F–P absorber is fabricated by incorporating lossy nanoporous Ag nanoparticles (NPs) and a phase change material—vanadium dioxide (VO2)— interlayer via a solution process. Coupled with finite-difference time-domain simulations and systematic experiments, we demonstrate that F–P absorbers generate enhanced reflective color purity due to their closely-coupled Ag NPs. The reflective colors were dynamically modulated by temperature changes owing to the variation of optical constants between the phase transition of the monoclinic VO2. Furthermore, the demostrated tunable color image with micro-patterned absorbers opens the way for designing thermo-optical devices operating in the visible wavelength. © 2021 Elsevier B.V.