Bioinspired Controllable Electro-Chemomechanical Coloration Films

Coloration materials and devices with broad manipulatable color spectra and precisely controllable capability are highly pursued in various applications, such as camouflage engineering, optical sensors, anticounterfeiting technology, real-time monitoring, and so on. For achieving the goals, in the present work, a conceptually novel bioinspired coloration film is demonstrated using nanoscale amorphous silicon (a-Si) layer deposited on a reflective metal substrate. With precisely manipulating the reversible lithiation/delithiation behaviors, such coloration films enable to present consecutively tunable chromogenic property in a broad visible band, since the simultaneous changes in both chemical components and film thickness upon electrochemical processes substantially vary the conditions of destructive interference. Accordingly, the corresponding model based on electro-chemomechanical coupling effects confirms the coloration mechanism induced by thickness and intrinsic properties (refraction index and optical absorptivity). Additionally, such coloration films also suggest universal design ability, namely tailoring the coloration spectra via simply changing film thicknesses and metal substrates. Thus, the results promise a versatile strategy for fabricating advanced coloration materials and devices that are pursued in specular reflection, sensing, anticounterfeiting, labels, displaying, and sensors.