Deterministic Model of Observed Colours on Metal-Anodic Aluminium Oxide-Al Nanostructures

Structural colours have produced immense attention in reproducing the vivid colours found in nature. In this study, metal-anodic aluminium oxide (AAO)-Al nanostructures were deposited using a two-step anodization and sputtering process to produce self-ordered anodic aluminium oxide films and a metal layer (8 nm Cr and 25,17.5 and 10 nm of Au), respectively. AAO films, of various thicknesses, were anodized and the Yxy values ( Y , luminance, and xy, chromaticity) were obtained via reflectance measurements. An empirical model, based on the thickness and porosity of the nanostructures, was determined, which would describe a gamut of colours. The proposed mathematical model can be applied in different fields, such as wavelength absorbers, RGB (red, green, blue) display devices, as well as chemical or optical sensors.