Rapid fabrication of iridescent alumina films supported on an aluminium substrate by high voltage anodization

Abstract Porous alumina photonic crystals supported on an aluminium substrate were successfully fabricated by applying a high voltage for a short period of time in an oxalic acid solution. These films show brilliant structural colors, and the highest applied voltage was 250 V. The experimental results indicate that a photonic crystal supported on an aluminium substrate shows a uniform structural colour when a voltage is increased to 150 V and, with oxidation time increasing, the colour gradually turns blue. A reasonable explanation was given for this phenomenon through a theoretical analysis combined with microstructure measurement. In this study, the growth process and colour generation mechanism of porous anodic alumina under a linear anodizing voltage were discussed and analyzed in detail. These films may have great potential in colour display, decoration, anti-counterfeiting, sensing and other fields.