Optical properties and color generation mechanism of porous anodic alumina films

Porous anodic alumina thin films with iridescent colors were fabricated electrochemically in phosphoric acid electrolyte. Compared to the color saturation of alumina films fabricated in oxalic acid electrolyte, the saturation obtained using phosphoric acid was enhanced dramatically. The mechanisms behind this observation are discussed, and the microstructure and optical characteristics of the films are characterized. Multicolor patterns were obtained by an organics-assisted process for which details are given.

► Porous anodic alumina thin films with iridescent colors are fabricated electrochemically in phosphoric acid electrolyte. ► Compared to the color saturation of alumina films fabricated in oxalic acid electrolyte, the saturation obtained using phosphoric acid was enhanced dramatically. ► The mechanisms behind this observation are discussed, and the microstructure and optical characteristics of the films are characterized.