Synthesis and Optical Properties of Iridescent Porous Anodic Alumina Thin Films

Highly ordered porous anodic alumina thin films with tunable structural colors covering the entire visible region have been fabricated using chemical etching. The relationship of the structural color to the anodization time and etching time in a phosphoric acid solution, as well as the angle of incidence of illuminating light are discussed. Multicolor patterns were obtained by an organics-assisted process. A theoretical study of the changes in structural color due to various factors is consistent with the experimental results. These films show promise in many areas including decoration, display and anti-counterfeiting applications.