Coatings, Vol. 15, Pages 1260: Perception of Structural Colors in Nanostructured Anodic Aluminum Oxide Films

Coatings doi: 10.3390/coatings15111260

Authors:
Woong Ki Jang
Yoo Su Kang
Young Ho Seo
Byeong Hee Kim

This study investigates the fabrication of anodic aluminum oxide (AAO)/Al bilayer films using a two-step aluminum anodization process and explores the perception and prediction of structural colors through these films. A composite AAO film with an AAO/Ni/Al structure was fabricated by electroplating an AAO/Al bilayer film with an AAO/Al structure. The fabricated composite AAO film was used to produce structural colors through changes in optical characteristics caused by Ni nanoplugs. Constructive-interference wavelengths resulting from variations in the pore diameter and interpore distance of AAO/Al bilayer films and composite AAO films were predicted using the Bragg–Snell law, with a maximum error margin of 9%. Additionally, the composite AAO film exhibited RGB colors within the predicted constructive-interference wavelength range. These results demonstrate that structural colors can be reliably predicted by estimating the constructive-interference wavelengths of composite AAO films. The approach provides a practical design rule for target colors in AAO-based coatings under normal incidence. The key advance is a single closed-form rule that links Dt, Dint, DP, and Dni to λ_peak at normal incidence, enabling forward and inverse color design without numerical optimization.

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Woong Ki Jang www.mdpi.com