Interplay between iridescent and non-iridescent coloration in bio-inspired electrically-tunable nanostructures

This work is inspired by biological nanostructured surfaces possessing structural color generation and wettability control. Nanostructured films consisting of a tantalum pentoxide (Ta2O5) nanopost array (nanograss) formed on top of a continuous Ta2O5 layer on a reflective Ta thin-film have been fabricated and investigated. A non-iridescent coloration typical for short-range order was produced by the nanograss while iridescent coloration was produced by the underlying continuous Ta2O5 layer. When the nanograss surface is wetted with organic liquids, a different non-iridescent blue color appears. Moreover, this blue color can be dynamically and reversibly switched on and off by applying electrical current to an indium-tin-oxide electrode. (C)2014 Optical Society of America