Multicolor Conjugated Polymer Thin Films with Tunable Responsivity to Oxidative and Reductive Environments

Dynamic colors that respond to environmental changes are of great interest for diverse areas of science and technology ranging from chemical and biological sensors to smart information display. Here, we demonstrate a multitude of responsive colors from a conjugated polymer film arising from a thin-film interference. This mechanism provides an excellent control over the thin-film color by varying the film thickness, type of substrate, and degree of polaron population and is generally applicable to various conjugated polymers for further color variation. Furthermore, multiple sets of responsive colors are achieved from a single polymer layer by patterning the underlying substrate to spatially modify the interference conditions. Using this system, we demonstrate the reversible color changes induced by an oxidative or reductive environment with color responsivity controllable with the nature of the polaron state.