Reversible colour changes of binary films composed of azobenzene-based amorphous molecular materials and p-toluene sulfonic acid in response to exhaled breath

Abstract

Binary films composed of azobenzene-based amorphous molecular materials and p-toluene sulfonic acid were found to exhibit drastic colour change when we breathed onto their films. When pausing the breath, the colour returned to the original immediately. Moisture in the breath was suggested to play a role in such phenomena.