Color-tunable, time-dependent, temperature and humidity-responsive afterglow from hyaluronic acid-based films

Pure organic afterglow materials with color-tunable and multiple stimuli-responsive afterglow are attractive but extremely scarce. Herein, a convenient strategy is reported to construct a series of hyaluronic acid (HA) -based afterglow films with color-tunable (from cyan to red) and multiple stimuli-responsive afterglow emissions (τafterglow, up to 971.05 ms). Disruption of hydrogen bonds and quenching of triplet excitons induced humidity-responsive afterglow, while time-dependent afterglow originates from diverse emissive species with different lifetimes. Moreover, due to the existence of dual-mode afterglow, the HA-based afterglow film doped with 9-aminophenanthrene (Aphe@HA) is endowed with temperature-responsive afterglow, and the Commission Internationale de l'Eclairage (CIE) coordinates of its colors could be linearly adjusted among yellow, white and blue from 298 K to 443 K. Considering the distinctive temperature-responsive afterglow, Aphe@HA can act as a temperature sensor in three-way catalytic converters (TWCs) and curling tongs. In addition, the color-tunable and humidity-responsive afterglow emissions of the HA-based films facilitate their applications in anti-counterfeiting and information encryption.