Photoswitchable Ion-Conducting Supramolecular Hydrogel Showing Adverse Photoconductivity Triggered by Anion Exchange

Ion-conducting supramolecular hydrogels with reversible photoconductive properties constructed by noncovalent bonds have attracted considerable attention due to their beneficial electrochemical properties. Herein, light-triggered supramolecular ionic hydrogels based on host-guest interactions between cyclodextrin, azobenzene, and an ionic liquid grated onto the gel matrix were prepared. In the hydrogel, not only can photoswitchable ionic conductivity be achieved but also adverse conductive behavior can be realized by simple ion exchange. With Br- anions, the hydrogel shows low resistance after 365 nm light irradiation and turns back to exhibiting high resistance after being irradiated by 470 nm light. When the anions were changed to bis(trifluoromethylsulfonyl)imide (TFSI-), the hydrogel exhibited opposite light-responsive properties, showing higher resistance when irradiated by 365 nm light. By changing the conductivity of the hydrogel through light-regulated ionic migration, an efficient way was provided to enhance the fundamental understanding of the photoconductive mechanism associated with competitive host-guest binding and manufacturing multifunction hydrogel electronics and optoelectronic materials.