Endowing Photodeformation Film With Near-Infrared Afterglow

The near-infrared (NIR) afterglow visualization in photodeformation materials offers real-time, light-off tracking of dynamic photoresponsive processes in deep tissues and optomechanical systems. However, it remains a fundamental challenge to simultaneously achieve photodeformation and NIR afterglow, due to the competing requirements of molecular design: molecular flexibility for photodeformation versus structural rigidity for afterglow emission, in addition to the intrinsic difficulty in realizing NIR afterglow. To resolve this dichotomy, we developed a rigidity–flexibility compartmentalized molecular structure. A rigid conjugated framework with strong charge transfer (CT) character is responsible for the persistent NIR afterglow via radiative recombination of charge-separated states (CSS), while flexible tautomerism units featuring an excited-state intramolecular proton transfer (ESIPT) process enable photodeformation. Once these dyes are doped into polyethylene terephthalate (PET) films, the visible-light-driven photocontraction (with a contraction rate up to 48%) and persistent NIR afterglow can be realized. Furthermore, it has been successfully utilized for in vivo precision control in bioimaging with high signal-to-background ratio (SBR), and applied in the dynamic modulation of vascular stents with afterglow visualization.