Day‐Long Organic Persistent Luminescence in Flexible Polymeric Materials

The progress in organic afterglow materials has drawn significant attention due to their extensive applications in fields such as optoelectronics, anti-counterfeiting, and bioimaging. Nonetheless, a general limitation of organic afterglow materials is their short emission lifetimes, typically spanning from milliseconds to seconds, which creates a substantial challenge in developing day-long organic afterglow (DOA). In this study, a DOA system is demonstrated through the incorporation of electron donor/acceptor exciplexes. Polyethylene naphthalate is used for both the electron acceptor and charge storage units, coupling with a spirobifluorene-carbazole derivative as the electron donor, providing effective charge separations under UV-light and sunlight excitation. The resulting DOA polymers demonstrate an exceptional bluish-green afterglow that endures for over 28 h under ambient conditions, setting a new record for the longest afterglow duration in polymeric materials. Moreover, the DOA-doped polymers, as both films and fibers, exhibit outstanding flexibility and transparency, making them highly suitable for flexible technologies and wearable devices.