Achieving Seconds-to-Hours Duration-Tunable Organic Long Persistent Luminescence from Carbon Dots-Based Exciplex Systems by Energy Gaps Regulation

Duration-tunable afterglow materials have garnered considerable attention in various applications. Herein, carbon dots (CDs)-based long persistent luminescence (LPL) composites with a tunable duration in an ultrawide range of seconds-to-hours levels were designed and prepared for the first time. In contrast to the established CD-based afterglow materials, we reported that CD-based composites exhibit LPL in the form of exciplexes and long-lived charge-separated states, enabling the LPL to be prolonged from several seconds to over one hour, exceeding the typical regulation range (limited to 1 min). Further studies revealed that the relationship between the excited and charge-transfer states of CDs plays a pivotal role in activating the LPL and regulating its duration. Furthermore, these composites exhibited high photoluminescence (PL) quantum yields of up to 60.63%, and their LPL was robust under ambient conditions, even in aqueous media. Their robust and superior LPL performance endows these composites with a strong competitive advantage in dynamic display systems, such as tags for time-resolved data encryption and displays of the remaining time of takeaways. This study offers an approach to preparing CDs-based LPL composites with tunable durations and may provide new insights for the development of rare-earth-free LPL materials.