Long‐Lived Luminescence Over an Ultra‐Broad Temperature Range via Sequential Exciplex and Chemiluminescence Pathways

ABSTRACT Persistent luminescent polymers have recently attracted significant research interest due to their tunable afterglow properties and flexible molecular design. However, these systems typically fail to exhibit long‐lived luminescence at elevated temperatures, primarily due to the rapid non‐radiative deactivation of triplet excitons and accelerated charge recombination. Herein, we report a relay strategy utilizing exciplexes and chemiluminescence that enables ultralong persistent luminescence across a broad temperature range (from 255 to 573 K). This can be facilely achieved by doping a dihydroacridine derivative into a polyethylene terephthalate matrix. The resulting flexible film exhibits a long exciplex emission (detectable after 32 h at room temperature), with a chemiluminescence that intensifies from 360 to 573 K and persists for over a month at 400 K. While these two luminescence modes exhibit opposite dependencies on temperature and oxygen, they share the same fundamental structural basis for achieving high performance: the design incorporating multiple isopropylidene bridges. Consequently, a switch between the two mechanisms occurs around 360 K, resulting in color‐tunable, ultra‐long persistent luminescence over a remarkably wide temperature range. This combination of properties paves the way for developing advanced optical materials for sensing and secure information technologies capable of operating in extreme environments.