Achieving High Afterglow Brightness in Organic Dopant‐Matrix Systems

Abstract Afterglow brightness upon ceasing excitation represents an important parameter for afterglow material applications, while purely‐organic room‐temperature afterglow materials with high quantum yields, long emission lifetimes, and strong absorption capability, which are necessary to realize high afterglow brightness, remain rarely reported. Using dopant‐matrix collaboration, thermally activated delayed fluorescence mechanism, and spiro molecular design, here a highly bright afterglow system is reported, that possesses persistent luminescence quantum yields as high as 30% and emission lifetimes up to 0.6 s at ambient conditions by doping spiro‐shaped difluoroboron β‐diketonate (spiroBF₂, ε = 6.5 × 10⁴ M⁻¹cm⁻¹) luminogens into benzophenone (BP) matrices. After being processed into desired shapes and large‐area panels by melt casting, the spiroBF₂‐BP material exhibits intense green afterglow that is much brighter than a typical SrAl₂O₄:Eu²⁺, Dy³⁺ inorganic afterglow material and can last for more than 5 s under room light, which is among the brightest afterglow in purely‐organic systems.