We report ahighly efficient dopant-matrix afterglow system enabled by TADF mechanism to realizea fterglow quantum yields of 60-70 %, which features am oderate rate constant for reverse intersystem crossing (k RISC )t os imultaneously improve afterglow quantum yields and maintain afterglow emission lifetime.D ifluoroboron b-diketonate (BF 2 bdk) compounds are designed with multiple electrondonating groups to possess moderate k RISC values and are selected as luminescent dopants.T he matrices with carbonyl functional groups such as phenyl benzoate (PhB) have been found to interact with and perturb BF 2 bdk excited states by dipole-dipole interactions and thus enhance the intersystem crossing of BF 2 bdk excited states.T hrough dopant-matrix collaboration, the efficient TADF-type afterglow materials have been achieved to exhibit excellent processability into desired shapes and large-area films by melt casting, as well as aqueous afterglow dispersions for potential bioimaging applications.

In organic systems, it is very challenging to simultaneously achieve long afterglow lifetimes (τAG) and high afterglow efficiency (ΦAG). Here, luminescent dopants which feature a small rate of phosphorescence decay (kP) and modest rate of reverse intersystem crossing (kRISC) are designed and knr + kq values (nonradiative decay and quenching) of triplet excited states are suppressed by all means that include increasing molecular rigidity of luminescent dopants, screening organic matrices to strongly inhibit intramolecular motions of luminescent dopants, and deuteration of the luminescent dopants. Organic matrices are selected with large dipole moments to stabilize the singlet excited states of luminescent dopants via dipole–dipole interactions, reduce singlet–triplet splitting energy, and thus enhance ΦISC, leading to significant population of triplet excited states. Thermally activated delayed fluorescence mechanism is also used with modest kRISC to harvest triplet energies, significantly improve ΦAG to 64%, and maintain long τAG > 1.0 s. The obtained materials display intense afterglow brightness, excellent processability, and temperature‐sensing function.

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.