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.

Due to the energy gap law, the direct fabrication of efficient organic afterglow materials with long emission wavelengths at ambient conditions remains challenging. Here, luminescent dopants with moderate k RISC values of 10 0 -10 1 s −1 are designed to harvest triplet energies, simultaneously improving afterglow efficiency and maintaining emission lifetimes >0.1 s. Organic matrices with large dipole moments are selected to populate the triplet excited states of the luminescent dopants and suppress their nonradiative decay and quenching. The dopant-matrix systems exhibit TADF-type organic afterglow with quantum efficiency of 20% to 60% and emission wavelengths exceeding 600 nm. Because of their singlet excited state nature, the TADF-type afterglow emitters can efficiently transfer excited energy to rhodamine B or cyanine 5.5 fluorescence dyes for the construction of red and near-infrared afterglow materials which display promising bioimaging applications.

A two-component design strategy developed by us and other research groups, where a second component is used to control the triplet excited state properties of the luminescent component (the first component), has been shown to allow a flexible choice of building blocks to prepare high-performance afterglow materials with intriguing properties. Here, we report the realization of intense organic afterglow and diverse functions by extending this two-component strategy to dopant-matrix systems, which feature small k F , small k P , and very small k nr + k q . With coronene molecules and deuterated coronene being fixed as luminescent dopants, variation of organic matrices reveals that either small-molecule organic matrices or polymeric matrices can be used to accommodate coronene molecules and largely reduce k nr + k q values, leading to the emergence of very bright organic afterglow at ambient conditions. The obtained coronene-matrix materials have been found to be readily processed into desired shapes, large-area thin films, and aqueous afterglow dispersions by melt casting and other techniques, function as efficient afterglow donors for the fabrication of red afterglow materials, and exhibit promising time-gated bioimaging functionality to avoid interference from strong fluorescence backgrounds.

We report intense dopant-matrix afterglow systems with an afterglow efficiency (Φ AG ) of 47% and an afterglow lifetime (τ AG ) of 1.3 s. Luminescent difluoroboron β-diketonate (BF 2 bdk) dopants and their deuterated counterparts are designed with naphthalene and carboxylic acid groups. After doping into benzoic acid (BA) matrices, room-temperature afterglow brightness and afterglow duration of the BF 2 bdk-BA materials have unexpectedly been found to reach the levels of those at 77 K, which indicates that hydrogen bonding between BF 2 bdk and BA, as well as the deuteration technique, can reduce k nr + k q of BF 2 bdk triplets to very small values even at room temperature. Detailed studies reveal that the BF 2 bdk possesses typical 1 ICT characters in the S 1 state and distinct 3 LE composition in the T 1 state, and thus shows a high Φ ISC and a small k P to obtain a high Φ AG and a long τ AG . Besides, triplet−triplet annihilation has been found in the dopant-matrix system at high doping concentrations to further increase Φ AG .

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The past several years have witnessed the tremendous development of novel chemical structures, new design strategies and intriguing applications in the field of room‐temperature phosphorescence (RTP) and organic afterglow materials. This Review article focuses on recent advancements of high‐performance organic afterglow materials obtained by two‐component design strategies such as a dopant‐matrix, donor–acceptor, sensitization, and energy‐transfer strategies. Based on some cutting‐edge studies, organic afterglow efficiency has been largely improved, exceeding 90 % in several cases. Organic afterglow durations reach tens of seconds in phosphorescence systems and hours in donor–acceptor systems. Organic afterglow brightness outcompetes some inorganic afterglow materials in the first several seconds after ceasing excitation source. Organic afterglow colors cover the whole visible regions and extend to near‐infrared regions with respectful afterglow efficiency. On the basis of these achievements, researchers demonstrate promising applications of organic afterglow materials in diverse fields, which has also been reviewed.

It is well known that benzophenone has short phosphorescence lifetime around 1 ms even at 77 K. Here we report benzophenone-containing emitter with unprecedented long phosphorescence lifetime of 1.8 s...