Highly‐Efficient Visible‐Light‐Excitable TADF‐Type Organic Afterglow Materials via Intramolecular Charge Transfer Technology

Abstract We present the development of three distinct highly efficient visible‐light‐excitable afterglow systems based on thermally activated delayed fluorescence (TADF) mechanisms, employing an intramolecular charge transfer strategy. The resulting TADF‐type afterglow materials demonstrate emission lifetimes in the range of hundreds of milliseconds and photoluminescence quantum yields (PLQY) between 65% and 80%, exhibiting remarkable temperature‐responsive properties. By incorporating an additional electron‐donor functional group (D') into the molecular framework of donor‐acceptor D‐A‐type luminophores, specifically difluoroboron β‐diketonate (BF 2 bdk), we designed novel D‐A‐D'‐type compounds that exhibit a moderate rate of reverse intersystem crossing which facilitates the emergence of TADF‐type afterglow from BF 2 bdk in a rigid crystalline matrix. Furthermore, this design approach elevates the highest occupied molecular orbital energy level, thereby realizing TADF‐type afterglow emission under visible light excitation. Our findings highlight the significance of this research in advancing the design of high‐performance organic TADF afterglow materials.