Li Shuai, Fu Liyuan, Xiao Xiaoxiao, Geng Hua, Liao Qing, Liao Yi, Fu Hongbing
Institute of Molecule Plus, Scholl of Chemical Engineering and Technology, Tianjin University, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin, 300072, China.
Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Beijing Advanced Innovation Center for Imaging Technology, Capital Normal University, Beijing, 100048, China.
Angew Chem Int Ed Engl. 2021 Aug 9;60(33):18059-18064. doi: 10.1002/anie.202103192. Epub 2021 Jul 7.
Control of excited-state dynamics is key in tuning room-temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) emissions but is challenging for organic luminescent materials (OLMs). We show the regulation of TADF and RTP emissions of a boron difluoride β-acetylnaphthalene chelate (βCBF ) by controlling the excited-state dynamics via its J- and H-aggregation states. Two crystalline polymorphs emitting green and red light have been controllably obtained. Although both monoclinic, the green and red crystals are dominated by J- and H-aggregation, respectively, owing to different molecular packing arrangements. J-aggregation significantly reduces the energy gap between the lowest singlet and triplet excited states for ultra-fast reverse intersystem crossing (RISC) and enhances the radiative singlet decay, together leading to TADF. The H-aggregation accelerates the ISC and suppresses the radiative singlet decay, helping to stabilize the triplet exciton for RTP.
控制激发态动力学是调节室温磷光（RTP）和热激活延迟荧光（TADF）发射的关键，但对有机发光材料（OLM）来说具有挑战性。我们展示了通过控制二氟化硼β-乙酰萘螯合物（βCBF）的J-和H-聚集态的激发态动力学来调节其TADF和RTP发射。可控地获得了发射绿光和红光的两种晶体多晶型物。尽管都是单斜晶系，但由于分子堆积排列不同，绿色和红色晶体分别以J-和H-聚集为主。J-聚集显著减小了最低单重态和三重态激发态之间的能隙，实现超快反向系间窜越（RISC），并增强了辐射单重态衰减，共同导致TADF。H-聚集加速了ISC并抑制了辐射单重态衰减，有助于稳定用于RTP的三重态激子。
