摘要
Thermally activated delayed fluorescence(TADF)materials with aggregationinduced emission(AIE)features can overcome aggregation-caused quenching(ACQ)and emit intensely in aggregate states and thus have attracted enormous attention in the fields of high-efficiency organic light-emitting diodes,bioimaging,photodynamic therapy,photocatalysis,etc.However,their corresponding exact working mechanisms at the microscopic level are still far from clear.Herein,by carefully investigating the physical properties of our newly designed TADF material 6-(10H-spiro[acridine-9,9′-fluoren]-10-yl)nicotinonitrile in various states,we concluded that conformational isomerization plays an important role in realizing high photoluminescence quantum yields in its amorphous neat film state,in which the high-lying quasi-axial conformations with non-TADF features and low-lying quasiequal conformations with TADF characteristics serve as the host matrix and dopant,respectively,thus suppressing ACQ in disordered aggregate states.Our work not only offers a new possible microscopic mechanism by using conformational isomerization for the AIE-TADF phenomenon but also provides a novel method for designing high-efficiency AIE-TADF emitters.
基金
National Natural Science Foundation of China,Grant/Award Numbers:52130304,51821002,52003185,52003186
National Key Research&Development Program of China,Grant/Award Numbers:2020YFA0714601,2020YFA0714604
Suzhou Key Laboratory of Functional Nano&Soft Materials
Collaborative Innovation Center of Suzhou Nano Science&Technology
the 111 Project
Joint International Research Laboratory of Carbon-Based Functional Materials and Devices。
