热活化延迟荧光分子材料固态发光性质及机理理论研究

作为新一代有机电致发光分子材料，热活化延迟荧光(TADF)分子材料备受关注，但其种类和数量尚不满足实际应用要求，缺乏对TADF分子电致发光机制的足够认识是阻碍开展TADF分子有效设计的重要原因之一。器件中TADF分子处于无定型固态，且TADF分子的激发态性质及动力学过程对环境非常敏感，因此，开展固态TADF分子材料电致发光机制研究很有必要。本项目拟采用分子动力学（MD）和量子力学/分子力学（QM/MM）及激发态动力学相结合的研究方案，通过MD方法模拟TADF分子薄膜，利用QM/MM方法计算聚集体中TADF分子的电子结构及振动信息，进而利用振动关联函数方法获得TADF分子的激发态衰减速率及振动分辨的发射光谱。研究结果有助于人们理解TADF分子的固态发光现象、掌握其发光性能调控规律，对TADF分子的有效设计及器件性能的提高具有重要参考意义。

As the new-generation organic electroluminescent molecular materials, thermally activated delayed fluorescence (TADF) molecules have attracted great attention recently. However, both the species and amounts of TADF molecules are far from meeting the requirement for applications. One important reason is the lack of enough knowledge of the electroluminescent mechanism of TADF molecules, which also impedes the effective design of TADF molecules. Since most TADF molecules in devices are in amorphous solid state, and the excited states properties and their dynamic processes are quite environment sensitive, it is of great necessity to perform the electroluminescent mechanism study on TADF molecules in solid state. In this project, a molecular dynamic (MD) simulations combined with quantum mechanics/molecular mechanics (QM/MM) method and excited-state dynamics scheme is proposed. MD simulations are carried out to obtain the film. Then the QM/MM method is used to calculate the electronic structures and vibrational information of aggregates. Based on the information above, the thermal vibration correlation function method is adopted to calculate the decay rates and emission spectra with vibrational structures. The research results are helpful for one to understand the light-emitting phenomenon of TADF molecules in solid state, and also to grasp the rules to modulate their performance. Important references could be provided for the effective design of TADF molecules and the performance enhancement of devices.