折叠型分子结构热活化延迟荧光材料构筑及其激子动力学和发光谱带宽调控研究

针对制约给-受体型TADF材料应用于有机信息显示产业存在的瓶颈问题：（1）OLED器件高亮度工作时效率迅速滚降；（2）材料发光谱半峰宽过宽。项目设计氧族五元杂环[2,3-B]喹喔啉类稠环骨架为受体单元，噻吩嗪/吩嗪为给体，萘环为桥连单元构筑折叠型结构分子。①研究通过分子内给、受体空间非键作用和递增的重原子效应协同叠加调制T与S间自旋-轨道耦合和反向系间转化过程电子自旋翻转动力学，实现显著缩短三线态激子寿命目标，解决效率滚降问题；②研究给、受体空间非键作用和位阻基团协同对分子发光过程引起结构弛豫的振动模式的抑制，实现发光谱半峰宽窄化的调控，解决材料发光谱过宽问题；③研究主体材料分子偶极矩和刚性对掺杂染料发光效率和发光谱半峰宽的影响规律，调控实现高效率窄带发光OLED器件。项目将研究出短三线态寿命和窄带发光的TADF材料，建立自主知识产权的TADF材料体系和新的TADF分子设计概念。

This project is pursuing to resolve two challenges of donor-acceptor type thermally activated delayed fluorescence (TADF) for information display. One is to suppress efficiency roll-off of TADF-based OLED，resulted from long lifetime of triplet exciton, and the other is to tune the spectral of TADF materials to achieve narrowband emission. This project would design and synthesize a new series of TADF materials with folded molecule geometries, in which the chalcogen-heterocyclic fused [2,3-B] quinoxalines and phenothiazines/phenazineto is used for acceptor and donor, respectively, and naphthalene for bridging unit. Firstly, heavy atom effect of chalcogen atoms in acceptor and intramolecular noncovalent interactions between the donor and acceptor are exploited to improve the mixing of singlet and triplet states via cooperatively enhanced spin-orbital coupling, which would speed the spin conversion of the reverse intersystem crossing, resulting in shorten lifetime of triplet exciton. This strategy hopes to resolve efficiency roll-off of the device. Secondly, intramolecular noncovalent interactions and the steric hindrance group in bridging unit are introduced to cooperatively suppress molecule relaxation during the light emitting, which would minimize the intramolecule reorganization energy and achieve the narrowband emission of resulting TADF materials. This strategy hopes to resolve the second challenges. Thirdly, OLED characterizing of developed TADF materials are focused on how the dipole moment and reorganization energy of the host affect the efficiency and the bandwidth of emission spectral, which would help to achieve highly efficient OLED with narrowband emission. This project would develop several advanced TADF materials with shorten lifetime of triplet exciton and narrowband emission, and also establish a new molecular design concept for concurrently achieving narrowband emission and efficient triplet–singlet spin conversion.