热活化延迟荧光(TADF)分子反向系间窜越的磁自旋效应调控机制研究

Thermally activated delayed fluorescence (TADF) materials possess the small the energy gap (ΔEST) between the lowest singlet (S1) and triplet (T1) excited states, TADF molecules have an efficient way to harvest triplet excitons for fluorescence through facilitated reverse intersystem crossing (RISC) (T1→S1)， allowing the internal quantum efficiency of the device to reach nearly 100%, which clearly breaks 25% efficiency limitation of fluorescent emitters. In recent years, it has attracted wide attention in organic transition metal complexes field. The ultimate challenge in TADF molecules is to develop universal approaches capable of controlling excited states for efficient electron-light conversions. This paper mainly study the influences of spin-orbit coupling, the spin exchange interaction, hyperfine coupling and magnetic field on the mechanism and rate of RISC during RISC for TADF molecules including Cu, Ag, Au transition metals. To clarify the RISC controlling mechanism of spin exchange interaction and magnetic spin effect and reveal the RISC rules of different metal centers, different ligands and steric hindrance on RISC. Research this subject, not only has a deeper understanding of the controlling mechanisms for RISC for transition metal TADF materials, providing effective approaches and mechanisms to tackle bottle-neck problem for TADF materials, but also offering scientific principles for multi-functional integration of magnetic - optical - electronic properties.

热活化延迟荧光(TDAF)分子材料具有较小的单-三重态能级差, 三重态可以反向系间窜越(RISC)转变成单重态发光，其内量子效率理论上可以达到100%, 远高于传统荧光材料的25%, 近年来特别是过渡金属TADF材料受到人们的广泛关注，其研究的挑战是发展调控光电转换效率的普适方法和原理. 本课题主要以Cu、Ag、Au配合物TADF材料为主要研究对象，借助量子化学计算程序，深入探讨RISC过程中自旋-轨道耦合作用、自旋交换作用、超精细耦合作用及磁场效应对RISC机理和速率的影响, 阐明自旋交换作用和磁自旋作用对RISC的调控机制，揭示不同金属中心、不同配体及空间位阻对RISC的影响规律. 开展此课题的研究，不仅能够更深层次理解过渡金属TADF分子中自旋交换作用和磁自旋作用对RISC的调控机制，而且为其解决瓶颈问题提供新的思路和机理，为实现磁-光-电多功能材料提供科学原理.

热活化延迟荧光(TDAF)材料分子其内量子效率理论上可以达到100%, 远高于传统荧光材料的25%,近年来特别是过渡金属TADF材料受到人们的广泛关注，其研究的挑战是发展调控光电转换效率的普适方法和原理.本项目主要以系列含铜(I)热活化延迟荧光（TADF）复合物为目标体系，借助于ORAC4.2.1、Gaussian16、MOMAP和optDFTw等程序包，在不同环境下，构建不同的计算模型，采用“最优调控区间分离密度泛函”结合极化连续介质模型（PCM）和ONIOM模块以及热振动相关函数（TVCF）方法计算获得几何结构、激发态电子结构及热活化延迟荧光物理参数(自旋-轨道耦合、辐射或无辐射跃迁速率和系间窜越及反向系间窜越速率等)，深入探讨交换耦合、磁偶极作用、自旋振动耦合及外加磁场对反向系间窜越及TADF机制的影响及其规律，并以此为基础设计新型高效的TADF材料，其详细理论和成果发表于J.Mater.Chem.C, Phys.Chem. Chem.Phys., J.Phys.Chem.A, Organic Electronics等高水平SCI学术期刊上，这为人们理解热活化延迟荧光现象提供理论基础，也为设计高效延迟荧光材料提供科学依据.