具有高激子利用率的基于扭曲D-π-A结构的OLED低聚物发光材料的激子行为研究

Printing technology applied in OLED fabrication exhibits such periorities as facile large-size fabrication, high efficiency of raw material consuming, rather lower production cost, and so on, which will grow up to be major fabrication technology of OLED. However, the OLEDs fabricated by printing technology show such key technology bottlenecks as rather lower luminous efficiency (EQE) and more inferior stability, which hold back its development. To solve them, the novel system of luminescent oligomer with high exciton utilization efficiency (χE), which can exceed the theoretical limit value of 25 % of classical fluorescent material, will be designed and prepared in this project. It will realize the final goal of improve EQE and stability of OLED fabricated by printing technology. To this aim, the following work will be carry on in this project. The luminescent oligomers based on twisting D-π-A structure will be designed and prepared. In this project, three types of luminescent oligomers are involved, which are straight-line type, ladder type, and dendrimer type, respectively. The relationship between material structure and performance of luminescent oligomers based on twisting D-π-A structure will be researched and investigated in detail. The exciton behavior in luminescent oligomers based on twisting D-π-A structure will be studied and discussed, which will interpret the enhancing mechanism of χE and regulation mechanism of charge transfer (CT) / local exited (LE). Based on above two mechanisms, the internal association between material structure and EQE will be disclosed, which will act theoretical direction of controllable designing and preparing of novel luminescent oligomers with high χE. Finaly, it will be utilized in printing technology OLED with high EQE (＞5 %) and good stability.

有机电致发光器件（OLED）的印刷制备技术具有易大面积成膜、材料利用率高和低成本等优势，将成为OLED制备技术的主要发展方向。针对制约OLED印刷制备技术发展的关键问题，即发光效率（EQE）较低和稳定性差，本项目旨在开发激子利用率（χE）突破传统荧光材料的极限值（25 %）的新型低聚物发光材料体系，实现提高印刷制备OLED的EQE与改善其稳定性的目标。围绕研究目标，本项目将开展以下工作：设计合成基于扭曲D-π-A结构的直链型、工字型和树枝型三种低聚物发光材料，研究探讨材料结构与材料性能间的关系规律；开展基于扭曲D-π-A结构的低聚物发光材料的激子行为研究，阐释χE强化机制和激子电荷转移（CT）态/局域激发（LE）态调控机制, 从而揭示材料结构与EQE间的内在关联，可用于指导新型高χE的低聚物发光材料的可控设计与合成，满足印刷法制备高效（EQE＞5%）稳定的OLED的要求。

OLED的印刷制备技术具有易大面积成膜、材料利用率高和低成本等优势，将成为OLED制备技术的主要发展方向。针对制约OLED印刷制备技术发展的关键问题，即发光效率（EQE）较低和稳定性差，本项目开发了激子利用率（χE）突破传统荧光材料的极限值（25 %）的新型低聚物发光材料体系，实现了提高OLED的EQE与改善其稳定性的目标。围绕研究目标，本项目开展了以下研究：设计合成了基于扭曲D-π-A结构的直链型、工字型和树枝型三种低聚物荧光材料，探讨了材料结构与材料性能间的关系规律，开展了基于扭曲D-π-A结构的低聚物荧光材料的激子行为研究。通过本项目工作，得到以下结论：1）获得了高效稳定的扭曲D-π-A结构的低聚物荧光材料，其器件的EQE均大于5%，χE均大于25 %，此外在高电流密度下的效率滚降较小；2）揭示了材料结构与光电特性间的关系，如D基团与A基团搭配、π基团的共轭长度、分子空间构型，可用于指导新型高效荧光材料的可控设计；3）探明了材料的光效强化机制和激子电荷转移（CT）态/局域激发（LE）态调控机制，完善了这类材料的相关理论研究，为高效稳定的OLED材料设计提供理论支撑。