具有自掺杂特性的树枝状蓝光荧光材料的设计合成与性能研究

Solution-processed blue fluorescent materials have encountered problems of low device efficiency and poor color purity, which has greatly affected the development of the printable organic light-emitting diodes (OLEDs). Considering that the host/dopant system has been widely used to enhance the device efficiency of light-emitting materials, this proposal aims to introduce the host/dopant concept which has been widely used in vacuum-deposited OLEDs into the design of solution-processed blue fluorescent materials, that is, to develop ‘self-host’ blue fluorescent dendrimers by using high-efficiency blue fluorescent dopant as the core, oligcarbazole/arylamine as the periphery dendritic host, and flexible alkyl chain as linkages. Herein，the flexible alkyl linkage can keep the optical-electronic properties of the dopant and host independent. By developing new pure-blue/deep-blue emitters or incorporating blue dopants with thermally activated delayed fluorescence (TADF) effect, modulating the HOMO energy levels and triplet energy levels of the periphery dendrons, and optimizing the topological structures of the dendrimers, we can coordinately enhance the efficiency and color purity of the dendrimers. This proposal is expected to enhance the device efficiency of the blue dendrimers up to 8～12 cd/A, and at the same time, the CIE coordinates are kept at the pure-blue or deep-blue zone with y value < 0.1. We believe that, this research will provide innovative solutions for developing low-cost solution-processed OLED materials and push forward the development of the OLED display technology.

可溶液加工蓝光荧光材料面临器件效率偏低、色纯度较差等问题，已经成为制约印刷型有机电致发光技术发展的瓶颈。鉴于主/客体掺杂体系在提高材料器件效率和改善稳定性方面的突出优势，本项目旨在将蒸镀型器件组装普遍采用的主/客体掺杂的概念引入到树枝状蓝光荧光材料的分子设计中，发展一类具有自掺杂特性的树枝状蓝光荧光材料，即采用高效蓝光荧光掺杂剂为发光核，以宽带隙齐聚咔唑/芳胺主体作为外围树枝，通过柔性烷基链的连接方式保障掺杂剂与主体的光电性质互不影响。通过开发新型纯蓝光/深蓝光荧光掺杂剂及引入具有TADF效应的蓝光掺杂剂、调节外围树枝主体的HOMO能级和三线态能级以及拓扑结构，实现材料的器件效率与色纯度的协同提升，力争在保证材料色坐标位于纯蓝光甚至深蓝光区(CIE坐标y值<0.1)的同时，将器件效率提高至目前蒸镀型小分子荧光材料的性能水平（8～12 cd/A），形成对本领域发展具有推动意义的研究成果。

溶液加工型高效蓝光材料的缺乏，是印刷显示产业化过程中一个不可回避的难点。针对这种瓶颈，本项目将主/客体掺杂的概念引入到树枝状蓝光荧光材料的设计中，开发了一类具有自掺杂特性的的树枝状蓝光荧光材料，旨在实现器件效率与色纯度的协同提升。我们通过对树枝状蓝光荧光材料的内核客体、树枝主体以及自掺杂树枝状荧光材料的化学结构优化和拓扑结构改进，系统揭示了其分子结构与其基本光物理性质、电化学性质以及器件性能之间的关系，探索出调控其热力学稳定性、能级结构（HOMO/LUMO能级）和光学带隙（发光颜色）等关键因素的有效途径，制备出了具有简单结构、高发光效率、高色纯度等特点的溶液加工型蓝光荧光器件。项目执行期间，发表学术论文3篇，申请中国发明专利1项，参加国际和国内会议交流3次。