双极树枝状主体材料的设计合成及性能研究

The scarcity of solution-processable host restricts the development of high-efficiency and low-cost phosphorescent organic light emitting diodes (PhOLEDs) seriously, which is also great challenge and opportunity to the chemists. In this proposal, we introduce the concept of bipolarity into the design of dendritic hosts, aiming at the acquisition of a novel solution-processable bipolar dendritic host for PhOLEDs. By judicious molecular design, the host materials in this proposal possess the following advantages: (a) dendrimers have well-defined molecular structures and high chemical purity can be reached, (b) more importantly, the good solubility of dendrimers makes them readily solution-processable, and thus the low-cost wet technique such as spin-coating and ink-jet printing can be applied in device fabrication, (c) the incorporation of both hole and electron injection/transporting units to the target molecules ensures balanced carrier fluxes in the emitting layer, which would lead to excellent device performance and low roll-off efficiency at high current density. By this way, we develop a series of novel host materials besides small molecular and polymer host. Eventually, our project will open up a new way for the realization of low-cost and high efficiency PhOLEDs.

可溶液加工的主体材料的缺乏，严重制约着高效、低成本的有机磷光电致发光器件的发展。鉴于其在基础前沿和应用研究上的机遇和挑战，本项目旨在面向低成本的溶液加工工艺，同时结合树枝状分子结构确定且具有良好的溶液加工性能的特点和双极主体有利于实现载流子的平衡注入/传输从而提高器件性能的优点，将双极的概念引入到树枝状主体材料的设计中，开发一类可溶液加工的双极树枝状主体材料，目的是在小分子主体和聚合物主体之外发展第三类材料体系，并为高效、低成本的有机磷光电致发光器件的组装提供材料保证。

可溶液加工的主体材料的缺乏，严重制约着高效、低成本的有机磷光电致发光器件的发展。本项目旨在将双极的概念引入到树枝状主体材料的设计中，开发一类可溶液加工的双极树枝状主体材料，目的是在小分子主体和聚合物主体之外发展第三类材料体系，为高效、低成本的有机磷光电致发光器件提供材料基础。我们通过对双极树枝状主体的各构建单元（空穴传输单元、电子传输单元、连接单元）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）、光学带隙（单线态/三线态能级）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、低效率衰减等特点的溶液加工型磷光器件。其中，基于简单单层器件结构的绿光和蓝光溶液加工型磷光器件的最大电流效率分别达到18.2 cd/A和2.9 cd/A。基于双层器件结构的绿光和蓝光器件的最大电流效率分别达到58.6 cd/A和26.3 cd/A。