超支化超分子磷光聚合物的合成及其性能研究

Hyperbranched polymers are of current interest for their potential applications in organic light-emitting diodes (OLEDs). Compared to linear polymers, hyperbranched polymers displayed many advantages, such as high solubility, good quality amorphous films and unfavorable crystallization. However, some challenges still exist in developing high-performance hyperbranched polymers. For example, it is difficult to control the distribution and exact content of the iridium complex in the conventional hyperbranched polymers. Moreover, a trace of metal catalyst remaining in the polymers would inevitably impede the improvement of device performances. In addition, the molecular weights and polydispersity of hyperbranched polymers are hard to be defined during the polymerization process, which usually generate the batch to batch variation. In this project, we present the concept of hyperbranched supramolecular polmer which inherits the advantages of hyperbranched polmer and overcomes the defects of it. Therefore, this project intends to design and synthesize the iridium complexes (Ir-3C) modified by three groups of dibenzo-24-crown-8 (DB24C8), the luminous monomers (L-2C) modified by two groups of DB24C8 and the luminous monomers (L-2D) modified by two groups of dibenzylammonium (DBA). Then, the hyperbranched supramolecular phosphorescent polymers were self-assembled using Ir-3C as core, L-2C and L-2D as branch, based on the host-guest interactions between DB24C8 and DBA at high concentration. Keeping the mole ratio of 1:1 between the monomers of DB24C8 and DBA, we will obtain a series of solution-processable white phosphorescent hyperbranched supramolecular polymers while changing the relative proportion of these luminous monomers. This project puts forward a new effective approach for designing of solution-processable white light-emitting materials, and will play a positive role in applying the organic light-emitting diodes into flat-panel displays and solid state lighting.

超支化聚合物具有溶解性好、容易成膜、不易结晶等优点，在有机电致发光器件（OLED）上有很好的应用。但是，传统的超支化聚合物纯化困难，重复性差，聚合物中各单体单元的比例难以控制。为了克服超支化聚合物的缺点，继承其优点，本项目将超分子概念引入到超支化聚合物中，得到超支化超分子聚合物。基于此，本项目拟合成含三个DB24C8基团的铱配合物（Ir-3C）、含两个DB24C8基团的发光单元（L-2C），以及含两个DBA基团的发光单元（L-2D）；利用DB24C8与DBA之间的超分子相互作用，以Ir-3C为核，以L-2C和L-2D为枝，自组装形成超支化超分子磷光聚合物。保持发光单元中DB24C8与DBA的总摩尔数相等，通过调节各发光单元的摩尔比来精确调控聚合物的发光颜色，获得白色磷光超支化超分子聚合物。本项目提出了一种新颖的制备可溶液加工磷光材料的有效方法，并将促进OLED在显示和照明中的应用。

超分子聚合物发光材料兼备有机小分子和传统聚合物发光材料的优点，克服了它们的缺陷，在电致发光器件上具有潜在的应用价值。另外，树枝状化合物具有溶解性好、容易成膜、不易结晶等优点，在有机电致发光器件（OLED）上有很好的应用。基于此，本项目合成了含双苯并-24-冠-8（DB24C8）单元的新型橙黄光铱配合物，以及含二级铵盐（DBA）单元的芴-硫氧芴主体材料单元；通过改变二级铵盐的对离子类型，得到了对离子分别为溴离子、六氟磷酸根离子和四咪唑硼离子的主体单元。利用含DB24C8的铱配合物与DBA的主体单元之间强的超分子相互作用，得到了含不同对离子的黄色磷光超分子聚合物。其中，以六氟磷酸为对离子的超分子聚合物为发光层的聚合物电致发光器件的性能最好，其最大流明效率为12.32 cd A-1，色坐标为(0.57, 0.43)。同时，我们合成了一系列含载流子基团的树枝状磷光铱配合物Ir-1，Ir-2和Ir-3（以二苯并噻吩为环金属配体，吡啶甲酸为辅助配体）。为了研究它们的电致发光性能，我们利用旋涂技术将Ir-1，Ir-2和Ir-3作为发光层制备了非掺杂的可溶液加工的OLEDs。我们成功地用制备了绿色可溶液加工的电致发光器件。其中，基于Ir-3的OLEDs的最大流明效率为0.24 cd/A，最大亮度为2520 cd/m2。本项目合成了多种可溶液加工的超分子磷光聚合物和树枝状磷光铱配合物，为制备可溶液加工的有机电致发光器件提供了材料基础。