深红/近红外磷光双核铱配合物的合成及其电致发光性能研究

The deep-red/near-infrared phosphorescent iridium(III) complexes are indispensable for developing high performance organic light-emitting diodes (OLED) applied to the fields of white solid-sate lighting, full-color display and night-vision readable display. However, the reported deep-red/near-infrared phosphorescent iridium(III) complexes are very few and their luminous efficiencies are quite low. Based on literature review and analysis, these problems may arise from the fact that when used to design deep-red/near-infrared phosphorescent iridium(III) complexes, the conventional methods for red-shifting the emissions of iridium(III) complexes by extending the conjugation of ligands and introducing substituents to ligands have run into bottleneck. Therefore, this project presents a novel strategy to significantly red-shift the emissions by using 2-phenylpyrimidine-type ligands as “bridge” to synthesize dinuclear iridium(III) complexes. This new strategy not only focuses on the design of the ligand but also enhances the effects of the iridium centers, which is beneficial to break the bottleneck for designing deep-red/near-infrared phosphorescent iridium(III) complexes with conventional methods. Based on this new strategy, this project will synthesize a serial of deep-red/near-infrared phosphorescent iridium(III) complexes by reasonably controlling the conjugation of ligands and introducing the functional substituents to ligands, and then investigate their photoluminescent and electroluminescent properties, and finally analyze and establish the relationship between the structures and properties. In short, the ultimate aim of this project is to provide a new approach to develop highly efficient deep-red/near-infrared phosphorescent materials; therefore, it holds great theoretical value and practical significance.

深红/近红外磷光铱配合物对于高性能有机发光二极管在白光照明领域、全色彩显示及夜视可读显示领域的应用至关重要，但是目前报道的该类配合物数量少且发光效率低。经过对文献的梳理分析可知，出现这些问题主要是因为通过延长配体共轭体系以及引入取代基使铱配合物发光红移的传统思路在设计深红/近红外磷光铱配合物时遇到了瓶颈。因此，本项目提出通过以2-苯基嘧啶类配体为“桥梁”合成双核铱配合物使材料发光大幅度红移的新策略。该新策略既重视配体结构设计又增强了铱金属中心的作用，有助于突破传统思路在设计深红/近红外磷光铱配合物时遇到的瓶颈。基于此新策略，本项目拟通过合理控制配体共轭体系并引入各类功能取代基合成一系列深红/近红外磷光双核铱配合物，表征测试其各类性质，研究其电致发光性能，分析建立其结构与性质之间的关系。本项目旨在为发展新型高效深红/近红外磷光材料提供新途径，因而具有十分重要的理论价值和实际研究意义。

红光、深红光以及近红外光磷光材料对于高性能有机发光二极管在白光照明领域、全色彩显示及夜视可读显示领域的应用至关重要，但是目前报道的该类配合物数量少且发光效率低。针对这一困境，本项目通过设计新型有机配体并结合多金属中心配合物分子骨架以及利用氢键作用增强分子间作用等策略调节相应磷光配合物的发光颜色、增强其发光效率以及改善其电致发光性能。本项目设计合成得到了多种多样的磷光材料，包括中性双金属中心铱配合物、结构非对称铱配合物、带电荷双金属中心铜配合物、中性单/双/三金属中心铂配合物等，表征鉴定了它们的结构信息、热稳定性、基本光物理性质、基本电化学性质以及电致发光性质，同时采用理论计算对相关实验结果加以更深入理解或解释。基于以上各种磷光材料，采用溶液旋涂或真空蒸镀的方法制备了相应的有机发光二极管。其中，红光器件最大外量子效率为28.5%；深红光器件最大外量子效率为18.0%，色坐标为(0.69, 0.30)；近红外器件最大外量子效率为16.7%, 最大发射波长724 nm。这些效率与同类有机发光二极管在类似条件下的发光效率相比处于领先水平之列。本项目的研究结果表明，通过增加配合物中的金属中心数目，可以有效红移配合物的发光波长，提高配合物的发光量子效率，进而增强其电致发光能力。因此，本项目为发展新型高效红光、深红光以及近红外光磷光材料提供了新途径。