位阻型咔唑/芴双极性主体材料的设计、合成及其发光器件

The unipolar host materials of organic electrophosphorescent devices have the key problems of unbalanced holes and electrons, narrow exciton recombination zone, the difficult match of HOMO/LUMO energy level with adjacent charge-transporting layer，and the host materials with large rigid plane structure could have low glass transition temperature and triplet energy level that would lead to device instability and energy reversion between host and guest, ect. This project plans to introduce different electron-transport ability groups into the high luminous efficiency of carbazole/fluorene to construct steric bipolar compounds, which make them can transport electrons and holes simultaneously, balance carrier injection/transportation through structure changes, broaden exciton recombination zone and retain high triplet energy level to assure excitons effective recombination and luminescence in the emitting layer, and bulky steric hindrance effect can endow them with high thermal stability, stable amorphous form, suppress intermolecular interaction effectively. Consequently, it can improve the guest dispersion extent, suppress concentration quenching, triplet-triplet annihilation and excimer emission. Blue, green, red and white devices could be fabricated by using steric carbazole/fluorene bipolar compounds as universal hosts to research the relation ship among molecular structure, materials properties and performance of devices systematically to realize simple structure, reduce costs, have stable and high performance of phosphorescent devices for the applications in full-color display and white lighting.

针对有机电致磷光器件中单极性主体材料的空穴和电子不平衡、激子复合区域窄、HOMO/LUMO与相邻电荷传输层能级匹配难以及大面积刚性平面结构的主体材料玻璃化转变温度和三线态能级低易导致器件性能不稳和主客体间能量反转等关键性问题。本项目拟将具有不同电子传输能力的官能团引入到发光效率高的咔唑/芴中以构建位阻型双极性化合物，使其能够同时传输空穴和电子并通过结构变化来平衡载流子的注入/传输、扩大激子复合区域、保持较高的三线态能级，从而使激子在发光层内有效复合发光，而大体积空间位阻效应使其具有高的热稳定性、稳定的无定形态、能够有效抑制分子间作用，从而改善客体材料的分散程度、抑制浓度猝灭、三线态湮灭和二聚体发光。以位阻型咔唑/芴双极性化合物为通用主体材料制备红、绿、蓝以及白光器件，系统研究分子结构、材料性质以及器件性能之间的关系，实现结构简单、低成本、稳定高效的磷光器件在全彩显示及白光照明领域的应用。

本项目旨在将具有不同电子传输性能的官能团引入到咔唑或芴中，设计合成一系列具有单极性、双极性传输特征的大体积空间位阻效应主体材料。通过设计不同位阻效应的主体材料能够有效抑制分子间的相互作用，以解决客体材料高浓度掺杂下的浓度猝灭和三线态湮灭等问题。此外，大体积空间位阻效应赋予材料高的热稳定性和稳定的无定形态，从而使得器件稳定性得到极大改善。将不同电子传输性能基团引入到体系中，以调节其HOMO和LUMO能级，使得主体材料、客体材料、以及注入传输层之间的轨道能级匹配，降低激子能量损失、扩大激子复合区域、提高器件性能、探索材料结构与器件性能之间的关系。器件结果表明，基于螺-9,9′-氧杂蒽芴以及9,9′-二芳基芴大体积空间位阻效应的主体材料能够有效抑制浓度猝灭，并可实现客体材料在较宽的高浓度掺杂范围内器件能稳定发光。因而，可以简化器件制备工艺条件，降低客体掺杂浓度微小波动造成不利影响，提高大规模制备器件产品良率，降低成本。