菲并咪唑衍生物双极分子构筑的CIEy<0.08的深蓝光OLED的光电性能研究

Due to the spontaneous emission performance, short response time, wide viewing angle, high contrast ratio and flexible display, organic light-emitting diodes (OLEDs) are promising candidates for flat-panel displays and next-generation solid-state lighting. However, almost the reported phosphorescent and TADF electroluminescences are difficult to realize deep-blue emitting with CIEy < 0.08. Low quantum yield and intricate relationship between device efficiency and the molecular energy level are the bottleneck for the development of deep-blue devices. Based on above problems, this study utilizes ambipolar characteristics organic molecules with D–π–A architecture by attaching the electron acceptor phenanthroimidazole and electron donor acridine derivatives, and further deprotonation for the NH group on imidazole employing by a wide variety of N–aromatic substituents linked electron-withdrawing groups. Non-doped deep-blue OLEDs employing by the phenanthroimidazole derivatives as emitting layers are fabricated. Efficient deep-blue electroluminescence with CIEy < 0.08 are obtained through the optimization of device structure to balance between carrier injection and transmission. This study will focus on explorations of the relationship between molecular structure and molecular energy level, and establishing the structure-function relationship between the molecular energy level and device efficiency. It is believed that this study can provide theoretical and experimental data for the molecular design, device structure optimization and structure-function relationship of the deep-blue OLEDs.

有机电致发光二极管(OLEDs)具有自发射、响应时间短、视角广、对比度高、可弯曲等优点，因而在平板显示和下一代固体照明技术中具有广阔的应用前景。本项目针对当前磷光材料和热活化延迟荧光材料难以实现CIEy<0.08的深蓝光发射，深蓝光OLED器件效率低且效率与分子结构/能级的构效关系相对复杂等问题，以菲并咪唑作为电子受体，吖啶衍生物作为电子给体，吸电子基团的芳香胺对咪唑NH去质子化修饰，形成具有双极特性D–π–A构型的菲并咪唑衍生物。利用合成的分子作为非掺杂型OLED的发光层，通过对器件结构的优化提升器件载流子注入和传输的相对平衡，制备高发光效率的CIEy<0.08的深蓝光OLED器件。重点探索发光层的分子结构与分子能级的关系，建立OLED器件发光层分子能级与OLED器件效率的“构效机理”。填补当前非掺杂型深蓝光OLED器件在分子设计、器件结构优化及分子对器件性能构效关系的理论与实验数据空白

制备非掺杂型CIEy<0.08的深蓝色电致发光器件在显示和医疗消杀领域具有广阔的应用前景。然而这类高能系的发光材料经过二十几年的发展，仍然无法实现器件效率和稳定性的兼顾，亟需一类新型的有机材料给显示和照明领域带来一场革命，同时打破日韩等国对我国材料专利的封锁。本项目利用菲并咪唑作为电子受体，咔唑衍生物作为电子给体，利用功能性基团二苯基膦氧对咪唑NH去质子化修饰，形成具有双极特性D–π–A构型的深蓝光分子。利用合成的分子作为非掺杂型OLED的发光层，通过器件结构的优化制备CIEy<0.08的深蓝光OLED器件，实现了最大电流效率为3.65 cd A−1，最大外量子效率为3.42%，激子利用率高达100%。结合量化计算和发光性能之间的构效关系，证明了分子设计中引入功能性基团二苯基膦氧能够不仅能够抑制分子间的聚集导致的发光猝灭，还可以增强了电子态的定域激发特征，有效抑制分子内和分子间电荷转移引起的红移。大位阻的二苯基膦氧调控激发态高度扭曲的构型，从而抑制分子间的相互作用，在器件工程中实现了电子和空穴传输的相对平衡。同时这类材料在光电器件制备中均采用了非掺杂的蒸镀技术，有利于实现器件的可控制备，这类研究为新型非掺杂型深蓝-近紫外OLED器件的分子设计、器件结构优化及实际应用奠定基础。申请人结合前期工作积累，系统阐述和类比了近紫外-深蓝色电致发光材料及器件的发展，给出了各类材料在构筑近紫外-深蓝色电致发光器件存在的优势和短板。并在国际顶级综述Chem. Soc. Rev.发表。