双极性树枝状蓝光PhOLED用Ir（Ⅲ）金属配合物的合成与性能研究

Phosphorescent organic light-emitting devices (PhOLED) based on luminescent heavy metal complexes, particularly iridium(Ⅲ), are playing a key role in next generation flat panel displays and solid-state lighting. To improve carrier-transporting balance, consequently to achieve the excellent PhOLEDs with high luminescence efficience and desired lifetime, blue ambipolar and solution-processable phosphorescent light-emitting dendrimers will be synthesized in this work, which consist of light-emitting cores, dendrons (branches), and surface groups. Several important design features will be considered: firstly, the high-triplet-energy fac-Ir(pmb)3 and fac-Ir(ppz)3 were employed to act as deep blue light-emitting cores; secondly, the dendrons are composed of tetrasubstituted phenyl rings and ambipolar P=O-Cz (Cz: carbazole) derivatives. The precise control over the intercore distances means that the emissive cores can be photophysically independent thus avoiding interactions that lead to the quenching of the luminescence. Therefore,this will made it possible to use dendrimers with electron and hole transport abilities as light-emitting layer to improve carrier-transport propertier in PhOLED, avoiding the need for a host. Thirdly, the surface groups of suitable alkyl or alkoxy chains ensure solubility and that good-quality spin-coated films can be formed. The designed blue phosphorescent light-emitting dendrimers will be optimized by DFT (DFT: density functional theory), and then will be synthesized by Suzuki, Ullmann, Vilsmeier-Hacck and Yamamoto reactions. Molecular structures of dendrimers will be identified by 1H-NMR, FT-IR, Mass spectrometry and so on. The single-layer and bilayered blue PhOLEDs will be fabricated by using dendrimers as light-emitting materials to research the carrier-transport properties of devices. Meanwhile,the influence of dendritic architecture, intermolecular interactions and energy-transfer process of blue light-emitting cores, branches and surface groups will be investigated. Consequently,the luminescente mechanism of mentioned blue light-emitting dendrimers will be discussed deeply by theoretical and experimental approaches.

本项目从平衡蓝光PhOLED的载流子传输、提高蓝光PhOLED效率、寿命为目标，设计并合成双极性树枝结构蓝色磷光Ir(Ⅲ)金属配合物。以三线态能级较高fac-Ir(pmb)3或fac-Ir(ppz)3为"发光中心"，保证蓝光的色纯度；以双极性的P=O-Cz衍生物为"树枝单元"，改善PhOLED的载流子传输平衡性，提高其效率；引入表面功能团改善发光材料的溶解性，实现器件的全"湿法"加工；构建具有稳定空间立体结构的蓝光PhOLED用发光材料。通过优化设计，合成并提纯上述材料，确定其分子结构，表征其光物理与光化学性能，将其作为主体发光材料制作蓝光PhOLED，研究器件的载流子传输特性；结合实验和理论模拟计算结果，深入地研究该类材料的空间结构、分子间相互作用以及各功能团间的能量传递过程，从深层次上揭示该类蓝色磷光发光材料的发光机理。

有机电致发光器件（OLED：Organic Light Emitting Devices）由于节能、低耗、可实现柔性显示等优点近年来备受研究者的关注。但是，三基色（红、绿、蓝）发光材料发展的不平衡，尤其是蓝光材料的严重缺乏，已成为OLED产业化和全彩色显示发展的瓶颈。而磷光有机电致发光器件（PhOLED：Phosphorescent organic light-emitting devices)由于其高效率成为研究的热点。本项目从克服PhOLED在高电流密度下严重的浓度淬灭现象，平衡载流子传输、提高器件稳定性，以及改善材料的溶解性出发，设计并合成以多氮唑为配体的蓝色及蓝绿色Ir(Ⅲ)金属配合物。多氮唑本身具有电子传输特性，同时咔唑具有空穴传输特性，而己烷则为柔性基团，通过引入不同的辅助配体来调节材料的发光颜色。主要工作包括：1）以三氮唑为主配体的蓝色以及蓝绿色Ir(Ⅲ)金属配合物；2）以苯基苯并咪唑为主配体的蓝色以及蓝绿色PhOLED用发光材料；3）以四氮唑为主配体的蓝色PhOLED用发光材料。所合成的上述材料均具有较好的溶解性和成膜性，为湿法制备蓝色PhOLED器件提供了可能性。同时材料具有较大的空间位阻效应，可制备自主体型的蓝色PhOLED器件。(Czphtz)2Ir(N^N)和(CzPtaN4)2Ir(N^N)的光电特性已进行了详细的研究，其自主体型器件的效率滚降现象非常微弱，达到了我们预期的目标。(CzPtaN4)2Ir(N^N)为中心的蓝色PhOLED用发光材料的光物理和光化学特性已进行了表征，关于自主体型器件的研究还在进行中。关于发光机理以及能量传递过程在其它双极性蓝色磷光Ir(Ⅲ)金属配合物中的应用还在进一步的研究中。