具有水平优势取向跃迁偶极距的有机荧光材料及其电致发光器件研究

In the past few years, improving ratios of horizontally orientated transition dipole moments (TDMs) of emitters has been regarded as an important approach of boosting optical outcoupling efficiencies and consequently external quantum efficiencies (EQEs) of organic light-emitting diodes (OLEDs). Recently phosphorescent heavy-metal complexes with preferentially horizontal TDMs have evolved rapidly, and thus considerable progresses have been made in the EQEs of phosphorescent OLEDs. In contrast, the development of excellent fluorescent emitters with high device performance remains far behind. To solve the key problems of fluorescent emitters, this project aims to design and synthesize a variety of full-color organic fluorescent emitters with preferentially horizontal TDMs. Through the suitable combination of theoretical simulations and experimental investigations, the relationship between molecular structure and preferential orientation of TDMs in fluorescent emitters will be systematically studied. Multicolor OLEDs with high optical outcoupling efficiency and excellent device performance will be designed and fabricated through employing the newly-designed organic fluorescent emitters and other compatible functional materials. The aim of this project is to produce competitive organic fluorescent emitters with intellectual property rights in the international academic community.

近年来，提高发光材料跃迁偶极矩的水平取向比例作为提升有机电致发光器件（organic light-emitting diodes，OLEDs）的光耦合输出效率的一种重要途径，引起了众多研究者的广泛关注。随着具有水平优势取向跃迁偶极矩的重金属磷光材料的不断涌现，磷光OLEDs的发光效率近来得到了显著提升。然而，与成熟的重金属磷光材料相比，有机荧光材料的发展则相对滞后。针对目前有机荧光材料发展的关键问题，本项目拟开发出具有水平优势取向跃迁偶极矩的全色高效荧光材料体系。通过理论模拟和实验测试相结合的模式，研究有机荧光材料的分子结构与跃迁偶极矩取向之间的关系。采用合适的材料配伍构筑兼具高的光耦合输出效率和优异发光性能的多色荧光OLEDs，形成在国际上具有影响力和自主知识产权的荧光材料体系。

针对目前国际上OLED发光材料及器件研究中的关键问题，本项目重点开展了具有水平优势取向跃迁偶极距的热活化延迟荧光（TADF）材料及器件的研究，获得了一系列重要研究成果，构筑的多色OLED的性能指标达到了国际先进水平。这些研究成果对有机光电子领域的发展具有重大意义。.发展了“分子长轴延伸”策略来调控TADF材料的激发态跃迁偶极矩，开发了一系列高效的蓝光、橙红光和红光TADF材料体系，获得了高效的多色荧光OLEDs。其中，蓝光TADF材料SBA-2DPS获得了87%的跃迁偶极矩水平取向度，构筑的OLED实现了深蓝光发射和高达25.5%的最大外量子效率；非对称的橙红光TADF材料TRZ–SBA–NAI获得了高达87%的发光量子效率和高达88%的跃迁偶极距水平取向度，构筑的器件实现了高达31.7%的最大外量子效率，是目前国际上报道的橙红光TADF材料的最高效率之一；红光TADF材料ANQDC-DMAC获得了高达95%的发光量子效率和约80%的跃迁偶极矩水平取向度，其器件实现了615 nm的红光发射和高达27.5%的外量子效率，是当时报道的红光型TADF器件的最高效率之一。发展了“受体平面拓展”策略来选择性提升TADF材料的跃迁偶极矩取向度，同时基本不改变TADF材料的电子结构和光电特性，构建了高效的绿光和黄绿光TADF材料体系，获得了高效的绿光和黄绿光TADF器件。其中，绿光TADF材料PXZPyPM获得了高达100%的发光量子效率和约85%的跃迁偶极矩水平取向度，构筑的绿光TADF器件实现了高达33.9%的外量子效率和118.9 lm/W的功率效率，是当时报道的绿光型TADF器件的最高效率之一。.本项目有关工作已发表标注基金号的SCI论文18篇，其中包括Sci. Adv. 1篇，Adv. Mater. 1篇，Angew. Chem. Int. Ed. 1篇，Adv. Funct. Mater. 2篇，Sci. China Mater. 1篇等。项目负责人龚少龙2020年获得国家优秀青年科学基金项目资助。