具有热活化延迟荧光性质的有机硼材料的开发及其在有机电致发光器件中的应用

Organic light-emitting diodes (OLED) have attracted a great deal of attention due to their application in displays and lighting. The development of high-performance organic materials is crucial for the development of OLED technique. Organoboron compounds are one of the material systems applied in the OLED study. However, the device performance of traditional fluorescent organoboron materials is generally low. Recently, organic materials with thermally activated delayed fluorescence (TADF) have become a hot topic of the OLED study because they can utilize both of the electrogenerated singlet and triplet excitons to realize high device performance and they could be economically synthesized. Very recent studies indicated that the TADF property can also greatly enhance the OLED performance of organoboron compounds, therefore, endows them with commercialization potential. However, the study on organoboron systems with the TADF character is in the neonatal stage. This project focuses on the further development of organoboron-based TADF systems by using several boron-containing electron acceptors that were not used in known TADF materials, in order to realize high-performance red, green and blue OLEDs and to provide theoretical support for the structural design of boron-containing TADF materials in the future by establishing the relationship between the chemical/electronic structures of the boron-containing acceptors and the properties of the materials.

有机电致发光技术在显示、照明等领域具有广泛的应用。开发性能优良的材料是推动电致发光技术和产业发展的有效手段。有机硼类材料是诸多已报道电致发光材料体系之一。然而，早期的有机硼类发光材料的器件性能普遍较低。近几年，具有热活化延迟荧光（TADF）性质的有机材料因其可有效利用单线态和三线态电生激子而实现高性能器件，并且具有相对低廉的生产成本，成为电致发光研究的热点。最近的研究表明，利用TADF性质可极大的提升有机硼类发光材料的电致发光性能，使这类材料具有商业化应用的可能。然而，具有TADF性质的有机硼类材料的研究刚刚起步，其潜力有待进一步开发。本项目利用多种含硼电子受体基团构建TADF体系，以期实现高性能的红光、绿光和蓝光电致发光器件。通过系统的研究，揭示含硼受体的化学和电子结构与材料性能之间的关联性，为今后有机硼类TADF材料的受体选择和结构设计提供理论支持。

有机电致发光二极管（OLED）技术是基于有机半导体材料的新一代显示、照明技术。目前，OLED显示面板已经大量应用于智能手机及平板电视，有望替代传统的液晶面板。但是，OLED面板仍然存在价格昂贵，使用寿命相对较短等突出缺点。新材料的开发不仅有望克服这些缺点，也有望进一步降低面板能耗，改善显示色域，提升OLED面板在显示领域的竞争力。本项目侧重于具有热活化延迟荧光（TADF）性质的有机半导体发光材料的开发。这类材料与目前显示面板上使用的磷光铱配合物材料（绿光及红光）相比具有价格相对低廉、结构及发光性能容易调节的优点，同时保留了与铱配合物相同的电致发光效率理论上限；与目前面板上使用的传统荧光小分子材料（蓝光）相比，具有电致发光效率理论上限显著提升的优点，有助于降低面板的能耗。本项目涉及材料的核心结构特点是具有含硼电子受体单元。我们利用多种含硼受体构筑了发光材料，且绝大部分材料展示出了TADF性质。我们也考察了材料的电致发光性能，深入研究了材料结构对OLED器件性能的影响。通过利用项目相关材料作为发光体，得到了高效率的蓝、绿、红光发射的OLED器件。其中，最优的蓝、绿光器件的外量子效率都超过了20%，已经接近理论极限。另外，蓝光材料显示出了较高的色纯度。集成了高电致发光效率、高色纯度及低成本优势的TADF材料有利于低能耗、宽色域、低价格的显示产品的实现。通过系统性的研究，我们揭示了高效率、高色纯度的含硼TADF材料的结构构筑策略，有助于更多的高性能显示、照明材料的开发。