窄发射的三维笼状热活化延迟红光材料的设计、合成及性能研究

Organic light-emitting diode (OLED), as a new high-efficiency and energy-saving luminous technology, has shown great application prospects in the field of lighting and display, and can achieve effective energy saving and emission reduction at the source, which is of great strategic significance to promote the sustainable development of China's economy. At present, the most promising luminescent material is thermally activated delayed fluorescence (TADF) material based on charge transfer state (CT state) luminescence, which can achieve 100% exciton utilization without the use of precious metals. However, traditional linear TADF small molecule materials generally have wide emission peaks, poor solubility and slow development of red-light materials. Based on this, in this project, we will make pioneering use of the advantages of the rigid framework of organic cage to build three-dimensional TADF small molecule material. Meanwhile, by adjusting the ability of the building unit to push and pull electrons, high-efficiency red-light emission with high color purity will be achieved by preparing soluble-processing devices. The research of this project will not only open up new structural design ideas for TADF small molecule materials with narrow emission and high solubility, but also accelerate the further commercial application of OLED.

有机发光二极管(OLED)，作为一种新型高效节能的发光技术，在照明显示领域展现出巨大的应用前景，并且可在源头上实现有效的节能减排，对促进我国经济可持续发展具有重大战略意义。目前，最具应用前景的发光材料是基于电荷转移态(CT态)发光的热活化延迟荧光(TADF)材料，得益于其既不需要用到贵重金属，又能实现100%的激子利用率。然而，传统线型TADF小分子材料普遍发射峰很宽、溶解性较差、红光材料发展缓慢。基于此，本项目将开创性地利用有机笼刚性骨架的优点，构筑三维TADF小分子材料，同时通过调节构筑单元推拉电子的能力，制备可溶液加工器件后，实现具有高色纯度的高效红光发射。本项目研究将不仅为窄发射及高溶解性的TADF小分子材料开辟新的结构设计思路，而且加速OLED的进一步商业化应用。

热活化延迟荧光(TADF)材料，作为第三代有机发光材料，其从理论上解决了传统荧光材料效率低以及磷光材料需要用到贵重金属的缺陷，成为目前最具应用前景的新一代发光材料。到目前为止，蒸镀型TADF有机发光器件已经能够实现远超过第一代传统荧光发光器件且能与第二代磷光发光器件比肩的外量子效率，但是对于其进一步商业化应用，仍存在一些问题：(1)作为构筑白光需要用到的红绿蓝三主色系，TADF材料在红光和深蓝光区域发展比较缓慢，可供选择的材料比较局限；(2)电荷转移激发态强烈的结构松弛以及大的斯托克斯位移导致发光色纯度很差，不利于在显示领域中应用；(3)TADF小分子普遍溶解性较差，蒸镀加工时材料浪费严重；(4)器件寿命和稳定性仍需改善。. 基于此，在本项目中，我们开创性地通过利用三维刚性笼状结构去设计合成了一系列新型的笼状TADF小分子材料，解决了小分子普遍较差的溶解性的问题，改善了化学结构对材料发光色纯度的影响，探索了更多兼具聚集诱导发光特性的发光材料，同时意外地发现了部分笼状TADF材料还具有潜在的空间异构手性。另外，为了寻找匹配性更好的红光给受体单元，我们也开发了一些D-A型、D-σ-A型红光TADF小分子材料，均取得了不错的器件性能。