基于庚嗪环的有机发光材料的分子设计、合成与发光机理研究

Organic light-emitting materials show peculiar application prospects in the displays and lighting. As compared to fluorescent and phosphorescent materials, thermally activated delayed fluorescence (TADF) materials have received widespread concern from academia and industry because they are considered as novel organic light-emitting materials which can simultaneously realize high efficiency and low-cost. However, luminescence of TADF molecules usually contains forbidden exciton transition process from ππ* triplet to ππ* singlet states, 3ππ*→1ππ*, resulting in low exciton transition rate and serious exciton quenching which aggravate efficiency roll-off of organic light-emitting devices, and further affect device stability. Therefore, study on novel luminescence mechanism to overcome this defect has important strategic value and scientific significance to enhance core-competitiveness of our country in the field of organic light-emitting materials and devices. The project intends to conduct molecular design of heptazine derivatives by using density functional theory, to explore the introduction of nπ* state for changing exciton transition from forbidden 3ππ*→1ππ* to allowed 3ππ*→1nπ*, thereby increase exciton transition rate, reduce exciton quenching and improve device stability. Meanwhile, luminescence mechanism, photophysical and device physical properties of nπ*-type heptazine derivatives will be systematically investigated to establish a comprehensive physical model of "molecular structure-luminescence mechanism-material properties".

有机发光材料在显示和照明领域展现了独特的应用前景。相对于荧光和磷光材料，热活性延迟荧光（TADF）材料作为一种可同时实现高效率和低成本的新型有机发光材料，受到了学术界和产业界的广泛关注。然而，TADF分子发光通常包含激子由ππ*三重态到ππ*单重态的跃迁禁阻过程，即3ππ*→1ππ*，造成激子跃迁速率低且淬灭严重，加剧有机发光器件的效率衰减，进而影响器件的稳定性。因此，研究新型发光机制以克服这一缺陷对于提高我国在有机发光材料及器件领域的核心竞争力具有重要的战略价值和科学意义。本项目拟运用密度泛函理论，对庚嗪环衍生物进行分子设计，探索引入nπ*能级使激子由3ππ*→1ππ*跃迁禁阻转变为3ππ*→1nπ*跃迁允许，从而提高激子跃迁速率，减少激子淬灭并提高器件稳定性。同时，系统研究nπ*型庚嗪环衍生物的发光机理、光物理和器件物理性能，建立一套完善的“分子结构-发光机理-材料性能”物理模型。

热活性延迟荧光分子发光通常包含激子由ππ*三重态到ππ*单重态的跃迁禁阻过程（3ππ*→1ππ*），造成激子跃迁速率低且淬灭严重，加剧有机发光器件的效率衰减，进而影响器件的稳定性。针对这一问题，本项目运用密度泛函理论，对庚嗪环衍生物进行分子设计，通过引入nπ*能级使激子由3ππ*→1ππ*跃迁禁阻转变为3ππ*→1nπ*跃迁允许，从而提高激子跃迁速率，减少激子淬灭并提高器件稳定性。同时，系统研究了nπ*型庚嗪环衍生物的发光机理、光物理和器件物理性能，建立了一套较为完善的“分子结构-发光机理-材料性能”物理模型。