基于热激活延迟荧光机制的高效近红外有机发光材料和器件

Near infrared luminescent materials and devices play important roles in the applications of information transmission, medical diagnosis, homeland security and so on. This project is intended to focus on how to improve near-infrared organic luminescence in materials and devices, striving to break the bottleneck in quantum efficiency. According to the basic principle of photophysics, with the redshift of the wavelength, the probability that the excitons go through the non-radiative trasition process will be increased in the organic molecule by the internal conversion, so that the quantum efficiency of the near-infrared luminescent material is often lower than that of the visible light-emitting materials. To this end, we will use a thermally activated delayed fluorescence (TADF) mechanism to design a series of new near-infrared organic luminescent materials, which not only in theory could achieve 100% of the internal quantum efficiency, but also in practice could avoid the shortcomings of using the currently high cost of precious metal complexes. At the same time, we will also combine the light-emitting materials with new device structure to further enhance the device's performance, so that the near-infrared organic light-emitting diodes could achieve the breakthroughs in both luminous efficiency and operational lifetime.

近红外发光材料和器件在信息传输、医疗诊断、国土安全等方面有着重要应用。本项目拟重点针对近红外有机发光材料进行研究，力求突破材料量子效率低的瓶颈限制。根据光物理的基本原理，随着波长的红移，激子在有机分子内通过内转换而发生非辐射衰减的几率升高，从而使得近红外发光材料的量子效率往往低于可见光发光材料的量子效率。为此，我们将利用热激活延迟荧光（Thermally activated delayed fluorescence, TADF）的发光机制来设计一系列新型的近红外有机发光材料，使其既能在理论上实现100%的内量子效率，又能在实际中规避目前贵金属配合物成本较高的缺点。同时，我们还将新型发光材料与新型发光二极管的器件结构相结合，进一步提升器件的光电性能，从而使近红外有机发光二极管在发光效率和工作寿命指标上，能够达到双双突破的目标。

近红外发光材料和器件在众多基础领域均有重要应用价值。针对近红外有机材料量子效率低，器件研究进展缓慢的现状，本项目基于热激活延迟荧光(TADF)机制，设计合成了高效近红外有机发光材料，制备了高效近红外有机发光器件。我们重点研究了给受体型近红外有机小分子的设计与合成，特别探索了不同的刚性的给受体修饰对于近红外有机小分子的发光特性的影响；同时研究了近红外激基复合物发光体系的构建。近红外有机小分子和激基复合物体系的器件发光峰均突破了800 nm。并开发了π-堆叠发光材料体系，多重共振发光材料体系，为发展新型近红外发光材料奠定基础。在器件结构优化方面，我们重点研究了双极性主体材料、金属配合物主体材料对于近红外发光客体的效率影响。并针对性地设计合成了螺芴类主体材料用于宽带隙主体及激基复合物主体组分用于窄带隙近红外器件。最终实现了外量子效率（EQE）接近30%的红光器件、EQE超过15%的近红外器件。