Yang Sizhuo, Streater Daniel, Fiankor Christian, Zhang Jian, Huang Jier
Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States.
Department of Chemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588, United States.
J Am Chem Soc. 2021 Jan 20;143(2):1061-1068. doi: 10.1021/jacs.0c11719. Epub 2021 Jan 4.
2D covalent organic frameworks (COFs) have emerged as a promising class of organic luminescent materials due to their structural diversity, which allows the systematic tuning of organic building blocks to optimize emitting properties. However, a significant knowledge gap exists between the design strategy and the fundamental understanding of the key structural parameters that determine their photophysical properties. In this work, we report two highly emissive sp-C-COFs and the direct correlation of the structure (conjugation and aggregation) with their light absorption/emission, charge transfer (CT), and exciton dynamics, the key properties that determine their function as luminescent materials. We show that white light can be obtained by simply coating COFs on an LED strip or mixing the two COFs. Using the combination of time-resolved absorption and emission spectroscopy as well as computational prediction, we show that the planarity, conjugation, orientation of the dipole moment, and interlayer aggregation not only determine the light-harvesting ability of COFs but also control the exciton relaxation pathway and photoluminescent quantum yield.
二维共价有机框架（COFs）因其结构多样性而成为一类很有前景的有机发光材料，这种结构多样性使得有机结构单元能够进行系统调节以优化发光性能。然而，在设计策略与对决定其光物理性质的关键结构参数的基本理解之间存在重大知识差距。在这项工作中，我们报告了两种高发射性的sp-C-COFs，以及结构（共轭和聚集）与其光吸收/发射、电荷转移（CT）和激子动力学之间的直接关联，这些关键性质决定了它们作为发光材料的功能。我们表明，通过简单地将COFs涂覆在LED灯条上或混合这两种COFs即可获得白光。利用时间分辨吸收和发射光谱以及计算预测相结合的方法，我们表明平面性、共轭、偶极矩方向和层间聚集不仅决定了COFs的光捕获能力，还控制着激子弛豫途径和光致发光量子产率。
