Department of Chemistry and Biochemistry, Kent State University, Kent, Ohio44242-0001, United States.
J Phys Chem A. 2023 Jan 12;127(1):216-223. doi: 10.1021/acs.jpca.2c08154. Epub 2022 Dec 23.
We study computationally thermally activated delayed fluorescence (TADF) in donor-acceptor compounds. The relevant electronic excited states that are strongly affected by the dielectric environment are treated by a polarization consistent framework. The high fidelity potential energy surfaces are used following a quantum-mechanical Fermi's golden rule (FGR) picture to calculate rates of intersystem crossing (ISC) and reverse intersystem crossing (RISC). To demonstrate the potency of the approach, we consider isomers of benzonitrile functionalized -butyl-substituted dimethylacridine (DMAC-BN), which were recently found to perform well as TADF emitters. The calculated excited state energies that appear to reproduce well measured spectral trends with respect to the dielectric constant are used to parametrize ISC/RISC FGR rates. The calculated rates reproduce well measured rates, whereas semiclassical based rates are grossly underestimated. In particular, we find in agreement with the recent experimental study [, , 044021] that the ortho and meta isomers are significantly more effective as TADF emitters. The computational framework provides valuable insight at the molecular level into RISC rates and therefore can contribute to the design of materials of increased TADF efficiency.
我们研究了给体-受体化合物中的热激活延迟荧光（TADF）。强关联介电环境的相关电子激发态，通过极化一致性框架进行处理。采用高精度的势能面，遵循量子力学费米黄金定则（FGR）的图像，计算体系间穿越（ISC）和反向体系间穿越（RISC）的速率。为了展示该方法的有效性，我们考虑了苯甲腈官能化 - 丁基取代的二甲基吖啶（DMAC-BN）的异构体，最近发现它们作为 TADF 发射器表现良好。所计算的激发态能量似乎很好地再现了与介电常数有关的测量光谱趋势，可用于参数化 ISC/RISC FGR 速率。计算得到的速率很好地再现了实验测量的速率，而基于半经典的速率则被严重低估。特别是，我们发现与最近的实验研究[31,32,33]一致，邻位和间位异构体作为 TADF 发射器的效率显著更高。该计算框架为 RISC 速率提供了有价值的分子水平见解，因此可以为提高 TADF 效率的材料设计做出贡献。
