Excited state properties of non-doped thermally activated delayed fluorescence emitters with aggregation-induced emission: a QM/MM study
Excited state properties of non-doped thermally activated delayed fluorescence emitters with aggregation-induced emission: a QM/MM study
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具有聚集诱导发射的非掺杂热激活延迟荧光发射体的激发态特性：QM/MM 研究
DOI：
10.1039/c7tc02541f
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发表时间：
2017-09-07
影响因子：
6.4
通讯作者：
Wang, Chuan-Kui
中科院分区：
文献类型：
--
作者：
Fan, Jianzhong;Lin, Lili;Wang, Chuan-Kui
采用量子力学和分子力学（QM/MM）相结合的方法，从理论上研究了二苯并噻吩-苯甲酰-9,9-二甲基-9,10-二氢吖啶（DBT-BZ-DMAC）在固相中的激发态性质。结果表明，由于抑制了分子中DMAC和DBT单元的旋转，分子在固相中的非辐射衰变速率显著降低，而由于增强了跃迁偶极矩，辐射速率大大增加。此外，DBT-BZ-DMAC的固相荧光效率（20.5%）远大于气相荧光效率（0.01 ppm），证实了DBT-BZ-DMAC是一种典型的聚集诱导发射（AIE）体系。结果进一步表明，系统间交叉（ISC）和反向系统间交叉（RISC）过程都发生在第一单重态（S1）和最低简并三重态（T1和T2）之间。此外，利用马库斯理论研究了电荷转移速率，并利用动力学蒙特卡罗方法计算了本征电荷迁移率。结果表明，DBT-BZ-DMAC晶体为p型半导体，室温下空穴迁移率为0.14 cm(2) V-1 s（-1）。本研究阐明了DBT-BZ-DMAC荧光发射器的实验测量结果，有助于了解其AIE机制，为开发新型TADF发射器提供参考。
The excited state properties of dibenzothiophene-benzoyl-9,9-dimethyl-9,10-dihydroacridine (DBT-BZ-DMAC) in the solid phase are theoretically studied through a combined quantum mechanics and molecular mechanics (QM/MM) method. The results indicate that the non-radiative decay rate of the molecule in the solid phase is significantly decreased due to the suppression of the rotation of the DMAC and DBT units in the molecule, while the radiative rate is greatly increased owing to the enhancement of the transition dipole moment. Moreover, the fluorescence efficiency in the solid phase (20.5%) is shown to be much larger than that in the gas phase (0.01 parts per thousand), which confirms that DBT-BZ-DMAC is a typical aggregation-induced emission (AIE) system. The results further display that both the intersystem crossing (ISC) and reverse intersystem crossing (RISC) processes take place between the first singlet excited state (S1) and the lowest degenerate triplet excited states (T1 and T2). In addition, the charge transfer rate is studied using the Marcus theory and the intrinsic charge mobility is calculated by performing the kinetic Monte Carlo method. The results show that the DBT-BZ-DMAC crystal is a p-type semiconductor with a hole mobility of 0.14 cm(2) V-1 s(-1) at room temperature. Our investigation elucidates the experimental measurements and helps one to understand the AIE mechanisms of the DBT-BZ-DMAC fluorescence emitter, which is beneficial for developing new TADF emitters.