Jacobs Matheus, Krumland Jannis, Valencia Ana M, Cocchi Caterina
Physics Department and IRIS Adlershof, Humboldt-Universität zu Berlin, Berlin 12489, Germany.
Institute of Physics, Carl von Ossietzky Universität Oldenburg, 26129 Oldenburg, Germany.
J Phys Chem A. 2023 Oct 26;127(42):8794-8805. doi: 10.1021/acs.jpca.3c03709. Epub 2023 Oct 12.
The ultrafast dynamics of charge carriers in organic donor-acceptor interfaces are of primary importance to understanding the fundamental properties of these systems. In this work, we focus on a charge-transfer complex formed by quaterthiophene p-doped by tetrafluoro-tetracyanoquinodimethane and investigate electron dynamics and vibronic interactions also at finite temperatures by applying a femtosecond pulse in resonance with the two lowest energy excitations of the system with perpendicular and parallel polarization with respect to the interface. The adopted formalism based on real-time time-dependent density-functional theory coupled to Ehrenfest dynamics enables monitoring the dynamical charge transfer across the interface and assessing the role played by the nuclear motion. Our results show that the strong intermolecular interactions binding the complex already in the ground state influence the dynamics, too. The analysis of the nuclear motion involved in these processes reveals the participation of different vibrational modes depending on the electronic states stimulated by the resonant pulse. Coupled donor-acceptor modes mostly influence the excited state polarized across the interface, while intramolecular vibrations in the donor molecule dominate the excitation in the orthogonal direction. The results obtained at finite temperatures are overall consistent with this picture, although thermal disorder contributes to slightly decreasing interfacial charge transfer.
有机供体 - 受体界面中电荷载流子的超快动力学对于理解这些系统的基本性质至关重要。在这项工作中，我们聚焦于由四氟 - 四氰基喹二甲烷对四噻吩进行p型掺杂形成的电荷转移复合物，并通过应用飞秒脉冲与系统的两个最低能量激发共振，在有限温度下研究电子动力学和振动 - 电子相互作用，该飞秒脉冲相对于界面具有垂直和平行极化。所采用的基于实时含时密度泛函理论与埃伦费斯特动力学相结合的形式体系，能够监测界面上的动态电荷转移，并评估核运动所起的作用。我们的结果表明，即使在基态就结合复合物的强分子间相互作用也会影响动力学。对这些过程中涉及的核运动的分析揭示了不同振动模式的参与情况，这取决于共振脉冲激发的电子态。耦合的供体 - 受体模式主要影响跨界面极化的激发态，而供体分子中的分子内振动在正交方向上主导激发。在有限温度下获得的结果总体上与这一情况一致，尽管热无序会导致界面电荷转移略有减少。
