Wallner Lisamaria, Remnant Charlotte, Vendrell Oriol
Theoretische Chemie, Physikalisch-Chemisches Institut, Universität Heidelberg, Im Neuenheimer Feld 229, Heidelberg 69120, Germany.
Interdisciplinary Center for Scientific Computing, Universität Heidelberg, Im Neuneheimer Feld 205, Heidelberg 69120, Germany.
J Phys Chem A. 2024 Oct 17;128(41):8897-8905. doi: 10.1021/acs.jpca.4c04207. Epub 2024 Oct 8.
We investigate theoretically the influence of strong light-matter coupling on the initial steps of the phototriggered singlet-fission process. In particular we focus on intramolecular singlet fission in a TIPS-pentacene dimer derivative described by a vibronic Hamiltonian including the optically active singlet excited states, doubly excited and charge transfer states, as well as the final triplet-triplet pair state. Quantum dynamics simulations of up to four dimers in the cavity indicate that the modified resonance condition imposed by the cavity strongly quenches the passage through the intermediate charge transfer and double-excitation states, thus largely reducing the triplet-triplet yield in the bare system. Subsequently, we modify the system parameters and construct a model Hamiltonian where the optically active singlet excitation lies below the final triplet-triplet state such that the yield of the bare system becomes insignificant. In this case we find that using the upper polariton as the doorway state for photoexcitation can lead to a much enhanced yield. This pathway is operative provided that the system is sufficiently rigid to prevent vibronic losses from the upper polariton to the dark-states manifold.
我们从理论上研究了强光 - 物质耦合对光触发单重态裂变过程初始步骤的影响。特别地，我们关注由一个包含光学活性单重态激发态、双激发态和电荷转移态以及最终三重态 - 三重态对态的振子哈密顿量描述的TIPS - 并五苯二聚体衍生物中的分子内单重态裂变。对腔内多达四个二聚体的量子动力学模拟表明，由腔施加的修改后的共振条件强烈抑制了通过中间电荷转移和双激发态的过程，从而在裸系统中大幅降低了三重态 - 三重态产率。随后，我们修改系统参数并构建一个模型哈密顿量，其中光学活性单重态激发低于最终的三重态 - 三重态态，使得裸系统的产率变得微不足道。在这种情况下，我们发现使用上极化激元作为光激发的门态可以导致产率大幅提高。只要系统足够刚性以防止上极化激元向暗态流形的振子损失，这条途径就是可行的。
