Coherent singlet fission activated by symmetry breaking
Coherent singlet fission activated by symmetry breaking
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DOI：
10.1038/nchem.2784
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发表时间：
2017-10-01
期刊：
影响因子：
21.8
通讯作者：
Matsumoto, Yoshiyasu
中科院分区：
文献类型：
--
作者：
Miyata, Kiyoshi;Kurashige, Yuki;Matsumoto, Yoshiyasu
单线态裂变，其中一个单线态激子转换为两个三重态激子，是一个可能有利于光伏应用的过程。要充分理解分子系统中单线态裂变的动力学，需要详细了解相关势能面及其（锥形）交点。然而，获得这样的信息是一项艰巨的任务，特别是对于分子聚集体。在这里，我们使用瞬态吸收光谱和最先进的量子化学计算来研究rubrene晶体中的单线态裂变。我们观察到相干和超快单线裂变通道以及众所周知的和传统的热辅助非相干通道。由于激发态势能面上单线态裂变的圆锥形交点非常接近基态势能面上的平衡位置，而且由于激发了分子间对称破缺模式，激活了单线态裂变所必需的电子耦合，因此可以获得这种相干通道。
Singlet fission, in which a singlet exciton is converted to two triplet excitons, is a process that could be beneficial in photovoltaic applications. A full understanding of the dynamics of singlet fission in molecular systems requires detailed knowledge of the relevant potential energy surfaces and their (conical) intersections. However, obtaining such information is a nontrivial task, particularly for molecular aggregates. Here we investigate singlet fission in rubrene crystals using transient absorption spectroscopy and state-of-the-art quantum chemical calculations. We observe a coherent and ultrafast singlet-fission channel as well as the well-known and conventional thermally assisted incoherent channel. This coherent channel is accessible because the conical intersection for singlet fission on the excited-state potential energy surface is located very close to the equilibrium position of the ground-state potential energy surface and also because of the excitation of an intermolecular symmetry-breaking mode, which activates the electronic coupling necessary for singlet fission.