Ultrafast Exciton Self-Trapping upon Geometry Deformation in Perylene-Based Molecular Aggregates.
Ultrafast Exciton Self-Trapping upon Geometry Deformation in Perylene-Based Molecular Aggregates.
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DOI：
10.1021/jz4000752
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发表时间：
2013-02
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影响因子：
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通讯作者：
A. Schubert;Volker Settels;Wenlan Liu;F. Würthner;C. Meier;R. Fink;Stefan Schindlbeck;S. Lochbrunner-S.-Loch
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文献类型：
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作者：
A. Schubert;Volker Settels;Wenlan Liu;F. Würthner;C. Meier;R. Fink;Stefan Schindlbeck;S. Lochbrunner-S.-Loch
飞秒时间分辨实验表明，聚集体的光激发态在215fs的时间尺度上无辐射衰减。二聚体的高级电子结构计算指出了沿反应坐标的激发态分子间几何畸变的重要性，这种畸变会引起各种电子态之间的能量转移和耦合。结合简单耗散机制的时变波包计算表明，快速能量猝灭是由具有瞬时填充的电荷转移特征的门口态引起的。所确定的弛豫机制对应于分子材料中可能存在的激子阱。
Femtosecond time-resolved experiments demonstrate that the photoexcited state of perylene tetracarboxylic acid bisimide (PBI) aggregates in solution decays nonradiatively on a time-scale of 215 fs. High-level electronic structure calculations on dimers point toward the importance of an excited state intermolecular geometry distortion along a reaction coordinate that induces energy shifts and couplings between various electronic states. Time-dependent wave packet calculations incorporating a simple dissipation mechanism indicate that the fast energy quenching results from a doorway state with a charge-transfer character that is only transiently populated. The identified relaxation mechanism corresponds to a possible exciton trap in molecular materials.