Dynamics of the Excitonic Coupling in Organic Crystals
Dynamics of the Excitonic Coupling in Organic Crystals
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DOI：
10.1103/physrevlett.114.026402
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发表时间：
2015-01-14
影响因子：
8.6
通讯作者：
Troisi, Alessandro
中科院分区：
文献类型：
--
作者：
Arago, Juan;Troisi, Alessandro
我们发现，在室温下，由于原子核的热运动，分子晶体中的激子耦合发生了很大的涨落。这一观察极大地影响了有机晶体中激子输运的描述，以及任何其他源自分子晶体或薄膜中激子的现象（如单线态裂变或激子解离）。这种意外的结果是由于在货车德瓦耳斯接触中分子的短程激子耦合机制（交换、重叠和电荷转移介导的）相对于库仑激子耦合的优势。为了量化这种效果，我们开发了一个程序来准确地评估短程激子耦合（通过diabatization方案）沿着分子动力学轨迹的蒽和并四苯的代表性分子晶体。
We show that the excitonic coupling in molecular crystals undergoes a very large fluctuation at room temperature as a result of the combined thermal motions of the nuclei. This observation dramatically affects the description of exciton transport in organic crystals and any other phenomenon (like singlet fission or exciton dissociation) that originates from an exciton in a molecular crystal or thin film. This unexpected result is due to the predominance of the short-range excitonic coupling mechanisms (exchange, overlap, and charge-transfer mediated) over the Coulombic excitonic coupling for molecules in van der Waals contact. To quantify this effect we develop a procedure to evaluate accurately the short-range excitonic coupling (via a diabatization scheme) along a molecular dynamics trajectory of the representative molecular crystals of anthracene and tetracene.