Exciton Dynamics from Strong to Weak Coupling Limit Illustrated on a Series of Squaraine Dimers
Exciton Dynamics from Strong to Weak Coupling Limit Illustrated on a Series of Squaraine Dimers
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在一系列方酸二聚体上说明从强耦合到弱耦合极限的激子动力学
DOI：
10.1021/acs.jpcc.8b00847
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发表时间：
2018
影响因子：
3.7
通讯作者：
C. Lambert
中科院分区：
文献类型：
--
作者：
M. I. S. Röhr;H. Marciniak;J. Hoche;M. H. Schreck;H. Ceymann;R. Mitric;C. Lambert
我们提出了一个联合的理论和实验研究的光诱导激子弛豫动力学在一系列的三个方酸二聚体跨越范围从弱到中间到强激子耦合强度制度。正如瞬态吸收光谱和混合量子经典动力学模拟所揭示的那样，明确考虑到激光脉冲的激发，可以观察到三种不同类型的激子动力学，尽管所研究的系统表现出非常相似的光谱特征。而在强耦合系统（Frenkel极限），激子保持离域的两个染料单体，在系统中与中间耦合，可以观察到飞秒时间尺度上的瞬态局域化-离域。最后，在弱耦合的异二聚体（Fo Prrster极限），有效的激子转移，介导的瞬态离域与强非绝热耦合，发生。通过对激子转移的不同机制进行首次系统的微观研究，我们的发现为有机分子激子材料中能量传输的可能机制提供了新的思路。
We present a joint theoretical and experimental study on the light-induced exciton relaxation dynamics in a series of three squaraine dimers spanning the range from weak to intermediate to strong excitonic coupling strength regime. As revealed by transient-absorption spectroscopy and mixed quantum-classical dynamics simulations that explicitly take into account excitation by the laser pulse, three different types of exciton dynamics could be observed, although the investigated systems exhibit very similar spectral features. While in the strongly coupled system (Frenkel limit), the exciton remains delocalized over both dye monomers, in the system with intermediate coupling, transient localization–delocalization on a femtosecond time scale can be observed. Finally, in the weakly coupled heterodimer (Förster limit), efficient exciton transfer, mediated by transient delocalization that correlates with a strong nonadiabatic coupling, takes place. By delivering the first systematic microscopic study on different regimes of exciton transfer, our findings shed new light on the possible mechanisms of energy transport in organic molecular excitonic materials.