Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
J Phys Chem B. 2013 Jan 10;117(1):457-66. doi: 10.1021/jp310298n. Epub 2012 Dec 18.
In organic materials, coupling of electronic excitations to vibrational degrees of freedom results in polaronic excited states. Through numerical calculations, we demonstrate that the vibrational distortion field accompanying such a polaron scales as the product of the excitonic interaction field and the exciton coherence function. This scaling relation is derived analytically in the regime where excitonic interactions are weak, yet it is shown to remain valid for interaction strengths ranging up to physically relevant values. Moreover, it is not affected by the magnitude of exciton-vibrational coupling or the presence of disorder in the molecular transition energies, despite the dramatic changes observed in the excited state. An application to helical MOPV4 aggregates is presented, followed by a quantitative study of the vibrational distortion field when excitonic interactions are strong. Our findings allow for a straightforward interpretation of widely varying polaron profiles, thereby facilitating the characterization of organic excited states.
在有机材料中，电子激发与振动自由度的耦合导致极化子激发态的形成。通过数值计算，我们证明了伴随这种极化子的振动变形场与激子相互作用场和激子相干函数的乘积成正比。该比例关系在激子相互作用较弱的情况下通过解析推导得出，但对于相互作用强度高达物理相关值的情况仍然有效。此外，尽管在激发态中观察到了显著的变化，但它不受激子-振动耦合的大小或分子跃迁能量中无序的影响。本文还介绍了对螺旋 MOPV4 聚集体的应用，并对激子相互作用较强时的振动变形场进行了定量研究。我们的发现为广泛变化的极化子分布提供了直接的解释，从而促进了对有机激发态的特征描述。
