Berkelbach Timothy C, Hybertsen Mark S, Reichman David R
Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York 11973-5000, USA.
J Chem Phys. 2014 Aug 21;141(7):074705. doi: 10.1063/1.4892793.
We extend our previous work on singlet exciton fission in isolated dimers to the case of crystalline materials, focusing on pentacene as a canonical and concrete example. We discuss the proper interpretation of the character of low-lying excited states of relevance to singlet fission. In particular, we consider a variety of metrics for measuring charge-transfer character, conclusively demonstrating significant charge-transfer character in the low-lying excited states. The impact of this electronic structure on the subsequent singlet fission dynamics is assessed by performing real-time master-equation calculations involving hundreds of quantum states. We make direct comparisons with experimental absorption spectra and singlet fission rates, finding good quantitative agreement in both cases, and we discuss the mechanistic distinctions that exist between small isolated aggregates and bulk systems.
我们将之前关于孤立二聚体中单线态激子裂变的研究工作扩展到晶体材料的情况，重点关注并五苯作为一个典型且具体的例子。我们讨论了与单线态裂变相关的低激发态性质的恰当解释。特别地，我们考虑了多种用于衡量电荷转移性质的指标，最终证明在低激发态中存在显著的电荷转移性质。通过进行涉及数百个量子态的实时主方程计算，评估了这种电子结构对后续单线态裂变动力学的影响。我们将计算结果与实验吸收光谱和单线态裂变速率进行直接比较，发现两者在定量上都有良好的一致性，并且我们还讨论了小的孤立聚集体与体相系统之间存在的机理差异。
