The singlet fission (SF) dynamics of pentacene linear aggregate models are investigated using the quantum master equation method by focusing on the Frenkel excitonic (FE) coupling effects on the SF rate and double triplet (TT) yield as well as on their aggregate size dependences. It is found that for the dimer model, unrealistically large FE couplings are needed to provide significant effects on the SF dynamics, while for the larger aggregate models a realistic FE coupling causes significant variations in the SF dynamics: as increasing the aggregate size, the SF rate rapidly increases, attains the maximum at 8‐mer (~3 times enhancement as compared to the non‐FE‐coupling case) and then decreases, approaching a stationary value after 12‐mer, although the stationary TT yield at 20‐mer remains slightly smaller than that in the non‐FE‐coupling case. These features are explained based on the relative relaxation factors between the adiabatic exciton states. The present results contribute to constructing the design guidelines for highly efficient SF aggregates. © 2018 Wiley Periodicals, Inc.

中文翻译：

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并五苯线性聚合模型中单线态裂变动力学的量子主方程方法：激子耦合效应的大小依赖性

使用量子主方程方法研究并五苯线性聚集体模型的单线态裂变 (SF) 动力学，重点关注 Frenkel 激子 (FE) 耦合对 SF 速率和双三线态 (TT) 产率的影响以及它们的聚集体尺寸依赖性. 发现对于二聚体模型，需要不切实际的大 FE 耦合才能对 SF 动力学产生显着影响，而对于较大的聚合模型，现实的 FE 耦合会导致 SF 动力学发生显着变化：随着聚合尺寸的增加，SF速率迅速增加，在 8-mer 处达到最大值（与非 FE 偶联情况相比增强约 3 倍）然后下降，在 12-mer 后接近稳定值，尽管 20-mer 的稳定 TT 产量仍然存在比非 FE 耦合情况下的略小。这些特征是基于绝热激子态之间的相对弛豫因子来解释的。目前的结果有助于构建高效 SF 骨料的设计指南。© 2018 Wiley Periodicals, Inc.