Kinetics of singlet fission in organic semiconductors: Specific features of T-exciton migration effects.
Kinetics of singlet fission in organic semiconductors: Specific features of T-exciton migration effects.
复制标题
有机半导体中单线态裂变动力学：T 激子迁移效应的具体特征。
DOI：
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发表时间：
2019
影响因子：
4.4
通讯作者：
A. Shushin
中科院分区：
文献类型：
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作者：
A. Shushin
在有机半导体中，与激发单重态（S1）自发分裂成一对三重态（T）激子相关的单重态裂变（SF）动力学，已知受到所产生的TT-对的成对湮灭的强烈影响。在这项工作中，我们详细分析了SF动力学内的晶格迁移（跳跃），扩散迁移，和指数动力学两态模型（TSM），这使我们能够准确地描述相对T-激子迁移TT对的影响。在所提出的TSM中，迁移效应在两个态的动力学耦合近似下处理：相互作用的TT-对的[TT]-态和自由迁移的T-激子的[T + T]-态。本文应用该模型研究了外磁场中SF过程动力学的一些重要特性。在我们的工作中，我们专注于分析T激子迁移对SF动力学的影响。它表明，特别是，T-激子迁移的各向异性强烈体现在SF-动力学，特别是在其（逆幂型）长时间的一部分。高迁移各向异性还导致T-激子从[TT]-状态逃逸的速率大幅降低，从而导致TT-锁定，这可能导致对应于不同磁场的SF-动力学曲线的交叉。对这种效应的分析表明，可以提供有关SF过程动力学具体特征的重要信息。
Kinetics of singlet fission (SF) in organic semiconductors, associated with spontaneous splitting of the excited singlet state (S1) into a pair of triplet (T) excitons, is known to be strongly affected by geminate annihilation of generated TT-pairs. In this work, we analyze in detail the SF-kinetics within lattice-migration (hopping), diffusion-migration, and exponential-kinetics two-state models (TSMs), which allow us to accurately describe the effects of relative T-exciton migration in TT-pairs. In the proposed TSMs, the migration effects are treated within the approximation of kinetic coupling of two states: [TT]-state of interacting TT-pairs and [T + T]-state of freely migrating T-excitons. The TSMs are applied to study some important specific properties of the kinetics of SF-processes in the external magnetic field. In our work, we concentrate on the analysis of T-exciton-migration effects on SF-kinetics. It is demonstrated, in particular, that the anisotropy of T-exciton migration strongly manifests itself in SF-kinetics, especially in its (inverse-power type) long time part. High migration anisotropy also leads to a substantial decrease in the rate of T-exciton escape from [TT]-state and thus to TT-caging which can result in crossing of SF-kinetic curves corresponding to different magnetic fields. The analysis of this effect is shown to provide important information on specific features of the kinetics of SF-processes.