Steady-State Fluorescence Signatures of Intramolecular Singlet Fission from Stochastic Predictions
Steady-State Fluorescence Signatures of Intramolecular Singlet Fission from Stochastic Predictions
复制标题
随机预测的分子内单线态裂变的稳态荧光特征
DOI：
10.1021/acs.jpca.0c06966
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Grey, John K.
中科院分区：
文献类型：
--
作者：
Walwark, David J.;Grey, John K.
能够进行有效的分子内单重态裂变（iSF）的新的多发色团系统的出现，大大扩展了有机光能收集材料的多激子产生方法的可能基序的范围。瞬态吸收（TA）光谱探针通常用于表征单线态裂变过程，可能会限制灵敏度和时间分辨率的规模相当的自旋禁戒三重态和相互作用的整个寿命。在这里，我们研究了基于荧光的光谱探针检测基于大的取代的共轭并苯的分离的二联体中的iSF活性的能力（例如，并四苯和并五苯衍生物）。从文献中报道的几个ISF活性二元系统模拟光物理模型，使用随机方法评估稳态荧光对三重态激子存在的敏感性。结果表明，对于ΦiSF> 0.5的系统（假设发色团间耦合较弱），预期荧光产率随激发速率常数的变化而波动较大。激子-激子相互作用也进行了研究，我们进一步证明了如何处理iSF二分体随机（即，有限数目的发色团）加重了电子物理产率与激发速率的依赖性。最后，我们的方法揭示了单分子水平荧光光谱检测iSF活性的潜在能力，可以帮助设计和优化候选iSF系统。
The advent of new multichromophoric systems capable of undergoing efficient intramolecular singlet fission (iSF) has greatly expanded the range of possible motifs for multiexciton generation approaches for organic light energy harvesting materials. Transient absorption (TA) spectroscopic probes are typically used to characterize singlet fission processes that may place limitations on sensitivity and time resolution on scales comparable to the full lifespan of spin-forbidden triplets and interactions. Here, we investigate the ability of fluorescence-based spectroscopic probes to detect iSF activity in isolated dyads based on large substituted conjugated acenes (e.g., tetracene and pentacene derivatives). Photophysical models are simulated from several iSF-active dyad systems reported in the literature using a stochastic approach to assess the sensitivity of steady-state fluorescence to the presence of triplet excitons. The results demonstrate large fluctuations in expected fluorescence yields with varying excitation rate constants for systems withΦiSF> 0.5 (assuming weak interchromophore coupling). Exciton–exciton interactions are also investigated, and we further demonstrate how treating iSF dyads stochastically (i.e., finite number of chromophores) accentuates dependences of photophysical yields with excitation rates. Last, our approach reveals the potential ability of single molecule level fluorescence spectroscopy to detect iSF activity that can aid efforts to design and optimize candidate iSF systems.