Singlet exciton fission via an intermolecular charge transfer state in coevaporated pentacene-perfluoropentacene thin films
Singlet exciton fission via an intermolecular charge transfer state in coevaporated pentacene-perfluoropentacene thin films
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DOI：
10.1063/1.5130400
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发表时间：
2019-10-28
影响因子：
4.4
通讯作者：
Friend, Richard
中科院分区：
文献类型：
--
作者：
Kim, Vincent O.;Broch, Katharina;Friend, Richard
单重态激子裂变是有机半导体中自旋允许的过程，通过该过程，一个吸收的光子产生两个三重态激子。理论预测，在具有适当的单重态-三重态能量间距的固态材料中，单重态裂变是由分子间电荷转移态介导的，但尚未提供这种状态参与该过程的直接证据。在这里，我们报告的观察亚皮秒单重态裂变并五苯和全氟并五苯的混合膜。通过结合瞬态光谱测量的非绝热量子动力学模拟，我们表明，在混合膜的电荷转移吸收带的直接激发导致三重态激子的形成，明确地证明，它们作为中间状态的裂变过程。由AIP Publishing授权出版。
Singlet exciton fission is a spin-allowed process in organic semiconductors by which one absorbed photon generates two triplet excitons. Theory predicts that singlet fission is mediated by intermolecular charge-transfer states in solid-state materials with appropriate singlet-triplet energy spacing, but direct evidence for the involvement of such states in the process has not been provided yet. Here, we report on the observation of subpicosecond singlet fission in mixed films of pentacene and perfluoropentacene. By combining transient spectroscopy measurements to nonadiabatic quantum-dynamics simulations, we show that direct excitation in the charge-transfer absorption band of the mixed films leads to the formation of triplet excitons, unambiguously proving that they act as intermediate states in the fission process. Published under license by AIP Publishing.