Femtosecond Raman Microscopy Reveals Structural Dynamics Leading to Triplet Separation in Rubrene Singlet Fission,The Journal of Physical Chemistry Letters

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Femtosecond Raman Microscopy Reveals Structural Dynamics Leading to Triplet Separation in Rubrene Singlet Fission
The Journal of Physical Chemistry Letters ( IF 4.8 ) Pub Date : 2017-11-22 00:00:00 , DOI: 10.1021/acs.jpclett.7b02769
Kajari Bera ₁ , Christopher J. Douglas ₁ , Renee R. Frontiera ₁

Affiliation

Singlet fission generates multiple excitons from a single photon, which in theory can result in solar cell efficiencies with values above the Shockley–Queisser limit. Understanding the molecular structural dynamics during singlet fission will help to fabricate efficient organic photovoltaic devices. Here we use femtosecond stimulated Raman spectroscopy to reveal the structural evolution during the triplet separation in rubrene. We observe vibrational signatures of the correlated triplet pair, as well as shifting of the vibrational frequencies of the 1430 and 1542 cm^–1 excited state modes, which increase by more than 25 cm^–1 in 5 ps. Our results indicate that the correlated pair separation into two individual triplets occurs concurrently with the loss of electron density from the tetracene backbone in rubrene. This study provides new insights into the triplet separation process and proves the utility of structurally sensitive ultrafast vibrational techniques to understand the mechanism of singlet fission.

中文翻译：

飞秒拉曼显微镜揭示了导致分子筛裂变中三重态分离的结构动力学

单重态裂变会从单个光子产生多个激子，从理论上讲，它可以提高太阳能电池的效率，其值应高于Shockley-Queisser极限。了解单线态裂变期间的分子结构动力学将有助于制造有效的有机光伏器件。在这里，我们使用飞秒激发的拉曼光谱来揭示红荧烯三重态分离过程中的结构演变。我们观察到相关三重态对的振动特征，以及1430和1542 cm ^–1激发态模式的振动频率的偏移，其增加了25 cm ^–1以上在5 ps。我们的结果表明，相关的成对分离成两个三重态与同时发生的红荧烯并四苯骨架的电子密度损失同时发生。这项研究提供了对三重态分离过程的新见解，并证明了结构敏感的超快振动技术对理解单重态裂变机理的实用性。

更新日期：2017-11-22

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