Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
J Chem Phys. 2017 May 7;146(17):174704. doi: 10.1063/1.4982359.
Singlet fission, the molecular process through which photons are effectively converted into pairs of lower energy triplet excitons, holds promise as a means of boosting photovoltaic device efficiencies. In the preceding article of this series, we formulated a vibronic theory of singlet fission, inspired by previous experimental and theoretical studies suggesting that vibronic coupling plays an important role in fission dynamics. Here, we extend our model in order to simulate two-dimensional electronic spectra, through which the theory is further validated based on a comparison to recent measurements on pentacene crystals. Moreover, by means of such spectral simulations, we provide new insights into the nature of the correlated triplet pair state, the first product intermediate in the fission process. In particular, we address a controversy in the literature regarding the identification, energies, and transition dipole moments of its optical transitions towards higher-lying triplet states.
单线态裂变是一种分子过程，通过该过程，光子有效地转化为一对低能量的三重态激子，有望提高光伏器件的效率。在本系列的前一篇文章中，我们根据先前的实验和理论研究提出了一种单线态裂变的振子理论，这些研究表明振子耦合在裂变动力学中起着重要作用。在这里，我们扩展了我们的模型，以便通过二维电子光谱进行模拟，通过与最近对并五苯晶体的测量结果进行比较，进一步验证了该理论。此外，通过这种光谱模拟，我们对相关的三重态对态的本质提供了新的见解，这是裂变过程中的第一个产物中间体。特别是，我们解决了文献中关于其向更高三重态态的光学跃迁的识别、能量和跃迁偶极矩的争议。
