Singlet fission, a process in which two pairs of charge carriers are generated upon absorption of a photon, is considered as a potential scheme to enhance the efficiency of current solar cells[1]. However, the actual mechanism is still a matter of debate, with charge transfer states believed to play an essential role. The probability of the overall process can be related to the electronic coupling between the electronic states. In this contribution, we show the applicability of the excited state analysis[2] to characterise the excited states of three tetracene pairs, with different relative orientation and electronic coupling, and to identify the role of charge transfer states. The results show the presence of low-lying charge transfer states in those tetracene pairs with non-zero electronic coupling, suggesting a superexchange-mediated mechanism, and high-lying charge resonance states for the pair with zero electronic coupling[3].  
[1] M.B. Smith and J. Michl, Chem. Rev. 110, 6891 (2010)
[2] F. Plasser, M. Wormit and A. Dreuw. J. Chem Phys. 141, 024106 (2014)
[3] L.E. Aguilar Suarez, M. F. S. J. Menger, S. Faraji. Mol. Phys. DOI: 10.1080/00268976.2020.1769870 (2020).

Singlet fission in tetracene: an excited state analysis

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