(Invited) Tetracene Molecular Architectures for High-Yield and Long-Lived Individual Triplet States through Singlet Fission

Abstract

Singlet fission (SF) is a multi-exciton generation process in two neighboring organic chromophores (S1 + S0) where two individual triplet excitons (T1 + T1) are generated from one-photon absorption through a correlated triplet pair (TT). Therefore, SF is highly promising for construction of next-generation solar energy conversion systems such as photovoltaics and photocatalysis. In addition to the close interaction of two nearby molecules, energy-level matching condition between a singlet and two triplet states: [E(S1) ≥ 2E(T1)] are required. Acene derivatives such as pentacene and tetracene satisfy the above condition. However, the number of high-yield and long-lived triplet excited states through SF using tetracene derivatives is extremely limited because of the acceleration of the reverse reaction: triplet-triplet annihilation. Namely, the precise structural control of orientation and distance between two nearby tetracene units is definitely required for long-lived individual triplets through SF. In this presentation, we mainly focus on the tetracene molecular assemblies for high-yield and long-lived individual triplet states through SF using a series of covalently-linked dimers1 and tetracene-modified gold nanoclusters.2 References Nakamura, S.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. ACS Energy Lett. 2019, 4, 26-31.Saegusa, T.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. J. Chem. Soc. 2019, 141, 14720-14727.