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) (see: the following equation). Therefore, SF is highly promising for construction of next-generation light energy conversion systems.

S₁ + S₀ → TT → T₁ + T₁

In addition to the close interaction of two neighboring chromophores, energy-level matching condition between a singlet and two triplet states: [E(S₁) ≥ 2E(T₁)] are required for efficient SF. Acene derivatives such as pentacene 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.^1-2 Namely, the precise structural control of orientation and distance between two nearby tetracene units is required for long-lived individual triplets through SF. In this presentation, we mainly focus on the high-yield and long-lived individual triplet exciton generation through intramolecular SF (ISF) using a series of phenylene-spacer-bridged tetracene dimers.³

References

1. Nakamura, S.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. ACS Energy Lett. 2019, 4, 26-31.
2. Saegusa, T.; Sakai, H.; Nagashima, H.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. J. Chem. Soc.2019, 141, 14720-14727.
3. Nakamura, S.; Sakai, H.; Nagashima, H.; Fuki, M.; Onishi, K.; Khan, R.; Kobori, Y.; Tkachenko, N. V.; Hasobe, T. Phys. Chem. C 2021, 125, 18287-18296.