Singlet and Triplet Exciton Dynamics of Violanthrone

The exciton dynamics of violanthrone-79 are investigated in solution and in the solid state. In solution, the photoprepared singlet is found to exhibit a strong ground-state bleach and stimulated emission feature, but when sensitized in its triplet state, it exhibits only a narrow and weak ground-state bleach. As supported by density functional theory calculations, this is explained by the triplet state having absorptions in the same region, with a similar oscillator strength, as the ground-state molecule. In solid films, the excited singlet is found to survive for up to 200 ps, giving way to a long-lived transient absorption spectrum with characteristics reminiscent of the triplet in solution. This is interpreted in terms of singlet fission in the solid film.

Automated summary

The exciton dynamics of violanthrone-79 were investigated in solution and in the solid state. In solution, the photoprepared singlet showed strong ground-state bleach and stimulated emission features, while the triplet state exhibited only a narrow and weak ground-state bleach when sensitized. In solid films, the excited singlet survived for up to 200 ps, leading to a long-lived transient absorption spectrum reminiscent of the triplet in solution.