Dynamics of molecular excitons near a semiconductor surface studied by fluorescence quenching of polycrystalline tetracene on silicon

- Fluorescence experiments are conducted on a tetracene/LiF/Si sample.
- The fluorescence intensity of tetracene increases as LiF thickness increases.
- Prompt fluorescence lifetimes decrease as the tetracene thickness increases.
- No evidence is found for triplet energy transfer from tetracene to the Si.

Tetracene, a molecule that undergoes singlet fission, is deposited on Si with variable thickness LiF spacer layers. In agreement with earlier work (Hayashi et al., 1983 [10]), the fluorescence intensity of the tetracene greatly increases as the LiF thickness approaches 100 nm. This increase is partly due to a 30% increase in the prompt fluorescence decay time but mostly results from weaker coupling of the luminescence into the Si substrate. A decrease in the prompt fluorescence lifetime is observed as the tetracene thickness is increased on bare Si. We find no evidence for triplet energy transfer to the Si.

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