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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