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Singlet Heterofission in Tetracene–Pentacene Thin‐Film Blends
Author(s) -
Zeiser Clemens,
Moretti Luca,
Lepple Daniel,
Cerullo Giulio,
Maiuri Margherita,
Broch Katharina
Publication year - 2020
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.202007412
Subject(s) - tetracene , pentacene , singlet fission , chromophore , singlet state , exciton , band gap , photochemistry , materials science , chemistry , organic semiconductor , chemical physics , excited state , optoelectronics , nanotechnology , atomic physics , condensed matter physics , physics , thin film transistor , anthracene , layer (electronics)
Heterofission is a photophysical process of fundamental and applied interest whereby an excited singlet state is converted into two triplets on chemically distinct chromophores. The potential of this process lies in the tuning of both the optical band gap and the splitting between singlet and triplet energies. Herein, we report the time‐domain observation of heterofission in mixed thin films of the prototypical singlet fission chromophores pentacene and tetracene using excitation wavelengths above and below the tetracene band gap. We found a time constant of 26 ps for endothermic heterofission of a singlet exciton on pentacene in blends with low pentacene fractions, which was outcompeted by pentacene homofission for increasing pentacene concentrations. Direct excitation of tetracene lead to fast energy transfer to pentacene and subsequent singlet fission, which prevented homo‐ or heterofission of a singlet exciton on tetracene.