Chromophore Multiplication To Enable Exciton Delocalization and Triplet Diffusion Following Singlet Fission in Tetrameric Pentacene
| Autor: | Dirk M. Guldi, Rik R. Tykwinski, Constantin Hetzer, Fraser J. White, Timothy Clark, Sebastian M. Kopp, Frank Hampel, Bettina S. Basel |
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| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Materials science
Exciton 010402 general chemistry 01 natural sciences Molecular physics time-resolved spectroscopy Catalysis Pentacene pentacene oligomers Delocalized electron chemistry.chemical_compound Ultrafast laser spectroscopy Charge Transfer 010405 organic chemistry Communication singlet fission General Medicine General Chemistry Chromophore Naturwissenschaftliche Fakultät Communications 0104 chemical sciences Intersystem crossing chemistry Intramolecular force Singlet fission ddc:540 triplet decorrelation |
| Zdroj: | Angewandte Chemie (International Ed. in English) |
| Popis: | A tetrameric pentacene, PT, has been used to explore the effects of exciton delocalization on singlet fission (SF). For the first time, triplet decorrelation through intramolecular triplet diffusion was observed following SF. Transient absorption spectroscopy was used to examine different decorrelation mechanisms (triplet diffusion versus structural changes) for PT and its dimeric equivalent PD on the basis of the rate and activation barrier of the decorrelation step. Charge‐separation experiments using tetracyano‐p‐quinodimethane (TCNQ) to quench triplet excitons formed through SF demonstrate that enhanced intersystem crossing, that is, spin catalysis, is a widely underestimated obstacle to quantitative harvesting of the SF products. The importance of spatial separation of the decorrelated triplet states is emphasized, and independent proof that the decorrelated triplet pair state consists of two (T1) states per molecule is provided. Not to be underestimated: A tetrameric pentacene (see structure) was designed as a model system to explore the influence of exciton delocalization on singlet fission (SF) and subsequent triplet decorrelation by exciton diffusion following intramolecular SF. Experiment and theory showed the delocalization of singlet and triplet excitons among the four pentacenes and highlighted spin catalysis as a substantial obstacle to quantitative harvesting of SF products. |
| Databáze: | OpenAIRE |
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