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Quantum interference effects elucidate triplet-pair formation dynamics in intramolecular singlet-fission molecules
Kaia R Parenti1, Rafi Chesler2, Guiying He3,4
1Department of Chemistry, Columbia University, New York, NY, USA.
Nature Chemistry
|December 30, 2022
Summary
Quantum interference (QI) principles predict triplet pair formation rates in molecular electronics. Destructive QI consistently slows triplet formation, highlighting the importance of bridge structure and orbital energies for multiexciton generation.
Area of Science:
- Physical Chemistry
- Organic Molecular Electronics
- Quantum Chemistry
Background:
- Quantum interference (QI) influences charge and spin transport in organic electronics by modulating conduction pathways through molecular orbitals.
- Existing graphical models successfully predict QI effects in polyaromatic hydrocarbons for charge transport but struggle with excitonic processes.
- Excitonic processes, involving photoexcited states and different orbital symmetries, present a challenge for current QI models.
Purpose of the Study:
- To extend quantum interference (QI) models to predict triplet pair formation rates in intramolecular singlet-fission compounds.
- To investigate the role of bridging moieties in modulating QI effects for multiexciton generation.
- To establish critical factors for applying QI principles to photoexcited processes.
Main Methods:
- Utilized a series of bridged intramolecular singlet-fission dimers for experimental and theoretical investigations.
- Applied quantum interference (QI) models to analyze conduction pathways through bridging moieties.
- Combined experimental measurements with theoretical calculations to assess triplet pair formation rates.
Main Results:
- Demonstrated that destructive quantum interference (QI) consistently leads to slower triplet pair formation rates.
- Observed this effect across various bridge lengths and geometries in the studied dimers.
- Identified bridge topology and frontier molecular orbital energies as critical parameters influencing QI effects.
Conclusions:
- Quantum interference (QI) models can be adapted to predict triplet pair formation rates in intramolecular singlet-fission systems.
- Destructive QI serves as a reliable indicator for reduced triplet pair formation efficiency.
- Bridge design and molecular orbital characteristics are crucial for optimizing multiexciton generation via controlled QI.
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