Lubert-Perquel, D;
Szumska, AA;
Azzouzi, M;
Salvadori, E;
Ruloff, S;
Kay, CMW;
Nelson, J;
(2020)
Structure Dependence of Kinetic and Thermodynamic Parameters in Singlet Fission Processes.
The Journal of Physical Chemistry Letters
, 11
(22)
pp. 9557-9565.
10.1021/acs.jpclett.0c02505.
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Abstract
Singlet fission—whereby one absorbed photon generates two coupled triplet excitons—is a key process for increasing the efficiency of optoelectronic devices by overcoming the Shockley–Queisser limit. A crucial parameter is the rate of dissociation of the coupled triplets, as this limits the number of free triplets subsequently available for harvesting and ultimately the overall efficiency of the device. Here we present an analysis of the thermodynamic and kinetic parameters for this process in parallel and herringbone dimers measured by electron paramagnetic resonance spectroscopy in coevaporated films of pentacene in p-terphenyl. The rate of dissociation is higher for parallel dimers than for their herringbone counterparts, as is the rate of recombination to the ground state. DFT calculations, which provide the magnitude of the electronic coupling as well as the distribution of molecular orbitals for each geometry, suggest that weaker triplet coupling in the parallel dimer is the driving force for faster dissociation. Conversely, localization of the molecular orbitals and a stronger triplet–triplet interaction result in slower dissociation and recombination. The identification and understanding of how the intermolecular geometry promotes efficient triplet dissociation provide the basis for control of triplet coupling and thereby the optimization of one important parameter of device performance.
| Type: | Article |
|---|---|
| Title: | Structure Dependence of Kinetic and Thermodynamic Parameters in Singlet Fission Processes |
| Location: | United States |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1021/acs.jpclett.0c02505 |
| Publisher version: | https://doi.org/10.1021/acs.jpclett.0c02505 |
| Language: | English |
| Additional information: | This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Hydrocarbons, Kinetic parameters, Dissociation, Oligomers, Aromatic compounds |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10116919 |
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