Substituent effects on singlet exciton fission in polycrystalline thin films of cyano-substituted diaryltetracenes

Margulies, Eric A., Kerisit, Nicolas, Gawel, Przemyslaw, Mauck, Catherine M., Ma, Lin, Miller, Claire E., Young, Ryan M., Trapp, Nils, Wu, Yi-Lin ORCID: https://orcid.org/0000-0003-0253-1625, Diederich, François and Wasielewski, Michael R. 2017. Substituent effects on singlet exciton fission in polycrystalline thin films of cyano-substituted diaryltetracenes. Journal of Physical Chemistry C 121 (39) , pp. 21262-21271. 10.1021/acs.jpcc.7b07870

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Abstract

Cyano-substituted tetracenes (5,11-dicyano-6,12-diphenyltetracene, Tet) undergo exoergic singlet fission (SF), a spin-allowed photophysical process that generates a pair of triplet excitons from one singlet exciton. To elucidate substituent effects on SF, we have measured the SF dynamics and triplet yields of thin films, formed by Tet bearing hydrogen (H), methyl (Me), fluoro (F), and trimethylsilyl (TMS) substituents on the p-phenyl positions and on the 3 and 9 positions of the tetracene core, by time-resolved spectroscopy in the vis-NIR and IR regions. The H-, Me-, and F-Tet display strong intramolecular electronic coupling (π–π distances <4 Å), and SF gives high triplet exciton yields up to 200% (quantitative). In addition, a charge-transfer state mediates SF in F-Tet films, while H-Tet and Me-Tet show no evidence for such a state. Correlations between the SF yields and the crystal structure show that chromophore slippage along both their short and long axes allows efficient SF and that a large degree of π contact between the chromophores is not necessary for rapid and efficient SF in the solid state. As expected, the large interchromophore distance in TMS-Tet (>4 Å) reduces its SF triplet yield to about 60%.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Chemistry
Publisher:	American Chemical Society
ISSN:	1932-7447
Date of First Compliant Deposit:	11 January 2019
Date of Acceptance:	10 August 2017
Last Modified:	29 Nov 2024 17:00
URI:	https://orca.cardiff.ac.uk/id/eprint/118311

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