Exciton delocalization drives rapid singlet fission in nanoparticles of acene derivatives

Ryan D. Pensack, Andrew J. Tilley, Sean R. Parkin, Tia S. Lee, Marcia M. Payne, Dong Gao, Ashlee A. Jahnke, Daniel G. Oblinsky, Peng Fei Li, John E. Anthony, Dwight S. Seferos, Gregory D. Scholes

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124 Scopus citations

Abstract

We compare the singlet fission dynamics of five pentacene derivatives precipitated to form nanoparticles. Two nanoparticle types were distinguished by differences in their solid-state order and kinetics of triplet formation. Nanoparticles that comprise primarily weakly coupled chromophores lack the bulk structural order of the single crystal and exhibit nonexponential triplet formation kinetics (Type I), while nanoparticles that comprise primarily more strongly coupled chromophores exhibit order resembling that of the bulk crystal and triplet formation kinetics associated with the intrinsic singlet fission rates (Type II). In the highly ordered nanoparticles, singlet fission occurs most rapidly. We relate the molecular packing arrangement derived from the crystal structure of the pentacene derivatives to their singlet fission dynamics and find that slip stacking leads to rapid, subpicosecond singlet fission. We present evidence that exciton delocalization, coincident with an increased relative admixture of charge-transfer configurations in the description of the exciton wave function, facilitates rapid triplet pair formation in the case of single-step singlet fission. We extend the study to include two hexacene derivatives and find that these conclusions are generally applicable. This work highlights acene derivatives as versatile singlet fission chromophores and shows how chemical functionalization affects both solid-state order and exciton interactions and how these attributes in turn affect the rate of singlet fission.

Original languageEnglish (US)
Pages (from-to)6790-6803
Number of pages14
JournalJournal of the American Chemical Society
Volume137
Issue number21
DOIs
StatePublished - Jun 3 2015

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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    Pensack, R. D., Tilley, A. J., Parkin, S. R., Lee, T. S., Payne, M. M., Gao, D., Jahnke, A. A., Oblinsky, D. G., Li, P. F., Anthony, J. E., Seferos, D. S., & Scholes, G. D. (2015). Exciton delocalization drives rapid singlet fission in nanoparticles of acene derivatives. Journal of the American Chemical Society, 137(21), 6790-6803. https://doi.org/10.1021/ja512668r