Tuning Singlet Fission in π-Bridge-π Chromophores

Elango Kumarasamy, Samuel N. Sanders, Murad J.Y. Tayebjee, Amir Asadpoordarvish, Timothy J.H. Hele, Eric G. Fuemmeler, Andrew B. Pun, Lauren M. Yablon, Jonathan Z. Low, Daniel W. Paley, Jacob C. Dean, Bonnie Choi, Gregory D. Scholes, Michael L. Steigerwald, Nandini Ananth, Dane R. McCamey, Matthew Y. Sfeir, Luis M. Campos

Research output: Contribution to journalArticle

65 Scopus citations

Abstract

We have designed a series of pentacene dimers separated by homoconjugated or nonconjugated bridges that exhibit fast and efficient intramolecular singlet exciton fission (iSF). These materials are distinctive among reported iSF compounds because they exist in the unexplored regime of close spatial proximity but weak electronic coupling between the singlet exciton and triplet pair states. Using transient absorption spectroscopy to investigate photophysics in these molecules, we find that homoconjugated dimers display desirable excited-state dynamics, with significantly reduced recombination rates as compared to conjugated dimers with similar singlet fission rates. In addition, unlike conjugated dimers, the time constants for singlet fission are relatively insensitive to the interplanar angle between chromophores, since rotation about σ bonds negligibly affects the orbital overlap within the π-bonding network. In the nonconjugated dimer, where the iSF occurs with a time constant >10 ns, comparable to the fluorescence lifetime, we used electron spin resonance spectroscopy to unequivocally establish the formation of triplet-triplet multiexcitons and uncoupled triplet excitons through singlet fission. Together, these studies enable us to articulate the role of the conjugation motif in iSF.

Original languageEnglish (US)
Pages (from-to)12488-12494
Number of pages7
JournalJournal of the American Chemical Society
Volume139
Issue number36
DOIs
StatePublished - 2017

All Science Journal Classification (ASJC) codes

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

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    Kumarasamy, E., Sanders, S. N., Tayebjee, M. J. Y., Asadpoordarvish, A., Hele, T. J. H., Fuemmeler, E. G., Pun, A. B., Yablon, L. M., Low, J. Z., Paley, D. W., Dean, J. C., Choi, B., Scholes, G. D., Steigerwald, M. L., Ananth, N., McCamey, D. R., Sfeir, M. Y., & Campos, L. M. (2017). Tuning Singlet Fission in π-Bridge-π Chromophores. Journal of the American Chemical Society, 139(36), 12488-12494. https://doi.org/10.1021/jacs.7b05204