Probing the Wave Function and Dynamics of the Quintet Multiexciton State with Coherent Control in a Singlet Fission Material

S. L. Bayliss, L. R. Weiss, F. Kraffert, D. B. Granger, J. E. Anthony, J. Behrends, R. Bittl

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

High-spin states play a key role in chemical reactions found in nature. In artificial molecular systems, singlet fission produces a correlated triplet-pair state, a spin-bearing excited state that can be harnessed for more efficient solar-energy conversion and photocatalysis. In particular, triplet-pair states with overall quintet character (total spin S=2) have been discovered, but many of the fundamental properties of these biexciton states remain unexplored. The net spin of these pair states makes spin-sensitive probes attractive for their characterization. Combined with their surprisingly long spin coherence (of order microseconds), this opens up techniques relying on coherent spin control. Here we apply coherent manipulation of triplet-pair states to (i) isolate their spectral signatures from coexisting free triplets and (ii) selectively couple quintet and triplet states to specific nuclear spins. Using this approach, we separate quintet and triplet transitions and extract the relaxation dynamics and hyperfine couplings of the fission-borne spin states. Our results highlight the distinct properties of correlated and free triplet excitons and demonstrate optically induced nuclear spin polarization by singlet fission.

Original languageEnglish
Article number021070
JournalPhysical Review X
Volume10
Issue number2
DOIs
StatePublished - Jun 2020

Bibliographical note

Funding Information:
We thank C. Teutloff and R. Steyrleuthner for experimental assistance, and A. D. Chepelianskii, R. H. Friend, and N. Panjwani for helpful comments. We acknowledge support from DFG SPP-1601 (Bi-464/10-2 and BE-5126/1-2). L. R. W. acknowledges support from the Clare College Junior Research Fellowship.

Publisher Copyright:
© 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "http://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI

ASJC Scopus subject areas

  • Physics and Astronomy (all)

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