Triplet-pair spin signatures from macroscopically aligned heteroacenes in an oriented single crystal

Brandon K. Rugg, Kori E. Smyser, Brian Fluegel, Christopher H. Chang, Karl J. Thorley, Sean Parkin, John E. Anthony, Joel D. Eaves, Justin C. Johnson

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The photo-driven process of singlet fission generates coupled triplet pairs (TT) with fundamentally intriguing and potentially useful properties. The quintet 5TT0 sublevel is particularly interesting for quantum information because it is highly entangled, is addressable with microwave pulses, and could be detected using optical techniques. Previous theoretical work on a model Hamiltonian and nonadiabatic transition theory, called the JDE model, has determined that this sublevel can be selectively populated if certain conditions are met. Among the most challenging, the molecules within the dimer undergoing singlet fission must have their principal magnetic axes parallel to one another and to an applied Zeeman field. Here, we present time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy of a single crystal sample of a tetracenethiophene compound featuring arrays of dimers aligned in this manner, which were mounted so that the orientation of the field relative to the molecular axes could be controlled. The observed spin sublevel populations in the paired TT and unpaired (T+T) triplets are consistent with predictions from the JDE model, including preferential 5TT0 formation at z || B0, with one caveat - two 5TT spin sublevels have little to no population. This may be due to crossings between the 5TT and 3TT manifolds in the field range investigated by TR-EPR, consistent with the intertriplet exchange energy determined by monitoring photoluminescence at varying magnetic fields.

Original languageEnglish
Article numbere2201879119
JournalProceedings of the National Academy of Sciences of the United States of America
Volume119
Issue number29
DOIs
StatePublished - Jul 19 2022

Bibliographical note

Funding Information:
Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US DOE under Contract No. DE-AC02-05CH11231. The views expressed in the article do not necessarily represent the views of the DOE or the US government. The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for US government purposes.

Funding Information:
ACKNOWLEDGMENTS. We thank Obadiah Reid and Ryan Dill for useful discussions and Petri Alahuhta for assistance with sample preparation. This work was authored by Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the US Department of Energy (DOE) under contract no. DE-AC36-08GO28308. Funding was provided by US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences, and Geosciences. A portion of the research was performed using computational resources sponsored by the DOE’s Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory. This research also used resources of the National Energy Research

Funding Information:
We thank Obadiah Reid and Ryan Dill for useful discussions and Petri Alahuhta for assistance with sample preparation. This work was authored by Alliance for Sustainable Energy, LLC, the manager and operator of the National Renewable Energy Laboratory for the US Department of Energy (DOE) under contract no. DE-AC36-08GO28308. Funding was provided by US Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Biosciences, and Geosciences. A portion of the research was performed using computational resources sponsored by the DOE's Office of Energy Efficiency and Renewable Energy and located at the National Renewable Energy Laboratory. This research also used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the US DOE under Contract No. DE-AC02-05CH11231. The views expressed in the article do not necessarily represent the views of the DOE or the US government. The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for US government purposes.

Publisher Copyright:
Copyright © 2022 the Author(s).

Keywords

  • magnetic resonance
  • photophysics
  • quantum information
  • singlet fission
  • triplet pair

ASJC Scopus subject areas

  • General

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