Transient Magnetophotoinduced Absorption Studies of Photoexcitations in π-Conjugated Donor-Acceptor Copolymers

Uyen N. V. Huynh, Tek P. Basel, Eitan Ehrenfreund, Gang Li, Yang Yang, S. Mazumdar, and Z. Valy Vardeny
Phys. Rev. Lett. 119, 017401 – Published 6 July 2017
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Abstract

We have utilized a plethora of transient and steady state optical and magneto-optical spectroscopies in a broad spectral range (0.25–2.5 eV) for elucidating the primary and long-lived photoexcitations in a low band-gap π-conjugated donor-acceptor (DA) copolymer used for efficient photovoltaic solar cells. We show that both singlet excitons (SE) and intrachain triplet-triplet (TT) pairs are photogenerated in the DA-copolymer chains. From the picosecond transient magnetic field response of these species we conclude that the SE and TT spin states are coupled. The TT decomposition into two intrachain geminate triplet excitons maintains spin coherence and thus their spin entanglement lasts into the microsecond time domain.

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  • Received 2 January 2017

DOI:https://doi.org/10.1103/PhysRevLett.119.017401

© 2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Uyen N. V. Huynh1,*, Tek P. Basel1, Eitan Ehrenfreund2, Gang Li3,†, Yang Yang3, S. Mazumdar4, and Z. Valy Vardeny1,‡

  • 1Department of Physics & Astronomy, University of Utah, Salt Lake City, Utah 84112, USA
  • 2Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
  • 3Department of Materials Science & Engineering, University of California-Los Angeles, Los Angeles, California 90095, USA
  • 4Department of Physics, University of Arizona, Tucson, Arizona 85721, USA

  • *Present address: Cavendish Laboratory, University of Cambridge, United Kingdom CB3 0HE.
  • Present address: Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong.
  • To whom all correspondence should be addressed. val@physics.utah.edu

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Issue

Vol. 119, Iss. 1 — 7 July 2017

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