Marin-Beloqui, J.M., Toolan, D.T.W., Panjwani, N.A. et al. (3 more authors) (2021) Triplet-charge annihilation in a small molecule donor: acceptor blend as a major loss mechanism in organic photovoltaics. Advanced Energy Materials, 11 (24). 2100539. ISSN 1614-6832
Abstract
Organic photovoltaics (OPV) are close to reaching a landmark 20% device efficiency. One of the proposed reasons that OPVs have yet to attain this milestone is their propensity toward triplet formation. Herein, a small molecule donor, DRCN5T, is studied using a variety of morphology and spectroscopy techniques, and blended with both fullerene and non-fullerene acceptors. Specifically, grazing incidence wide-angle X-ray scattering and transient absorption, Raman, and electron paramagnetic resonance spectroscopies are focused on. It is shown that despite DRCN5T's ability to achieve OPV efficiencies of over 10%, it generates an unusually high population of triplets. These triplets are primarily formed in amorphous regions via back recombination from a charge transfer state, and also undergo triplet-charge annihilation. As such, triplets have a dual role in DRCN5T device efficiency suppression: they both hinder free charge carrier formation and annihilate those free charges that do form. Using microsecond transient absorption spectroscopy under oxygen conditions, this triplet-charge annihilation (TCA) is directly observed as a general phenomenon in a variety of DRCN5T: fullerene and non-fullerene blends. Since TCA is usually inferred rather than directly observed, it is demonstrated that this technique is a reliable method to establish the presence of TCA.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 The Authors. Advanced Energy Materials published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, (http://creativecommons.org/licenses/by/4.0/) which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
Keywords: | DRCN5T; non-fullerene acceptors; Raman; spectroscopy; transient absorption spectroscopy; triplets |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Chemistry (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 26 May 2021 16:03 |
Last Modified: | 21 Feb 2022 14:32 |
Status: | Published |
Publisher: | Wiley |
Refereed: | Yes |
Identification Number: | 10.1002/aenm.202100539 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:174560 |