Hynes, E.L., Cabral, J.T., Parnell, A.J. orcid.org/0000-0001-8606-8644 et al. (5 more authors) (2019) Interfacial width and phase equilibrium in polymer-fullerene thin-films. Communications Physics, 2 (1). 112.
Abstract
Domain composition and interfacial structure are critical factors in organic photovoltaic performance. Here, we report neutron reflectivity, grazing-incidence X-ray diffraction and atomic force microscopy measurements of polymer/fullerene thin-films to test a hypothesis that these partially miscible blends rapidly develop composition profiles consisting of co-existing phases in liquid-liquid equilibrium. We study a range of polymer molecular weights between 2 and 300 kg mol−1, annealing temperatures between 120 and 170 oC, and timescales up to 10 min, yielding over 50 distinct measurement conditions. Model bilayers of fullerene-derivatives and polystyrene enable a rigorous examination of theoretical predictions of the effect of polymer mass and interaction parameter on the compositions, ϕ, and interfacial width, w, of the coexistent phases. We independently measure ϕ and w and find that both Flory-Huggins mean-field-theory and key aspects of self-consistent-field-theory are remarkably consistent with experiment. Our findings pave the way for predictive composition and interface design in organic photovoltaics based on simple experimental measurements and equilibrium thermodynamic theory.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2019 The Authors. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > Department of Chemical and Biological Engineering (Sheffield) The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 23 Oct 2019 13:41 |
Last Modified: | 23 Oct 2019 13:45 |
Status: | Published |
Publisher: | Nature Research (part of Springer Nature) |
Refereed: | Yes |
Identification Number: | 10.1038/s42005-019-0211-z |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:152240 |