Twist and degrade – Impact of molecular structure on the photostability of non-fullerene acceptors and their photovoltaic blends

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Title: Twist and degrade – Impact of molecular structure on the photostability of non-fullerene acceptors and their photovoltaic blends
Authors: Luke, J
Speller, EM
Wadsworth, A
Wyatt, MF
Dmiitrov, S
Lee, HKH
Li, Z
Tsoi, WC
McCulloch, I
Bagnis, D
Durrant, JR
Kim, J-S
Item Type: Journal Article
Abstract: Non-fullerene acceptors (NFAs) dominate organic photovoltaic (OPV) research due to their promising efficiencies and stabilities. However, there is very little investigation into the molecular processes of degradation, which is critical to guiding design of novel NFAs for long-lived, commercially viable OPVs. Here we investigate the important role of molecular structure and conformation on NFA photostability in air by comparing structurally similar but conformationally different promising NFAs; planar O-IDTBR and non-planar O-IDFBR. We identify a three-phase degradation process: (i) initial photo-induced conformational change (i.e. torsion about the Core-BT dihedral), induced by non-covalent interactions with environmental molecules, (ii) followed by photo-oxidation and fragmentation, leading to chromophore bleaching and degradation product formation, and (iii) finally complete chromophore bleaching. Initial conformational change is a critical prerequisite for further degradation, providing fundamental understanding of the relative stability of IDTBR and IDFBR, where the alreadytwisted IDFBR is more prone to degradation. When blended with the donor polymer P3HT, both NFAs exhibit improved photostability whilst the photostability of the polymer itself is significantly reduced by the more miscible twisted NFA. Our findings elucidate the important role of NFA molecular structure on photostability of OPV systems, and provide vital insights into molecular design rules for intrinsically photostable NFAs.
Issue Date: 18-Apr-2019
Date of Acceptance: 8-Feb-2019
URI: http://hdl.handle.net/10044/1/66401
DOI: https://doi.org/10.1002/aenm.201803755
ISSN: 1614-6832
Publisher: Wiley
Start Page: 1
End Page: 14
Journal / Book Title: Advanced Energy Materials
Volume: 9
Issue: 15
Copyright Statement: © 2019 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim. This is the accepted version of the following article: Luke, J., Speller, E. M., Wadsworth, A., Wyatt, M. F., Dimitrov, S., Lee, H. K. H., Li, Z., Tsoi, W. C., McCulloch, I., Bagnis, D., Durrant, J. R., Kim, J.‐S., Adv. Energy Mater. 2019, 9, 1803755, which has been published in final form at https://doi.org/10.1002/aenm.201803755
Sponsor/Funder: Engineering and Physical Sciences Research Council
National Research Foundation of Korea (NRF)
Engineering and Physical Sciences Research Council
CSEM Brasil
Funder's Grant Number: EP/L016702/1
NRF-2017K1A1A2013153
EP/G037515/1
Keywords: Science & Technology
Physical Sciences
Technology
Chemistry, Physical
Energy & Fuels
Materials Science, Multidisciplinary
Physics, Applied
Physics, Condensed Matter
Chemistry
Materials Science
Physics
conformational change
nonfullerene acceptor molecular structures
nonfullerene acceptors
organic solar cells
photostability
SET MODEL CHEMISTRY
POLYMER SOLAR-CELLS
ENVIRONMENTAL STABILITY
11-PERCENT EFFICIENCY
TOTAL ENERGIES
SERS SPECTRA
THIN-FILMS
POLY(3-HEXYLTHIOPHENE)
MORPHOLOGY
CONFORMATION
0303 Macromolecular and Materials Chemistry
0912 Materials Engineering
0915 Interdisciplinary Engineering
Publication Status: Published
Embargo Date: 2020-02-21
Online Publication Date: 2019-02-21
Appears in Collections:Physics
Chemistry
Experimental Solid State
Faculty of Natural Sciences



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