Twist and degrade – Impact of molecular structure on the photostability of non-fullerene acceptors and their photovoltaic blends
File(s)
Supporting information
Accepted version
Author(s)
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.
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.
Date Issued
2019-04-18
Date Acceptance
2019-02-08
Citation
Advanced Energy Materials, 2019, 9 (15), pp.1-14
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
Engineering and Physical Sciences Research Council
National Research Foundation of Korea (NRF)
Engineering and Physical Sciences Research Council
CSEM Brasil
Identifier
https://onlinelibrary.wiley.com/doi/full/10.1002/aenm.201803755
Grant Number
EP/L016702/1
NRF-2017K1A1A2013153
EP/G037515/1
Subjects
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
Date Publish Online
2019-02-21