Abstract
We investigate the photostability of a set of organic semiconductor blends comprising a conjugated polymer as the donor and a fullerene as the acceptor using electron spin resonance (ESR). In the absence of oxygen, all blends show excellent stability. Even after several hundred hours of exposure to solar or UV radiation, the ESR spectra and the recombination of photoinduced charges recorded at low temperature are found to be unchanged. By contrast, the presence of oxygen leads to a fast light-induced degradation rendering the ability of the donor/acceptor system to form photoinduced charge carriers. Our findings suggest that conjugated polymer–fullerene blends exhibit very good photostability and that oxygen needs to be excluded in optoelectronic applications. Our findings also suggest that at low temperature, a universal recombination process of long-lived photoinduced charges is active, which does not depend on the electronic structure or the morphology of the investigated materials.
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References
National Renewable Energy Laboratory (2018). Available at: www.nrel.gov/pv/assets/images/efficiency-chart.png (accessed June 5, 2018).
M. Jørgensen, K. Norrman, S. Gevorgyan, T. Tromholt, B. Andreasen, and F.C. Krebs: Stability of polymer solar cells. Adv. Mater. 24, 580–612 (2012).
G. Grancini, M. De Bastiani, N. Martino, D. Fazzi, H-J. Egelhaaf, T. Sauermann, M.R. Antognazza, G. Lanzani, M. Caironi, and L. Franco: The critical role of interfacial dynamics in the stability of organic photovoltaic devices. Phys. Chem. Chem. Phys. 16, 8294–8300 (2014).
P. Možíšková, P. Heinrichová, M. Šedina, M. Vala, J. David, and M. Weiter: The influence of transport layers on the photodegradation stability of polymer solar cell structures. J. Polym. Eng. 34, 1–11 (2014).
X. Wang, H-J. Egelhaaf, H.G. Mack, H. Azimi, C.J. Brabec, A.J. Meixner, and D. Zhang: Morphology related photodegradation of low-band-gap polymer blends. Adv. Energy Mater. 4, 1–12 (2014).
R.A. Street, M. Schoendorf, A. Roy, and J.H. Lee: Interface state recombination in organic solar cells. Phys. Rev. Appl. 81, 1–12 (2010).
V. Dyakonov, G. Zoriniants, M. Scharber, C.J. Brabec, R. Janssen, J. Hummelen, and N. Sariciftci: Photoinduced charge carriers in conjugated polymer–fullerene composites studied with light-induced electron-spin resonance. Phys. Rev. B 59, 8019–8025 (1999).
D.K. Susarova, N.P. Piven, A.V. Akkuratov, L.A. Frolova, M.S. Polinskaya, S.A. Ponomarenko, S.D. Babenko, and P.A. Troshin: ESR spectroscopy as a powerful tool for probing the quality of conjugated polymers designed for photovoltaic applications. Chem. Commun. 51, 2239–2241 (2015).
A. Sperlich, H. Kraus, C. Deibel, H. Blok, J. Schmidt, and V. Dyakonov: Reversible and irreversible interactions of poly(3-hexylthiophene) with oxygen studied by spin-sensitive methods. J. Phys. Chem. B 115, 13513–13518 (2011).
C.J. Brabec, S. Gowrisanker, J.J.M. Halls, D. Laird, S. Jia, and S.P. Williams: Polymer–fullerene bulk-heterojunction solar cells. Adv. Mater. 22, 3839–3856 (2010).
C. Carati, L. Bonoldi, and R. Po: Density of trap states in organic photovoltaic materials from LESR studies of carrier recombination kinetics. Phys. Rev. B 84, 245205 (2011).
L.N. Inasaridze, A.I. Shames, I.V. Martynov, B. Li, A.V. Mumyatov, D.K. Susarova, E.A. Katz, and P.A. Troshin: Light-induced generation of free radicals by fullerene derivatives: An important degradation pathway in organic photovoltaics? J. Mater. Chem. A 5, 8044–8050 (2017).
A.I. Shames, L.N. Inasaridze, A.V. Akkuratov, A.E. Goryachev, E.A. Katz, and P.A. Troshin: Assessing the outdoor photochemical stability of conjugated polymers by EPR spectroscopy. J. Mater. Chem. A 4, 13166–13170 (2016).
N. Schultz, M. Scharber, C. Brabec, and N. Sariciftci: Low-temperature recombination kinetics of photoexcited persistent charge carriers in conjugated polymer/fullerene composite films. Phys. Rev. B 64, 1–7 (2001).
Y. Udum, P. Denk, G. Adam, D.H. Apaydin, A. Nevosad, C. Teichert, M.S. White, N.S. Sariciftci, and M.C. Scharber: Inverted bulk-heterojunction solar cell with cross-linked hole-blocking layer. Org. Electron. 15, 997–1001 (2014).
M.C. Scharber: Manuscript in preparation.
M. Salvador, N. Gasparini, J.D. Perea, S. Harish Paleti, A. Distler, L.N. Inasaridze, P.A. Troshin, L. Lüer, H-J. Egelhaaf, and C. Brabec: Suppressing photooxidation of conjugated polymers and their blends with fullerenes through nickel chelates. Energy Environ. Sci. 10, 2005–2016 (2017).
J. Razzell-Hollis, J. Wade, W. Chung Tsoi, Y. Soon, J. Durrant, and J-S. Kim: Photochemical stability of high efficiency PTB7:PC70BM solar cell blends. J. Mater. Chem. A 2, 20189–20195 (2014).
ACKNOWLEDGMENT
M.H. and M.C.S. acknowledge the FWF Austria Science Fund for financial support (FWF P25724-N19). N.S.S. acknowledges the FWF Austria Science Fund within the Wittgenstein Prize scheme (Z222-N19 Solare Energieumwandlung).
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Havlicek, M., Sariciftci, N.S. & Scharber, M.C. Degradation kinetics in different polymer–fullerene blends investigated by electron spin resonance. Journal of Materials Research 33, 1853–1859 (2018). https://doi.org/10.1557/jmr.2018.210
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DOI: https://doi.org/10.1557/jmr.2018.210