The Role of Electron Affinity in Determining Whether Fullerenes Catalyze or Inhibit Photooxidation of Polymers for Solar Cells

Type
Article

Authors
Hoke, Eric T.
Sachs-Quintana, I. T.
Lloyd, Matthew T.
Kauvar, Isaac
Mateker, William R.
Nardes, Alexandre M.
Peters, Craig H.
Kopidakis, Nikos
McGehee, Michael D.

KAUST Grant Number
KUS-C1-015-21

Online Publication Date
2012-05-21

Print Publication Date
2012-11

Date
2012-05-21

Abstract
Understanding the stability and degradation mechanisms of organic solar materials is critically important to achieving long device lifetimes. Here, an investigation of the photodegradation of polymer:fullerene blend fi lms exposed to ambient conditions for a variety of polymer and fullerene derivative combinations is presented. Despite the wide range in polymer stabilities to photodegradation, the rate of irreversible polymer photobleaching in blend fi lms is found to consistently and dramatically increase with decreasing electron affi nity of the fullerene derivative. Furthermore, blends containing fullerenes with the smallest electron affi nities photobleached at a faster rate than fi lms of the pure polymer. These observations can be explained by a mechanism where both the polymer and fullerene donate photogenerated electrons to diatomic oxygen to form the superoxide radical anion which degrades the polymer. © 2012 WILEY-VCH Verlag GmbH & Co.

Citation
Hoke ET, Sachs-Quintana IT, Lloyd MT, Kauvar I, Mateker WR, et al. (2012) The Role of Electron Affinity in Determining Whether Fullerenes Catalyze or Inhibit Photooxidation of Polymers for Solar Cells. Adv Energy Mater 2: 1351–1357. Available: http://dx.doi.org/10.1002/aenm.201200169.

Acknowledgements
E.T.H., I.T.S.Q., and M.T.L. contributed equally to this work. This publication was supported by the Center for Advanced Molecular Photovoltaics (Award No KUS-C1-015-21), made by King Abdullah University of Science and Technology (KAUST). M.T.L, A.M.N and N.K. acknowledge support from the US Department of Energy under Contract No. DE-AC36-08-GO28308 with the National Renewable Energy Laboratory through the DOE SETP program. We thank Plextronics for providing some of the fullerenes (ICMA, ICBA, and ICTA) and LG providing the sulfur plasma lamps. We thank H.-J. Egelhaaf for helpful discussions. Additional support was provided for E.T.H. by the Fannie and John Hertz Foundation, for I.T.S.Q. by the National Science Foundation Graduate Research Fellowship and I. K. was supported by the DOE SULI fellowship program.

Publisher
Wiley

Journal
Advanced Energy Materials

DOI
10.1002/aenm.201200169

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