Steric control of the donor/acceptor interface: Implications in organic photovoltaic charge generation

Thomas W. Holcombe, Joseph E. Norton, Jonathan Rivnay, Claire Woo, Ludwig J. Goris, Claudia Piliego, Gianmarco Griffini, Alan Sellinger, Jean Luc Brédas, Alberto Salleo, Jean Frechet

Research output: Contribution to journalArticlepeer-review

188 Scopus citations

Abstract

The performance of organic photovoltaic (OPV) devices is currently limited by modest short-circuit current densities. Approaches toward improving this output parameter may provide new avenues to advance OPV technologies and the basic science of charge transfer in organic semiconductors. This work highlights how steric control of the charge separation interface can be effectively tuned in OPV devices. By introducing an octylphenyl substituent onto the investigated polymer backbones, the thermally relaxed charge-transfer state, and potentially excited charge-transfer states, can be raised in energy. This decreases the barrier to charge separation and results in increased photocurrent generation. This finding is of particular significance for nonfullerene OPVs, which have many potential advantages such as tunable energy levels and spectral breadth, but are prone to poor exciton separation efficiencies. Computational, spectroscopic, and synthetic methods were combined to develop a structure-property relationship that correlates polymer substituents with charge-transfer state energies and, ultimately, device efficiencies. © 2011 American Chemical Society.
Original languageEnglish (US)
Pages (from-to)12106-12114
Number of pages9
JournalJournal of the American Chemical Society
Volume133
Issue number31
DOIs
StatePublished - Aug 10 2011

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUS-C1-015-21
Acknowledgements: This work was supported by the Center for Advanced Molecular Photovoltaics (Award No. KUS-C1-015-21), supported by King Abdullah University of Science and Technology (KAUST), and the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 (synthesis and some device characterization work). T.W.H., C.H.W., and J.R. thank the National Science Foundation for graduate research fellowships. We gratefully acknowledge Polyera Inc. and Paul Armstrong for providing the Active Ink N2200 and PDL respectively, used in this study. Paul Armstrong and Yoshi Miyamoto are thanked for assistance with device optimization. We also thank David Kavulak and Barry Thompson for helpful discussions.

ASJC Scopus subject areas

  • Biochemistry
  • Colloid and Surface Chemistry
  • Chemistry(all)
  • Catalysis

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