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Impact of mesoscale order on open-circuit voltage in organic solar cells

Nature Materials volume 14, pages 434439 (2015) | Download Citation

Abstract

Structural order in organic solar cells is paramount: it reduces energetic disorder, boosts charge and exciton mobilities, and assists exciton splitting. Owing to spatial localization of electronic states, microscopic descriptions of photovoltaic processes tend to overlook the influence of structural features at the mesoscale. Long-range electrostatic interactions nevertheless probe this ordering, making local properties depend on the mesoscopic order. Using a technique developed to address spatially aperiodic excitations in thin films and in bulk, we show how inclusion of mesoscale order resolves the controversy between experimental and theoretical results for the energy-level profile and alignment in a variety of photovoltaic systems, with direct experimental validation. Optimal use of long-range ordering also rationalizes the acceptor–donor–acceptor paradigm for molecular design of donor dyes. We predict open-circuit voltages of planar heterojunction solar cells in excellent agreement with experimental data, based only on crystal structures and interfacial orientation.

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Acknowledgements

This work has been supported by the BMBF programme MEDOS (FKZ 03EK3503B). We are grateful to T. Bereau for critical reading of the manuscript and P. Bäuerle and C. Körner for fruitful collaborations.

Author information

Affiliations

  1. Max Planck Institute for Polymer Research, Ackermannweg 10 55128 Mainz, Germany

    • Carl Poelking
    • , Björn Baumeier
    •  & Denis Andrienko
  2. Heidelberg Graduate School of Fundamental Physics, INF 226 69120 Heidelberg, Germany

    • Carl Poelking
  3. Institut für Angewandte Photophysik, George-Bähr-Straße 10 01062 Dresden, Germany

    • Max Tietze
    • , Chris Elschner
    •  & Karl Leo
  4. Physikalische Chemie, Universität zu Köln, Luxemburger Straße 116 50939 Köln, Germany

    • Selina Olthof
    • , Dirk Hertel
    •  & Klaus Meerholz
  5. Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany

    • Frank Würthner

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Contributions

C.P., B.B. and D.A. conceived and performed simulations. M.T., C.E. and K.L. contributed experimental results on DCVnTs. S.O., D.H., F.W. and K.M. contributed experimental results on merocyanines. C.P. and D.A. wrote the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Carl Poelking or Denis Andrienko.

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DOI

https://doi.org/10.1038/nmat4167

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