Double doping of conjugated polymers with monomer molecular dopants

David Kiefer*, Renee Kroon, Anna I. Hofmann, Hengda Sun, Xianjie Liu, Alexander Giovannitti, Dominik Stegerer, Alexander Cano, Jonna Hynynen, Liyang Yu, Yadong Zhang, Dingqi Nai, Thomas F. Harrelson, Michael Sommer, Adam J. Moulé, Martijn Kemerink, Seth R. Marder, Iain McCulloch, Mats Fahlman, Simone FabianoChristian Müller

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

175 Scopus citations


Molecular doping is a crucial tool for controlling the charge-carrier concentration in organic semiconductors. Each dopant molecule is commonly thought to give rise to only one polaron, leading to a maximum of one donor:acceptor charge-transfer complex and hence an ionization efficiency of 100%. However, this theoretical limit is rarely achieved because of incomplete charge transfer and the presence of unreacted dopant. Here, we establish that common p-dopants can in fact accept two electrons per molecule from conjugated polymers with a low ionization energy. Each dopant molecule participates in two charge-transfer events, leading to the formation of dopant dianions and an ionization efficiency of up to 200%. Furthermore, we show that the resulting integer charge-transfer complex can dissociate with an efficiency of up to 170%. The concept of double doping introduced here may allow the dopant fraction required to optimize charge conduction to be halved.

Original languageEnglish (US)
Pages (from-to)149-155
Number of pages7
JournalNature Materials
Issue number2
StatePublished - Feb 1 2019

Bibliographical note

Funding Information:
We gratefully acknowledge financial support from the Swedish Research Council through grant no. 2016-06146, the Knut and Alice Wallenberg Foundation through a Wallenberg Academy Fellowship and the European Research Council (ERC) under grant agreement no. 637624. The authors thank the Cornell High Energy Synchrotron Source (CHESS) (supported by the NSF & NIH/NIGMS through NSF award DMR-1332208) for providing experimental time for GIWAXS measurements. We thank the Freiburg Materials Research Center (FMF) and Anders Mårtensson (Chalmers) for help with SEC measurements. We would like to thank Professor Koen Vandewal for helpful discussions. S.R.M. and Y.Z. thank the US National Science Foundation for support of this work, under award no. DMR-1729737. S.F. and H.S. acknowledge financial support from VINNOVA (grant no. 2015-04859) and the Swedish Research Council (grant no. 2016-03979). DFT simulations by T.F.H., D.N. and A.J.M. were supported by the US Department of Energy, Office of Basic Energy Sciences under award DE-SC0010419. M.F. and X.L. acknowledge support by the Swedish Research Council (grant no. 2016-05498). A.G. and I.M. acknowledge funding from the Engineering and Physical Sciences Research Council (EP/G037515/1).

Publisher Copyright:
© 2019, The Author(s), under exclusive licence to Springer Nature Limited.

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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