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Ground-state electron transfer in all-polymer donor–acceptor heterojunctions

Nature Materials volume 19, pages 738–744 (2020)Cite this article

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Abstract

Doping of organic semiconductors is crucial for the operation of organic (opto)electronic and electrochemical devices. Typically, this is achieved by adding heterogeneous dopant molecules to the polymer bulk, often resulting in poor stability and performance due to dopant sublimation or aggregation. In small-molecule donor–acceptor systems, charge transfer can yield high and stable electrical conductivities, an approach not yet explored in all-conjugated polymer systems. Here, we report ground-state electron transfer in all-polymer donor–acceptor heterojunctions. Combining low-ionization-energy polymers with high-electron-affinity counterparts yields conducting interfaces with resistivity values five to six orders of magnitude lower than the separate single-layer polymers. The large decrease in resistivity originates from two parallel quasi-two-dimensional electron and hole distributions reaching a concentration of ∼1013 cm–2. Furthermore, we transfer the concept to three-dimensional bulk heterojunctions, displaying exceptional thermal stability due to the absence of molecular dopants. Our findings hold promise for electro-active composites of potential use in, for example, thermoelectrics and wearable electronics.

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Fig. 1: Energetics of the all-polymer D–A heterojunctions.
Fig. 2: Electrical characterization of the all-polymer D–A heterojunctions.
Fig. 3: Kinetic Monte Carlo simulation of GSET heterojunctions.
Fig. 4: GSET confirmed by EPR and UV–vis–NIR spectroscopies.
Fig. 5: Electrical characterization of BBL:P(g42T-T) blend films.

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Data availability

The authors declare that the main data supporting the findings of this study are available within the paper and its Supplementary Information files. Source data for Figs. 2–5 are provided with the paper.

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Acknowledgements

We thank C. Musumeci (Linköping University) for assistance with atomic force microscopy and S. Gustafsson (Chalmers) for assistance with TEM specimen preparation. This work was supported by the Knut and Alice Wallenberg foundation, VINNOVA (grant no. 2015-04859), the Swedish Research Council (grant agreement nos. 2016-03979, 2016-06146, 2016-05498, 2016-05990, 2018-03824), the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO Mat LiU no. 2009 00971), ÅForsk (18-313) and the European Research Council (ERC) under grant agreement no. 637624. We also thank the Chalmers Material Analysis Laboratory for their support of microscopes. T.P.R acknowledges funding from the Finnish Cultural Foundation and the Finnish Foundation for Technology Promotion. N.S. thanks the National Natural Science Foundation of China (grant no. 61805211). H.Y. acknowledges JST ALCA (JPMJAL1404) and the Futaba Foundation. Work at the University of Washington was supported by the National Science Foundation (DMR-1708450). D.F. acknowledges the Deutsche Forschungsgemeinschaft (DFG) for the grant ‘Molecular Understanding of Thermo-Electric Properties in Organic Polymers (FA 1502/1-1)’, and the Regional Computing Centre (RRZK) of Universität zu Köln, for providing computing time and resources on the HPC CHEOPS.

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Authors and Affiliations

  1. Laboratory of Organic Electronics, Department of Science and Technology, Linköping University, Norrköping, Sweden

    Kai Xu, Hengda Sun, Tero-Petri Ruoko, Gang Wang, Xianjie Liu, Chi-Yuan Yang, Mats Fahlman, Magnus Berggren & Simone Fabiano

  2. Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Göteborg, Sweden

    Renee Kroon & Christian Müller

  3. Department of Chemical Engineering and Department of Chemistry, University of Washington, Seattle, WA, USA

    Nagesh B. Kolhe & Samson A. Jenekhe

  4. Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden

    Yuttapoom Puttisong & Weimin M. Chen

  5. Institute of Physical Chemistry, Department Chemistry, University of Cologne, Cologne, Germany

    Daniele Fazzi

  6. Graduate School of Science and Engineering, Chiba University, Inage-ku, Chiba, Japan

    Koki Shibata

  7. Department of Physics, Center for Optoelectronics Engineering Research, Yunnan University, Kunming, China

    Ning Sun

  8. Department of Physics, Chalmers University of Technology, Göteborg, Sweden

    Gustav Persson, Andrew B. Yankovich & Eva Olsson

  9. Wallenberg Wood Science Center, Chalmers University of Technology, Göteborg, Sweden

    Eva Olsson & Christian Müller

  10. Graduate School of Engineering, Chiba University, Inage-ku, Chiba, Japan

    Hiroyuki Yoshida

  11. Molecular Chirality Research Center, Chiba University, Inage-ku, Chiba, Japan

    Hiroyuki Yoshida

  12. Wallenberg Wood Science Center, Linköping University, Norrköping, Sweden

    Mats Fahlman, Magnus Berggren & Simone Fabiano

  13. Complex Materials and Devices, Department of Physics Chemistry and Biology, Linköping University, Linköping, Sweden

    Martijn Kemerink

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Contributions

S.F. conceived, designed and supervised the project. H.S. initiated the study. K.X. and H.S. prepared the samples, performed the electrical measurements and analysed the data. T.P.R. recorded and analysed the UV–vis–NIR data. G.W. performed the grazing-incidence wide-angle X-ray scattering and atomic force microscopy measurements. R.K. synthesized P(g42T-T) and P(g42T-TT). N.B.K. synthesized BBL, under S.A.J.’s supervision. Y.P. and W.M.C. performed and analysed the EPR data. X.L. and M.F. recorded and analysed the UPS spectra. D.F. performed the DFT calculations. K.S. and H.Y. performed and analysed the LEIPS data. C.Y.Y fabricated and tested the paper circuits. N.S. fabricated and tested the OLEDs. G.P., A.B.Y. and E.O. performed and analysed TEM. M.K. performed the kMC simulations. K.X., H.S., M.K., C.M. and S.F. wrote the manuscript. All authors contributed to discussion and manuscript preparation.

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Correspondence to Hengda Sun, Magnus Berggren or Simone Fabiano.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–26, Table 1 and first principles calculations data.

Source data

Source Data Fig. 2

Source Data for electrical characterization of bilayers.

Source Data Fig. 3

Statistical Source Data for kinetic Monte Carlo simulation.

Source Data Fig. 4

Source Data for EPR and UV–vis–NIR spectroscopies.

Source Data Fig. 5

Source Data for electrical characterization of blend films.

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Xu, K., Sun, H., Ruoko, TP. et al. Ground-state electron transfer in all-polymer donor–acceptor heterojunctions. Nat. Mater. 19, 738–744 (2020). https://doi.org/10.1038/s41563-020-0618-7

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