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A solution-processed n-type conducting polymer with ultrahigh conductivity

Abstract

Conducting polymers (CPs) with high conductivity and solution processability have made great advances since the pioneering work on doped polyacetylene1,2,3, thus creating the new field of ‘organic synthetic metals,4. Various high-performance CPs have been realized, which enable the applications of several organic electronic devices5,6. Nevertheless, most CPs exhibit hole-dominant (p-type) transport behaviour7,8, whereas the development of n-type analogues lags far behind and only a few exhibit metallic state, typically limited by low doping efficiency and ambient instability. Here we present a facilely synthesized highly conductive n-type polymer poly(benzodifurandione) (PBFDO). The reaction combines oxidative polymerization and in situ reductive n-doping, greatly increasing the doping efficiency, and a doping level of almost 0.9 charges per repeating unit can be achieved. The resultant polymer exhibits a breakthrough conductivity of more than 2,000 S cm−1 with excellent stability and an unexpected solution processability without extra side chains or surfactants. Furthermore, detailed investigations on PBFDO show coherent charge-transport properties and existence of metallic state. The benchmark performances in electrochemical transistors and thermoelectric generators are further demonstrated, thus paving the way for application of the n-type CPs in organic electronics.

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Fig. 1: The chemical structure of PBFDO and its charge-balanced form under solution and film state.
Fig. 2: The temperature-dependent conductivity and Hall measurement of PBFDO.
Fig. 3: Investigation of charge transport of PBFDO.
Fig. 4: Demonstration of device applications of PBFDO in organic electronics.

Data availability

The main data supporting the findings of this study are available within the paper and its Supplementary Information file, and related source data are available from the corresponding author on reasonable request.

References

  1. Shirakawa, H., Louis, E. J., MacDiarmid, A. G., Chiang, C. K. & Heeger, A. J. Synthesis of electrically conducting organic polymers: halogen derivatives of polyacetylene, (CH)x. J. Chem. Soc. Chem. Commun. 16, 578–580 (1977).

    Article  Google Scholar 

  2. Basescu, N. et al. High electrical conductivity in doped polyacetylene. Nature 327, 403–405 (1987).

    Article  CAS  ADS  Google Scholar 

  3. MacDiarmid, A. G. & Heeger, A. J. Organic metals and semiconductors: the chemistry of polyacetylene, (CH)x, and its derivatives. Synth. Met. 1, 101–118 (1980).

    Article  CAS  Google Scholar 

  4. Heeger, A. J. Semiconducting and metallic polymers: the fourth generation of polymeric materials (Nobel Lecture). Angew. Chem. Int. Ed. 40, 2591–2611 (2001).

    Article  CAS  Google Scholar 

  5. Bharti, M., Singh, A., Samanta, S. & Aswal, D. K. Conductive polymers for thermoelectric power generation. Prog. Mater. Sci. 93, 270–310 (2018).

    Article  CAS  Google Scholar 

  6. Rivnay, J. et al. Organic electrochemical transistors. Nat. Rev. Mater. 3, 17086 (2018).

    Article  CAS  ADS  Google Scholar 

  7. Bhadra, S., Khastgir, D., Singha, N. K. & Lee, J. H. Progress in preparation, processing and applications of polyaniline. Prog. Polym. Sci. 34, 783–810 (2009).

    Article  CAS  Google Scholar 

  8. Gueye, M. N., Carella, A., Faure-Vincent, J., Demadrille, R. & Simonato, J.-P. Progress in understanding structure and transport properties of PEDOT-based materials: a critical review. Prog. Mater. Sci. 108, 100616 (2020).

    Article  CAS  Google Scholar 

  9. Lu, Y. et al. Rigid coplanar polymers for stable n-type polymer thermoelectrics. Angew. Chem. Int. Ed. 58, 11390–11394 (2019).

    Article  CAS  Google Scholar 

  10. Yang, C.-Y. et al. A high-conductivity n-type polymeric ink for printed electronics. Nat. Commun. 12, 2354 (2021).

    Article  CAS  PubMed  PubMed Central  ADS  Google Scholar 

  11. Lüssem, B. et al. Doped organic transistors. Chem. Rev. 116, 13714–13751 (2016).

    Article  PubMed  Google Scholar 

  12. Zhao, X. et al. High conductivity and electron-transfer validation in an n-type fluoride-anion-doped polymer for thermoelectrics in air. Adv. Mater. 29, 1606928 (2017).

    Article  Google Scholar 

  13. Han, J. et al. Dichlorinated dithienylethene-based copolymers for air-stable n-type conductivity and thermoelectricity. Adv. Funct. Mater. 31, 2005901 (2021).

    Article  CAS  Google Scholar 

  14. Wei, P. et al. 2-(2-Methoxyphenyl)-1,3-dimethyl-1H-benzoimidazol-3-ium iodide as a new air-stable n-type dopant for vacuum-processed organic semiconductor thin films. J. Am. Chem. Soc. 134, 3999–4002 (2012).

    Article  CAS  PubMed  Google Scholar 

  15. Li, F., Werner, A., Pfeiffer, M., Leo, K. & Liu, X. Leuco crystal violet as a dopant for n-doping of organic thin films of fullerene C60. J. Phys. Chem. B 108, 17076–17082 (2004).

    Article  CAS  Google Scholar 

  16. Yang, C.-Y. et al. A thermally activated and highly miscible dopant for n-type organic thermoelectrics. Nat. Commun. 11, 3292 (2020).

    Article  CAS  PubMed  PubMed Central  ADS  Google Scholar 

  17. Guo, S. et al. N-doping of organic electronic materials using air-stable organometallics. Adv. Mater. 24, 699–703 (2012).

    Article  CAS  PubMed  Google Scholar 

  18. Naab, B. D. et al. Effective solution- and vacuum-processed n-doping by dimers of benzimidazoline radicals. Adv. Mater. 26, 4268–4272 (2014).

    Article  CAS  PubMed  Google Scholar 

  19. Tang, C. G. et al. Multivalent anions as universal latent electron donors. Nature 573, 519–525 (2019).

    Article  CAS  PubMed  ADS  Google Scholar 

  20. Guha, S., Goodson, F. S., Corson, L. J. & Saha, S. Boundaries of anion/naphthalenediimide interactions: from anion–π interactions to anion-induced charge-transfer and electron-transfer phenomena. J. Am. Chem. Soc. 134, 13679–13691 (2012).

    Article  CAS  PubMed  Google Scholar 

  21. Lu, Y. et al. The critical role of dopant cations in electrical conductivity and thermoelectric performance of n-doped polymers. J. Am. Chem. Soc. 142, 15340–15348 (2020).

    Article  CAS  PubMed  Google Scholar 

  22. Liu, J. et al. Enhancing molecular n-type doping of donor–acceptor copolymers by tailoring side chains. Adv. Mater. 30, 1704630 (2018).

    Article  Google Scholar 

  23. Kiefer, D. et al. Enhanced n-doping efficiency of a naphthalenediimide-based copolymer through polar side chains for organic thermoelectrics. ACS Energy Lett. 3, 278–285 (2018).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  24. Guo, H. et al. Transition metal-catalysed molecular n-doping of organic semiconductors. Nature 599, 67–73 (2021).

    Article  CAS  PubMed  ADS  Google Scholar 

  25. Lu, Y. et al. Persistent conjugated backbone and disordered lamellar packing impart polymers with efficient n-doping and high conductivities. Adv. Mater. 33, 2005946 (2021).

    Article  CAS  Google Scholar 

  26. Sun, Y. et al. Flexible n-type high-performance thermoelectric thin films of poly(nickel-ethylenetetrathiolate) prepared by an electrochemical method. Adv. Mater. 28, 3351–3358 (2016).

    Article  CAS  PubMed  Google Scholar 

  27. Guo, X. & Facchetti, A. The journey of conducting polymers from discovery to application. Nat. Mater. 19, 922–928 (2020).

    Article  CAS  PubMed  ADS  Google Scholar 

  28. Zozoulenko, I. et al. Polarons, bipolarons, and absorption spectroscopy of PEDOT. ACS Appl. Polym. Mater. 1, 83–94 (2019).

    Article  CAS  Google Scholar 

  29. Emin, D. Optical properties of large and small polarons and bipolarons. Phys. Rev. B 48, 13691–13702 (1993).

    Article  CAS  ADS  Google Scholar 

  30. Mueller, P. & Rocek, J. Oxidations of hydroaromatic systems. II. 2,3-Dichloro-5,6-dicyanobenzoquinone. J. Am. Chem. Soc. 94, 2716–2719 (1972).

    Article  CAS  Google Scholar 

  31. Cheng, D. & Bao, W. Propargylation of 1,3-dicarbonyl compounds with 1,3-diarylpropynes via oxidative cross-coupling between sp3 C–H and sp3 C–H. J. Org. Chem. 73, 6881–6883 (2008).

    Article  CAS  PubMed  Google Scholar 

  32. Zhang, Y. & Li, C.-J. DDQ-mediated direct cross-dehydrogenative-coupling (CDC) between benzyl ethers and simple ketones. J. Am. Chem. Soc. 128, 4242–4243 (2006).

    Article  CAS  PubMed  Google Scholar 

  33. Li, Z. et al. C–H bond oxidation initiated Pummerer- and Knoevenagel-type reactions of benzyl sulfide and 1,3-dicarbonyl compounds. Org. Lett. 10, 803–805 (2008).

    Article  CAS  PubMed  Google Scholar 

  34. Fischer, H. The persistent radical effect: a principle for selective radical reactions and living radical polymerizations. Chem. Rev. 101, 3581–3610 (2001).

    Article  CAS  PubMed  Google Scholar 

  35. Kobayashi, Y., Yoshioka, M., Saigo, K., Hashizume, D. & Ogura, T. Hydrogen-bonding-assisted self-doping in tetrathiafulvalene (TTF) conductor. J. Am. Chem. Soc. 131, 9995–10002 (2009).

    Article  CAS  PubMed  Google Scholar 

  36. Menon, R., Yoon, C. O., Moses, D., Heeger, A. J. & Cao, Y. Transport in polyaniline near the critical regime of the metal-insulator transition. Phys. Rev. B 48, 17685–17694 (1993).

    Article  CAS  ADS  Google Scholar 

  37. Ahlskog, M., Reghu, M. & Heeger, A. J. The temperature dependence of the conductivity in the critical regime of the metal-insulator transition in conducting polymers. J. Phys. Condens. Matter 9, 4145–4156 (1997).

    Article  ADS  Google Scholar 

  38. Zanettini, S. et al. Magnetoconductance anisotropy of a polymer thin film at the onset of metallicity. Appl. Phys. Lett. 106, 063303 (2015).

    Article  ADS  Google Scholar 

  39. Kang, K. et al. 2D coherent charge transport in highly ordered conducting polymers doped by solid state diffusion. Nat. Mater. 15, 896–902 (2016).

    Article  CAS  PubMed  ADS  Google Scholar 

  40. Ji, X. et al. Pauli paramagnetism of stable analogues of pernigraniline salt featuring ladder-type constitution. J. Am. Chem. Soc. 142, 641–648 (2020).

    Article  CAS  PubMed  Google Scholar 

  41. Moraes, F. et al. Doped poly(thiophene): electron spin resonance determination of the magnetic susceptibility. Synth. Met. 10, 169–179 (1985).

    Article  CAS  Google Scholar 

  42. Tanaka, H., Hirate, M., Watanabe, S. & Kuroda, S.-I. Microscopic signature of metallic state in semicrystalline conjugated polymers doped with fluoroalkylsilane molecules. Adv. Mater. 26, 2376–2383 (2014).

    Article  CAS  PubMed  Google Scholar 

  43. Jin, E. et al. Two-dimensional sp2 carbon–conjugated covalent organic frameworks. Science 357, 673–676 (2017).

    Article  CAS  PubMed  ADS  Google Scholar 

  44. Aleshin, A. N., Kozub, V. I., Suh, D. S. & Park, Y. W. Saturation of dephasing and magnetoresistance features in heavily doped polyacetylene. Synth. Met. 135–136, 303–304 (2003).

    Article  Google Scholar 

  45. Suh, D. S. et al. Linear high-field magnetoconductivity of doped polyacetylene up to 30 Tesla. Phys. Rev. B 65, 165210 (2002).

    Article  ADS  Google Scholar 

  46. Wu, H.-Y. et al. Influence of molecular weight on the organic electrochemical transistor performance of ladder-type conjugated polymers. Adv. Mater. 34, 2106235 (2022).

    Article  CAS  Google Scholar 

  47. Feng, K. et al. Cyano-functionalized n-type polymer with high electron mobility for high-performance organic electrochemical transistors. Adv. Mater. 34, 2201340 (2022).

    Article  CAS  Google Scholar 

  48. Frisch, M. J. et al. Gaussian 16, Revision C.01 (Gaussian, Inc., 2016).

  49. Mukherjee, A. K. & Menon, R. Magnetotransport in doped polyaniline. J. Phys. Condens. Matter 17, 1947–1960 (2005).

    Article  CAS  ADS  Google Scholar 

  50. Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. OLEX2: a complete structure solution, refinement and analysis program. J. Appl. Crystallogr. 42, 339–341 (2009).

    Article  CAS  Google Scholar 

  51. Sheldrick, G. M. Crystal structure refinement with SHELXL. Acta Crystallogr. C Struct. Chem. 71, 3–8 (2015).

    Article  PubMed  PubMed Central  MATH  Google Scholar 

  52. Rivnay, J., Noriega, R., Kline, R. J., Salleo, A. & Toney, M. F. Quantitative analysis of lattice disorder and crystallite size in organic semiconductor thin films. Phys. Rev. B 84, 045203 (2011).

    Article  ADS  Google Scholar 

  53. Noriega, R. et al. A general relationship between disorder, aggregation and charge transport in conjugated polymers. Nat. Mater. 12, 1038–1044 (2013).

    Article  CAS  PubMed  ADS  Google Scholar 

  54. Chen, Z. et al. Evolution of the electronic structure in open-shell donor-acceptor organic semiconductors. Nat. Commun. 12, 5889 (2021).

    Article  CAS  PubMed  PubMed Central  ADS  Google Scholar 

  55. Elliott, R. J. Theory of the effect of spin-orbit coupling on magnetic resonance in some semiconductors. Phys. Rev. 96, 266–279 (1954).

    Article  CAS  MATH  ADS  Google Scholar 

  56. Lee, P. A. & Ramakrishnan, T. V. Disordered electronic systems. Rev. Mod. Phys. 57, 287–337 (1985).

    Article  CAS  ADS  Google Scholar 

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Acknowledgements

This work was financially supported by the National Key Research and Development Program of China (no. 2019YFA0705900) funded by MOST, the Basic and Applied Basic Research Major Program of Guangdong Province (no. 2019B030302007) and the National Natural Science Foundation of China (no. U21A6002).

Author information

Authors and Affiliations

Authors

Contributions

H.T. conceived the project and conducted materials synthesis and characterizations under the supervision of Y.C. and F.H. H.T., C.L. and Z.H. discussed and analysed data. Y.L. fabricated and measured the OECTs. Y.D. and Y.Z. conducted the SQUID and MH measurements. A.S. and H.Z. assisted the synthesis and characterization of oligomers. D.Z. and Y.M. performed parts of the Seebeck coefficient measurements. H.T., F.H., H.G., X.G. and J.P. discussed the mechanism in PBFDO synthesis and its charge-transport mechanism. J.P. and Z.Y. helped verify the conductivity and Hall effect. H.T., C.L. and F.H. wrote the draft of the paper and all authors read and approved the paper.

Corresponding author

Correspondence to Fei Huang.

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Competing interests

H.T. and F.H. have filed a PCT patent application (no. PCT/CN2021/124545). The other authors declare no competing interests.

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Nature thanks Simone Fabiano, Jianguo Mei and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data figures and tables

Extended Data Fig. 1 Investigations of reaction mechanisms.

a, In situ monitoring of change in absorption for reactions in DMSO (with TMQ and protected by argon). (Note: the concentration of H-BFDO at the beginning was 5 mg ml−1 and the reaction mixture was left to stand without stirring to prevent influence on absorption collection.) b, The chemical structure of oligomers in different solvents obtained in the model reaction. c, The UV–vis absorption of different oligomers. Addition of 2,3,5,6-tetramethylbenzene-1,4-diol (TMQH, 10 mg ml−1 in DMF) in the undoped oligomers part (oligomers (THF), heating at 80 °C for 30 min after addition) would cause the increase of absorption around 900 nm (blue line), verifying the electron-transfer n-doping process from TMQH to the polymer. d, The corresponding electrochemical cyclic voltammetry curves of oligomers. The oxidation of oligomers (DMF) was not shown, owing to the very opaque signal, which is consistent with the oxidation of PBFDO (Fig. S42) and was attributed to the doping and conductive states of the material. e, Calculated distribution of LUMO profiles and energy levels of oligomers with different repeating units. Benefitting from the rigid conjugated backbones (dihedral angles between adjacent units are less than 6°), the LUMO could delocalize over more than six repeating units, which promoted electron transport and delocalization of negative (bi)polarons. Moreover, with increasing repeating units, the LUMO levels of oligomers decreased sharply, which was in accordance with the experimental results and would promote the electron-transfer doping from hydroquinone derivatives to the polymers.

Extended Data Fig. 2 The possible mechanisms of combined oxidative polymerization and reductive n-doping for the synthesis of PBFDO.

The reaction begins from TMQ-promoted lactone dimerization through a radical pathway, which is followed by oxidative dehydrogenation. Along with the oxidative polymerization proceeding, the formed polymer can be doped with the generated TMQH simultaneously. Doping also makes the doped polymer soluble in DMSO.

Extended Data Fig. 3 The microstructure analysis of PBFDO films.

a,b, Height image and current image of PBFDO films. c,d, GIWAXS characterization of PBFDO films deposited on Si substrates. e, Corresponding (100) lamellar packing analysis of PBFDO films. f, (010) π–π packing analysis of PBFDO films.

Extended Data Fig. 4 Investigations of transport mechanisms in PBFDO.

a,b, ESR spectroscopy of PBFDO at different temperatures. The ESR intensities of the PBFDO solid slightly increased with elevating temperature from 140 to 260 K (a), which was considered as a signature of open-shell diradical resonance54. Another phenomenon of line broadening of the ESR signal was observed above 298 K, implying the existence of conduction electrons, which is a typical signature in CPs25,42 (b). These conduction electrons are increasingly scattered by phonons with increasing temperature, resulting in a shortening of the spin-lattice relaxation time and, hence, a decrease in conductivity and broadening of the ESR signals above 298 K (ref. 55). c, The total electromagnetic-wave shielding percentage versus frequency. d, Electromagnetic-interference shielding efficiency (EMI SE) of PBFDO. SEr represents shielding efficiency from reflection and SEa represents that from absorption. The outstanding SE of PBFDO can be considered as another characteristic of metallic state. e,f, Temperature dependence of phase coherence time, τφ (e), and coherence length, Lφ (f), extracted from MC. Inelastic scattering would interfere with the coherence of delocalized charge wave, especially when the Lφ is comparable with the magnetic length, LB= (ħ/eB)1/2 ≈ 25.66 B−1/2 nm (ref. 56). g,h, The conductivity of PBFDO film under the applied magnetic field B = 5 T (g) (the values were corrected using the conductivity under B = −5 T to eliminate the deviation caused by the Hall effect; the error bar represents the standard deviation caused by the uncertainty of film thickness) and corresponding log–log plot of W versus temperature (h). The zero-field conductivity was also measured for the same sample, exhibiting the characteristic of critical region, thus eliminating the deviations between different samples.

Extended Data Fig. 5 The stability characterizations of PBFDO.

a, Stability of a PBFDO film under ambient environment (25 °C, 60% relative humidity). b, Stability of PBFDO films washed by common organic solvents through spin-coating (THF, chloroform (CF), chlorobenzene (CB), acetonitrile (MeCN) and water), showing changes in conductivity. Error bars indicate the standard deviations of six experimental replicates. c, Stability of PBFDO films dealt with acid or ammonia (thickness is around 3 μm). The film was immersed in the corresponding solution for 1 min and washed with water. Error bars indicate the standard deviations of six experimental replicates. The large error bar of PBFDO immersed in conc. H2SO4 may be caused by destroyed film morphology.

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Tang, H., Liang, Y., Liu, C. et al. A solution-processed n-type conducting polymer with ultrahigh conductivity. Nature 611, 271–277 (2022). https://doi.org/10.1038/s41586-022-05295-8

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