Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Understanding asymmetric switching times in accumulation mode organic electrochemical transistors

Nature Materials (2024)Cite this article

Subjects

Abstract

Understanding the factors underpinning device switching times is crucial for the implementation of organic electrochemical transistors in neuromorphic computing, bioelectronics and real-time sensing applications. Existing models of device operation cannot explain the experimental observations that turn-off times are generally much faster than turn-on times in accumulation mode organic electrochemical transistors. Here, using operando optical microscopy, we image the local doping level of the transistor channel and show that turn-on occurs in two stages—propagation of a doping front, followed by uniform doping—while turn-off occurs in one stage. We attribute the faster turn-off to a combination of engineering as well as physical and chemical factors including channel geometry, differences in doping and dedoping kinetics and the phenomena of carrier-density-dependent mobility. We show that ion transport limits the operation speed in our devices. Our study provides insights into the kinetics of organic electrochemical transistors and guidelines for engineering faster organic electrochemical transistors.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: OECT response times.
Fig. 2: Comparison between OECT and UV–visible spectroelectrochemistry.
Fig. 3: Operando optical microscope coupled with OECT switching.
Fig. 4: OECT mobility and carrier density.
Fig. 5: Dependency of OECT response times on the operation variables.

Similar content being viewed by others

Data availability

The data that support the findings of this study are available within the paper and its Supplementary Information. Source data are provided with this paper. Additional data may be requested from the authors.

References

  1. Guo, K. et al. Rapid single-molecule detection of COVID-19 and MERS antigens via nanobody-functionalized organic electrochemical transistors. Nat. Biomed. Eng. 5, 666–677 (2021).

    CAS  PubMed  Google Scholar 

  2. Bischak, C. G., Flagg, L. Q. & Ginger, D. S. Ion exchange gels allow organic electrochemical transistor operation with hydrophobic polymers in aqueous solution. Adv. Mater. 32, 2002610 (2020).

    CAS  Google Scholar 

  3. Strakosas, X., Bongo, M. & Owens, R. M. The organic electrochemical transistor for biological applications. J. Appl. Polym. Sci. 132, 41735 (2015).

    Google Scholar 

  4. Pappa, A. M. et al. Organic transistor arrays integrated with finger-powered microfluidics for multianalyte saliva testing. Adv. Healthc. Mater. 5, 2295–2302 (2016).

    CAS  PubMed  Google Scholar 

  5. Huang, W. et al. Vertical organic electrochemical transistors for complementary circuits. Nature 613, 496–502 (2023).

    CAS  PubMed  PubMed Central  Google Scholar 

  6. Andersson Ersman, P. et al. All-printed large-scale integrated circuits based on organic electrochemical transistors. Nat. Commun. 10, 5053 (2019).

    CAS  PubMed  PubMed Central  Google Scholar 

  7. Fuller, E. J. et al. Parallel programming of an ionic floating-gate memory array for scalable neuromorphic computing. Science 364, 570–574 (2019).

    CAS  PubMed  Google Scholar 

  8. Harikesh, P. C. et al. Ion-tunable antiambipolarity in mixed ion–electron conducting polymers enables biorealistic organic electrochemical neurons. Nat. Mater. 22, 242–248 (2023).

    CAS  PubMed  PubMed Central  Google Scholar 

  9. Chen, S. E., Giridharagopal, R. & Ginger, D. S. Artificial neuron transmits chemical signals. Nat. Mater. 22, 416–418 (2023).

    CAS  PubMed  Google Scholar 

  10. Sarkar, T. et al. An organic artificial spiking neuron for in situ neuromorphic sensing and biointerfacing. Nat. Electron. 5, 774–783 (2022).

    Google Scholar 

  11. Yamamoto, S. & Malliaras, G. G. Controlling the neuromorphic behavior of organic electrochemical transistors by blending mixed and ion conductors. ACS Appl. Electron. Mater. 2, 2224–2228 (2020).

    CAS  Google Scholar 

  12. Gkoupidenis, P., Schaefer, N., Garlan, B. & Malliaras, G. G. Neuromorphic functions in PEDOT:PSS organic electrochemical transistors. Adv. Mater. 27, 7176–7180 (2015).

    CAS  PubMed  Google Scholar 

  13. Khodagholy, D. et al. High transconductance organic electrochemical transistors. Nat. Commun. 4, 2133 (2013).

    PubMed  Google Scholar 

  14. Lin, P., Yan, F. & Chan, H. L. W. Ion-sensitive properties of organic electrochemical transistors. Appl. Mater. Interfaces 2, 1637–1641 (2010).

    CAS  Google Scholar 

  15. Ghittorelli, M. et al. High-sensitivity ion detection at low voltages with current-driven organic electrochemical transistors. Nat. Commun. 9, 1441 (2018).

    PubMed  PubMed Central  Google Scholar 

  16. Gualandi, I. et al. Selective detection of dopamine with an all PEDOT:PSS organic electrochemical transistor. Sci. Rep. 6, 35419 (2016).

    CAS  PubMed  PubMed Central  Google Scholar 

  17. Xie, K. et al. Organic electrochemical transistor arrays for real-time mapping of evoked neurotransmitter release in vivo. eLife 9, e50345 (2020).

    CAS  PubMed  PubMed Central  Google Scholar 

  18. Khodagholy, D. et al. In vivo recordings of brain activity using organic transistors. Nat. Commun. 4, 1575 (2013).

    PubMed  Google Scholar 

  19. Tang, X., Shen, H., Zhao, S., Li, N. & Liu, J. Flexible brain–computer interfaces. Nat. Electron. 6, 109–118 (2023).

    Google Scholar 

  20. Berggren, M., Głowacki, E. D., Simon, D. T., Stavrinidou, E. & Tybrandt, K. In vivo organic bioelectronics for neuromodulation. Chem. Rev. 122, 4826–4846 (2022).

    CAS  PubMed  PubMed Central  Google Scholar 

  21. Go, G.-T., Lee, Y., Seo, D.-G. & Lee, T.-W. Organic neuroelectronics: from neural interfaces to neuroprosthetics. Adv. Mater. 34, 2201864 (2022).

    CAS  Google Scholar 

  22. Van DeBurgt, Y., Melianas, A., Keene, S. T., Malliaras, G. & Salleo, A. Organic electronics for neuromorphic computing. Nat. Electron. 1, 386–397 (2018).

    Google Scholar 

  23. Gumyusenge, A., Melianas, A., Keene, S. T. & Salleo, A. Materials strategies for organic neuromorphic devices. Annu. Rev. Mater. Res. 51, 47–71 (2021).

    CAS  Google Scholar 

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

    CAS  Google Scholar 

  25. Zeglio, E. & Inganäs, O. Active materials for organic electrochemical transistors. Adv. Mater. 30, 1800941 (2018).

    Google Scholar 

  26. Kukhta, N. A., Marks, A. & Luscombe, C. K. Molecular design strategies toward improvement of charge injection and ionic conduction in organic mixed ionic–electronic conductors for organic electrochemical transistors. Chem. Rev. 122, 4325–4355 (2022).

    CAS  PubMed  Google Scholar 

  27. He, Y., Kukhta, N. A., Marks, A. & Luscombe, C. K. The effect of side chain engineering on conjugated polymers in organic electrochemical transistors for bioelectronic applications. J. Mater. Chem. C 10, 2314–2332 (2022).

    CAS  Google Scholar 

  28. Paulsen, B. D., Tybrandt, K., Stavrinidou, E. & Rivnay, J. Organic mixed ionic–electronic conductors. Nat. Mater. 19, 13–26 (2020).

    CAS  PubMed  Google Scholar 

  29. Flagg, L. Q. et al. P-Type electrochemical doping can occur by cation expulsion in a high-performing polymer for organic electrochemical transistors. ACS Mater. Lett. 2, 254–260 (2020).

    CAS  Google Scholar 

  30. Bernards, D. A. & Malliaras, G. G. Steady-state and transient behavior of organic electrochemical transistors. Adv. Funct. Mater. 17, 3538–3544 (2007).

    CAS  Google Scholar 

  31. Ohayon, D., Druet, V. & Inal, S. A guide for the characterization of organic electrochemical transistors and channel materials. Chem. Soc. Rev. 52, 1001–1023 (2023).

  32. Inal, S., Malliaras, G. G. & Rivnay, J. Benchmarking organic mixed conductors for transistors. Nat. Commun. 8, 1767 (2017).

    PubMed  PubMed Central  Google Scholar 

  33. Li, P. & Lei, T. Molecular design strategies for high-performance organic electrochemical transistors. J. Polym. Sci. 60, 377–392 (2022).

    CAS  Google Scholar 

  34. Gentile, F. et al. A theoretical model for the time varying current in organic electrochemical transistors in a dynamic regime. Org. Electron. 35, 59–64 (2016).

    CAS  Google Scholar 

  35. Faria, G. C., Duong, D. T. & Salleo, A. On the transient response of organic electrochemical transistors. Org. Electron. 45, 215–221 (2017).

    CAS  Google Scholar 

  36. Paudel, P. R. et al. The transient response of organic electrochemical transistors. Adv. Theory Simul. 5, 2100563 (2022).

  37. Keene, S. T. et al. Hole-limited electrochemical doping in conjugated polymers. Nat. Mater. 22, 1121–1127 (2023).

    CAS  PubMed  PubMed Central  Google Scholar 

  38. Ersman, P. A. et al. Screen printed digital circuits based on vertical organic electrochemical transistors. Flex. Print. Electron. 2, 045008 (2017).

    Google Scholar 

  39. Butler, J. A. V. Studies in heterogeneous equilibria. Part II.—The kinetic interpretation of the nernst theory of electromotive force. Trans. Faraday Soc. 19, 729–733 (1924).

    Google Scholar 

  40. Butler, J. A. V. Studies in heterogeneous equilibria. Part III. A kinetic theory of reversible oxidation potentials at inert electrodes. Trans. Faraday Soc. 19, 734–739 (1924).

    Google Scholar 

  41. Erdey-Grúz, T. & Volmer, M. Zur theorie der wasserstoff überspannung. Z. Phys. Chem. 150A, 203–213 (1930).

    Google Scholar 

  42. Bischak, C. G. et al. A reversible structural phase transition by electrochemically-driven ion injection into a conjugated polymer. J. Am. Chem. Soc. 142, 7434–7442 (2020).

    CAS  PubMed  Google Scholar 

  43. Flagg, L. Q. et al. Polymer crystallinity controls water uptake in glycol side-chain polymer organic electrochemical transistors. J. Am. Chem. Soc. 141, 4345–4354 (2019).

    CAS  PubMed  Google Scholar 

  44. Chen, S. E. et al. Impact of varying side chain structure on organic electrochemical transistor performance: a series of oligoethylene glycol-substituted polythiophenes. J. Mater. Chem. A 10, 10738–10749 (2022).

    CAS  Google Scholar 

  45. Neusser, D. et al. High conductivities of disordered P3HT films by an electrochemical doping strategy. Chem. Mater. 32, 6003–6013 (2020).

    CAS  Google Scholar 

  46. Hornberger, L. S., Neusser, D., Malacrida, C., Kaake, L. G. & Ludwigs, S. How charge trapping affects the conductivity of electrochemically doped poly(3-hexylthiophene) films. Appl. Phys. Lett. 119, 163301 (2021).

    CAS  Google Scholar 

  47. Jackson, S. R., Kingsford, R. L., Collins, G. W. & Bischak, C. G. Crystallinity determines ion injection kinetics and local ion density in organic mixed conductors. Chem. Mater. 35, 5392–5400 (2023).

    CAS  Google Scholar 

  48. Friedlein, J. T., Shaheen, S. E., Malliaras, G. G. & McLeod, R. R. Optical measurements revealing nonuniform hole mobility in organic electrochemical transistors. Adv. Electron. Mater. 1, 1500189 (2015).

    Google Scholar 

  49. Tanase, C., Meijer, E. J., Blom, P. W. M. & DeLeeuw, D. M. Unification of the hole transport in polymeric field-effect transistors and light-emitting diodes. Phys. Rev. Lett. 9, 216601 (2003).

    Google Scholar 

  50. Bässler, H., Kroh, D., Schauer, F., Nádaždy, V. & Köhler, A. Mapping the density of states distribution of organic semiconductors by employing energy resolved–electrochemical impedance spectroscopy. Adv. Funct. Mater. 31, 2007738 (2021).

    Google Scholar 

  51. Flagg, L. Q., Giridharagopal, R., Guo, J. & Ginger, D. S. Anion-dependent doping and charge transport in organic electrochemical transistors. Chem. Mater. 30, 5380–5389 (2018).

    CAS  Google Scholar 

  52. Wu, R., Paulsen, B. D., Ma, Q. & Rivnay, J. Mass and charge transport kinetics in an organic mixed ionic–electronic conductor. Chem. Mater. 34, 9699–9710 (2022).

    CAS  Google Scholar 

  53. Colucci, R., Barbosa, H. F. D. P., Günther, F., Cavassin, P. & Faria, G. C. Recent advances in modeling organic electrochemical transistors. Flex. Print. Electron. 5, 013001 (2020).

    CAS  Google Scholar 

  54. Guo, J. et al. Hydration of a side-chain-free n-type semiconducting ladder polymer driven by electrochemical doping. J. Am. Chem. Soc. 145, 1866–1876 (2023).

    CAS  PubMed  Google Scholar 

  55. West, S. M. et al. Phenazine-substituted poly(benzimidazobenzophenanthrolinedione): electronic structure, thin film morphology, electron transport, and mechanical properties of an n-type semiconducting ladder polymer. Macromolecules 56, 2081–2091 (2023).

    CAS  Google Scholar 

  56. Zhang, Z. et al. Modulate molecular interaction between hole extraction polymers and lead ions toward hysteresis-free and efficient perovskite solar cells. Adv. Mater. Interfaces 5, 1800090 (2018).

    Google Scholar 

Download references

Acknowledgements

This paper is based on research supported primarily by the National Science Foundation, first under DMR-2003456 and then under DMR-2309577. K.Y., Z.S. and C.-Z.L. acknowledge support from the National Natural Science Foundation of China (22125901) for supporting the synthesis of the PB2T-TEG polymer. J.W.O. and C.K.L.’s contributions to P3MEEMT polymer synthesis are based in part on work supported by the National Science Foundation, DMREF-1922259. Part of this work (transistor fabrication) was conducted at the Washington Nanofabrication Facility/Molecular Analysis Facility, a National Nanotechnology Coordinated Infrastructure (NNCI) site at the University of Washington with partial support from the National Science Foundation via awards NNCI-1542101 and NNCI-2025489.

Author information

Author notes

  1. These authors contributed equally: Jiajie Guo, Shinya E. Chen.

Authors and Affiliations

  1. Molecular Engineering and Sciences Institute, University of Washington, Seattle, WA, USA

    Jiajie Guo & Shinya E. Chen

  2. Department of Chemistry, University of Washington, Seattle, WA, USA

    Rajiv Giridharagopal, Connor G. Bischak & David S. Ginger

  3. Department of Materials Science and Engineering, University of Washington, Seattle, WA, USA

    Jonathan W. Onorato & Christine K. Luscombe

  4. State Key Laboratory of Silicon and Advanced Semiconductor Materials, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou, P. R. China

    Kangrong Yan, Ziqiu Shen & Chang-Zhi Li

  5. pi-Conjugated Polymers Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan

    Christine K. Luscombe

Authors
  1. Jiajie Guo
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Shinya E. Chen
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Rajiv Giridharagopal
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Connor G. Bischak
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Jonathan W. Onorato
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Kangrong Yan
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Ziqiu Shen
    View author publications

    You can also search for this author in PubMed Google Scholar

  8. Chang-Zhi Li
    View author publications

    You can also search for this author in PubMed Google Scholar

  9. Christine K. Luscombe
    View author publications

    You can also search for this author in PubMed Google Scholar

  10. David S. Ginger
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

J.G. and S.E.C. contributed equally to the work. J.G., S.E.C. and D.S.G. conceived the project, designed the experiments and discussed the results together. J.G. and S.E.C. performed the experiments and analysed the data. S.E.C. wrote the first draft and J.G. made the figures. R.G. performed the SPICE circuit modelling. C.G.B designed the preliminary microscope experiment. K.Y., Z.S. and C.-Z.L. provided the PB2T-TEG polymer. J.W.O. and C.K.L. provided the P3MEEMT polymer. J.G., S.E.C., R.G. and D.S.G. revised the paper with input from all the authors.

Corresponding author

Correspondence to David S. Ginger.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature Materials thanks the anonymous reviewer(s) for their contribution to the peer review of this work.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Figs. 1–20, Notes 1–8 and Tables 1–5.

Supplementary Video 1

Doping video coupled with the OECT drain current.

Supplementary Video 2

Comparison of doping front propagation at various VD values.

Supplementary Video 3

Five-cycle switching of PB2T-TEG.

Supplementary Video 4

P3MEEMT switching.

Supplementary Video 5

The VD and VG applied at the same time during transistor turn-on.

Supplementary Video 6

Dedoping video coupled with the OECT drain current.

Source data

Source Data Fig. 1

Source data for Fig. 1a.

Source Data Fig. 2

Source data for Fig. 2c–h.

Source Data Fig. 3

Source data for Fig. 3b,d–h,j,k.

Source Data Fig. 4

Source data for Fig. 4a,b.

Source Data Fig. 5

Source data for Fig. 5a–e.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Guo, J., Chen, S.E., Giridharagopal, R. et al. Understanding asymmetric switching times in accumulation mode organic electrochemical transistors. Nat. Mater. (2024). https://doi.org/10.1038/s41563-024-01875-3

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1038/s41563-024-01875-3

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing