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Electrochemical strain microscopy probes morphology-induced variations in ion uptake and performance in organic electrochemical transistors

Abstract

Ionic transport phenomena in organic semiconductor materials underpin emerging technologies ranging from bioelectronics to energy storage. The performance of these systems is affected by an interplay of film morphology, ionic transport and electronic transport that is unique to organic semiconductors yet poorly understood. Using in situ electrochemical strain microscopy (ESM), we demonstrate that we can directly probe local variations in ion transport in polymer devices by measuring subnanometre volumetric expansion due to ion uptake following electrochemical oxidation of the semiconductor. The ESM data show that poly(3-hexylthiophene) electrochemical devices exhibit voltage-dependent heterogeneous swelling consistent with device operation and electrochromism. Our data show that polymer semiconductors can simultaneously exhibit field-effect and electrochemical operation regimes, with the operation modality and its distribution varying locally as a function of nanoscale film morphology, ion concentration and potential. Importantly, we provide a direct test of structure–function relationships by correlating strain heterogeneity with local stiffness maps. These data indicate that nanoscale variations in ion uptake are associated with local changes in polymer packing that may impede ion transport to different extents within the same macroscopic film and can inform future materials optimization.

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Figure 1: Electrical and optical measurements of P3HT devices.
Figure 2: In situ electrochemical strain microscopy.
Figure 3: Electrochemical strain imaging as a function of bias.
Figure 4: Electrochemical strain correlated with stiffness.

References

  1. 1

    Rivnay, J. et al. High-performance transistors for bioelectronics through tuning of channel thickness. Sci. Adv. 1, e1400251 (2015).

    Google Scholar 

  2. 2

    van de Burgt, Y. et al. A non-volatile organic electrochemical device as a low-voltage artificial synapse for neuromorphic computing. Nat. Mater. 16, 414–418 (2017).

    CAS  Google Scholar 

  3. 3

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

    CAS  Google Scholar 

  4. 4

    Mirfakhrai, T., Madden, J. D. W. & Baughman, R. H. Polymer artificial muscles. Mater. Today 10, 30–38 (2007).

    CAS  Google Scholar 

  5. 5

    Malti, A. et al. An organic mixed ion-electron conductor for power electronics. Adv. Sci. 3, 1500305 (2016).

    Google Scholar 

  6. 6

    Rivnay, J., Owens, R. M. & Malliaras, G. G. The rise of organic bioelectronics. Chem. Mater. 26, 679–685 (2014).

    CAS  Google Scholar 

  7. 7

    Wang, D., Noël, V. & Piro, B. Electrolytic gated organic field-effect transistors for application in biosensors—a review. Electronics 5, 9 (2016).

    Google Scholar 

  8. 8

    Rivnay, J. et al. Structural control of mixed ionic and electronic transport in conducting polymers. Nat. Commun. 7, 11287 (2016).

    Google Scholar 

  9. 9

    Bihar, E. et al. A disposable paper breathalyzer with an alcohol sensing organic electrochemical transistor. Sci. Rep. 6, 27582 (2016).

    CAS  Google Scholar 

  10. 10

    Inal, S. et al. A high transconductance accumulation mode electrochemical transistor. Adv. Mater. 26, 7450–7455 (2014).

    CAS  Google Scholar 

  11. 11

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

    Google Scholar 

  12. 12

    Giovannitti, A. et al. N-type organic electrochemical transistors with stability in water. Nat. Commun. 7, 13066 (2016).

    CAS  Google Scholar 

  13. 13

    Hess, L. H. et al. High-transconductance graphene solution-gated field effect transistors. Appl. Phys. Lett. 99, 033503 (2011).

    Google Scholar 

  14. 14

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

    Google Scholar 

  15. 15

    Pappa, A.-M. et al. Polyelectrolyte layer by layer assembly on organic electrochemical transistors. ACS Appl. Mater. Interfaces 9, 10427–10434 (2017).

    CAS  Google Scholar 

  16. 16

    Giovannitti, A. et al. Controlling the mode of operation of organic transistors through side-chain engineering. Proc. Natl Acad. Sci. USA 113, 12017–12022 (2016).

    CAS  Google Scholar 

  17. 17

    Inal, S., Malliaras, G. G. & Rivnay, J. Optical study of electrochromic moving fronts for the investigation of ion transport in conducting polymers. J. Mater. Chem. 4, 3942–3947 (2016).

    CAS  Google Scholar 

  18. 18

    Stavrinidou, E. et al. Direct measurement of ion mobility in a conducting polymer. Adv. Mater. 25, 4488–4493 (2013).

    CAS  Google Scholar 

  19. 19

    Stavrinidou, E. et al. A simple model for ion injection and transport in conducting polymers. J. Appl. Phys. 113, 244501 (2013).

    Google Scholar 

  20. 20

    Enengl, C. et al. Doping-induced absorption bands in P3HT: polarons and bipolarons. ChemPhysChem 17, 3836–3844 (2016).

    CAS  Google Scholar 

  21. 21

    Aoki, K., Aramoto, T. & Hoshino, Y. Photographic measurements of propagation speeds of the conducting zone in polyaniline films during electrochemical switching. J. Electroanal. Chem. 340, 127–135 (1992).

    CAS  Google Scholar 

  22. 22

    Sirringhaus, H., Brown, P. & Friend, R. Two-dimensional charge transport in self-organized, high-mobility conjugated polymers. Nature 401, 685–688 (1999).

    CAS  Google Scholar 

  23. 23

    Kline, R. J., McGehee, M. D. & Toney, M. F. Highly oriented crystals at the buried interface in polythiophene thin-film transistors. Nat. Mater. 5, 222–228 (2006).

    Google Scholar 

  24. 24

    Laiho, A., Herlogsson, L., Forchheimer, R., Crispin, X. & Berggren, M. Controlling the dimensionality of charge transport in organic thin-film transistors. Proc. Natl Acad. Sci. USA 108, 15069–15073 (2011).

    CAS  Google Scholar 

  25. 25

    Melzer, K. et al. Characterization and simulation of electrolyte-gated organic field-effect transistors. Faraday Discuss. 174, 399–411 (2014).

    CAS  Google Scholar 

  26. 26

    Schmoltner, K., Kofler, J., Klug, A. & List-Kratochvil, E. J. W. Electrolyte-gated organic field-effect transistors for sensing in aqueous media. Proc. SPIE 8831, 88311N1–88311N12 (2013).

    Google Scholar 

  27. 27

    Toss, H. et al. On the mode of operation in electrolyte-gated thin film transistors based on different substituted polythiophenes. Org. Electron. 15, 2420–2427 (2014).

    CAS  Google Scholar 

  28. 28

    Said, E., Larsson, O., Berggren, M. & Crispin, X. Effects of the ionic currents in electrolyte-gated organic field-effect transistors. Adv. Funct. Mater. 18, 3529–3536 (2008).

    CAS  Google Scholar 

  29. 29

    DeLongchamp, D. M., Kline, R. J., Fischer, D. A., Richter, L. J. & Toney, M. F. Molecular characterization of organic electronic films. Adv. Mater. 23, 319–337 (2011).

    CAS  Google Scholar 

  30. 30

    Kim, S. H. et al. Electrolyte-gated transistors for organic and printed electronics. Adv. Mater. 25, 1822–1846 (2013).

    CAS  Google Scholar 

  31. 31

    Wang, S., Ha, M., Manno, M., Daniel Frisbie, C. & Leighton, C. Hopping transport and the Hall effect near the insulator-metal transition in electrochemically gated poly(3-hexylthiophene) transistors. Nat. Commun. 3, 1210 (2012).

    Google Scholar 

  32. 32

    Mills, T., Kaake, L. G. & Zhu, X. Y. Polaron and ion diffusion in a poly(3-hexylthiophene) thin-film transistor gated with polymer electrolyte dielectric. Appl. Phys. A 95, 291–296 (2008).

    Google Scholar 

  33. 33

    Larsson, O., Laiho, A., Schmickler, W., Berggren, M. & Crispin, X. Controlling the dimensionality of charge transport in an organic electrochemical transistor by capacitive coupling. Adv. Mater. 23, 4764–4769 (2011).

    CAS  Google Scholar 

  34. 34

    Johansson, T., Persson, N.-K. & Inganäs, O. Moving redox fronts in conjugated polymers studies from lateral electrochemistry in polythiophenes. J. Electrochem. Soc. 151, E119–E124 (2004).

    CAS  Google Scholar 

  35. 35

    Nielsen, C. B. et al. Molecular design of semiconducting polymers for high-performance organic electrochemical transistors. J. Am. Chem. Soc. 138, 10252–10259 (2016).

    CAS  Google Scholar 

  36. 36

    Huang, J.-H. et al. Solvent-annealing-induced self-organization of poly(3-hexylthiophene), a high-performance electrochromic material. ACS Appl. Mater. Interfaces 1, 2821–2828 (2009).

    CAS  Google Scholar 

  37. 37

    Balke, N. et al. Local detection of activation energy for ionic transport in lithium cobalt oxide. Nano Lett. 12, 3399–3403 (2012).

    CAS  Google Scholar 

  38. 38

    Balke, N. et al. Real space mapping of Li-ion transport in amorphous Si anodes with nanometer resolution. Nano Lett. 10, 3420–3425 (2010).

    CAS  Google Scholar 

  39. 39

    Balke, N. et al. Nanoscale mapping of ion diffusion in a lithium-ion battery cathode. Nat. Nanotech. 5, 749–754 (2010).

    CAS  Google Scholar 

  40. 40

    Pytel, R. Z., Thomas, E. L. & Hunter, I. W. In situ observation of dynamic elastic modulus in polypyrrole actuators. Polymer 49, 2008–2013 (2008).

    CAS  Google Scholar 

  41. 41

    Wang, J. & Bard, A. J. On the absence of a diffuse double layer at electronically conductive polymer film electrodes. Direct evidence by atomic force microscopy of complete charge compensation. J. Am. Chem. Soc. 123, 498–499 (2001).

    CAS  Google Scholar 

  42. 42

    Collins, L. et al. Probing charge screening dynamics and electrochemical processes at the solid–liquid interface with electrochemical force microscopy. Nat. Commun. 5, 3871 (2014).

    CAS  Google Scholar 

  43. 43

    Rodriguez, B. J., Callahan, C., Kalinin, S. V. & Proksch, R. Dual-frequency resonance-tracking atomic force microscopy. Nanotechnology 18, 475504 (2007).

    Google Scholar 

  44. 44

    Kim, Y., Kim, Y., Kim, S. & Kim, E. Electrochromic diffraction from nanopatterned poly(3-hexylthiophene). ACS Nano 4, 5277–5284 (2010).

    CAS  Google Scholar 

  45. 45

    Dennler, G. et al. Unusual electromechanical effects in organic semiconductor Schottky contacts: between piezoelectricity and electrostriction. Appl. Phys. Lett. 87, 163501 (2005).

    Google Scholar 

  46. 46

    Balke, N. et al. Probing local electromechanical effects in highly conductive electrolytes. ACS Nano 6, 10139–10146 (2012).

    CAS  Google Scholar 

  47. 47

    Rodriguez, B. J., Jesse, S., Baddorf, A. P. & Kalinin, S. V. High resolution electromechanical imaging of ferroelectric materials in a liquid environment by piezoresponse force microscopy. Phys. Rev. Lett. 96, 237602 (2006).

    Google Scholar 

  48. 48

    Popescu, D., Popescu, B., Brändlein, M., Melzer, K. & Lugli, P. Modeling of electrolyte-gated organic thin-film transistors for sensing applications. IEEE Trans. Electron Devices 62, 4206–4212 (2015).

    CAS  Google Scholar 

  49. 49

    Jesse, S., Baddorf, A. P. & Kalinin, S. V. Switching spectroscopy piezoresponse force microscopy of ferroelectric materials. App. Phys. Lett. 88, 21–24 (2006).

    Google Scholar 

  50. 50

    Balke, N. et al. Decoupling electrochemical reaction and diffusion processes in ionically-conductive solids on the nanometer scale. ACS Nano 4, 7349–7357 (2010).

    CAS  Google Scholar 

  51. 51

    Garcia, R. & Proksch, R. Nanomechanical mapping of soft matter by bimodal force microscopy. Eur. Polym. J. 49, 1897–1906 (2013).

    CAS  Google Scholar 

  52. 52

    Wood, D., Hancox, I., Jones, T. S. & Wilson, N. R. Quantitative nanoscale mapping with temperature dependence of the mechanical and electrical properties of poly(3-hexylthiophene) by conductive atomic force microscopy. J. Phys. Chem. C 119, 11459–11467 (2015).

    CAS  Google Scholar 

  53. 53

    Thurn-Albrecht, T., Thomann, R., Heinzel, T. & Hugger, S. Semicrystalline morphology in thin films of poly(3-hexylthiophene). Colloid Polym. Sci. 282, 932–938 (2004).

    Google Scholar 

  54. 54

    Chang, J.-F. et al. Enhanced mobility of poly(3-hexylthiophene) transistors by spin-coating from high-boiling-point solvents. Chem. Mater. 16, 4772–4776 (2004).

    CAS  Google Scholar 

  55. 55

    Proctor, C. M., Rivnay, J. & Malliaras, G. G. Understanding volumetric capacitance in conducting polymers. J. Polym. Sci. B 54, 1433–1436 (2016).

    CAS  Google Scholar 

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Acknowledgements

This paper is based primarily on work supported by the National Science Foundation, NSF DMR-1607242. We gratefully acknowledge graduate fellowship support for L.Q.F. from the University of Washington Clean Energy Institute, as well as support from the Washington Research Foundation and Alvin L. and Verla R. Kwiram endowed fund. J.O. and C.K.L. acknowledge support from the University of Washington Clean Energy Institute, as well as support from the National Science Foundation under NSF DMR-1533372 and 1629369. The authors thank P. A. Cox, D. Moerman, K. Corp and L. Bradshaw for experimental assistance, as well as S. Holliday and T. Martin for helpful discussions. Part of this work was conducted at the Molecular Analysis Facility, a National Nanotechnology Coordinated Infrastructure site at the University of Washington that is supported in part by the National Science Foundation (grant ECC-1542101), the University of Washington, the Molecular Engineering & Sciences Institute, the Clean Energy Institute and the National Institutes of Health.

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R.G. completed the AFM experiments, fabricated films for ESM, and oversaw experiments. L.Q.F. completed all device preparation and measurements, all UV–vis measurements, and assisted with ESM measurements. J.S.H. contributed to control experiments. M.E.Z. performed the ellipsometry analysis. J.O. and C.K.L. provided additional materials and experimental guidance for regiorandomness tests. D.S.G. conceived the project, and R.G. and D.S.G. designed the experiments, interpreted the results and wrote the manuscript.

Corresponding author

Correspondence to D. S. Ginger.

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The authors declare no competing financial interests.

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Giridharagopal, R., Flagg, L., Harrison, J. et al. Electrochemical strain microscopy probes morphology-induced variations in ion uptake and performance in organic electrochemical transistors. Nature Mater 16, 737–742 (2017). https://doi.org/10.1038/nmat4918

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