Stretching-Induced Growth of PEDOT-Rich Cores: A New Mechanism for Strain-Dependent Resistivity Change in PEDOT:PSS Films

Authors

  • Yoo-Yong Lee,

    1. Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Ji-Hoon Lee,

    1. Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Ju-Young Cho,

    1. Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Na-Rae Kim,

    1. Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Dae-Hyun Nam,

    1. Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • In-Suk Choi,

    Corresponding author
    1. High Temperature Energy Materials Research Center, Korea Institute of Science and Technology (KIST), Seoul, 136-791, Republic of Korea
    • High Temperature Energy Materials Research Center, Korea Institute of Science and Technology (KIST), Seoul, 136-791, Republic of Korea.
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  • Ki Tae Nam,

    Corresponding author
    1. Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
    • Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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  • Young-Chang Joo

    Corresponding author
    1. Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
    • Department of Materials Science and Engineering, Seoul National University, Seoul, 151-744, Republic of Korea
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Abstract

It remains a fundamental challenge in the development of stretchable electronics to understand how mechanical strain changes the electrical properties of materials. Although the piezoresistive behavior of poly(3,4-ethylene- dioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) has been observed, its intrinsic origin is not yet fully understood because there are many extrinsic contributing factors and an experimental platform with which to assess such behavior has not been established. Here, systematic analysis shows that the matching Poisson's ratio and elastic modulus between PEDOT:PSS films and their underlying substrates is important in decoupling the factors that affect the material's piezoresistivity, allowing for tunable resistivity. Based on such a fundamental understanding, the conductivity of PEDOT:PSS can be controlled to be invariant and decrease as a function of applied tensile stress. Furthermore, a linear response of the resistivity with respect to mechanical strains of up to 60%, which has never before been realized, is shown. The irreversible conductivity enhancement is primarily caused by the coalescence-induced growth of conductive PEDOT-rich cores.

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