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Issue 32, 2017
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Wrinkle and crack-dependent charge transport in a uniaxially strained conducting polymer film on a flexible substrate

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Abstract

We investigate charge transport in poly(3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) films on functionalized polydimethylsiloxane (PDMS) substrates under varying uniaxial strain up to 16%. Strong anisotropy in transport is observed at a large applied strain (ε > 4%), which is understood in terms of an extrinsic process, involving a change in density of cracks from a few cracks per mm at ε = 4% to >100 cracks per mm at ε = 16%. The quasi-periodic cracks are aligned perpendicular to the stretching direction. A strain-history dependent response of the resistance of PEDOT:PSS films cycled through a uniaxial strain up to 4% is also observed, for current paths which are both parallel and perpendicular to the direction of stretching. The resistance–strain plots of strained PEDOT:PSS films for the second and subsequent few strain cycles follow the reverse path of the previous strain cycle. This unique strain-history dependence of resistance helps to identify the source of resistance changes at a low strain (ε < 4%). We demonstrate that the out-of-plane uniaxial wrinkle arrays that appear in a direction parallel to stretching have the same hysteresis response as the resistance, and therefore wrinkle formation governs the low-strain resistance changes. These phenomena are extensively investigated with dc-conductivity and frequency-dependent-ac-conductivity measurements, and surface morphological studies of the films under various applied strains. Our work quantitatively identifies the contributions of wrinkles and cracks to the change in resistance of PEDOT:PSS under an applied strain.

Graphical abstract: Wrinkle and crack-dependent charge transport in a uniaxially strained conducting polymer film on a flexible substrate

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Publication details

The article was received on 16 May 2017, accepted on 04 Jul 2017 and first published on 04 Jul 2017


Article type: Paper
DOI: 10.1039/C7SM00972K
Citation: Soft Matter, 2017,13, 5437-5444
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    Wrinkle and crack-dependent charge transport in a uniaxially strained conducting polymer film on a flexible substrate

    B. Sarkar, D. K. Satapathy and M. Jaiswal, Soft Matter, 2017, 13, 5437
    DOI: 10.1039/C7SM00972K

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