Isotropic charge transport in conducting PEDOT:PSS thin films on pre-strained stretchable substrates

In this work, we engineer the film morphology of 3,4-(poly ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS) thin film on a stretchable poly dimethyl siloxane (PDMS) substrate to achieve strain-insensitive response. A strongly anisotropic transport is observed in pristine PEDOT:PSS thin film under uniaxial applied strain in parallel geometry. This anisotropy originates from extrinsically formed quasi periodic parallel cracks perpendicular to the applied strain. On the contrary, the transport remains isotropic with the uniaxial applied strain in both parallel and perpendicular geometry, for substrates which are subject to pre-straining before casting the conducting polymer dispersion. We discuss the isotropic nature of transport with reference to morphological features such as buckles, wrinkles and cracks.