High-Performance Post-Treatment-Free Pedot Based Thermoelectric with the Establishment of Long-Range Ordered Conductive Paths

Abstract

In this work, post-treatment-free polymer hybrids, consisting of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and ionic liquids (ILs), were fabricated for the thermoelectric (TE) application. By optimizing the ILs’ molar concentration (0-0.5 M) and chemical composition, that is varying the cyano-based anions coupled with 1-ethyl-3-methylimidazolium cations, a superior TE performance (power factor of 190 μW m −1 K −2 ) was achieved. The excellent TE performance was attributed to the conductive network under the coupling effect of molecular structure (such as oxidation level, conformation and crystallization of PEDOT chains) and microstructure (long-range ordered conductive paths). Especially, the long-range conductive paths were proved to be made of rod-like microdomains, based on detailed structure analysis with micro-Fourier transform infrared spectroscopy and small-angle X-ray scattering. These paths enabled carrier transport among microdomains of PEDOT:PSS/IL hybrids. Moreover, the conductive network of PEDOT:PSS/IL hybrids showed good environmental and mechanical stability, enabling the fabrication of flexible TE generators.

Keywords: PEDOT:PSS, Ionic liquid, Thermoelectric, post-treatment-free, structure-property correlation