Giant Seebeck Effect in a PEDOT Material Coated on a Felt Fiber

Poly(3,4-ethylenedioxythiophene) (PEDOT) has been extensively investigated not only as a conductive polymer but also as a promising thermoelectric material. Numerous efforts have been undertaken to enhance the thermoelectric performance, particularly because improving the Seebeck coefficient is crucial for practical applications. In this study, we explored the thermoelectric property modification of PEDOT using a low-molecular carrier dopant and a fibrous substrate. PEDOT was coated on a felt texture with p-toluenesulfonic acid (PTSA) as the carrier dopant. The thermoelectric properties, including the Seebeck coefficient and electric conductivity, were measured. Raman spectroscopy was used to characterize the molecular strain of the PEDOT. The PEDOT sample coated on a felt texture with PTSA exhibited a wide range of Seebeck coefficients (-2100 to 3100 μV K^-1). An estimation suggested the power factor reached 2400 µW m^-1 K^-2 for the p-type and 1100 µW m^-1 K^-2 for the n-type at the maxima. Raman spectroscopy showed a strong correlation between the strain in the C_β-C_β bond of the PEDOT molecule and its Seebeck coefficient.