Optimizing the thermoelectric properties of PEDOT:PSS films by combining organic co-solvents with inorganic base

Abstract

A simple optimizing approach that effectively improves the thermoelectric performance of poly(3,4-ethylenedioxylthiophene):poly(styrenesulfonate) (PEDOT:PSS) films is presented in this paper. The optimizing process is performed by over-dropping a mixture of DMSO/NaOH ethanol solution onto the PEDOT:PSS films, achieving the facile combination of co-solvents effect and dedoping effect. Largely varied electrical conductivity from 837.2 to 0.04 S cm−1 and the Seebeck coefficient from 12.6 to 54.8 μV K−1 are observed by changing the ratios between DMSO and NaOH ethanol solution. Due to the precise control of the dedoping level of PEDOT chains, an optimized power factor of 33.04 μW m−1 K−2 is obtained at the ratio of 10:12 in volume, which is four orders of magnitude higher than that of the pristine film and more than twice the value of DMSO-treated one, simultaneously with the corresponding electrical conductivity and Seebeck coefficient being 598.2 S cm−1 and 23.5 μV K−1, respectively. Based on the measured thermal conductivity of 0.173 W m−1 K−1, the maximum ZT value is calculated to be 0.057 at room temperature.