Thermoelectric properties of PEDOT:PSS aerogel secondary-doped in supercritical CO2 atmosphere with low thermal conductivity

Abstract A poly (3,4-ethylenedioxythiophene):poly (styrene sulfonate) (PEDOT:PSS) aerogel was fabricated simply by freeze-drying as a thermoelectric (TE) material with low thermal conductivity. Conventional methods used to enhance the electrical conductivity of PEDOT:PSS, such as the addition of a secondary dopant to the dispersion and dipping in a secondary dopant, caused shrinkage and a reduction of the advantageous low thermal conductivity in the case of aerogel. Therefore, we have applied secondary doping in supercritical CO2 (ScCO2) atmosphere to maintain the porous structure of the aerogel so that a temperature gradient can be maintained. The structure and TE performance of PEDOT:PSS aerogels treated with secondary doping by the dipping and ScCO2 methods were investigated. The ScCO2 method caused little shrinkage of PEDOT:PSS aerogel with conductivity improvement by four orders of magnitude. The secondary doping with ScCO2 could be promising method for PEDOT-based TE devices with porous structure.