A facile dedoping approach for effectively tuning thermoelectricity and acidity of PEDOT:PSS films

A facile approach namely controlling the pH level of 5 wt% dimethyl sulfoxide (DMSO) doped poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) solution with sodium hydroxide (NaOH) was utilized for the first time in successfully optimizing the thermoelectric conversion efficiency of PEDOT:PSS films. The largely varied Seebeck coefficients and electrical conductivities of the pH controlled PEDOT:PSS films which could thus construct a beneficial curve for locating the optimized power factor are clearly shown from the significant changes of the carrier concentration via the dedoping of PEDOT. The correlation between pH value and carrier concentration as well as the power factor is experimentally found with numerical description covering a full pH range. The applied technique and the resulting optimized thermoelectric properties and possible bio-compatibility not only provide a fundamental understanding of the thermoelectric conducting polymers but widely disclose a variety of potential applications in the future. (C) 2014 Elsevier B. V. All rights reserved.