Synthesis and thermoelectric properties of hydrochloric acid-doped polyaniline

A series of hydrochloric acid-doped polyaniline (PANI) were prepared by chemical oxidative polymerization. And the effects of HCl-doping concentration on the thermoelectric properties in the temperature range of 303–423 K were discussed. The results show that an increase in HCl-doping concentration will lead to a trend of first increase and then decrease in both the electrical conductivity and thermoelectric figure-of-merit ZT, accompanied by the opposite trend of the Seebeck coefficient. The maximum ZT can reach 2.67 × 10−4 at 423 K when HCl-doping concentration is 1.0 M. Moreover, the temperature dependence of the electrical conductivity shows a transition from non-metallic to metallic sign with doping level increasing, while the Seebeck coefficient of all the samples has a metallic character.