Thermoelectric properties of electrically conductive polypyrrole film

Usually organic polymers are considered as practical materials suitable for wide applications because of easy synthesis with potentially low cost due to plenty of carbon resources and easy processing into versatile forms. Previously we have reported fundamental thermoelectric properties of polyaniline films, one of electrically conductive organic polymers, and pointed out that enhancement of electrical conductivity results in improvement of thermoelectric power factor, by which, nevertheless, no increase of the corresponding thermal conductivity occurs. Here we present thermoelectric properties of films of another electrically conductive organic polymer polypyrrole. Highly electrically conductive polypyrrole films were electrochemically prepared using sodium p-toluenesulfonate as a supporting electrolyte. Thermoelectric properties of thus-prepared polypyrrole films were systematically investigated at wide range of temperatures above room temperature. High electrical conductivity of the polypyrrole films gives a significant advantage of high thermoelectric power factor. In addition polypyrrole films showed extremely low thermal diffusivity, like electrically conductive polyaniline films as previously reported by us. The maximum ZT of the polypyrrole film, which was calculated using estimated thermal conductivity from the polyaniline films, is 10(-2) at ca. 423 K. The value is comparable with that of inorganic thermoelectric materials FeSi2.