Electrical and thermal transport properties of polyaniline/silver composites and their use as thermoelectric materials

Electrical, thermal and thermoelectric properties of chemically synthesized polyanilines (PANI)/metallic silver composites are reported and discussed in regard to their morphological features as determined by SEM. The metal-intrinsic conducting polymer power factor (PF) and figure of merit (ZT) are deduced from measurements of the electrical conductivity (σ), Seebeck coefficient (S), thermal diffusivity (α), thermal effusivity (e) and thermal conductivity (κ). It is shown that the PANI/Ag thermoelectric (TE) characteristics are much more improved as compared to those of pure PANI. In addition, the results reveal that the metal/PANI properties are inherently dependent on the volume concentration of silver and morphology of the composites. It is observed that electrical percolation takes place for samples having 16 vol% Ag content without any significant thermal percolation. The composite with 26 vol% Ag loading exhibits the best thermoelectric performance (PF ≈ 3 μW m−1 K−2; ZT ≈ 0.5 10−3). The overall enhanced TE performance of the PANI/Ag composites is attributed to an improved electrical conductivity with a concomitant limitation in the rise of thermal transport via scattering.