Low Interfacial Energy Barrier and Improved Thermoelectric Performance in Te-Incorporated Polypyrrole
Ajit Debnath, Krishna Deb, Kamanashis Sarkar, Bıswajıt Saha
Abstract
Controlled carrier dynamics and energy band engineering in polymer systems can provide a wider scope for studying the thermoelectric (TE) performance of such systems. With such an objective, polypyrrole (PPy) powders were prepared, incorporating a small amount of tellurium (Te) during the polymerization of pyrrole. The polymerization process was conducted through an oxidative chemical polymerization technique using ammonium peroxydisulfate (APS) as an oxidizing agent. The crystal structure, morphological, optical, and electrical transport properties were studied to explore the possibility of the better performance of PPy as a thermoelectric material when incorporated with Te. Since achieving a high thermo emf at a considerably low temperature difference is of great significance, and the thermoelectric performances of the prepared samples were studied in a 100 °C temperature difference range in this work. A TE power factor of as much as 23.89 μW/mK2 has been recorded for Te-incorporated PPy, which is about 859 times larger than that of pure PPy. This has been achieved by influencing the carrier dynamics in the system mainly in two ways: first, by inducing a carrier-filtering effect acquired by lowering the interfacial energy barrier between the polymer and Te and, second, by improving the carrier transport over the polymer chains with enhanced carrier hopping. As a result, a noticeably improved electrical conductivity of 0.472 S/cm and an exceptionally high Seebeck coefficient of 0.74 mV/°C have been recorded.