Notably enhanced thermoelectric properties of lamellar polypyrrole by doping with β-naphthalene sulfonic acid

Abstract

Polypyrrole (PPy) is a type of potential organic thermoelectric material that has attracted extensive attention in recent years. Its application is mainly limited by the relatively low intrinsic electrical conductivity and Seebeck coefficient, so it is necessary to find an effective way to improve the electrical transport properties of PPy. In this work, lamellar PPy doped with β-naphthalene sulfonic acid (β-NSA) was synthesized chemically using ferric chloride (FeCl₃) as the oxidant, and the thermoelectric performance of β-NSA doped PPy was significantly enhanced. FTIR, XRD, Raman and FESEM analyses indicated that the presence of β-NSA and FeCl₃ could effectively control the morphology of PPy to form a lamellar structure during the polymerization process, which improves the thermoelectric properties of PPy greatly. The highest thermoelectric figure of merit ZT, 0.62 × 10⁻³, was obtained with the molar ratio of monomer pyrrole (py) to β-NSA of 1.0 : 0.45 at 300 K, and was 10 times higher than that of pure PPy. Furthermore, the TGA, elastic modulus, Vickers hardness results showed that the thermal stability and mechanical properties of β-NSA doped PPy was better than that of pure PPy.