Hydrothermal synthesis and thermoelectric transport properties of uniform single-crystalline pearl-necklace-shaped PbTe nanowires

Uniform single-crystalline pearl-necklace-shaped PbTe nanowires with an average diameter of about 30 nm, smaller than its average excitonic Bohr radius of 46 nm, were successfully synthesized by a hydrothermal process using tellurium nanowires as templates and Pb(NO₃)₂ as a precursor at a molar ratio of 1:1. It is shown that the reaction temperature, duration, and concentration of Pb(NO₃)₂ play important roles in the formation of the PbTe nanowires. The growth process of the pearl-necklace-shaped PbTe nanowires can be reasonably explained by an oriented attachment mechanism. Thermoelectric transport measurement indicates that the film composed of the obtained PbTe nanowires has a Seebeck coefficient of about 307 μV/K, up to about 16% higher than that of the state-of-the-art bulk PbTe at room temperature. The synthetic route can be applied to obtain other low-dimensional semiconducting telluride nanostructures and optimization of the thermoelectric properties through nanowire alignment and doping may lead to practical applications.