Optimum Thermoelectric Performance of Bismuth–Antimony–Telluride Alloy/PEDOT:PSS Nanocomposites Prepared by an Innovative Redox Process

A thermoelectric nanocomposite material was prepared using the bismuth–antimony–telluride alloy (Bi0.5Sb1.5Te3 (BST)) nanorod-forming process in poly(3,4-ethylenedioxythiphene):polystyrene (PEDOT:PSS) solution. A new two-step reduction process allows easy formation of the BST-alloy in nanorods as well as the simultaneous oxidation of PEDOT:PSS. Scattering at the interface between BST nanorods and the PEDOT:PSS facilitates even lower thermal conductivity, whereas high electron conductivity in BST nanorods and PEDOT:PSS could significantly improve the thermoelectric performance of the nanocomposite. The BST-PEDOT:PSS nanocomposite has a Seebeck coefficient of 49 μV K–1 and an electrical conductivity 1285 S cm–1 at room temperature. The corresponding power factor is 308 μW m–1 K–2 to yield a figure of merit (ZT) = 0.484 at room temperature recording the highest ZT value among the organic–inorganic thermoelectric materials, which proves that this nanocomposite material is close to fulfilling the requirement for efficient waste energy harvesting at low temperatures. The nanocomposite materials are readily synthesized, environmentally friendly, air-stable, and solution-processable to easily produce patterns on large areas. The easy preparation process provides a viable technology platform for the fabrication of highly efficient thermoelectric nanocomposites for waste energy harvesting at low temperature.