Influence of diameter and annealing on the electrical and thermoelectric properties of electrodeposited Bi0.89Sb0.11 crossed nanowires

Abstract

Interconnected networks of Bi0.89Sb0.11 crossed nanowires (CNWs) with controlled diameters were fabricated by electrodeposition within track-etched polyimide (PI) membranes, following a single irradiation step from multiple angles, by fine-tuning the density and pore diameter. These PI membranes exhibit excellent thermal resistance, allowing annealing at temperatures close to the melting point of the bismuth–antimony (Bi–Sb) alloy. For Bi0.89Sb0.11 CNWs with a diameter of 200 nm annealed at 285 °C, a significant increase in the Seebeck coefficient is observed, with values identical to those of the bulk alloy for temperatures between 170 and 320 K. Furthermore, a significant magneto-thermoelectric effect is observed at relatively low magnetic fields, which until now had only been reported in Bi–Sb alloy single crystals. The thermopower decreases with the reduction in nanowire diameter, as does the mobility of charge carriers. The temperature variations in electrical resistance and Hall coefficient are consistent with those of n-type semiconductors with narrow bandgap. These results are promising for obtaining flexible thermoelectric films for the direct conversion of wasted heat into electrical power.