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Abstract
Interconnected networks of Bi 0.89 Sb 0.11 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 bis-muth-antimony (Bi-Sb) alloy. For Bi 0.89 Sb 0.11 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. Published under an exclusive license by AIP Publishing. https://doi.org/10.1063/5.0349868 Lightweight and flexible thermoelectric materials capable of directly converting thermal energy into electricity are attracting increasing interest for wearable electronics. 1-8 Among the various flexible thermoelectric systems, networks of interconnected nanowires electrodeposited in cross-porous polymer membranes are particularly promising because their architecture, dimensions, and composition can be readily tailored. 9-14 A key advantage of crossed nanowires (CNWs) embedded in polymer membranes is their ability to harvest thermal energy both in-plane and perpendicular to the nanocompo-site film. 11,15 Moreover, their three-dimensional (3D) architecture enables transverse thermoelectric effects, as recently demonstrated by Nernst measurements on interconnected bismuth (Bi) nanowires. 12 Bulk bismuth-antimony (Bi-Sb) alloys, long recognized for applications near and below room temperature, 16-18 have recently regained interest due to a marked enhancement in thermoelectric performance under weak magnetic fields achievable with permanent magnets. 19 The thermoelectric performance of a material is quantified by the dimensionless figure of merit, ZT à S 2 T=qj, where S is the Seebeck coefficient, q the electrical resistivity, j the thermal conductivity, and T the absolute temperature. Although enhanced ZT values in high-quality Bi-Sb alloy single crystals under weak magnetic fields were previously reported, 20-22 recent measurements on high charge carrier mobility Bi 0.88 Sb 0.12 single crystals yielded ZT values two to three times higher than in the zero field. 19 Consequently, record performance below room temperature was achieved, reaching ZT à 1.7 6 0.2 between 160 and 220 K for magnetic fields less than 1 T. 19 Since the figure of merit is proportional to the square of the Seebeck coefficient, this enhancement primarily originates from a giant magneto-Seebeck effect.
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Carabogdan, A., da Câmara Santa Clara Gomes, T., Van Velthem, P., Ferain, E., Abreu Araujo, F., Piraux, L., & Antohe, V.-A. (2026). Influence of diameter and annealing on the electrical and thermoelectric properties of electrodeposited Bi0.89Sb0.11 crossed nanowires. Applied Physics Letters, 129(10), 103903. https://doi.org/10.1063/5.0349868 (Original work published 2026)