Thermal and thermoelectric transport in highly resistive single Sb₂Se₃ nanowires and nanowire bundles

In this study, we measured the thermal conductivity and Seebeck coefficient of single Sb₂Se₃ nanowires and nanowire bundles with a high resistivity (σ ∼ 4.37 × 10^-4S/m). Microdevices consisting of two adjacent suspended silicon nitride membranes were fabricated to measure the thermal transport properties of the nanowires in vacuum. Single Sb₂Se₃ nanowires with different diameters and nanowire bundles were carefully placed on the device to bridge the two membranes. The relationship of temperature difference on each heating/sensing suspension membranes with joule heating was accurately determined. A single Sb₂Se₃ nanowire with a diameter of ∼ 680 nm was found to have a thermal conductivity (k_NW) of 0.037 ± 0.002 W/m·K. The thermal conductivity of the nanowires is more than an order of magnitude lower than that of bulk materials (k ∼ 0.36-1.9 W/m·K) and highly conductive (σ ∼ 3 × 10⁴S/m) Sb₂Se₃ single nanowires (k ∼ 1 W/m·K). The measured Seebeck coefficient with a positive value of ∼ 661 μV/K is comparable to that of highly conductive Sb₂Se₃ single nanowires (∼ 750 μV/K). The thermal transport between wires with different diameters and nanowire bundles was compared and discussed.