Ultra-low thermal conductivity and thermoelectric properties of polymer-mixed Bi2Te3 nanofibers by electrospinning

In the present work, polyvinylpyrrolidone (PVP)-assisted bismuth telluride (Bi2Te3) fibers were synthesized by electrospinning technique. These fibers were then compacted at a very slow rate at a constant temperature of 283 K. The as-prepared and compacted fibers were structurally and morphologically characterized via X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Thermogravimetric analysis (TGA) along with differential scanning calorimetry (DSC) were also carried out up to 800 K for the thermal analysis of the as-prepared and compacted composite fibers. Thermoelectric characterizations (Seebeck coefficient, electrical conductivity and thermal conductivity) along with diffusive reflectance spectroscopy (DRS) were performed to study the thermoelectric properties and optical properties of the as-synthesized and compacted electrospun fibers. High Seebeck coefficient value of 3062µVK−1 and an ultra-low thermal conductivity value of 0.5 Wm−1 K−1 have been observed for the fibers at room temperature. The compacted samples have shown much better thermoelectric performance, and their zT increased significantly from 10−12 to 10−2 due to the compaction.