Thermoelectric properties of polyvinylpyrrolidone/polyaniline‐mixed Bi2Te3 composites prepared by electrospinning

Abstract Composite fibers of bismuth telluride (Bi 2 Te 3 ) with polyaniline (PANI) and polyvinylpyrrolidone (PVP), synthesized via electrospinning in different ratios, were studied. Initially, three solutions were synthesized in different ratios of PVP and composite (Bi 2 Te 3 and PANI). However, due to the loading capacity of polymer only two samples were successfully synthesized. The formation and surface morphology of as‐prepared and compacted fibers were studied by scanning electron microscopy. The X‐ray diffraction confirmed the increase in crystalline phase of the composites after compaction. The influence of functional groups on the thermal and electrical conductivity as well as the existence of various polymer functional groups in pure and composite samples were revealed by Fourier transform infrared spectroscopy. Thermogravimetric analysis and differential scanning calorimetric were carried out simultaneously up to 800 K, which revealed the thermal stability of composite up‐to 473 K and a glass transition temperature ( T g ) of ~412 K for the composites. Diffuse reflectance spectroscopy confirmed the decrease in the bandgap from ~3 to ~1.2 eV of the compacted fibers. The thermopower of the as‐prepared and compacted fibers increased significantly compared with pure Bi 2 Te 3 and PANI, while the thermal conductivity decreased to 0.45 Wm −1 K −1 . As a result, zT was enhanced from 1.7 × 10 −10 to 1.7 × 10 −1 in the composite samples near room temperature.