p-Type PVA/MWCNT-Sb(2)Te(3) Composites for Application in Different Types of Flexible Thermoelectric Generators in Combination with n-Type PVA/MWCNT-Bi(2)Se(3) Composites

This work is devoted to the fabrication of p-type polyvinyl alcohol (PVA)-based flexible thermoelectric composites using multiwall carbon nanotubes-antimony telluride (MWCNT-Sb(2)Te(3)) hybrid filler, the study of the thermoelectrical and mechanical properties of these composites, and the application of these composites in two types (planar and radial) of thermoelectric generators (TEG) in combination with the previously reported PVA/MWCNT-Bi(2)Se(3) flexible thermoelectric composites. While the power factors of PVA/MWCNT-Sb(2)Te(3) and PVA/MWCNT-Bi(2)Se(3) composites with 15 wt.% filler were found to be similar, the PVA/MWCNT-Sb(2)Te(3) composite with 25 wt.% filler showed a ~2 times higher power factor in comparison with the PVA/MWCNT-Bi(2)Se(3) composites with 30 wt.% filler, which is attributed to its reduced electrical resistivity. In addition, developed PVA/MWCNT-Sb(2)Te(3) composites showed a superior mechanical, electrical, and thermoelectric stability during 100 consequent bending cycles down to a 3 mm radius, with insignificant fluctuations of the resistance within 0.01% of the initial resistance value of the not bent sample. Demonstrated for the first time, 2-leg TEGs composed from p-type PVA/MWCNT-Sb(2)Te(3) and n-type PVA/MWCNT-Bi(2)Se(3) composites showed a stable performance under different external loads and showed their potential for applications involving low temperature gradients and power requirements in the range of nW.