Influence of sintering temperature on thermoelectric properties of Bi2Te3/Polythiophene composite materials

Bi2Te3/Polythiophene (PTH) thermoelectric bulk composite materials were prepared by a two-step method. Firstly, Bi2Te3 and PTH nanopowders were prepared by hydrothermal synthesis and chemical oxidative polymerization, respectively. Secondly, the mixture of the Bi2Te3 and PTH nanopowders (50:50 wt) was pressed under vacuum at 80 MPa and 298, 473, or 623 K. For comparison, Bi2Te3 powders were hot pressed at 623 K. The bulk materials were analyzed by conventional methods, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and field emission scanning electron microscopy equipped with electron dispersive X-ray spectroscopy. The XRD and TGA results showed that the PTH decomposed when the hot pressing temperature exceeded 473 K, and Bi2Te2S phase was formed. The thermoelectric properties of the bulk composite materials were investigated. The composite pressed at 623 K showed a higher power factor, similar to 2.54 mu Wm(-1) K-2 at 473 K, which is as similar to 20 times as that of the composite pressed at 473 K, although, it is still much lower than that of the pressed Bi2Te3 material (similar to 1,266 mu Wm(-1) K-2 at 348 K).