Influence of sintering temperature on thermoelectric properties of Bi^sub 2^Te^sub 3^/Polythiophene composite materials

Bi^sub 2^Te^sub 3^/Polythiophene (PTH) thermoelectric bulk composite materials were prepared by a two-step method. Firstly, Bi^sub 2^Te^sub 3^ and PTH nanopowders were prepared by hydrothermal synthesis and chemical oxidative polymerization, respectively. Secondly, the mixture of the Bi^sub 2^Te^sub 3^ and PTH nanopowders (50:50 wt) was pressed under vacuum at 80 MPa and 298, 473, or 623 K. For comparison, Bi^sub 2^Te^sub 3^ 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 Bi^sub 2^Te^sub 2^S phase was formed. The thermoelectric properties of the bulk composite materials were investigated. The composite pressed at 623 K showed a higher power factor, ~2.54 μ Wm^sup -1^ K^sup -2^ at 473 K, which is as ~20 times as that of the composite pressed at 473 K, although, it is still much lower than that of the pressed Bi^sub 2^Te^sub 3^ material (~1,266 μ Wm^sup -1^ K^sup -2^ at 348 K).[PUBLICATION ABSTRACT]