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A1: Low temperature materials
The figure of merit (ZT) is an indicator to demonstrate the thermodynamic efficiency of thermoelectric material in order to conversion of thermal difference into electrical voltage difference. To obtain a large ZT value, the Seebeck coefficient and the electrical conductivity of a thermoelectric material should be as high as possible whereas the thermal conductivity of the material should be as low as possible. In this work a segregated polymer composite network based on carbon nanotube (CNT), Bi-Te nanowire (NW) and an insulating polymer, poly-vinyl acetate (PVAc) was prepared and thermoelectric properties of the network was measured. In order to make a homogenous network, the CNTs and Bi-Te NWs were first well dispersed in Gum Arabic (GA) solution and then mixed with PVAc. The CNTs and Bi-Te NWs in the segregated network is placed in the vicinity of large polymer atoms and attached by a weak Van Der Waals force due to the thin layer of GA surrounding them. The thermoelectric characterizations suggests a trade-off between the thermoelectric properties of the components of the network; i.e, electrical conductivity of the network of the composites mainly influenced by CNT concentration whereas Seebeck coefficient influenced by Bi-Te NW concentration. For a composite network with 10 wt% CNT and 5 wt% Bi-Te NW, the electrical conductivity and the Seebeck coefficient was measured around 950 S.m-1 and 135 µV.K-1 respectively. This work implies that the segregated network with hybrid filler in polymer composite demonstrates a strategy to trade-off between all three thermoelectric parameters and finally enhance the overall ZT value for thermoelectric energy harvesting application.