Advances in thermoelectric(TE) technology have shown promise in the extension of TEs to consumer electronics and wearable energy harvesting devices. While the TE performance of the material is of obvious importance, certain mechanical properties need to be optimized while maintaining as much of the energy conversion efficiency as possible.
A (Bi2Te3) nanowire/SWCNT composite material was developed in our research group and has exhibited excellent n-type thermoelectric properties that are required for extension of TEs to wearable devices. In addition to conversion performance, flexibility and durability are highly desired qualities, especially for wearable TEs applications. For the preliminary experiments, Bi2Te3 nanowires/CNTs composite was drop-casted onto a flexible polyimide substrate and was analyzed by performing various mechanical tests that could affect the TE properties of the material. The electrical conductivity was measured using the van der Pauw method with an automated four-point probe. Multiple bends in 100 count increments were performed and the conductivity was remeasured. The electrical conductivity of the samples is shown to decrease gradually with each cycle, as expected, yet maintains 70-80% of the initial conductivity after thousands of cycles. Based on the previously obtained results, we will further investigate on film thickness effects and different substrate effects on mechanical properties of composite films. The different types of mechanical testing will be conducted using a Bose dynamic mechanical analysis machine. The knowledge obtained from this research will be beneficial to designing flexible thermoelectric devices using hybrid composite films.