Improvement of Thermoelectric Properties of Evaporated ZnO:Al Films by CNT and Au Nanocomposites

Nanocomposites are a popular choice to improve the thermoelectric (TE) performance of materials by breaking the tradeoff among the TE parameters. However, the generation of depletion layers at the nanocomposite interfaces limits the improvement of the TE performance. This study employs carbon nanotube (CNT) and Au nanocomposites to solve this problem in evaporated ZnO:Al films assisted by a radio frequency atomic source. The results show that the carrier concentration and mobility are tuned individually by the CNT and Au nanocomposites. The conductivity increases by increasing the carrier concentration and mobility of the Au and CNT nanocomposites, respectively. The disappearance of the depletion layer at the CNT interface, eliminated by the substrate temperature, enhances the Seebeck coefficient and thereby doubles the power factor, which is 502.72 mu W.m(-1).K-2. for the 300 degrees C-CNT-ZnO:Al film. The CNT composite has no effect on thermal conductivity. This results in the ZT improvement by 1.35 times (0.081 at 523 K). This nanocomposite method presents an effective and low-cost method to improve the ZT value of TE materials.