Enhanced thermoelectric performance of p-type Bi2Te3-based materials by suppressing bipolar thermal conductivity

Thermal excitation causes a surge in carrier concentration in narrow bandgap semiconductors that seriously limit its application in the high-temperature zone. Therefore, suppressing bipolar thermal conductivity and broadening the application temperature zone is vitally important for commercial Bi2Te3-based thermoelectric materials. Here, Cu0.6Ni0.4 (CN) nanoparticles synthesized via hydrothermal method are introduced into Bi0.4Sb1.6Te3 (BST) commercial materials. Then, the electrical and thermal properties of BST-CN (with x wt%, x = 0, 0.1, 0.2, 0.4, BST-x-CN) materials are systematically investigated. The results exhibited that the weighted mobility could be improved and the bipolar thermal conductivity could be suppressed for all dealt samples. The maximum and average ZT (figure of merit) values were 1.3 at 393 K and 1.17 in the temperature range of 303-483 K for BST-0.1-CN sample, which exhibited an enhancement by 28.7% and 28.6% than that of the pure sample, respectively. And the optimal ZT values are attained at higher temperatures with the CN nanoparticles contents increasing. Meanwhile, the sintered technique was optimized to enhance electron transport properties, the highest room-temperature power factor of 5.08 mW/m/K-2 was attained for the BST-0.1-CN cycle-2 sintered sample. And the optimal ZT value is 1.35 at 393 K for the BST-0.1-CN cycle-1 sintered sample. Finally, the results indicated that the thermoelectric performance could be improved and the application temperature zone could be broadened by suppressing bipolar thermal conductivity owing to the existence of CN nanoparticles.