Synergetic effects of co-dispersed Cu and insulating HfO2 nanoparticles enabled high thermoelectric figure of merit in Bi0.5Sb1.5Te3 composites

Considerable efforts have been invested in improving the thermoelectric (TE) performance of Bi0.5Sb1.5Te3 (BST) materials for room temperature power generation and cooling. In this contribution, we study the effect of co-dispersed Cu and insulating HfO2 nanoparticles (NPs) into BST matrix and synergistically optimized TE performance. The Seebeck coefficient increased for the BST-Cu/xHfO(2) (x = 0.5 and 1.0 wt%) composites compared to BST-Cu sample due to enhance the energy filtering effect (EFE) caused by the potential barriers. Specifically, the dual incorporated (Cu and 0.5HfO(2)) BST sample reaches 1.35 at 400 K, which is 80% higher than that of BST at the same temperature. A peak ZT(ave) of 1.25 and maximum conversion efficiency of similar to 9.2% were obtained in the temperature range of 300-500 K. The significant enhancement of ZT in dual incorporated samples mainly attributed to the increased power factor (PF) and shifting the minimum k at higher temperatures.