Synergistic carrier concentration and porosity optimization strategies enhancing the thermoelectric performances of Bi0.5Sb1.5Te3 alloys

The enhancement of thermoelectric (TE) material performances is crucial for the optimization of energy conversion efficiency of TE devices. The primary strategy for enhancing TE performances entails the maintenance of high carrier mobility while concurrently reducing thermal conductivity. In this study, p-type Bi0.5Sb1.5Te3 porous materials were fabricated via a high-pressure synthesis technique. The results demonstrated that antimony doping effectively increased the carrier concentration and grain size of the produced bulk materials. In addition, the introduced nanopore structures significantly reduced the thermal conductivity of the materials. The combination of antimony doping with porous structures has been demonstrated to result in significant enhancements in the figure-of-merit (zT) value of the Bi0.5Sb1.5Te3 alloys. The lattice thermal conductivity of the Bi0.5Sb1.5Te3 porous samples was reduced to 0.31 W m−1 K−1 at 413 K. The peak zT value was enhanced to 0.98 at 373 K, which was 53% higher than that of the undoped dense sample (zT = 0.64). Sb doping contributed one-third, while porosity contributed two-thirds of zT enhancement during the dual-optimization strategy. This work highlighted the importance of the synergistic strategy of both carrier concentration modulation and porosification in achieving superior TE performances. The study presented a new dual-strategy for developing high-performance porous TE materials for applications.