Point Defect Engineering of High-Performance Bismuth-Telluride-Based Thermoelectric Materials

Developing high‐performance thermoelectric materials is one of the crucial aspects for direct thermal‐to‐electric energy conversion. Herein, atomic scale point defect engineering is introduced as a new strategy to simultaneously optimize the electrical properties and lattice thermal conductivity of thermoelectric materials, and (Bi,Sb)2(Te,Se)3 thermoelectric solid solutions are selected as a paradigm to demonstrate the applicability of this new approach. Intrinsic point defects play an important role in enhancing the thermoelectric properties. Antisite defects and donor‐like effects are engineered in this system by tuning the formation energy of point defects and hot deformation. As a result, a record value of the figure of merit ZT of ≈1.2 at 445 K is obtained for n‐type polycrystalline Bi2Te2.3Se0.7 alloys, and a high ZT value of ≈1.3 at 380 K is achieved for p‐type polycrystalline Bi0.3Sb1.7Te3 alloys, both values being higher than those of commercial zone‐melted ingots. These results demonstrate the promise of point defect engineering as a new strategy to optimize thermoelectric properties. Atomic scale point defect engineering is introduced as a new strategy to optimize the electrical properties and lattice thermal conductivity of thermoelectric materials simultaneously. (Bi,Sb)2(Te,Se)3 thermoelectric materials are selected as a paradigm to demonstrate the applicability of this new approach. The present results strongly demonstrate the efficacy of this strategy and provide a new route for improving thermoelectric properties.