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

TLDR

Developing high‑performance thermoelectric materials is crucial for direct thermal‑to‑electric energy conversion, and intrinsic point defects are known to enhance their properties. The study introduces atomic‑scale point defect engineering as a new strategy to simultaneously optimize electrical properties and lattice thermal conductivity in thermoelectric materials, using (Bi,Sb)₂(Te,Se)₃ solid solutions as a paradigm. The authors engineer antisite defects and donor‑like effects by tuning point‑defect formation energies and applying hot deformation. The approach yields record ZT values of ≈1.2 at 445 K for n‑type Bi₂Te₂.₃Se₀.₇ and ≈1.3 at 380 K for p‑type Bi₀.₃Sb₁.₇Te₃, surpassing commercial zone‑melted ingots, demonstrating the promise of point‑defect engineering.

Abstract

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 Bi 2 Te 2.3 Se 0.7 alloys, and a high ZT value of ≈1.3 at 380 K is achieved for p‐type polycrystalline Bi 0.3 Sb 1.7 Te 3 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.