High-performance near-room-temperature n-type Bi₂Te₃-based thermoelectric alloys with superior mechanical properties

Hot deformation is an important technique for fabricating high-strength n-type Bi₂Te₃-based thermoelectric (TE) alloys. However, the poor controllability of the oxygen-induced donor-like effect during the fabrication process often results in an overhigh carrier concentration, significantly worsening the near-room-temperature TE performance. Here, by maximumly avoiding the oxygen-induced donor-like effect, the carrier concentration of n-type TeI₄-doped Bi₂Te_2.7Se_0.3 can maintain nearly the optimal one during the repetitive hot deformation processes while the enhanced texture contributes to higher carrier mobility. Moreover, the hot deformation-induced dislocations and local distortions are conducive to lowering the phonon transport. Consequently, a high zT of 1.0 and a large bending strength of 122 MPa are simultaneously achieved at 300 K. Additionally, a 23-pair TE cooling module of 8.20 × 6.10 × 1.65 mm³ was fabricated, which shows a maximum temperature difference of 82 K at the hot-end temperature of 350 K. These results highlight the crucial role of controlling the oxygen-induced donor-like effect in achieving high-performance near-room-temperature n-type Bi₂Te₃-based TE alloys.