Innovative rotary swaging method drives high performance of n-Type Bi2(Te, Se)3 thermoelectrics

Abstract

The thermoelectric transport of n-type Bi₂Te₃ heavily depends on grain alignment, causing performance limitations that severely restrict the demand for low-grade waste heat recovery. Here, the n-type Bi₂Te_2.7Se_0.3 material with a certain textured structure is prepared by an innovative rotary swaging method. It is found that various defects including Te vacancies, dislocations, and grain boundaries significantly strengthen the phonon scattering. With an obviously suppressed thermal conductivity and well-maintained carrier mobility, the obtained rods extending up to several tens of centimeters achieve a peak ZT of 1.2 at 450 K and an average ZT of 1.0 (300–550 K), with Vickers hardness and compressive strength increased to 0.42 GPa and 52.6 MPa, respectively. Moreover, the assembled 17-pair thermoelectric module achieves a competitive conversion efficiency of up to 6.3% and a high output power of 0.93 W at a temperature difference of 250 K. This study develops an effective strategy for synergistically enhancing the thermoelectric and mechanical properties of n-type Bi₂(Te,Se)₃.