Achieving superior performance in thermoelectric Bi_0.4Sb_1.6Te_3.72 by enhancing texture and inducing high-density line defects

Miniaturization of efficient thermoelectric (TE) devices has long been hindered by the weak mechanical strength and insufficient heat-to-electricity conversion efficiency of zone-melted (ZM) ingots. Here, we successfully prepared a robust high-performance p-type Bi_0.4Sb_1.6Te_3.72 bulk alloy by combining an ultrafast thermal explosion reaction with the spark plasma sintering (TER-SPS) process. It is observed that the introduced excess Te not only enhances the (00l)-oriented texture to ensure an outstanding power factor (PF) of 5 mW m⁻¹ K⁻², but also induces extremely high-density line defects of up to 10¹¹–10¹² cm⁻². Benefiting from such heavily dense line defects, the enhancement of the electronic thermal conductance from the increased electron mobility is fully compensated by the stronger phonon scattering, leading to an evident net reduction in total thermal conductivity. As a result, a superior ZT value of ~1.4 at 350 K is achieved, which is 40% higher than that of commercial ZM ingots. Moreover, owing to the strengthening of grain refinement and high-density line defects, the mechanical compressive stress reaches up to 94 MPa, which is 154% more than that of commercial single crystals. This research presents an effective strategy for the collaborative optimization of the texture, TE performance, and mechanical strength of Bi₂Te₃-based materials. As such, the present study contributes significantly to the future commercial development of miniature TE devices.