Cu₃SbSe₃-Alloying-Induced High Thermoelectric Performance and Mechanical Robustness in Bi₂Te₃-Based Thermoelectric...

Bi₂Te₃-based thermoelectric materials remain the only commercially viable candidates for low-grade waste heat recovery. However, their moderate thermoelectric performance and limited mechanical robustness constrain broader industrial applications. Here, a synergistic enhancement of both the thermoelectric and mechanical properties of Bi_0.4Sb_1.6Te_3.01 is demonstrated by alloying with Cu₃SbSe₃ via high‑energy ball milling followed by hot pressing. This approach optimizes carrier concentration and reduces microscale porosity, yielding a significant improvement in the power factor across the entire temperature range. Simultaneously, the introduction of stacking faults and dislocations intensifies phonon scattering, effectively suppressing lattice thermal conductivity. As a result, the optimized sample achieves a peak zT of ≈1.45 at 378 K and an average zT of ≈1.3 over 303-503 K. Its mechanical properties are also substantially enhanced, with a Vickers hardness of 96 Hv and a compressive strength of 187 MPa. A 7‑pair thermoelectric device fabricated from the optimized material delivers a maximum conversion efficiency of ≈6.9% at a temperature difference of 182 K. This work highlights the efficacy of combining microstructural engineering with strategic alloying as a promising route to advance both the thermoelectric and mechanical performance of Bi₂Te₃‑based materials.