CuSbSe-Alloying-Induced High Thermoelectric Performance and Mechanical Robustness in BiTe-Based Thermoelectric Materials.

BiTe-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 BiSbTe is demonstrated by alloying with CuSbSe 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 BiTe‑based materials.