Facile composite engineering to boost thermoelectric power conversion in ZnSb device

Zinc antimonide (ZnSb) is one of the alternatives for commercial thermoelectric materials due to its non-toxic, low-cost, and earth-abundant nature. However, its simple crystal structure causes strong phonon vibrations, which enhance lattice thermal conductivity. In this work, we systematically studied the effect of γ-Al₂O₃ nano-inclusions on ZnSb. Our results show that composite engineering imparts lattice phonon scattering for reduced thermal conductivity and low-energy carrier filtering for enhanced Seebeck coefficient. The obtained figure of merit in the ZnSb+5% γ-Al₂O₃ sample at 673 K is nearly two-fold higher than the pristine sample. Our fabricated 2-leg ZnSb+5% γ-Al₂O₃ device displayed a power generation of 0.11 μW at ΔT of 200 °C. Furthermore, adding γ-Al₂O₃ nano-inclusions improve the mechanical and thermal stabilities due to grain boundary hardening and dispersion strengthening. Overall, the addition of γ-Al₂O₃ nano-inclusions to ZnSb enhancing the Seebeck coefficient, reducing thethermal conductivity, and improving mechanical and thermal stability significantly.