Enhanced Thermoelectric Properties of p-Type Bi_0.48Sb_1.52Te₃/Sb₂Te₃ Composite

Constructing a nanocomposite to introduce a coherent interface is an effective way to improve the property of thermoelectric material. Here, a series composites of Bi_0.48Sb_1.52Te₃-x wt % Sb₂Te₃ (x = 0, 0.3, 0.5, 0.8, and 1.0) were synthesized, where the hydrothermally prepared Sb₂Te₃ nanosheets were intimately wrapped in the solid-state-reacted Bi_0.48Sb_1.52Te₃ matrix. The formation of a coherent interface was observed and confirmed by the scanning electron microscopy characterization. As the Sb₂Te₃ content was over 0.5 wt %, the carrier mobility could increase by 26%, while the carrier concentration decreased by 9% compared to those of the pure matrix at 300 K, enhancing the power factor to 40.1 μW/cm K². Moreover, the Bi_0.48Sb_1.52Te₃-0.5 wt % Sb₂Te₃ sample exhibited a reduced lattice thermal conductivity of 0.83 W/m K at room temperature, resulting from the strengthened phonon scattering by interfaces. Combined with the manipulations of both the electronic and thermal transport by constructing a coherent interface, a maximum ZT of 1.05 was obtained in the x = 0.5 composite at 300 K, and it was improved by 20% compared with the result of the Bi_0.48Sb_1.52Te₃ matrix.