High cooling and power generation performance of α-MgAgSb with intrinsic low lattice thermal conductivity

α-MgAgSb is a promising near-room temperature thermoelectric material, characterized by its intrinsically low lattice thermal conductivity, a feature attributed to the significant atomic mass contrast and complex crystal structure. In this work, we achieved respective zT_avg values of 0.58 in the temperature range of 150–300 K and 1.22 in the range of 300–550 K for α-MgAgSb, indicating exceptional potential for both cooling and power generation applications. Additionally, through the reduction of cross-sectional size, the stability of MgAgSb/Ag interface was enhanced under high temperature, which is crucial for the practical application of thermoelectric module. To verify the property of α-MgAgSb material, a 7-pair MgAgSb/Bi₂Te₃ module was fabricated, demonstrating a maximum cooling temperature difference ΔT_max of 60 K at hot-side temperature of 300 K and a power generation efficiency η_max of 7.2 % with ΔT of 275 K. This work paves the way for the application of Mg-based thermoelectric materials.