Atomic-scale interface strengthening unlocks efficient and durable Mg-based thermoelectric devices

Abstract

Solid-state thermoelectric technology presents a compelling solution for converting waste heat into electrical energy. However, its widespread application is hindered by long-term stability issues, particularly at the electrode–thermoelectric material interface. Here we address this challenge by constructing an atomic-scale direct bonding interface. By forming robust chemical bonds between Co and Sb atoms, we develop MgAgSb/Co thermoelectric junctions with a low interfacial resistivity (2.5 µΩ cm2), high bonding strength (60.6 MPa) and high thermal stability at 573 K. This thermally stable and ohmic contact interface enables MgAgSb-based thermoelectric modules to achieve a conversion efficiency of 10.2% at a temperature difference of 287 K and to exhibit negligible degradation over 1,440 h of thermal cycling. Our findings underscore the critical role of atomic-scale interface engineering in advancing thermoelectric semiconductor devices, enabling more efficient and durable thermoelectric modules. Solid-state thermoelectrics can convert waste heat to electrical energy, but applications are hindered by long-term stability issues. Here cobalt is used as a contact layer with direct bonding to thermoelectric MgAgSb, enabling a thermoelectric module to achieve 10.2% conversion efficiency over 1,440 h of thermal cycling.