One‐Step‐Sintered GeTe‐Bi₂Te₃ Segmented Thermoelectric Legs with Robust Interface‐Connection Performance

Abstract Segmented thermoelectric (TE) legs are promising for improving heat‐electricity conversion efficiency, but their practical applications are still limited by the lack of cost‐effective interface‐connection technology. Here, an interface‐connection method for one‐step sintering of GeTe‐Bi₂Te₃ segmented TE legs is developed using mixtures of Al_0.88Si_0.12 and Ni (ASN) as diffusion barrier materials. Although the interface‐connection performance using Ni or Al_0.88Si_0.12 alone is poor, their mixtures can realize a compromise optimization of interface‐connection properties, simultaneously achieving a matched coefficient of thermal expansion, low contact resistivity, high shear strength, and high reliability. These robust interface‐connection properties can be attributed to the activation of the eutectic‐alloy Al_0.88Si_0.12 and the formation of appropriate reaction‐diffusion layers between ASN and GeTe/Bi₂Te₃ and between Al_0.88Si_0.12 and Ni in ASN. Finally, a remarkable energy conversion efficiency of ≈15.5% at a temperature difference of 449 K can be obtained in this segmented TE leg. Moreover, ASN can also be applied in fabricating n‐type PbTe‐Bi₂Te₃ segmented legs and multi‐pair TE devices, demonstrating the universality of this methodology. This work accelerates the development of robust, low‐cost, one‐step‐sintered segmented TE legs and promotes the use of eutectic alloys as “alloy glues” for advancing TE‐device connection technology.