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

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 Al0.88Si0.12 and Ni (ASN) as diffusion barrier materials. Although the interface-connection performance using Ni or Al0.88Si0.12 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 Al0.88Si0.12 and the formation of appropriate reaction-diffusion layers between ASN and GeTe/Bi2Te3 and between Al0.88Si0.12 and Ni in ASN. Finally, a remarkable energy conversion efficiency of approximate to 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.