Interface performance of PbTe-based thermoelectric joints

Abstract

The conversion efficiency of thermoelectric material PbTe is high. A high-quality and high-conversion-efficiency PbTe thermoelectric connector is investigated systematically. Excess Pb in composition can increase the carrier concentration and improve the thermoelectric performance of PbTe. The composite electrode can improve the interface barrier and reduce the contact resistance. Traditional processes of making contacts onto bulk crystalline PbTe-based materials do not work for reducing the contact resistance by inhibiting element diffusion and increasing the shear strength at the same time. In this study, we consider a composite electrode which can form an intermediate layer to suppress the diffusion of the Pb element on the PbTe side. This work not only reduces the contact resistance, but also increases the shear strength. The sample Pb_50.01Te_49.99is obtained by adjusting the stoichiometric ratio of PbTe; Te and Pb are mixed in the Fe electrode. The composite electrode and Pb_50.01Te_49.99 are hot-pressed and sintered in one step to obtain the required PbTe thermoelectric electrode joint. We find that the contact resistance of the composite electrode is reduced by nearly 75% compared with that of metallization layer (Fe) connection. The smallest value is 26.610 μΩ·cm² which is closer to the lowest 10 μΩ·cm² reported in the literature than the counterpart of pure Fe electrode, and the shear strength is also greatly improved simultaneously. This work provides a new idea for obtaining PbTe thermoelectric connectors with excellent performance.