Application of low-temperature soldering in TE material/electrode interfaces of thermoelectric devices: a review

Purpose This review aims to synthesize and analyze recent advancements in low-temperature soldering technology for enhancing the bonding interfaces of thermoelectric (TE) devices. It focuses on joint quality, efficiency and reliability at TE material/electrode interfaces, while highlighting strategies to optimize interfacial reactions and material compatibility. Design/methodology/approach The review systematically evaluates research on interfacial behaviors between TE materials and solder. After that, it reports main methods to regulate the interfacial reaction at joints, which include incorporating diffusion barrier layers, optimizing solder composition and optimizing TE materials composition. Findings Adding barrier layers, such as Ni-based and Co-based alloys, could prevent the formation of brittle intermetallics. The bonding strength of the joints with barrier layers could reach about 15 MPa. And the interfacial resistances can be kept at the level of 10–6 Ω cm2. Furthermore, the addition of Ag/Cu nanoparticles in solder to enhance electrical conductivity synergistically improves the efficiency of TE devices by 15–20%. For TE material optimization, doping Se or Mn improves the thermoelectric figure of merit (ZT) value to 1.5–1.8 and carrier mobility by 30–50%. Originality/value This review points out the limitations of soldering in bonding low-temperature TE modules and their future development prospects. With the continuous optimization of the barrier layer, solder, soldering parameters and TE material, it is expected to achieve a more efficient, reliable and economical TE device in the future.