Interfacial reactions in thermoelectric modules

Abstract

Engineering transport properties of thermoelectric (TE) materials leads to incessantly breakthroughs in the zT values. Nevertheless, modular design holds a key factor to advance the TE technology. Herein, we discuss the structures of TE module and illustrate the inter-diffusions across the interface of constituent layers. For Bi 2 Te 3 -based module, soldering is the primary bonding method, giving rise to the investigations on the selections of solder, diffusion barrier layer and electrode. For midtemperature PbTe-based TE module, hot-pressing or spark plasma sintering are alternative bonding approaches; the inter-diffusions between the diffusion barrier layer, electrode and TE substrate are addressed as well. ARTICLE HISTORY

Modelling a Segmented Skutterudite-Based Thermoelectric Generator to Achieve Maximum Conversion Efficiency

“…Lead-free solder alloys are often used to join an electrode and a TE material. It has been confirmed that an interfacial reaction exists between the solder and the TE material, leading to the creation of contact resistance and the possible degradation of TEG module performance [50]. In practical TEG modules, a diffusion barrier, usually in µm thickness, is inserted in between the solder and the TE material via either ultra-high-vacuum (UHV) radio frequency (RF) sputtering, spark plasma sintering, or electroplating procedures to inhibit the formation of intermetallic compounds at the same time as ensuring a good electrical bond.…”

“…Its analysis is often conducted via SEM. The effect of diffusion layers, such Au, Pt, Ti, Ni, Co-P, and Ni-P on TEG modules has been investigated [50][51][52][53]. If an appropriate thickness is used, the diffusion layer can enhance the efficiency of a module.…”

Characterizing thermoelectric stability

“…Mo, Cu and W. 54–57 During thermal aging, formation of an intermetallic layer occurs, which is highly detrimental for the mechanical stability and the physical properties of the thermoelectric module. 58 Often, such issues are solved by introducing a diffusion blocking interlayer. 59,60…”

Challenges and Progress in Contact Development for PbTe‐based Thermoelectrics

“…Among these criteria are low electrical and thermal interfacial resistance, matching CTE, prevention of interdiffusion and formation of secondary phases at the interface between contact layer and thermoelectric materials. [15,[24][25][26][27][28] The contact material must have low electrical resistivity (1) to enable efficient extraction of electrical energy from the thermoelectric materials. It also requires high thermal conductivity (k) to efficiently provide heat to the thermoelectric materials and maximize the temperature gradient.…”

“…This is followed by a discussion of contact layer fabrication methods. This article is recommended to be studied in conjunction with previously published general review articles [24][25][26][27][28][29] to gain a better understanding of contacts for PbTe-based thermoelectrics.…”