Challenges and Progress in Contact Development for PbTe‐based Thermoelectrics

Over the decades, tremendous efforts have been put into developing lead telluride (PbTe)‐based thermoelectric materials, dramatically improving the thermoelectric figure of merit zT. However, application of PbTe‐based thermoelectrics has been limited to radioisotope generators supplying electrical power for space probes and in remote terrestrial locations. One of the key factors for translating the progress in material performance into social implementation of thermoelectrics is the realization of stable electrical and thermal contacts between PbTe‐based materials and electrodes in modules. To realize stable operation of thermoelectric modules, unwanted chemical reactions, atomic diffusion, and crack formation near the contacts need to be prevented. Here, we summarize the challenges and recent progress of bonding between PbTe and contact layer. This review discusses and highlights the contact resistance as well as chemical and mechanical stability in PbTe/contact layer bonding.