Mechanical behaviour of thermoelectric materials – a perspective

Research on thermoelectric materials – with their vast potential for applications in solid-state cooling or energy-conversion devices – has so far mainly focused on enhancing their conversion efficiency. However, understanding and tailoring the mechanical performance of thermoelectric modules and devices is crucial for their long-term use, as they are subjected to spatially-complex and time-varying thermomechanical stresses – both internal and external – which may lead to plastic, fatigue and/or creep deformation. This leads to changes in thermoelectric performance, dimensions ( via strain accumulation) and mechanical integrity ( via crack and pore formation, leading to failure). This review addresses the current understanding of various modes of stress-induced deformation that can take place during extended operation of thermoelectric materials and their impact on the strain (elastic, plastic, and creep), and the associated damage (bloating, fatigue, and fracture). Finally, some new areas of research straddling mechanical and thermoelectric behaviour are identified.