Lifetime prediction of thermoelectric devices under thermal cycling

Thermoelectric (TE) devices under thermal cycling are prone to interface defects. Based on the experimental observation, this paper proposes a generalized model to analyze the interface damage growth and predict the lifetime of thermoelectric (TE) devices under thermal cycling. The closed-form solutions of the temperature profile, interface stresses, and damage growth are first derived and validated by either finite element (FE) simulation or experiment. Then, based on the derived interface damage growth, we propose the analytical lifetime prediction model. Furthermore, we find that shorter leg length leads to lower stress level and results in reduced damage growth rate. As the initial interface thermal resistance goes up, the rate of damage growth decreases, which means that TE modules with higher initial interface thermal resistance may have a longer lifetime. This work provides an analytical model to evaluate the long-term reliability of TE devices.