Analysis of thermally induced delamination and buckling of thin-film thermoelectric generators made up of pn-junctions

This paper investigates the problem of delamination and buckling of thermoelectric pn-junctions, which have many potential civil and military applications including thermal protection systems in space industry. Based on the compatibility equations of deformation, equilibrium equations of axial force and the strain compatibility equation at the interface of the bonding part are derived. Analytical solution of the delamination energy release rate is obtained. It is noted that there is no energy release rate when the magnitude of the temperature difference between the right end and the left end of the pn-junction is zero. The energy release rate can decrease or increase with the coefficient of thermal expansion. Distributions of the critical temperature differences for the delamination propagation and buckling are presented graphically. The critical temperature differences decrease continually with delamination and buckling lengths. Either a higher temperature difference or a higher electric current density can result in a bigger delamination energy release rate, a larger buckling deflection and a strong axial force. The buckling deflection increases but the axial force decreases with the increase of buckling length.