Effects of Interfacial Properties on Conversion Efficiency of Bi2Te3-based Segmented Thermoelectric Devices

The conversion efficiency η of a thermoelectric (TE) device can be effectively improved by constructing segmented TE legs, but the specific interfaces between the heterogeneous materials inevitably degrade the performance. Focusing on the Bi2Te3-based two-segmented module, we systematically investigated the influences of the Peltier effect, interfacial electrical resistance Re, and interfacial thermal resistance Rt on the conversion efficiency η. It is found that the Peltier heat can increase the conversion efficiency if the Seebeck coefficient increases along the direction of an electric current. An applicable Re should be kept on the order of magnitudes of 10−5 Ω cm2 for segmented TE devices, since the increased Re significantly decreases η. With a determined Re, η depends on the leg height L rather than the cross-sectional area A. In contrast, η is hardly affected by the variation in the interfacial thermal resistance Rt, while both the input heat flux Qin and output power P decrease with the increasing Rt.