High performance of Bi2Te3-based thermoelectric generator owing to pressure in fabrication process

A Bi2Te3-based thermoelectric generator (TEG) is known to be the leading technology in low-temperature heat energy recovery. In its fabricating process, the thermoelectric (TE) materials should be heated over the melting temperature of tin solder, but the unmatched thermal expansion between p-type and n-type TE materials will lead to considerable interfacial resistivity, resulting in the sharp decrease of the output power and conversion efficiency. Here, we introduce the pressure to suppress interfacial resistance of Bi2Te3-based TEGs. The theoretical model governing the pressure and interfacial resistivity is built based on the equations of thermal-electric-elastic coupling, and the explicit expressions for maximum output power and conversion efficiency are derived when considering interfacial resistivity. With the guidance of theoretical and simulation results, the average interfacial resistivity of 10 mu omega middotcm(2) is measured in a Bi2Te3-based TEG, while the conversion efficiency is increased by 44% from the commercial devices. Besides, the stress caused by suitable pressure force is less than the allowable stress of Bi2Te3-based TE materials. These findings provide strong support for the fabrication of high-performance TEGs.