Realization of high-performance screen-printed flexible thermoelectric generator by improving contact characteristics

Abstract

To fabricate a flexible thermoelectric generator (f-TEG) that can be applied to curvilinear surfaces such as the human body, the screen-printing technique is a practical method for forming the thermoelectric (TE) elements. One of the main obstacles to fabricating high-performance screen-printed f-TEGs is the high contact resistance. In this work, the output power of a screen-printed f-TEG is increased by 80% through engineering of the contact and its formation process. Reduction ambient annealing is a process that removes the surface oxides while modulating the tellurium (Te) concentration on the surface, easily forming a favorable intermetallic compound at the contact interface. The wetting angle of the solder is also drastically reduced by applying an anti-diffusion bilayer. Using these methods, the specific contact resistivity (ρC) is reduced from 8.2 to 3.3 × 10−6 Ω cm−2 and 75 to 4.7 × 10−6 Ω cm−2 for p- and n-type TE material respectively. The device figure of merit measured for one leg is increased from 0.301 to 0.595 and 0.247 to 0.481 for p- and n-type respectively. The improved contact characteristics result in an increase in the output power of the complete module (a 72-couple f-TEG) from 0.25 to 0.4 W at a temperature difference of 40K.