Highly deformable Ag2Te1-xSex-based thermoelectric compounds

Abstract

Thermoelectric semiconductors are crucial for many critical applications, but are also universally fragile, which greatly limits the development of room temperature flexible thermoelectric devices. Herein, an extraordinary deformability at room temperature and high thermoelectric performance are simultaneously realized in wide composition of Ag2Te1-xSex (x = 0–0.2) compounds with monoclinic structure. An average compressive strain rate of 24% at room temperature is attained for the pristine Ag2Te compound. Moreover, a tensile strain rate of 43% is measured at room temperature using the in-situ transmission electron microscopy. First Principles calculations and in-situ transmission electron microscope tensile test results indicate that the Ag2Te compound is inclined to slip along the (−102) [010] plane under external forces due to a larger ratio between the cleavage energy (Ec) and the slip energy barrier. The slipping process generates high concentrations of dislocations, deformations, and amorphous structures, which together dissipate the externally applied load energy, yielding superior deformability. Meanwhile, the maximum dimensionless figure of merit ZT of 0.61 is obtained at 380 K. This study demonstrates that Ag2Te-based compounds are promising for the fabrication of flexible thermoelectric devices in applications, such as wearable, room temperature electronic gadgets.