Silver vacancy concentration engineering leading to the ultralow lattice thermal conductivity and improved thermoelectric performance of AgInTe.

AgInTe compound has not received enough recognition in thermoelectrics, possibly due to the fact that the presence of Te vacancy (V) and antisite defect of In at Ag site (In) degrades its electrical conductivity. In this work, we prepared the AgInTe compounds with substoichiometric amounts of Ag and observed an ultralow lattice thermal conductivity (κ = 0.1 WmK) for the sample at x = 0.15 and 814 K. This leads to more than 2-fold enhancement in the ZT value (ZT = 0.62) compared to the pristine AgInTe. In addition, we have traced the origin of the untralow κ using the Callaway model. The results attained in this work suggest that the engineering of the silver vacancy (V) concentration is still an effective way to manipulate the thermoelectric performance of AgInTe, realized by the increased point defects and modified crystal structure distortion as the V concentration increases.