Investigation of Thermoelectric Properties of Ag2SxSe1−x (x = 0.0, 0.2 and 0.4)

Materials best-suited for direct application exhibit a high thermoelectric figure of merit (ZT) close to unity, from room temperature to ∼ 400 K. In this work, we investigated the thermoelectric behavior of Ag2Se, and a sulfur substituted Ag2Se system, i.e. Ag2S0.2Se0.8 and Ag2S0.4Se0.6 , in the temperature range of 300 K to 500 K. With strong anharmonic lattice vibration and semiconducting electronic structure, these materials showed thermal conductivity less than 1 W m−1 K−1, electrical resistivity ∼ 1 mΩ cm, together with moderate Seebeck coefficient values of ∼ − 140 μV K−1 in the low-temperature phase. We were able to achieve ZT equal to unity in a wide temperature range of 350–400 K, with a maximum value of ZT = 1.08 at 350 K for the Ag2S0.4Se0.6 material.