Flexible Ag-S-Te System with Promising Room-Temperature Thermoelectric Performance.

Silver chalcogenides demonstrate great potential as flexible thermoelectric materials due to their excellent ductility and tunable electrical and thermal transport properties. In this work, we report that the amorphous/crystalline phase ratio and thermoelectric properties of the Ag2SxTe1-x (x = 0.55-0.75) samples can be modified by altering the S content. The room-temperature power factor of the Ag2S0.55Te0.45 sample is 4.9 µW cm-1 K-2, and a higher power factor can be achieved by decreasing the carrier concentration as predicted by the single parabolic band model. The addition of a small amount of excessive Te into Ag2S0.55Te0.45 (Ag2S0.55Te0.45+y) not only enhances the power factor by decreasing the carrier concentration but also reduces the total thermal conductivity due to decreased electronic thermal conductivity. Owing to the effectively optimized carrier concentration, the thermoelectric power factor and dimensionless figure of merit zT of the sample with y = 0.007 reaches, respectively, 6.2 µW cm-1 K-2 and 0.39, while the excellent plastic deformability is well maintained, demonstrating its promising potential as a flexible thermoelectric material at room temperature.