Thermoelectric Properties of (Ag₂Se)_1-x(Bi₂Se₃)_x

Abstract

Ternary chalcogenides I-V-VI 2 compounds attract extensive attentions for thermoelectric applications due to their intrinsically low lattice thermal conductivity.AgBiSe 2 , as one of a few n-type semiconductors among these compounds, shows the potential to be a promising thermoelectric material.Therefore, this work focuses on its thermoelectric properties.According to the phase diagram of Ag 2 Se-Bi 2 Se 3 system, the single phase region of (Ag 2 Se) 1-x (Bi 2 Se 3 ) x allows x to be varied in the range of 0.4~0.62.This large variation of x suggests a tunability of carrier concentration for this material.A broad carrier concentration of 1.0×10 19 ~5.7×10 19 cm -3 for single phased (Ag 2 Se) 1-x (Bi 2 Se 3 ) x is obtained through a composition manipulation, which enables a comprehensive assessment on electronic transport properties based on a single parabolic band model with acoustic scattering.The highest carrier concentration obtained in this work, approaching to the theoretical optimal one, leads to a peak ZT of 0.5 at 700 K.This work offers a well understanding of its transport properties and underlying physical parameters determining the thermoelectric performance.