Effects of AgSnSe2 addition on the thermoelectric properties of Bi0.5Sb1.5Te3

Abstract

In this study, the thermoelectric properties of Bi0.5Sb1.5Te3 with the addition of AgSnSe2 were investigated. It was found that the addition of AgSnSe2 significantly improved the electrical conductivity of the Bi0.5Sb1.5Te3 based sample, which was attributed to the spontaneous Ag doping and the generation of the high carrier concentration SnTe secondary phase. Due to the significant increase in σ, the maximum PF increased to ∼39 μW cm−1K−2 at 323 K. Meanwhile, owing to the larger lattice anharmonicity by spontaneous Ag doping and enhanced interfacial scattering of phonons by secondary phase SnTe, κl decreases from 1.17 W m−1 K−1 for the intrinsic sample to 0.72 W m−1 K−1 for the x = 0.5 sample at 300 K. Thanks to the synergistic effect of AgSnSe2 addition, a larger ZT of 1.1 at 373 K is obtained in Bi0.5Sb1.5Te3-0.4% AgSnSe2, which is 1.45 times higher than that of the intrinsic sample.