Enhancement of thermoelectric performance of layered SnSe2 by synergistic modulation of carrier concentration and suppression of lattice thermal conductivity

Eco-friendly and low-cost layered SnSe2 based material has been attracting a great attention in the thermoelectric field for its intrinsically low thermal conductivity. In this work, we applied AgCl as Cl-dopant and formed Ag-rich precipitates in SnSe2 polycrystals, and their thermoelectric properties was investigated. The results demonstrate that Cl was artificially incorporated into SnSe2 martix by the substitution of Se atoms, playing as donor centers and thus increasing the carrier concentration by two orders magnitude, leading to a tremendous improvement of electrical conductivity and power factor. However, Ag atoms hardly enter into the Sn lattice sites and brought about the generation of Ag-rich precipitates. The complicated microstructures with multiple types of defects, such as point defects, boundaries，dislocations, etc., result in a relatively low lattice thermal conductivity in the AgCl-introduced SnSe2 samples. Additionally, the anisotropic electrical and thermal transport properties were inv...