Anisotropic thermoelectric transport properties in polycrystalline SnSe2 *

It is reported that SnSe 2 consisting of the same elements as SnSe, is a new promising thermoelectric material with advantageous layered structure. In this work, the thermoelectric performance of polycrystalline SnSe 2 is improved through introducing SnSe phase and electron doping (Cl doped in Se sites). The anisotropic transport properties of SnSe 2 are investigated. A great reduction of the thermal conductivity is achieved in SnSe 2 through introducing SnSe phase, which mainly results from the strong SnSe 2 –SnSe inter-phase scattering. Then the carrier concentration is optimized via Cl doping, leading to a great enhancement of the electrical transport properties, thus an extraordinary power factor of ∼5.12 μW⋅cm −1 ⋅K −2 is achieved along the direction parallel to the spark plasma sintering (SPS) pressure direction (∥ P ). Through the comprehensive consideration on the anisotropic thermoelectric transport properties, an enhanced figure of merit ZT is attained and reaches to ∼ 0.6 at 773 K in SnSe 2 -2% SnSe after 5% Cl doping along the ∥ P direction, which is much higher than ∼ 0.13 and ∼ 0.09 obtained in SnSe 2 -2% SnSe and pristine SnSe 2 samples, respectively.