Electronic structure and engineered thermoelectric properties of SnSe

Thermoelectric properties of SnSe like the maximum thermoelectric performance and the Lorenz number are obtained from density functional theory and Boltzmann transport theory. The transport properties have been engineered by assuming a rigid band shift for modeling the n- and p-type SnSe. In consistent with the experimental data close to the Fermi-level a two-valley valence-band structure along the Γ-Z direction has been observed. Furthermore, our calculated lattice thermal conductivity along the three axes shows the same trend as the experimental data (i.e. increasing from the x to the y to the z-axis). The engineered power factor enables us to obtain the maximum figure of merit of 2.89 at 850 K in the n-type SnSe which is higher than experimentally achieved value of 2.6. Finally, our calculated Lorenz number L for the p-doped SnSe at 300 K is close to the value of 2.44 × 10−8 WσK−2 from fundamental theory.