Enhanced Out-of-Plane Electrical Transport in n-Type SnSe Thermoelectrics Induced by Resonant States and Charge Delocalization

Doping effects of various elements in the boron, carbon, and pnictogen groups on the electronic structure and electrical transport properties of SnSe were studied from first principles. It is identified that Sb and Bi induce significant resonant states near the conduction band minimum, and increase the delocalization of charge density in the out-of-plane direction. Our Boltzmann transport calculations further demonstrate that these doping effects on the electronic structure are related to the simultaneously improved Seebeck coefficient and electrical conductivity. Using the band unfolding technique, we analyze the resonant states in detail based on the effective band structures.