Electronic structure and thermoelectric properties of (PbSe)$_{\mathrm{m}}$/(SnSe)$_{\mathrm{n}}$ superlattice: A first principles study*

Figure of merit (ZT) of thermoelectric materials can be enhanced by lowering thermal conductivity or/and increasing electrical conductivity. The extremely high ZT of layered structure SnSe\footnote{Li-Dong Zhao \textit{et al}., Nature \textbf{508}, 373 (2014).} opened up a new direction in study of thermoelectricity due to its low thermal conductivity, which, however, is limited to high temperature. Here, we performed first principles density functional calculations to explore room-temperature thermoelectricity. We consider (PbSe)$_{\mathrm{m}}$/(SnSe)$_{\mathrm{n}}$ superlattices with different period, whose quantum well structure is expected to increase electrical conductivity by modulation of charge doping at interface. Calculations of Seebeck coefficients for the superlattices are presented.