Hybrid CaS/CaSe bilayer as a wide temperature range thermoelectric material

The present work reports a detail density functional investigation on the structure, vibrational, electronic and thermoelectric properties of bilayered CaS and CaSe and their hybrid CaS/CaSe bilayer, based on our recently developed hexagonal monolayers CaS and CaSe as promising thermoelectric materials from a series of calcium chalcogenides CaX (X = O, S, Se and Te). The minimized structures of the considered bilayers are assessed for the dynamical stability with phonon dispersion analysis. In order to look into the electronic properties of stable compounds, we have generated electronic band structure and projected density of states (PDOS) through first principle methods. To study the thermoelectric properties, we have utilized the semi-classical Boltzmann transport equations (BTE) for computing electrical and thermal conductivities, Seebeck coefficient and figure of merit (ZT). Present study reveals hybrid CaS/CaSe bilayer as the best promising thermoelectric material for a wide range of temperature toward future applications in thermopower generation devices.