Electronic structure, thermodynamics, and thermoelectric properties of β-BaCu2S2: A first-principles study

Electronic structure, thermodynamics, and thermoelectric properties of β-BaCu2S2 with naturally layered structure have been systematically investigated by using first-principles calculations and the Boltzmann transport theory. Our calculated results show that the Ba-S bonding interactions play an important role in determining the structural stability of β-BaCu2S2 considering the Cu-S and Cu-Cu antibonding states at the top of valence band. Thermoelectric transport properties of β-BaCu2S2 are significantly anisotropic depending on the crystallographic orientation. The slow carrier mobility, especially that along the c axis, would be responsible for its relatively low thermoelectric figure of merit. Metal doping is expected to be an effective route to improve the thermoelectric properties of β-BaCu2S2 significantly through enhancing its electrical conductivity.