Ab initio study of thermoelectric transport properties of pure and doped quaternary compounds

Recent experiments on thermoelectric characterization of doped quaternary compounds of sattanite or kesterite-type Cu2ZnSnSe4, Cu2ZnSnS4, and Cu2CdSnSe4, show promise for their use as bulk thermoelectrics. In this paper we present and discuss the energetic, electronic, and transport properties of several tetrahedrally bonded quaternary compounds Cu(2)QSnX(4), where Q=Zn, Cd; X=S, Se, Te and their alloyed/doped structures, Cu doped at Q sites and M doped (M= Al, Ga, In) at Sn sites, for elucidating their thermoelectric performance. In our calculations, using density-functional theory and Boltzmann transport equations, we determine Seebeck coefficients, conductivities, power factors, a simple measure maximum ZT for each compound at experimentally amenable doping levels. Based on the electronic-structure and transport property calculations, we conclude that the base compounds and several doped compounds show similar potential as thermoelectric materials to the experimentally characterized one.