Etude des matériaux semi-conducteurs pour les applications thermoélectriques

Abstract

Based on first principle methods, structural, electronic and thermoelectric properties of cubic structures of spinel sufides A2BS4 with (A=Sc and Y; B=Cd and Zn), bi-alkali antimonite AB2Sb with (A= K, Cs and Rb ; B= K and Na) and Zintl materials NaXAs with (X = Sn and Pb) have been investigated. We have calculated the lattice parameter a, the bulk modulus B, its pressure derivative B0 and the density of states (DOS) by using the full potential-linearized augmented plane wave method within the density functional theory (DFT). The computations were done by treating the exchangecorrelation potential with the generalized gradient approximation (GGA) and modified Becke-Johnson potential approximation (TB-mBJ) and by using new parameters of the original TB-mBJ proposed by Koller et al. This new parameterization yields band gaps in very good agreement with experiments. This compounds treated were found semiconductors and they have all direct bandgaps at the center of Brillouin zone (). Furthermore, the thermoelectric parameters represented by the Seebeck coefficient, electrical and thermal conductivities were calculated employing the Boltzmann transport equations resolved in respect to DFT eigenvalues. Based on the reported results, the reported parameters recommend that these compounds are suitable candidates for thermoelectric applications.