Enhancing thermoelectric performance of SnSb₂Te₄ through inducing impurity energy levels and improving carrier mobility

The layered compound SnSb₂Te₄ has emerged as a promising environmentally friendly thermoelectric material that has attracted considerable attention due to its remarkably low lattice thermal conductivity. However, the high carrier concentration associated with SnSb₂Te₄ results in an inferior Seebeck coefficient and limited carrier mobility. In this study, the thermoelectric performance of SnSb₂Te₄ has been successfully enhanced by synergistically optimizing effective mass and carrier mobility through In and Bi co-doping. The introduction of impurity energy levels owing to doping with In elements leads to flattening of the valence band edge and promotes the distortion of density of states. The incorporation of Bi elements contributes to a significant reduction in carrier concentration and an improvement in carrier mobility. Consequently, a maximum ZT value of ∼ 0.45 and an average ZT value of ∼ 0.31 are obtained in Sn_0.82Bi_0.1In_0.08Sb₂Te₄, representing a twofold improvement compared to the SnSb₂Te₄ matrix.