Synergistic Manipulation of Interdependent Thermoelectric Parameters in SnTe-AgBiTe₂ Alloys by Mn Doping

In the mid-temperature region, SnTe is a promising substitute for PbTe, whereas the thermoelectric (TE) property of pristine SnTe is severely limited by the good thermal conductivity and inferior Seebeck coefficient. In this research, we synergistically manipulate the interdependent TE parameters of SnTe-AgBiTe₂ alloys by Mn doping to increase the ZT value. The AgBiTe₂ alloying is found to greatly reduce the electrical conductivity and electronic contribution for thermal transport by reducing the carrier mobility, while Mn doping obviously improves the Seebeck coefficient by effectively decreasing the valence band offset. The lowest κ_l of Mn-doped SnTe-AgBiTe₂ alloys is 0.49 W m^-1 K^-1 at 823 K since the various defects strengthen the phonon scattering. Collectively, these manipulations yield a peak ZT value of 1.40 at 823 K and an average ZT value of 0.73 (300-823 K) in the Mn-doped SnTe-AgBiTe₂ alloys. This research suggests that Mn doping is a valid scheme to constantly improve the thermoelectric property of SnTe-AgBiTe₂ alloys in a wide temperature range.