Using the calculated electronic (Figure ), phonon (Figure ) and electronphonon properties from DFT, the carrier mobilities were computed using the Boltzmann transport equations as implemented in the AMSET package (see Methods and Supplementary Information). The individual scattering mechanisms are plotted as functions of temperature, carrier concentration and electronic energy in , respectively. As expected, we witness decreases in electrical conductivity with increasing temperature, however the effect is relatively minor for high carrier concentrations due to the dominance of (mostly) temperature-independent impurity scattering over carrierphonon scattering in these regimes. For n-type Sb2Si2Te6, the temperature dependence is stronger due to greater carrier-phonon interactions for this case. Overall, Sb2Si2Te6 exhibits higher electrical conductivity than Sc2Si2Te6 under both n and (particularly) ptype conditions due to the lower carrier effective masses (Figure , Table ) and scattering rates (Figures and). The enhanced band degeneracy in Sc2Si2Te6 may also increase the rate of inter-valley scattering, contributing to a decrease in carrier mobility. As expected from the Wiedemann-Franz law (κe = LσT, where L is the Lorenz number and T is temperature), the trends in electronic thermal conductivity (κe) mostly follow those of electrical conductivity (σ). K and 1023 K, respectively, and so these ranges are used in our analysis. The Seebeck coefficient (S) reflects the voltage generated in response to a temperature gradient, and its sign depends on the dominant charge carrier type (positive for holes, negative for electrons). In general, the Seebeck coefficient can be expressed as: