suggest that Sc2Si2Te6 holds promise as an excellent thermoelectric material for applications in the moderate-to-high temperature range, and also demonstrate the power of band engineering for enhancing thermoelectric performance within compound families. The calculated optimal ZT and associated carrier concentrations, PF, electronic thermal conductivity, and lattice thermal conductivity for Sb2Si2Te6 and Sc2Si2Te6 are summarized in Tables and. We note that the theoretically predicted maximum ZT for p-type Sb2Si2Te6 exceeds the experimentally reported result (~1.08 at 823 K, increased to ~1.65 when incorporated in a cellular nanostructure with Si2Te3). Notably, the calculated lattice thermal conductivity of Sb2Si2Te6 matches well with the experimental measurements, suggesting the primary origin of reduced ZTs in experiment are due to additional scattering mechanisms, for example due to impurities and grain boundaries, and suboptimal electronic properties such as carrier concentration. This discrepancy can be explained by the following two aspects. On the one hand, in experiment, thermal radiation, air-induced thermal convection impurity phases and the effect of grain boundary scattering on carrier mobility can lead to degradation of thermoelectric performance -effects which are not included in our theoretical model. On the other hand, this experimental value corresponds to a single carrier concentration (measured to be ~5.6×10 cm -3 at room temperature) which may vary with temperature, but we calculate the thermoelectric properties over a range of temperatures and carrier concentrations. Indeed, as expected, we find a high sensitivity of the overall ZT to the carrier concentration (Figure ), with different optimal concentrations for the in-plane and cross-plane directions. Thus, given the un-optimised experimental carrier concentration and potential additional factors not accounted for in our model, a lower experimental figure of merit is expected. Our simulations therefore reflect an idealised model which can help guide experimental efforts in further improving the thermoelectric performance of this material. In particular, the anisotropy in thermoelectric properties indicates that controlled-orientation single crystals (with optimised carrier concentrations) are expected to achieve significantly higher ZT values than polycrystalline samples for these layered compounds.