We also investigated the anisoptropy in the electronic transport of the four systems (Figs S9 -S16, ESI †). The Seebeck coefficients of the Pnma phases are predicted to be relatively isotropic for n > 5 × 10 17 cm -3 . On the other hand, the calculations predict strong anisotropy in the σ . In the p-doped systems, the inplane conductivity along the a and c directions is up to 2 -3× higher than along the layered b direction, while, conversely, in the n-doped systems the interlayer conductivity along the b direction is more than 5× higher than along the in-plane directions. This anisotropy is reflected in the power factors, and is largely preserved across the 300 -900 K temperature range with a fixed n = 2×10 19 cm -3 . In contrast to the Pnma phases, the transport in the R3m phases is relatively isotropic. The largest discrepancies are that the Seebeck coefficients of the p-and n-doped systems are smaller and larger along the c direction, respectively, but the relatively small absolute values of S mean that the anisotropy in the PFs is minimal.