We have computationally assessed the prospect of Y 2 Te 3 as a ntype TE material. A high conduction band valley degeneracy contributes to the superior n-type electrical transport properties, which combined with the low lattice thermal conductivity, yields a high figure-of-merit zT > 1.0 when Y 2 Te 3 is optimally doped to electron concentrations of 1 -2 × 10 20 cm -3 . Our defect calculations reveal that Y 2 Te 3 is natively n-type under Y-rich growth conditions due to the facile formation of donor cation interstitials. The free electron concentration can be enhanced through halogen doping on the Te site, with I being the most effective dopant. We also clarify through defect calculations that the reported ntype character of Bi-doped Y 2 Te 3 is not a direct consequence of electron generation from Bi substitution, and further studies are necessary to resolve the unusual experimental observation. We propose that halogens are "better" n-type dopants because they preferentially substitute on the Te site and likely do not perturb the conduction band edge, which is dominated by Y-d states.