Defect chemistry is critical for tailoring the electrical conductivity and optical properties of the TCOs. As shown above, to achieve sufficiently high conductivities for TCO application, high doping concentrations are required for this material. Thus, to investigate the dopability of this compound, a thorough study of the intrinsic defect chemistry was performed. Chemical potential limits need to be analyzed first as they provide a thermodynamic reference for the formation energy and stability of defects in materials. Table lists the calculated chemical potential limits using the total energy per atom for each competing phase shown in Tables and. Figure demonstrates the thermostability region of Sb 2 O 5 where it exhibits a relatively wide Sb chemical potential range of around 2 eV and a smaller oxygen chemical potential range of 0.76 eV.