We begin with a discussion of the electronic structure, arguably the most decisive indicator of a prospective transparent conductor. The electronic band structure of ZnSb 2 O 6 was calculated using the PBE0 functional and is displayed in Figure . A direct band gap of 3.54 eV at Γ is observed, with relatively high dispersion at the (CBM), ideal for a prospective transparent conductor. The electron effective mass in the Γ → X and Γ → M directions is 0.27m e , and improves further along Γ → Z (in the c-direction) to 0.22m e . The high dispersion originates from the broad overlap of Sb 5s orbitals, which are the main contributor to the CBM density of states, with Zn and O s states. Qualitatively, the conduction band shape is in good agreement with previous GGA-DFT calculations, while the hybrid functional corrects for the systematic underestimation of the band gap, which we note is competitive with state-of-the-art TCOs In 2 O 3 , SnO 2 , ZnO and BaSnO 3 . Figure shows the band structure computed with hQSGW theory, which shows a small (3%) decrease in the direct band gap to 3.41 eV, with the electron effective masses unchanged. Ultimately, the PBE0 description is sufficient, accurately describing the nature of the band gap compared to the next level of theory, and is used subsequently for defect calculations. The transition from VBM to CBM is symmetry forbidden, and the first allowed transition occurs from states around 0.7 eV below the VBM (similar to the case in In 2 O 3 ) , as denoted by the green arrow in Figure . This is discussed in greater detail in the optical properties section. shown in Figure , plotted using galore. The simulated spectrum was obtained from the PBE0 density of states calculation, where the orbital contributions were weighted with tabulated photoionisation cross-sections and broadened with Guassian and Lorentzian functions to reproduce the experimental lineshapes. The spectra were approximately aligned to the Fermi level. The key valence band features in Figure are in agreement: an initial onset mainly comprised of Zn 3d, Sb 4d and O 2p states followed by a sharp peak assigned to Zn 3d states. However, the position of this peak is under-bound by approximately 3 eV. The under-binding of transition metal d states with hybrid DFT is well documented and has been observed in other well-known TCOs, such as the Zn 3d