Overall, for the intrinsic point defect chemistry of t-Se, selfinterstitials are lowest in energy and thus present in relatively high concentrations due to their split-interstitial type geometry. However, they are inactive for doping or electron-hole recombination (the primary mechanisms by which defects impact PV performance) due to the dominance of the neutral state across most of the band gap. On the other hand, Se vacancies adopt a variety of charge states and so can contribute to both doping and recombination, however, their higher formation energies suggest that they will be present in much lower concentrations.