From the above discussions, we see that low carrier lifetimes in state-of-the-art Se solar cells cannot be explained by electronhole recombination mediated by intrinsic point defects. Intrinsic defects also fail to explain the reported hole densities of 10 13 -10 17 cm 3 in polycrystalline samples. We therefore revisit the champion photovoltaic device from Nielsen et al. exhibiting a record 1-Sun V oc of 0.992 V (Fig. ), to further investigate photovoltaic losses and impurity concentrations. In Fig. , the experimental current-voltage (JV)-curve and the reconstructed JV-curve from Suns-Voc measurements (which determine the open-circuit voltage as a function of light intensity) are shown, illustrating the various contributions to photovoltaic losses. This includes a fill factor (FF) loss originating from parasitic series resistance R S , and a more significant loss in current density due to incomplete photon absorption and carrier collection -in line with our optical results (Figs. and) and measured external quantum efficiency (EQE) of ⇠ 65 % (Fig. ) for a 300 nm-thick film. While the use of an Au back contact in singlejunction devices already boosts absorption by acting as a reflective surface, further light-trapping strategies could avoid this loss, as demonstrated by the visible-light EQEs close to 100% recently reported by Lu et al. , using an anti-reflective coating. Fig. also shows the loss from carrier management (i.e. V oc deficit) which typically results from non-radiative recombination, but is also influenced by band tailing -investigated in Fig. . A moderate Urbach energy of 44 meV is extracted from the fit of the absorption onset in the EQE spectrum (as elaborated in Section S6). However, the band tailing deviates from a linear trend in the semilog plot, indicating that standard Urbach behaviour may not fully explain the observed tailing.