Influence of solvent additive on the performance and aging behavior of non-fullerene organic solar cells

•The incorporation of DIO to the solvent of the active layer PBDB-T:ITIC improves morphology, increases mobility and enhances device efficiency in pristine state.•The incorporation of DIO reduces the initial burn-in effect, but enhances degradation at longer time scales.•During degradation, DIO cells show an increase of series resistance that dramatically affects FF.•Physical simulations confirm that the quasi-Fermi level for holes pins at the HTL interface when the anode WF is 5 eV or below, removing the VOC dependence on light intensity.