Fig. 2: Aging influence on optical and electrical properties.

a Illuminated and b dark current–voltage curves of fresh and aged 200 nm devices. For reference, the molecular structures of PM6 and Y6 are shown. c The schematic band diagram of the device. The energy level markers of MoO₃ are dotted because different values can be found in the literature. d Normalized absorption (Abs) was obtained using photothermal deflection spectroscopy, photovoltaic external quantum efficiency (EQE_PV), and electroluminescence emission (EL) for fresh and 96 h aged samples at room temperature. Data from the aged sample was shifted down by two orders of magnitude for clarity. By comparing the external quantum efficiency EQE_PV multiplied by the 300 K black body spectra (EQE_PV ⋅ ϕ_BB) to EL, it can be seen that they fit very closely, suggesting through the reciprocity relation that the active layer absorption is dominated by Y6 around the 1.4 eV optical bandgap. e Extracted horizontal and f vertical information from 2D GIWAXS data of PM6:Y6/ZnO/ITO samples. The gaps seen in the vertical information correspond to missing q-values due to detector gaps^43,44.