Fig. 4: Photovoltaic characteristics and stability.

a Loss analysis for FF and VOC of control and bilayer-treated devices. FF and VOC losses are extracted from pseudo-J-V measurements detailed in Fig. S14 and Table S2. b Reverse and forward J−V scans under 100 mW cm−2 AM 1.5 G standard solar irradiation. c The stabilized PCE outputs of the AlOx/PDAI2-treated cells. d Evolution of PCE of unencapsulated tandem solar cells with aging time at 85 °C in the nitrogen-filled glovebox. Error bars represent the standard deviation, calculated from 3 cells. e Continuous maximum power point tracking for the unencapsulated tandem solar cells under AM 1.5 G illumination in the nitrogen-filled glovebox. Calculated local electrostatic potential (ESP) for f AlOx- and g PDAI2-passivated perovskite thin film. Planar macroscopic average of ESP of h PVSK/AlOx and i PVSK/PDAI2 calculated as functions of fractional coordinate.