Perovskite solar cells with a typical device architecture of ITO/
PEDOT:PSS/perovskite/PCBM/Ca/Al (Fig. S1a) were employed to
evaluate the photovoltaic performance of the perovskite layer.
Fig. 3a shows the photo- and dark-current density versus voltage
curves of such a perovskite solar cell under revere scan with a step
voltage 10 mV.