Ion Migration Magnified Photoresponse in Perovskite Devices

Here, we have studied the effect of ion migration on the photoresponse of the photovoltaic perovskite devices by changing the contact material behavior in a lateral structure. Two devices were fabricated by making perovskite micro-channel using capillary motion. Indium tin oxide (ITO) Schottky contact and copper contact with a linear characteristic were used as the electrode to form two separate lateral structures with the perovskite material. The devices were characterized by scanning electron microscope (SEM) imaging and energy dispersive X-Ray spectroscopy (EDS). The electrical and optical properties of the samples were measured by the Potentiostat. In both devices, the photocurrent increased with time. A non-capacitive currentvoltage hysteresis was observed which was independent of the contact behavior with the perovskite material. However, it depended on the biasing history and lighting condition. The nonsteady state part of the photoresponse was significantly changed over time. The magnified photoresponse was attributed to the light-induced ion drift at the perovskite/contact interfaces which lead to a bandgap modification. This study may help in better understanding of the nature of the ion migration in perovskite solar cells.