Direct Imaging of Current‐Induced Transformation of a Perovskite/Electrode Interface

Abstract Formamidinium‐lead‐iodide (FAPbI 3 ) perovskite films are subjected to a long‐term action of the constant electrical current in the dark, using planar vacuum‐deposited gold electrodes. The current‐induced transformation is monitored by the time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) mapping complemented by microscopic, spectroscopic methods, and X‐ray diffraction. The migration of chemical species inside the lateral interelectrode gap is clearly visualized by ToF‐SIMS. Those species correspond to both electrode material and perovskite itself, so that the perovskite/electrode interface becomes disrupted. As a result, the interelectrode gap shrinks, which is reflected in the surface images.