(a) Schematics of ion drift in perovskite during positive poling (top) and negative poling (bottom). The accumulated ions in the perovskite near the electrodes induce p- and n-doping. εext represents an external electric field. (b) Snapshots of the in situ recorded video with the poled lateral structure device, showing the modified perovskite material near the anode side. The inset shows the setup used for the in situ monitoring of the poling process. Reproduced from Nat. Mater., 2015, 14, 193 with permission.23