Fig. 2: The in-situ ToF-SIMS investigation of ion migration in perovskites under applied electric field.

Pb-ion distribution of perovskite film surface in (a, b) control and (e, f) 1-BP perovskite films; I-ion distribution of perovskite film surface in (c, d) control and (g, h) 1-BP perovskite films.