Solid-state ionic rectification in perovskite nanowire heterostructures

Halide perovskites have attracted increasing research attention regarding their outstanding optoelectronic applications. Owing to its low activation energy, ion migration is implicated in the long-term stability and many unusual transport behaviors of halide perovskite devices. However, precise control of the ionic transport in halide perovskite crystals remains challenging. Here we visualized and quantified the electric-field-induced halide ion migration in an axial CsPbBr$_3$-CsPbCl$_3$ nanowire heterostructure and demonstrated a solid-state ionic rectification, which is due to the non-uniform distribution of the ionic vacancies in the nanowire that results from a competition between electrical screening and their creation and destruction at the electrode interface. The asymmetric heterostructure characteristics add an additional knob to the ion-movement manipulation in the design of advanced ionic circuits with halide perovskites as building blocks.