Photoinduced Ions Migration to Brighten Perovskite Nanowires on Glass

Mixed‐halide perovskite nanostructures possess widely‐tunable optical and electronic properties that are desirable for applications in optics and optoelectronics, such as photodetectors, micro‐LEDs, photovoltaics and lasers. Photoinducing phase segregation often occur on these nanostructures with halide ions, e.g., iodide ions, migrating away from the original mixed‐halide crystal lattice, which impairs their photoluminescence (PL) properties and impedes the integrated applications. Herein, significant photoinduced PL enhancement is reported with a PL shift from green to red on the Br‐I halides‐containing perovskite nanowires (NWs). This is proposed to be caused by the formation of Br‐I mixed phase due to the migration and incorporation of iodide ions into the deficient‐rich CsPbBr 3 lattice within the NWs. It is demonstrated that this principle is general to regulate the PL on NWs with various halide compositions. Optoelectronic applications in waveguiding and short‐time optical storage are exploited experimentally. This work provides new insights into the photoinduced PL modulation, which would advance and expand the optoelectronic applications.