Energy transfer and wavelength tunable lasing of single perovskite alloy nanowire

Single perovskite alloy nanowire capable of emitting lasing broadly and continuously is highly desirable for the miniaturization and integration of all-photonic devices. However, due to the limitation of a soft and dynamic crystal lattice and the synthesized strategy, single perovskite nanowire with single-band lasing emission is mostly observed. Here, we propose a solid-solid anion-diffusion process to construct single CsPbCl3-3xBr3x perovskite alloy nanowire with a widely tunable bandgap from 2.41 to 2.82 eV and a regularly geometrical structure. We realized a broadly and continuously tunable nanolaser from 480 to 525 nm in single CsPbCl3-3xBr3x nanowire, as different spots along the length serve as a gain medium and microcavity simultaneously. The kinetics and atomic-scale mechanism of solid-solid anion diffusion were analyzed by a quantitative study and theoretical calculations, giving a small activation energy of halide migrations. The dynamics of carrier transportations revealed the energy transfer in single CsPbCl3-3xBr3x alloy nanowire, that's why broadly tunable lasers are difficult to realize in single isolated nanowire. Our work proposes a new strategy to construct single perovskite alloy nanowire for achieving a broadly and continuously tunable laser, clarifies the mechanism and kinetics of anion diffusion in perovskite alloy nanowires.