Multi-color perovskite nanowire lasers through kinetically controlled solution growth followed by gas-phase halide exchange

Integration of multi-color semiconductor nanowire lasers (NWLs) on a silicon substrate is a very challenging task, owing to both the material lattice mismatch and the incompatible growth temperature. Recently, organic-inorganic perovskite (CH₃NH₃PbX₃; X = Cl, Br, I) NWLs have been developed using a surface-initiated solution-growth method, which, however, requires post-synthesis transfer of nanowires from a growth substrate to a silicon wafer for device fabrication. Herein, we report multi-color perovskite nanowire lasers on arbitrary substrates (silicon or quartz substrates) through kinetically controlled growth followed by gas-phase halide exchange. First, we developed an antisolvent-vapor-diffusion induced crystallization method to kinetically direct the growth of CH₃NH₃PbCl₃ towards single-crystal nanowires rather than the crystal habit of plate-like morphology. The ratio of nanowires to square microplates was adjusted to be as high as 97% : 3%. Then we introduced a gas-phase halide-anion-exchange reaction to convert chloride nanowires into bromide and iodide ones upon exposure to the vapor of HX (X = Br, I), while preserving both the high crystallinity and the nanowire morphology. Upon optical excitation, Fabry-Perot lasing around 550 and 785 nm occurs from CH₃NH₃PbBr₃ and CH₃NH₃PbI₃ nanowires with an onset of 9.8 and 9.2 μJ cm^-2, respectively, with a maximum quality factor of 1260.