Ligand-controlled formation and photoluminescence properties of CH₃NH₃PbBr₃ nanocubes and nanowires

Light-emitting halide perovskites are currently emerging as promising solution-processed materials for optoelectronic applications, and correlations between their physical properties and morphologies are important drivers to guide material and device optimization. There is still a lack of precise control of the morphology in colloidal perovskite materials, and in the related studies of their shape-dependent optical properties. Capitalizing on our previous works on the ligand-assisted reprecipitation synthesis of colloidal perovskite nanocrystals, we have addressed the role of key experimental parameters in determining the degree of supersaturation that drives the crystallization of CH₃NH₃PbBr₃ precursors. By adjusting the amount of ligands, we fabricated single crystalline CH₃NH₃PbBr₃ nanocubes (size: ≈500 nm) and nanowires (length: 2–4.5 μm, width: ≈100 nm), and conducted steady-state, time-resolved, excitation power and temperature-dependent photoluminescence measurements to investigate their shape-dependent photoluminescence properties.