Inorganic Ligand Triggered Transformation from Cs₄PbBr₆ Nanocrystals to Blue-Emitting CsPbBr₃ Nanoplatelets

Blue-emitting perovskite nanoplates (NPLs) have been widely investigated for display application. However, the traditional synthetic techniques for high-quality perovskite NPLs are still limited due to their rapid crystallization rate. Here, we developed an inorganic ligand (NOBF₄) mediated transformation strategy to obtain blue-emitting CsPbBr₃ NPLs. The transformation process was based on the dissolution–recrystallization in a nonpolar environment, involving the dissociation of Cs₄PbBr₆ NCs to Pb ions, which then reformed PbBr₆^4– octahedrons and finally formed two monolayer NPLs with pure blue-emission (line width ∼12 nm). The whole transformation process was clearly detected, and during the process the reorganization of organic ligands tuned by NO⁺ played a crucial role in the formation of NPLs. This work provides an effective strategy for obtaining pure blue-emitting NPLs and builds a platform for exploring the mechanism for the anisotropic growth of perovskite crystals.