Facet-induced coordination competition for highly ordered CsPbBr₃ nanoplatelets with strong polarized emission

Controllable anisotropic growth of perovskite nanocrystals (NCs) is challenging since it is difficult to separate the nucleation and growth processes. Here, a two-step nucleation strategy is proposed to control the binding interaction between surface ligands and NCs, resulting in facet-induced coordination competition. Oleic acid as surface activated ligand leads to the formation of defective lead bromine octahedron, and the binding interaction between 4-dodecylbenzenesulfonic acid and lead atoms promotes the formation of two kinds of binding interactions. Based on this strategy, the anisotropic growth of CsPbBr₃ nanoplatelet (NPLs) with adjusted length from 11.4 to 24 nm, and the evolution of NPLs from stacked to tongue-shaped have been realized. Elemental line scan reveals the sulfur atoms mainly distribute at the edge of NPLs. Furthermore, binding energy calculation and experimental results illustrate the coordination competition of different binding interaction on specific facets induces the anisotropic growth of NPLs. Importantly, strong emission anisotropy of highly ordered NPLs with polarization ratio up to 0.58 is illustrated. This work not only deepens our understanding of the controllable synthesis of perovskite NCs, but also provides a reference for the regulation of light emitting diode and soler cells.