Stable CsPbBr3 Nanoclusters Feature a Disk-like Shape and aDistorted Orthorhombic Structure

CsPbBr3nanoclusters have been synthesized byseveral groups and mostly employed as single-source precursors forthe synthesis of anisotropic perovskite nanostructures or perov-skite-based heterostructures. Yet, a detailed characterization ofsuch clusters is still lacking due to their high instability. In thiswork, we were able to stabilize CsPbBr3nanoclusters by carefullyselecting ad hoc ligands (benzoic acid together with oleylamine) topassivate their surface. The clusters have a narrow absorption peakat 400 nm, a band-edge emission peaked at 410 nm at roomtemperature, and their composition is identified as CsPbBr2.3.Synchrotron X-ray pair distribution function measurementsindicate that the clusters exhibit a disk-like shape with a thicknesssmaller than 2 nm and a diameter of 13 nm, and their crystalstructure is a highly distorted orthorhombic CsPbBr3. Based on small- and wide-angle X-ray scattering analyses, the clusters tend toform a two-dimensional (2D) hexagonal packing with a short-range order and a lamellar packing with a long-range order.