Ligand Induced Shape Control of Cesium Lead Bromide Nanocrystals by Post Synthetic Treatments

All-inorganic lead halide perovskite materials have attracted significant attention in the context of photovoltaic and optoelectronic applications, and recently, efforts have been devoted to the fabrication of colloidally... [ view full abstract ]

All-inorganic lead halide perovskite materials have attracted significant attention in the context of photovoltaic and optoelectronic applications, and recently, efforts have been devoted to the fabrication of colloidally stable versions of these materials. Cesium Lead Halide Bromide (CsPbBr₃) colloidal nanocrystals (NCs), in particular, exhibit bright, size and shape-tunable photoluminescence in the blue-green region of the visible spectrum, that is usually not easily accessible with conventional quantum dots. It is worth to note that surfactants assist the shape and size regulation during the synthetic step, provide the better stability and help to maintain the optical properties of the final colloidal forms, but the role of  ligands in post-synthetic treatments at room temperature is still a critical issue towards the application of this class of material for devices fabrication. The ionic nature of the CsPbBr₃ NCs and dynamic interaction of the ligands with the colloidal NC surface suggest a crucial role of surface chemistry of the as prepared NCs. In this regards this work investigates the shape regulation, structural changes and, thus modification of the optical properties, of as synthesized CsPbBr₃ NCs induced by post synthetic ligand treatments,based on addition of freshly oleylamine and oleic acid. The morphological, optical and structural characterization will shed light  on the colloidal stability of this appealing new class of material, and also predict its transformation and properties in multicomponent complex systems for optoelectronic device fabrication.