Selective Growthof FAPbBr₃ Nanocrystalswith Precisely Tailored Optical Properties for Advanced OptoelectronicApplications

Understanding the evolution of semiconductor nanocrystals (NCs) during their colloidal synthesis is essential for achieving improved control over their physical and chemical properties. The fast reaction kinetics and concurrent nucleation and growth periods of lead halide perovskite NCs pose significant challenges in controlling the synthesis. Here, we present the room-temperature colloidal synthesis of FAPbBr₃ NCs with physically decoupled nucleation and growth periods by using the common oleylamine and oleic acid ligand pair for lead halide perovskite NCs. Importantly, in this method, the nucleation and growth phases are entirely decoupled by halting the reaction at a metastable state, where the FAPbBr₃ nuclei are formed. Subsequently, preformed FAPbBr₃ nuclei are selectively grown by increasing supersaturation. This is achieved by reducing the monomer solubility through the injection of oleic acid into the solution. Notably, two-dimensional perovskite nanostructures form as intermediate products during the synthesis. Furthermore, the size of the FAPbBr₃ NCs is tuned from 5.7 to 13.5 nm by controlling the injected oleic acid amount. Photoluminescence quantum yields of the FAPbBr₃ perovskite NCs synthesized by using this method reached up to 95%. These findings demonstrate a robust strategy for the controlled synthesis of FAPbBr₃ perovskite NCs, providing precisely tailored optical properties for advanced applications such as solar cells, photodetectors, and light-emitting diodes.