Control of oleylamine to perovskite ratio in synthesis of MAPbBr3 nanoparticles

Highlights: • The nanocrystals were synthesized by direct injection of precursors into toluene. • The oleylamine to perovskite ratio (OPR) controls morphology and optical properties. • The size of unit cells of CH₃NH₃PbBr₃ nanocrystals can be varied by increasing OPR. • Possible formation mechanism for nanocrystals by different OPR values was suggested. Methylammonium lead bromide (CH₃NH₃PbBr₃) nanocrystals have great potentials for lighting and display applications. Previously we synthesized CH₃NH₃PbBr₃ nanocrystals using oleylamine as capping molecule and found that by increasing the oleylamine to CH₃NH₃PbBr₃ perovskite ratio (OPR), the photoluminescence wavelengths and morphology of CH₃NH₃PbBr₃ nanocrystals could be varied from 530 nm (green) platelets to 460 nm (blue) particles. Here we modified the synthesis to direct injection of precursors into toluene and found that increasing OPR not only changes the wavelength and morphology of nanocrystals but also the size of the unit cells.