Multicolored Mixed-Organic-Cation Perovskite Quantum Dots (FAxMA1-xPbX3, X = Br and I) for White Light-Emitting Diodes

Organometal halide perovskites (such as CH3NH3PbX3, X = Cl, Br, I) have received enormous interest due to their strikingly photoelectric properties. Here we develop a facile ligand-assisted reprecipitation method to synthesize NH2CH = NH2PbX3 (NH2CH = NH2+, FA; X = Br and I) perovskite quantum dots (QDs) at room temperature. The FAPbX-3 perovskite QDs with uniform monodispersity (sized 4-7 nm) display relatively high photoluminescence quantum yields (PLQYs) of 60-75%. Through manipulating the mixed-organic-cation reactions, we achieve a series of multicolored perovskite QDs with continuously controllable emission wavelengths from 460 to 565 nm. Furthermore, we discuss the influence of ligands (oleic acid and n-octylamine) on PL properties and stabilities of perovskite QDs. Finally, we have successfully designed a white LED via compositing perovskite QDs and poly(methyl methacrylate) (PMMA), which presents a high color rendering index. Considering those remarkable achievements, we believe our work will have great potential to meet various optoelectronic applications.