Slowing Down for Growth Mechanism and Speeding Up for Performance Optimization Based on Single Ligand Passivated CsPbBr_3 Nanoplatelets

摘要

Quasi 2D metal halide perovskite nanoplatelets (NPls), as a kind of importantmaterials to achieve pure blue emission, attract significant attention in pursuitof high gamut trichromatic display. However, in-depth study on the specificgrowth processes of NPls is still lacking due to the ultrafast reaction rate.Here, a single ligand passivation strategy to investigate the concrete growthmechanism of NPls is proposed, in which the PbBr_x(OAm)_y clusters play apivotal template role in guiding the growth of crystals, and the final productswith 3-monolayer (3ML) are grown from the intermediate 2ML NPls instead ofbeing synthesized directly. Based on the new discovery about growth mechanismof NPls, the reaction time has been shortened from hours to seconds byintroducing hydrobromic acid and ethanol. The ethanol used here is consideredas an accelerator for the transition from 2ML to 3ML NPls rather thanan initiator for nucleation of products, which is different from the generallyaccepted viewpoints. With further passivation of hydrobromic acid, the synthesized3ML NPls show 462 nm emission with quantum yield of 97.04% andgreat photostability. The novel growth model proposed in this work will providea paradigm for future design and optimization of new synthesis schemes.