Thickness Control and Aggregation Inhibition Achieved by Ammonium Bromide-Modified Tetraphenylethylene for Stable CH₃NH₃PbBr₃ Nanoplates

Deep blue-emitting perovskite nanoplates have become potential luminous materials. However, the photoluminescence emission and stability of the perovskite platelets are considerably dependent on the thickness and aggregation state. In this study, the ratio of the CH 3 NH 3 + (MA + ) cations and ammonium bromide-modified tetraphenylethylene (TPE) was tuned to effectually control the thickness and consequently the photoluminescence and aggregation state of the MAPbBr 3 nanoplates. Specifically, the content of TPE in the precursor suspension was increased and the thickness of the produced nanoplatelets was reduced, bringing about the enhanced quantum size effect. Moreover, the TPE with a large steric resistance group stuck outward and restrained nanoplate aggregation in that dimension, inducing the formation of three-layer MAPbBr 3 -TPE nanoplates. The hydrogen bond and electrostatic interaction were formed between TPE and MAPbBr 3, contributing to preventing phase segregation and facilitating an effective energy transfer. Furthermore, the stability of MAPbBr 3 -TPE was significantly strengthened by water exposure, light irradiation, and a moderate temperature. Optical anticounterfeiting labels were prepared through the different stimulus responses of the synthesized MAPbBr 3 -TPE in the external environment for encryption and decryption of information. This study lays a foundation for exploring the stability of perovskite nanoplates, anticounterfeiting, and other applications in advanced optical smart technologies.