Dual-Site Passivation for Bright and Stable Blue-emitting CsPbBr₃ Nanoplatelets

Blue-emitting perovskite nanocrystals (NCs) are important components of high-definition display device, but their instability to light and moisture severely hinders the commercial application. Here, a dual-site passivation strategy is proposed and the halogen-halogen bond to surface capping molecules is applied. The bi-functional molecule with a fluorine group and carboxyl group on the phenyl ring, would form a shell-like molecular structure covering the nanocrystal surface at halogen and lead site via halogen-halogen bond and coordination effect, respectively. Considering the binding strength and acid dissociation constant of several fluoro acids, the optimal optical properties and film stability confirm the para-fluorobenzoic acid molecule provides the most effective protection for initial perovskite products account for their stronger anchoring affinity and more comprehensive surface coverage. Consequently, this work sheds light on the molecular functionality and configuration are crucial for surface properties of perovskite NCs.