Chelating Ligand Surface Functionalization for Ultrastable Efficient Blue Emissive Nanoplatelets

Abstract

Surface ligand coordination chemistry is vital for the growth and stability of nanocrystals, particularly perovskite nanoplatelets (NPLs). Yet, the inherent proton exchange between conventional capping molecules introduces an unstable surface, consistently leading to diminished performance. Here, a sole chelating ligand capping method is proposed for synthesizing anisotropic CsPbBr₃ NPLs, which serve as the model system due to their significant appeal for blue light-emitting applications. A chelating ligand (CTE) is designed via a straightforward solution-based amidation reaction between oleylamine and ethylenediaminetetraacetic acid; acting as the sole surfactant, CTE strongly coordinates with the Pb²⁺ precursor, directly facilitating the formation of (PbBr₆)^4– octahedrons and circumventing the protonation/deprotonation process. This strategy allows further post-treatment with 4-phenylbutylammonium bromide while maintaining NPLs’ emission characteristics and anisotropic morphology. As a result, pure blue-emitting CsPbBr₃ NPLs with a PLQY of 97% can be achieved, and their photophysical and structural characteristics remain stable over 30 days under ambient conditions.