Controlling the Surface Morphology of Strongly Confined CsPbBr3 Perovskite Quantum Dots.

Understanding the relationship between the structural and optical properties of lead halide perovskite quantum dots (QDs) requires precise control over their composition, size, surface passivation, and morphology. Although significant progress has been made in tuning the composition and size of perovskite QDs, less attention has been given to controlling their surface morphology, especially when the QDs are size-confined. Here, we present a synthesis of monodisperse, quantum-confined CsPbBr3 QDs with carefully controlled surface morphology. The exposure of surface facets is regulated by annealing the QDs with facet-selective dicationic ligands, which are designed to match the spacing of Cs+ vacancies on specific facets. Our QDs remain morphologically stable during purification and can self-assemble via drop-casting. By monitoring the circularity indices of QDs, we reveal that the evolution of surface facet exposure during annealing is driven thermodynamically. Our straightforward synthesis approach offers an additional degree of tuning freedom for perovskite QDs.