Ligand-mediated interaction in a dispersion of lead-halide perovskite nanocubes: implications on directed structures in equilibrium

Abstract

Motivated by the experimental reports on the formation of ordered nano-structures of ligand-dressed Cs–Pb-halide nanoparticles, employing a combination of density functional theory, molecular dynamics, metadynamics and Monte Carlo simulation techniques, we investigate the microscopic mechanism driving such structures. Our rigorous studies focused on CsPbBr₃ nanoparticles take into account the realistic situation in terms of different synthesis conditions. In particular, Br vacancies, the neutral and charged forms of ligands, and the presence of a variety of solvents of different polarities are considered. Our work establishes the crucial role of electrostatics driving preferential matching of facets paving the way to the formation of directed structures. In particular, the importance of Br vacancies, the polarity of solvents, and the preference for slightly alkaline synthesis conditions are highlighted. The microscopic understanding thus provided will be useful in designing targeted nano-structures.