Quantitative Correlation between Ligand Shell Composition and Photoluminescence in CsPbBr3 Nanocrystals with Mixed Didodecyldimethylammonium Bromide and Oleic Acid Ligands

Abstract

The optoelectronic properties of halide perovskite nanocrystals are strongly determined by their surface chemistry; therefore, their improvement hinges on a detailed understanding and control of their surface properties. Given that most recombination occurs at the surface, the ligand-induced reconstruction of the lattice can remove or add trapping sites that increase or decrease the emission quantum yield. Great strides have been made in elucidating the binding sites of different ligands along with their modification of the energy levels. However, quantitative measurement has not been fully achieved. In this work, we present a quantitative correlation between the composition of a mixed-ligand shell containing oleic acid (OA) and didodecyldimethylammonium bromide (DDAB) and the photoluminescence of CsPbBr₃. We identify three different regions corresponding to three different ligand shell compositions with their associated recombination dynamics and find that an added concentration of 0.5 mM of DDAB results in a surface with both Pb and Br defects maximally passivated by the ligand shell.