C 2015 American Chemical Society Counterion-Mediated Ligand Exchange for PbS Colloidal

n the past decade, colloidal quantumdot (CQDs) solids have attracted much inter-est for their promising applicability in solution-processed transistors, solar cells, and other optoelectronic devices.14 These materials are built up by forcing the indivi-dual quantum dots into proximity with each other by replacing the long capping ligands with shorter ones. This ligand exchange (LE) simultaneously affects the electronic cou-plingand the surface composition, altogether determining the electronic properties of the material; hence, a detailed understanding of the nature of the ligands, the LE process, and careful design of the procedure is required