A CXXXX American Chemical Society Energy Level Modification in Lead Sulfide Quantum Dot Thin Films through Ligand Exchange

olloidal quantum dots (QDs) possess a uniquely tunable set of electronic properties that has generated con-siderable interest in their use as active materials in solution-processed photovol-taics.1 Synthetic techniques allowing repro-ducible control of QD size enable the pre-paration of strongly confined lead sulfide (PbS) colloidal QDs with bandgaps ranging from 0.7 to 2.1 eV, spanning the ideal range for single- and multijunction photovoltaic device applications.2 In complement to the control over the QD bandgap afforded by modification of the nanocrystal size, the electronic properties of coupled colloida