Control of Photoinduced Ligand Detachment from Quantum Dot Surfaces Using Nanocrystal Architecture.

We investigated the influence that nanocrystal architecture has on the extent to which colloidal quantum dots undergo photoinduced ligand detachment. We took advantage of the ability of electrons to delocalize throughout both the core and shell of CdSe/CdS core/shell nanostructures to modulate the surface electron density of a series of colloidal quantum dots. Then, we used infrared transient absorption spectroscopy to monitor the ligand photodetachment process on the surfaces of quantum dots with varying shell thicknesses. CdSe core-only and CdSe/CdS quantum dots with thin CdS shells exhibit little photoinduced ligand detachment in the solid film environment. In contrast, CdSe/CdS core/shell nanostructures with thicker CdS shells that localize surface electron density in their excited states undergo extensive ligand photodetachment even in solid films. Our findings suggest that core/shell architectures with tuned shell thicknesses could enhance the extent of photoinduced ligand detachment and could increase the photocatalytic activity of colloidal quantum dots.