Ligand-Induced Changes in the Characteristic Size-Dependent Electronic Energies of CdSe Nanocrystals

This work explores the electronic energy of CdSe nanoparticles as a function of nanoparticle (NP) size and capping ligand. Differential pulse voltammetry was used to determine the valence band edge of CdSe NPs that are capped with three different ligands (aniline, thiophenol, and phenylphosphonic acid), and the experimental values are compared with DFT calculations. These results show how the energy position and the size-dependent behavior of the energy bands of CdSe can be modulated by the chemical nature of the capping ligand. The computations underscore how the nature of the highest lying filled states of the nanoparticle can change with ligand type and how this can explain differences between previously reported size-dependent data on similar systems. The findings show that both the ligand and quantum confinement effects should be accounted for in modeling size-dependent effects for different NP ligand systems.