Surface passivation of quantum dots (QDs) by various molecules plays an important role in photophysics of these nanomaterials. Using Density Functional Theory and Time Dependent DFT, we investigate ground and excited state properties of PbSe, CdSe and ZnO QDs passivated by phosphine, phosphine oxide, and hydrazine ligands; and Ru(II)-bipyridine complexes. Absorption spectra of the bare or partially ligated QDs demonstrate the lowest energy transitions with weak intensities, whereas fully passivated QDs have brighter blue-shifted transitions. Independent on their number, ligands do not introduce any electronic states to the bandgap of QDs, but appear deep inside in the valance and conduction bands of QDs. In contrast, Ru(II)-complex introduces unoccupied orbitals to the edge of the conduction band, while occupied orbitals are deep inside in the valance band of QDs. Such alignment of the electronic states suggests that the hole transfer from the photoexcited QD to the complex is unfavorable.

Effect of surface ligands and functionalization groups on photophysical properties of quantum dots

246th National Meeting (2013)

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