Theoretical study of ligand and solvent effects on optical properties and stabilities of CdSe nanoclusters

Abstract

It is of paramount importance to understand the ligand, solvent and temperature effects on the structure, growth and properties of quantum dot (QD) nanoclusters. In this work, using molecular models, we investigated the organic ligand effect on the geometric and electronic structure, stabilities and absorption spectra of CdnSen (n = 3, 6, 13) clusters by means of DFT and TDDFT calculations. The results indicate that the ligand can saturate dangling bonds on the cluster surface, which results in the charge redistribution, the opening of the HOMO–LUMO gap, stabilization of the cluster and a remarkable blue shift in the absorption peaks. When considering the solvent effect, the absorption peaks of clusters were found to blue shift further and in good agreement with the experimental results. The Cd13Se13 cluster displayed various stabilities in different states: weak polar ligands, low temperature and a strong polar agent are favorable for bulk-like Cd13Se13, whereas the reverse is favorable for cage-like Cd13Se13.