Structural and Electronic Properties of Bare and Capped Cd33Se33 and Cd33Te33 Quantum Dots

We performed comparative DFT (B3LYP/ Lan12dz) studies of the structural and electronic properties of bare and NH3-, SCH3-, and OPH3-capped Cd33Se33 and Cd33Te33 quantum dots (QDs). The capping groups were chosen as simple models for capping ligands used broadly in experiments. We explored the effects of the capping ligands, coordinated to the QDs via N, S, and 0 atoms, on the stabilization/destabilization of the QD HOMO and LUMO energies, and on the HOMO/LUMO energy related quantities: vertical ionization potentials and electron affinities. The effects of solvents commonly used in experimental studies of capped Qps (water, toluene, and acetonitrile) on QD structures and electronic properties were investigated as well. Analysis of the bare and capped QD frontier orbital composition was performed using the projected density of states approach. We also studied Cd33Se33 and Cd33Te33 QDs capped with N(CH3)(3) and SCH2CO2H ligands.