Computational Study of the Excitation Energies of CdSe Nanoparticles With Defects

Defects in CdSe nanoparticles (NPs) have been studied within the framework of density functional theory (DFT) and time dependent DFT. Both vacancies and substitutional defects were examined and their energy levels as well as their excitations were calculated. The energy gap of the NPs is significantly affected and reduced upon the introduction of Se vacancies, substitution of Cd with either Al, Ga, In, and substitution of Se with either Cl, or Br, or I. This leads to excitations with significantly lower energies compared to chemically and phase pure NPs in a wide range of the visible spectrum. Such derived CdSe NPs may be used in solar cells and biosensing applications.