Optical properties of CdSe/ZnTe type II core shell nanostructures

CdSe/ZnTe core shell nanoparticles present original optical and electronic properties because of the spatial separation of electrons and holes caused by the type-II alignment of energy states. Such structure permits access to optical transition energies that are not limited to band gap energies and hence can provide narrow emission spectra and a broad absorption range. In this study, we have investigated the nanostructure size effect on the electronic and optical properties of type II CdSe/ZnTe core shell quantum dot. The carriers wave functions and eigenenergies have been achieved by solving the Schrlidinger equation, in the framework of the effective-mass envelope-function theory. The impact of core radius R-1 and the shell radius R-2 on electron and hole energies has been studied for the fundamental and the first excited states. The Coulomb interaction has been calculated and the exciton energy has been deduced. Then, the absorption coefficient has been examined by means of the compact density matrix, the pick of the absorption increases with R-2 and is red shifted. Good excitonic radiative life time in this type II core shell quantum dot has been obtained. The photoluminescence from the CdSe/ZnTe core shell can be adjusted to covers practically all the visible wavelength, which is very important for biomedical and photovoltaics. (C) 2017 Elsevier GmbH. All rights reserved.