from the conferences organized by TANGER Ltd.
Recently investigated colloidal quantum dots, constructed from chalcogenide materials became very attractive for researchers due to their applications in quantum dot solar cells. In this work the electron and heavy hole states in spherical and ellipsoidal CdSe/CdS colloidal core-shell quantum dot, which is wildly used in solar cells technologies, have been investigated theoretically in the frame of finite element method calculations. Usually CdSe/CdS core-shell quantum dots are type I heterostructures. We have determined the ranges of the sizes of the dot, for which type I - quasi type II transitions of the system can be observed, which means that the electron and the hole can be localizes in different parts of the considered core-shell structure. This effect can change the optical characteristics of the dot. Here we have considered also interband optical transitions between heavy hole ground state to various electron states. The dependencies of optical transition intensities on sizes of quantum dot have been obtained. The effect of external electric filed on electron and hole states and on transition intensities also have been investigated. We have demonstrated that for spherical quantum dots the interband transition energies are changing with the increase of electric field strength, but the intensity of transitions remains almost constant, which shows the stability of considered system from point of view of their usage in solar cell technologies. For the ellipsoidal dots we observed intensity changes in absorption spectrum during the increase of electric field.
Keywords: Quantum dots, electron and hole states, optical transitions© This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.