Electronic structures of the CdSe/CdS core-shell nanorods.

The electronic structures of the CdSe/CdS core-shell nanorods are systemically investigated by large-scale first-principles quality calculations. The effects of band alignment, quantum confinement, piezoelectric field, and dipole moments are analyzed and delineated by comparing the results of systems with or without some of these attributes. We found complicated interplays between these effects in determining the nanorod band gap and electron hole wave function localizations. The hole wave function is found to be localized inside the CdSe core, while the electron wave function is localized in the CdS shell, with its distance to the CdSe core depending on the surface passivation. The permanent dipole moment induced by different surface passivations can change the electron hole separation, while the piezoelectric effect plays a relatively minor role. Finally, we demonstrate that it is straightforward to manipulate the nanorod electronic structure by changing its CdSe core position.