Controlling the electronic energy levels of ZnO quantum dots using mixed capping ligands

Abstract

The surface passivation of nanocrystals with mixed ligands is an important way to enhance the performance of quantum dot based optoelectronic devices through tuning the electronic energy levels. By attaching two or three different ligands on the surface of a single nanoparticle, one can induce electric fields large enough to significantly alter the electronic and optoelectronic properties of the nanocrystals. By using the self-consistent-charge density-functional tight-binding (SCC-DFTB) method we demonstrate the tuning of the electronic energy levels of ZnO quantum dots (QDs) through exchanging the surface capping ligands. The tuning of the energy levels is largely dependent on the surface linking groups as well as on the ratio of the different passivated molecules attached on to the surface of the QDs.