Band gap engineering of graphene–CdTe quantum dot hybrid nanostructures

Abstract

We report the results of our theoretical studies on the electronic structure of graphene–CdTe quantum dot (QD) hybrid nanostructures. We put emphasis on the possibility of engineering the electronic energy levels of hybrid systems either through the variation of the size of the CdTeQD or by controlling the H coverage of graphene. We also extend our study to see the effect of Se doping on the electronic energy levels of graphene–CdTeQD hybrid nanostructures. It is well known that for solar cell applications the composite system should have a type-II band alignment that hinders the recombination of charge carriers, thereby improving the photovoltaic performance. By analyzing the electronic energy levels of the composite systems we have shown that one can engineer the band gap of the system by controlling either the size of the QD or percentage of the hydrogen atoms on graphene to achieve the type-II band alignment. Based on the relative positions of the frontier energy levels we offer qualitative understanding of the dynamics of electron transfer from QDs to the graphene and also the dynamics of recombination of the charge carriers.