Size engineering optoelectronic features of C, Si and CSi hybrid diamond-shaped quantum dots

Based on the density functional theory and many-body ab initio calculations, we investigate the optoelectronic properties of diamond-shaped quantum dots based graphene, silicene and graphene–silicene hybrid. The HOMO–LUMO (H–L) energy gap, the exciton binding energy, the singlet–triplet energy splitting and the electron–hole overlap are all determined and discussed. Smaller nanostructures show high chemical stability and strong quantum confinement resulting in a significant increase in H–L gap and exciton binding energy. On the other hand, the larger configurations are reactive which implies characteristics favorable to possible electronic transport and conductivity. In addition, the typically strong splitting between singlet and triplet excitonic states and the big electron–hole overlap make these QDs emergent systems for nanomedicine applications.