Graphane/fully hydrogenated h-BN bilayer: Marvellous dihydrogen bonding and effective band structure engineering

In this work, density functional theory (DFT) computations with van der Waals (vdW) corrections were performed to investigate the dihydrogen bondings and their effects on the electronic band structures of graphane/fully hydrogenated h-BN (G/fHBN) bilayers. The type of dihydrogen bonding (C-H···H-B or C-H···H-N) defined the conformation and stability of G/fHBN bilayer, leads to significant band structure modifications of the nanosystems. Interestingly, the bilayer combined by C-H···H-B bilayers has an energy gap (~1.2 eV) much lower than those of individual building blocks graphane and fHBN. Especially, changing the direction and strength of external electric field can effectively tune the band gap of G/fHBN bilayer, and correspondingly cause a semiconductor-metal transition. These findings offer new opportunities for developing electronic and opto-electronic devices based on G/fHBN bilayer, and inspire more endeavor in the usage of weak interactions for band structure engineering.