Graphane/Fluorographene Bilayer: Considerable C–H···F–C Hydrogen Bonding and Effective Band Structure Engineering

Systematic density functional theory (DFT) computations revealed the existence of considerable C–H···F–C bonding between the experimentally realized graphane and fluorographene layers. The unique C–H···F–C bonds define the conformation of graphane/fluorographene (G/FG) bilayer and contribute to its stability. Interestingly, G/FG bilayer has an energy gap (0.5 eV) much lower than those of individual graphane and fluorographene. The binding strength of G/FG bilayer can be significantly enhanced by applying appropriate external electric field (E-field). Especially, changing the direction and strength of E-field can effectively modulate the energy gap of G/FG bilayer, and correspondingly causes a semiconductor–metal transition. These findings open new opportunities in fabricating new electronics and opto-electronics devices based on G/FG bilayer, and call for more efforts in using weak interactions for band structure engineering