▎ 摘　　要

Herein, we have explored theoretically the effects of surface modification (fluorination) on electronic and optical properties of graphene/h-BN heterobilayer. Graphene/h-BN heterobilayer is predicted to have a semimetal characteristics. After fluorination, the heterobilayer becomes a diamane-like configuration by the interfacial atom bonding. The fluorinated graphene/h-BN (C2BNF2) has been assessed to be energetically, dynamically, and thermally stable by negative cohesive/formation energy, absence of soft mode, and intact structure at high temperature. The electronic property analysis shows that the C2BNF2 is a wide-gap direct semiconductor. Considering the photogenerated electron and hole coupling, the optical absorption spectrum of the C2BNF2 is dominated by discrete excitonic peaks, in which a large exciton binding energy beyond 1 eV is observed. The electronic and optical properties are very sensitive to the interfacial atom bonding (i.e., C-B or C-N bonding). Compared with the interfacial C-N bonding configuration, the C-B bonding configuration possesses an enhanced optical absorption for the ultraviolet light. Our results reveal that the interfacial sp(3) atom bonding induced by fluorinating graphene/h-BN heterobilayer could play an important role in tuning its optoelectronic performance.