Electronic Properties of Bilayer Zigzag Graphene Nanoribbons: First Principles Study

Based on the density functional theory, we calculate the dependence of the band structures of bilayer zigzag-edged graphene nanoribbons (BZGNRs) upon ribbon width, interlayer distance and stacking styles. Unlike monolayer zigzag GNR, whose energy gap is always zero under different ribbon widths, the gap of BZGNR varies greatly with the ribbon width or the interlayer distance. The greatest gaps for AA-stacking and AB-stacking BZGNRs are about 0.22 eV and 0.12 eV, respectively, which implies that gap-tuning of AA-BZGNRs is more effective than that of AB-BZGNRs. These results present a way to tune the band structures of BZGNRs and also provide theoretical guidance for the fabrication of GNR-based piezoelectric devices.