Electronic Properties of Homo- and Heterobilayer Graphyne: The Idea of a Nanocapacitor

We have investigated the capacitive behavior of bilayer graphyne and its boron nitride derivatives by first-principles simulations based on density functional theory, including van der Waals interactions. Our predicted energy and charge-storing capacities are greater than those predicted for nanocapacitors based on graphene and hexagonal boron nitride. In the most stable configuration, the two layers are stacked on top of each other, just as in bulk graphyne. The stacking arrangement has a strong effect on the electronic properties of the system: the stable stacking configurations for the graphyne systems are semiconductors with direct band gaps of 0.38 and 0.50 eV. Substitutional boron-nitrogen doping provides a way to tune the band gap of the system. The band gap generally increases in the presence of the dopants, but the value of the band gap depends on the substitution sites. This suggests that controlled boron nitride doping of graphyne could be a useful and flexible method for building nanoscale electronic and optoelectronic devices.