Cto-graphene: A Two-Dimensional Graphene Allotrope with High Hole Mobility

Graphene allotropes with nonhexagonal carbon rings havehuge potentialin the application of field-effect transistors. However, two-dimensionalnonhexagonal graphene allotropes with an appropriate band gap anda high hole mobility are still rare. Here, a novel two-dimensionalgraphene allotrope, cto-graphene, consisting of triangular and octagonalcarbon rings was designed by using first-principles calculations.Cto-graphene is a metallic and anisotropic two-dimensional ultraplanargraphene allotrope with a band gap of 0.99 eV. The energy per atomof cto-graphene (-8.57 eV/atom) is much lower than that ofpenta-graphene and slightly larger than that of planar T-graphene,indicating that it is a metastable graphene allotrope. The calculatedhole mobilities are 7.3 x 10(4) and 1.3 x 10(4) cm(2) V-1 s(-1)along the armchair and zigzag directions, respectively. The carriermobility depends on the structural orientation. The hole mobilityof cto-graphene is better than those of some previously reported grapheneallotropes, such as C-568 and pentagraphyne. It is alsoan optical material, which corresponds to the absorption spectrumdiffusing in the visible region and a portion of the ultraviolet region.The exceptional carrier mobility and superior optical performancemake cto-graphene a potential candidate for future field-effect transistors,optical solar cells, and optoelectronic devices.

Automated summary

Through first-principles calculations, a novel two-dimensional graphene allotrope called cto-graphene was designed, which consists of triangular and octagonal carbon rings. Cto-graphene is a metallic and anisotropic graphene allotrope with a band gap of 0.99 eV. The calculated hole mobilities are 7.3 x 10(4) and 1.3 x 10(4) cm(2) V-1 s(-1) along the armchair and zigzag directions, respectively. With exceptional carrier mobility and superior optical performance, cto-graphene shows great potential for future field-effect transistors, optical solar cells, and optoelectronic devices.