First-Principles Study of Twin 4–8 Graphene in Carbon and Boron Nitride Nanostructures: Implications for Mechanical and Optoelectronic Nanodevices

A nanosheet with the name twin 4–8 graphene composed of 4- and 8-membered rings is suggested. The structural, mechanical, electronic, and optical properties of carbon (C) twin 4–8 graphene and twin 4–8 graphene-like boron nitride (BN) sheets are studied by using density functional theory. These sheets exhibit dynamic stability as well as good energetic and thermal stability, especially at room temperature. The C and BN twin graphene sheets are softer and more prone to deformation compared to graphene. Thus, they can be used, particularly when softer materials are required rather than graphene. The C twin 4–8 graphene exhibits semiconductor properties, while the BN twin 4–8 graphene is an indirect band gap insulator. An anisotropic behavior is observed for the optical properties of the sheets. These sheets could store energy and filter out harmful ultraviolet radiation due to their high dielectric constants and optical absorption, particularly in the ultraviolet region. These nanosheets are well suited for use in nanomechanics and nano-optoelectronics due to their favorable mechanical, electronic, and optical characteristics.