First-principles study of structural, elastic and electronic properties of naphyne and naphdiyne.

The structural, elastic and electronic properties of 2D naphyne and naphdiyne sheets, which consist of naphthyl rings and acetylenic linkages, are investigated using first-principles calculations. Both naphyne and naphdiyne belong to the orthorhombic lattice family and exhibit the Cmmm plane group. The structural stability of naphyne and naphdiyne are comparable to those of experimentally synthesized graphdiyne and graphtetrayne, respectively. The increase of acetylenic linkages provides naphdiyne with a larger pore size, a lower planar packing density and a lower in-plane stiffness than naphyne. Naphyne is found to be an indirect semiconductor with a band gap of 0.273 eV, while naphdiyne has no band gap and has a Dirac point. The band gaps of naphyne and naphdiyne are found to be modified by applied strain in the elastic range. These facts make naphyne and naphdiyne potential candidates for a wide variety of membrane separations and for fabrication of soft and strain-tunable nanoelectronic devices.