Carbon, 195, 154-164 (2022) [pdf]

Four-Penta-Graphenes: Novel Two-dimensional Fenestrane-based Auxetic Nanocarbon Allotropes for Nanoelectronics and Optoelectronics

Mehmet Emin Kilic, Kwang-Ryeol Lee

The great success of graphene has encouraged tremendous interest in searching for new two-dimensional (2D) carbon allotropes. Based on first principles calculations, we proposed new 2D carbon allotropes, conceptually obtained from the assembly of fenestrane molecule unit, named as fourpentagraphenes (fPG). The fPG monolayers are energetically more favorable than pentagraphene and show excellent stability veri ed from the dynamical, thermal, and mechanical aspects. They exhibit exotic mechanical properties including anisotropic in-plane sti ness and auxetic behavior with sign-tunable Poisson's ratio. Their electronic properties are diverse, ranging from narrow bandgap semiconductors to metallic. The fPG semiconductors exhibit a tunable band gap by strain engineering. Besides, an indirect-to-direct band gap transition emerges with compressive strain while a semiconductor to metal transformation can be observed with tensile strain. The anisotropic effective mass of carries with high mobility make them promising for nanoelectronics. Using many body GW_o+BSE approximations, we reveal that the fPG semiconductors exhibit strong excitonic effects with distinct optical absorption peaks in the visible light region. These remarkable optical properties make them also promising devices for optoelectronics.