  Silicon-based two-dimensional (2D) materials, including well-known silicene,
have garnered considerable attention due to their potential in advanced
electronic and optoelectronic applications. Here, we introduce a novel 2D
silicon variant, pentahexoctite silicon (PH-Si), inspired by the unique
structural attributes of pentahexoctite carbon. By using state-of-the-art
density functional theory (DFT) calculations and ab initio molecular dynamics
(AIMD) simulations, we investigated the fundamental optoelectronic traits of
PH-Si. Our findings unveil that PH-Si boasts promising electronic properties
characterized by anisotropic conductance and metallic behavior along specific
directions. We also examine its structural and dynamic stability through phonon
calculations and AIMD simulations. PH-Si structural stability was also
confirmed by its low formation energy of -3.62 eV. The material exhibits
substantial optical absorption in visible (Vis) and ultraviolet (UV) spectral
regions, positioning it as a potential Vis-UV detector and absorber.
Additionally, we assess its crucial mechanical attributes, encompassing elastic
stiffness constants, Young's modulus (ranging from 5 to 40 GPa), and a Poisson
ratio of 0.8, collectively offering valuable insights into its mechanical
performance.
