Among the reported two-dimensional silicon materials, only hexagonal and kagome-like silicene have been reported experimentally. Thus, designing such materials with another strategy is desirable. Based on the experimentally synthesized pentagonal silicon cluster recently and via a swarm structure search method, herein we report a two-dimensional silicene allotrope by combining pentagonal silicon clusters. Further calculations show that this silicene allotrope exhibits great anisotropic conductance, it behaves as a metal with linear energy dispersions along the b -direction and Dirac point located at about 0.10 eV below the Fermi energy level, while it exhibits semiconducting state along the a -direction. This strong anisotropic conductance is driven by the different coordination numbers of silicon atoms. Through hydrogenating the three-fold coordinated silicon atoms, the silicene allotrope would turn into a semiconductor with a direct band gap of 1.60 eV (2.05 eV under HSE level). Particularly, the hydrogenated model possesses high carrier mobility of and at room temperature for electrons and holes, respectively. This finding promotes potential applications of silicon nanomaterials in in-plane anisotropic nanoelectronic, high-speed electronic, and photovoltaic devices.

在已报道的二维硅材料中，实验上仅报道了六角形和类kagome 硅烯。因此，使用另一种策略设计此类材料是可取的。基于最近实验合成的五边形硅簇，通过群结构搜索方法，我们在此报告了一种通过组合五边形硅簇的二维硅烯同素异形体。进一步的计算表明，该硅烯同素异形体显示出很大的各向异性导电性，其表现为与沿着线性能量分散体的金属b -方向和狄拉克点位于下面的费米能级约0.10电子伏特，而它显示出沿半导体状态一-方向。这种强大的各向异性电导是由硅原子的不同配位数驱动的。通过氢化三重配位的硅原子，硅烯同素异形体将变成直接带隙为 1.60 eV（HSE 水平下为 2.05 eV）的半导体。特别是，氢化模型分别具有电子和空穴的高载流子迁移率和室温下的载流子迁移率。这一发现促进了硅纳米材料在面内各向异性纳米电子、高速电子和光伏器件中的潜在应用。