CI24‐Si: a Semiconducting Silicon Phase with an All‐sp³ Bonding Network

Abstract

A silicon allotrope which consists of 24 atoms in a body centered cubic cell and displays an symmetry (termed as cI24‐Si) with a mass density of 2.38 g/cm3, is theoretically investigated. This silicon phase has an all‐sp3 network with hexagons. Phonon dispersion confirms its dynamical stability and elastic constant implies it is mechanically stable. The analysis of electronic band structure performing by HSE06 functional shows that cI24‐Si is an indirect semiconductor with a small band gap of 0.83 eV. Additionally, its direct band gap is only 0.02 eV larger than the indirect band gap, indicating that cI24‐Si possesses a quasi‐direct band gap. The calculations of imaginary part of dielectric function and optical absorption for cI24‐Si show that it has better optical properties than diamond‐like Si−I phase as it can capture more sunlight from visible to ultraviolet range. To provide more characterizations for future experimental observations, X‐ray diffraction patterns and Raman spectra are also theoretically simulated. Due to its small band gap, cI24‐Si may possess potential electronic, optical and photovoltaic applications.

Six novel carbon and silicon allotropes with their potential application in photovoltaic field

“…First-principle calculation based on density functional theory is the most commonly used theory in material prediction [31,32]. Lu et al [33] predicted a low density silicon allotrope (cI24-Si), which has a quasi-direct band gap. They found that cI24-Si has better optical properties than diamond-like Si-I because it can capture more sunlight from the visible-light to ultraviolet band.…”

A New Metallic Porous Carbon Phase tP‐C12 with an sp2‐sp3 Bonding Network: A First‐Principle Calculation

“…Sp‐hybridized carbon allotropes, including one‐dimensional sp‐carbyne and two‐dimensional sp‐sp 2 ‐graphyne were also investigated. Porous structures, such as T carbon, Y carbon, TY carbon, C 96 carbon and CY carbon were also proposed for the potential applications of hydrogen storage, catalysis, charge storage and molecular sieves. Additionally, the metallic carbon allotropes, such as T6‐carbon, T14‐carbon, Hex‐C 18 and ψ‐graphene, are also theoretically proposed for potential applications of lithium ion battery anode material.…”