Group 14 elements in the Cmcm phase with a direct band structure for photoelectric application

Abstract

This work presents two novel group 14 element allotropes, oC24 Si24 and oC24 Ge24, and the physical properties of oC24 C24, oC24 Si24, and oC24 Ge24 are studied in detail by means of first-principles calculations. The mechanical stability, dynamic stability, and thermodynamic stability of oC24 Si24 and oC24 Ge24 are proven by the elastic parameters, phonon spectrum, and relative enthalpy, respectively. According to the B/G value, all oC24 C24, oC24 Si24, and oC24 Ge24 are brittle materials. By analysing the directional dependence of Young’s modulus, it is clear that oC24 Si24 possesses the largest mechanical anisotropy. From the electronic properties, it can be concluded that oC24 Si24 is a semiconductor material with a direct band gap of 1.047 eV, which suggests that oC24 Si24 may be suitable to make solar cells. More importantly, the light absorption ability of oC24 Si24 is stronger than that of diamond Si in the visible light region. In addition, the κmin of oC24 Si24 and oC24 Ge24 have better thermal conductivity, indicating that oC24 Si24 and oC24 Ge24 have great application potential in solar cells, optoelectronic devices and other microelectronic devices.

Effect of Vacancy on Physical Properties of Cmcm Si24

“…Since the continuous progress of the new energy industry, solar energy, with great potential for development, has been widely discussed [1]. Due to the rapid development of computational materials science, many related materials such as carbon, silicon, germanium, and some metal alloys have been explored [2][3][4][5][6]. For decades, silicon-based photovoltaic devices dominated the solar cell industry due to their great stability, environmentally friendliness, superior efficiency of photoelectric conversion, and technical advantages.…”

High-throughput calculation screening for new silicon allotropes with monoclinic symmetry

“…Computer-aided materials science has been widely used in the field of electronic materials simulation (Wang et al, 2021;Wei et al, 2023;Zhang et al, 2022) and there have been many theoretical reports on the design of new silicon materials (Lee et al, 2014;Su et al, 2022;Song et al, 2022;He et al, 2018;Fan et al, 2023;Cui et al, 2023;Wei et al, 2022;Cheng et al, 2018) based on density functional theory (Hohenberg & Kohn, 1964;Kohn & Sham, 1965). However, most of the new silicon structures still belong to the class of indirect band gap semiconductor materials (Cui et al, 2023;Wei et al, 2022;Cheng et al, 2018).…”