Electro-optical properties of a pressure-induced g -SiC7 sheet from many-body perturbation theory

Alongside a vast number of two-dimensional (2D) materials, g -SiC₇ siligraphene has already been introduced to the 2D nanomaterial family with extraordinary sunlight absorption. In this work, we exploit the concept of the in-plane biaxial strain-induced electro-optical engineering in siligraphene from ab initio many-body perturbation theory calculations (GW + Bethe-Salpeter equation). While the semiconductor nature of the system is robust for both tensile and compressive strains, the direct GW band gap of 1.35 eV is decreased (increased) linearly with tensile (compressive) strain. This is accompanied by a variation in the optical transitions. The tensile strain in g -SiC₇ shifts the optical absorption peaks to the lower photon energies, the so-called red shift, whereas the compressive strain causes a shift to the higher frequencies, the so-called blue shift. Eventually, the exciton binding energy trend and the real-space exciton distribution for the bright bound state is studied with strain, resulting in a alteration of the spatial distribution radius of exciton wave functions from tensile to compressive. Our findings extend the logic applications of siligraphene in photovoltaic devices, especially in tailoring the power conversion efficiency of excitonic solar cells.