Electronic properties of SrFCl and SrFBr monolayers using density functional theory and GW approximation

Abstract Two-dimensional materials, known as 2D materials, have attracted increasing interest in recent years. 2D semiconductors can potentially be used in a multitude of applications in flexible electronics and atomic applications. In this framework, we investigate the structural, vibrational, and electronic properties of new 2D SrFCl and SrFBr monolayers, employing density functional theory and beyond with GW approximation. We have obtained these monolayers are dynamically stable since there are not imaginary modes in their phonon dispersion, confirming the stability of the two-dimensional form of these compounds. Our GW results show that the bandgap energy of SrFCl monolayer is significantly larger than the bandgap of PbFCl monolayer (6.38 eV with GW) by ∼ 1.17 eV. Further, the bandgap energy value obtained for the SrFBr monolayer is larger than the bandgap of the PbFI sheet (6.64 eV with GW) by ∼ 0.62 eV.