Effect of optoelectronic properties of vacancy defect in monolayer PtS 2 under strain: A first-principles study

In this paper, the optoelectronic properties of monolayer PtS ₂ under vacancy and strain are calculated based on density functional theory (DFT). Phonon spectrum verifies the stability of the model. Formation energy calculations show that the single S-atom defect system possesses lower energy and is easier to prepare experimentally. The single S-atom defect system is converted from an indirect bandgap to a direct bandgap, which is more favorable for electron transition. Under biaxial strain, the band gap of monolayer PtS ₂ decreases with increasing tensile strain and increases with increasing compressive strain. In addition, optical property calculations show that the initial absorption and reflection coefficients of the defect system gradually increase under tensile strain and decrease under compressive strain, and are located in the low-energy region where red-shift and blue-shift phenomena occur respectively. This paper reveals the modulation effect of strain on the electronic properties of monolayer PtS ₂ in the defect system, which is of great significance for the extension of material functionality and the optimization of device performance.