Strain Engineering on the Electronic Structure and Optical Properties of Monolayer WSi₂X₄ (X = N, P, As)

Two-dimensional WSi₂X₄ (X = N, P, As) has stimulated extensive studies due to its structural diversity and intriguing properties. Here, a systematic study on the strain engineering of electronic and optical properties in monolayer WSi₂X₄ is presented. Our results demonstrate that the monolayer WSi₂X₄ can withstand biaxial tensile strains of 13.1%, 16.3%, and 12.2% for X = N, P, and As, respectively, while the corresponding critical stresses are 27.90 GPa, 14.58 GPa,and 13.56 GPa, respectively. Furthermore, the bandgap of monolayer WSi₂X₄ can undergo a direct-to-indirect transition and even achieve a semiconductor-to-metal transition under appropriate biaxial strains. In addition, the light absorption of monolayer WSi₂X₄ in the visible region can be effectively improved by tensile strain, and the red (blue) shift of the absorption peak can be observed by tensile (compression) strain. The results show that monolayer WSi₂X₄ exhibits outstanding mechanical strength and physical properties, which is promising for future optoelectronic devices.