First-principle study on the photoelectric properties of monolayer h-BN under different strain types

Two-dimensional materials are a new and promising research field in materials science. This is mainly attributed to their unique photoelectric and chemical properties. In addition to possessing unique optoelectronic and chemical properties, two-dimensional materials also have important application prospects in the field of field-effect devices. Based on density functional theory, the effects of uniaxial strain and equibiaxial strain on the mechanical properties, electronic structure, and optical properties of monolayer h-BN were studied using first principles. The results indicate that compressive strain has a significant impact on the stability of monolayer h-BN. The band gap width of monolayer h-BN decreases with increasing strain, and the optical properties of monolayer h-BN exhibit a relative trend under tensile and compressive strains. The influence of biaxial strain on the mechanical properties, electronic structure, and optical properties of monolayer h-BN is greater than that of uniaxial strain. All the calculations were done by the VASP software based on density functional theory. The interaction between atomic nuclei and electrons is described by the projected added wave pseudopotential (PAW), using the generalized gradient approximation (GGA) to exchange the Perdew-Burke-Ernzerhof (PBE) of the functional. To avoid interlayer interactions, a 15-Å vacuum layer was set up. The Brillouin zone selects the Monkhorst–Pack method to generate 9 × 9 × 1 of k-point grid, the cut off energy is set to 500 eV, the energy convergence standard of the system is 1 × 10−5 eV, and the interaction force between atoms is 0.01 eV/Å.