First-principles investigation of tensile strain effects on optoelectronic properties in nitrogen-doped tungsten diselenide (N-WSe₂)

Abstract Two-dimensional layered compounds featuring transition metal-chalcogen covalent bonding WSe 2 exhibit outstanding performance in optoelectronic properties, making it highly suitable for emerging optoelectronic technologies. However, the modulation mechanism of its optoelectronic performance by the synergistic effect of tensile strain and doping remains unclear. This study is grounded in the framework of density functional theory (DFT). The present investigation conducts a thorough analysis of how tensile deformation alters the electronic band structure and photonic-electronic interaction mechanisms in N-doped two-dimensional WSe 2 systems. By constructing a 3 × 3 × 1 supercell model, utilizing the generalized gradient approximation (GGA) with the Perdew–Burke–Ernzerhof (PBE) exchange–correlation functional, we performed precise geometric relaxation and thorough property calculations on the system, with tensile strain gradually applied from 0% to 10%. Computational results indicate a marked improvement in system stability following nitrogen incorporation, with the lowest formation energy (−3.324 eV) and the largest negative binding energy (−6.672 eV). Under tensile deformation, the system exhibits a VBM approaching the Fermi level, a monotonically decreasing bandgap, and elevated hole carrier concentrations compared to the unstrained state. Furthermore, the N-2p orbital in the valence band region stabilizes the acceptor level, further enhancing the p-type conductivity. Optical property analysis reveals that strain modulates the onset energy of light absorption and the intensity of absorption peaks. The low-frequency reflectivity increases significantly with increasing strain, and the shift of reflection peak positions in the mid-to-high frequency region reveals changes in the electronic transition mechanism. The peak changes in the energy loss function in the mid-to-high frequency region reflect the profound impact of strain on the electronic density of states distribution. This study reveals the microscopic mechanism of the synergistic regulation of WSe 2 optoelectronic performance by tensile strain and N doping, providing a theoretical basis for designing high-performance strain-adaptive optoelectronic devices.