Photogalvanic Effect in the WSe₂ Monolayer with Defects Generated by Electron-Beam Irradiation for Self-Powered 2D Photodetectors: A Computational Study

The photogalvanic effect (PGE) in two-dimensional materials offers a unique pathway to generate photocurrent in noncentrosymmetric crystals without requiring a semiconductor p–n junction or external bias voltage. In this study, we construct atomic models for the experimentally observed 8|8 and 8|10 defects in the WSe 2 monolayer generated by electron-beam irradiation (EBI). The band structures and densities of states are calculated by density functional theory. Quantum transport simulations based on nonequilibrium Green’s function reveal that the two defects significantly enhance the photocurrent under linearly polarized light in the visible light region, primarily due to the reduction of symmetry. The average enhancement ratios for the 8|8 and 8|10 defects reflect substantial increases in photocurrent intensity, with peak values reaching up to two orders of magnitude compared to the pristine WSe 2 monolayer. These findings provide valuable insights into defect engineering in a self-powered 2D photodetector.