The structures, electronic and photoelectronic properties of the line defects in two-dimensional Bi 2 O 2 Se

Atomic-layered material Bi 2 O 2 Se has emerged as a novel two-dimensional (2D) semiconductor with the moderate band gap, high carrier mobility and excellent environmental stability, showing great potential for many applications such as the design of photodetectors. However, in 2D Bi 2 O 2 Se various structural defects are inevitable and these structural defects will significantly affect the physical and chemical properties. Here, combining density functional theory with non-equilibrium Green's function, we systematically investigated the structures, electronic and photoelectronic properties of the adsorption-, vacancy-, antisite- and exchange-type line defects in 2D Bi 2 O 2 Se. The obtained results suggest that the adsorption-type line defects can enhance the thermodynamic stability of 2D Bi 2 O 2 Se and that the vacancy- and exchange-type line defects weaken the thermodynamic stability. While the antisite-type line defects have complicated thermodynamic behaviors. The line defects usually give rise to significant influences on the hole effective masses of 2D Bi 2 O 2 Se and, more interestingly, typical metallized phenomena have been observed for some line defects. Compared with the perfect 2D Bi 2 O 2 Se, we also found that some line defects can increase the photocurrents in the infrared and ultraviolet regions noticeably. While in the visible region the line defects exhibit rich photoelectronic properties.