Recent Advances in Two-Dimensional Bismuth Oxysulfide

Two-dimensional (2D) semiconductors have attracted significant attention for their potential in low-power and high-performance electronic applications. Among these, bismuth oxysulfide (Bi₂O₂S) has recently emerged as a candidate owing to its wide bandgap, low effective electron mass, and environmental stability. This review summarizes the synthesis strategies and device applications of 2D Bi₂O₂S. It systematically analyzes recent advancements in synthesis methodologies, ranging from scalable solution-based synthesis to back-end-of-line compatible, low-temperature metal-organic chemical vapor deposition. Furthermore, defect engineering, particularly through oxygen-vacancy control and doping, is discussed as a strategy to modulate the electronic band structure, enhance broadband nonlinear optical properties, and accelerate the photocarrier relaxation kinetics of 2D Bi₂O₂S. These tunable characteristics have enabled 2D Bi₂O₂S to be employed in electronic and optoelectronic devices. The review, therefore, discusses recent developments in device applications of Bi₂O₂S, including field-effect transistors, broadband photodetectors, and flexible photoelectrochemical sensors. Finally, the remaining challenges, such as wafer-scale single-crystal growth and reliable p-type doping, and future research directions are discussed for integrating Bi₂O₂S into three-dimensional integrated circuits and neuromorphic computing.