Recent progress in two-dimensional Bi 2 O 2 Se and its heterostructures

Ever since the identification of graphene, research on two-dimensional (2D) materials has garnered significant attention. As a typical layered bismuth oxyselenide, Bi O Se has attracted growing interest not only due to its conventional thermoelectricity but also because of the excellent optoelectronic properties found in the 2D limit. Moreover, 2D Bi O Se exhibits remarkable properties, including high carrier mobility, air stability, tunable band gap, unique defect characteristics, and favorable mechanical properties. These properties make it a promising candidate for next-generation electronic and optoelectronic devices, such as logic devices, photodetectors, sensors, energy technologies, and memory devices. However, despite significant progress, there are still challenges that must be addressed for widespread commercial use. This review provides an overview of progress in Bi O Se research. We start by introducing the crystal structure and physical properties of Bi O Se and a compilation of methods for modulating its physical properties is further outlined. Then, a series of methods for synthesizing high-quality 2D Bi O Se are summarized and compared. We next focus on the advancements made in the practical applications of Bi O Se in the fields of field-effect transistors (FETs), photodetectors, neuromorphic computing and optoelectronic synapses. As heterostructures induce a new degree of freedom to modulate the properties and broaden applications, we especially discuss the heterostructures and corresponding applications of Bi O Se integrated with 0D, 1D and 2D materials, providing insights into constructing heterojunctions and enhancing device performance. Finally, the development prospects for Bi O Se and future challenges are discussed.