Recent Progress in 2D Layered III–VI Semiconductors and their Heterostructures for Optoelectronic Device Applications

During the past decade, great effort has been devoted to research on 2D layered materials due to their reduced thickness and extraordinary physical properties, which open new opportunities for developing next-generation applications in various fields. Ultrathin III–VI semiconductors (e.g., GaSe, InSe, In₂Se₃, etc.) have emerged as potential candidates for nano-optoelectronic applications thanks to their sizable layer-dependent bandgaps and high carrier mobility, which could enable broadband photodetection and efficient conversion of solar energy. A systematic review is provided on 2D III–VI semiconductor-based state-of-the-art optoelectronic devices, such as phototransistors, photoconductors, and solar cells, reported in recent years. To better understand the mechanism and performance of the devices, an introduction to the electronic structures and optical properties of several representative III–VI members is first given. A comprehensive overview is then given on device geometry design, operating principles, and performance in optoelectronic applications based on III–VI semiconductors and their heterostructures. The techniques to enhance the performances of devices are also discussed. Finally, a brief discussion on the challenges and future opportunities in this field is provided.