Fundamental Characteristics of Photodetectors and Applications of Two-Dimensional Materials in Photodetection

Two-dimensional (2D) nanomaterials, due to their atomic-level thickness, tunable bandgap, and strong light-matter interaction, have emerged as a transformative platform for high-performance photodetectors. In recent years, devices based on emerging materials such as graphene, transition metal dichalcogenides (TMDs), Bi2O2Se, and InSe have achieved record-breaking light response, detection rate, and ultrafast response times. This article reviews performance optimization strategies, including heterostructure design, defect and doping control, interface passivation, and novel device structures (such as self-powered and flexible devices). It systematically compares key performance indicators such as response rate, external quantum efficiency, specific detection rate, dark current, and time-domain response. It assesses the trade-off between gain and speed, as well as challenges in large-scale fabrication, device consistency, and multi-functional integration. Finally, it looks forward to new directions such as wafer-level direct growth, polarization-sensitive detection, plasma or cavity enhancement technology to promote the development of next-generation wide-spectrum, low-power, and flexible photodetectors.