Research Progress on Broadband Photodetectors Based on Two-Dimensional Materials

The growing demands of high-speed imaging, aerospace, and optical communication have driven intensive research on broadband photodetectors with high sensitivity and fast response. Twodimensional (2D) materials, featuring atomic-scale thickness, tunable bandgaps, and excellent carrier transport properties, are regarded as ideal candidates for next-generation optoelectronics. However, their limited light absorption and intrinsic recombination losses remain key challenges. This review provides an overview of recent progress in 2Dmaterial-based broadband photodetectors. First, the fundamental optoelectronic properties of 2D materials, including bandgap modulation, carrier dynamics, and light - matter interactions, are discussed to clarify their broadband detection potential. Representative material systems - such as narrow-bandgap semiconductors, 2D topological materials, and perovskites - are summarized, demonstrating detection capabilities spanning from ultraviolet to mid-infrared regions. To overcome intrinsic limitations, four optimization strategies are highlighted: heterostructure engineering for efficient charge separation and extended spectral response; defect engineering to introduce mid-gap states and enhance sub-bandgap absorption; optical field enhancement through plasmonic nanostructures and optical cavities to improve responsivity; and strain engineering for reversible band structure tuning, particularly suited for flexible devices. These strategies have enabled remarkable improvements in responsivity, detectivity, and bandwidth, with some devices achieving ultrabroadband detection and multifunctionality. In summary, 2D materials and their hybrids have shown great promise for broadband photodetection, with advances spanning from material innovation to device architecture optimization. The reviewed strategies - heterostructure integration, defect modulation, optical field enhancement, and strain engineering - collectively demonstrate the diverse pathways to overcome intrinsic limitations and boost device performance. Looking forward, the rational combination of these approaches is expected to further expand the detection window, improve sensitivity, and enable multifunctional operation, thereby paving the way toward nextgeneration broadband photodetectors with versatile applications in imaging, sensing, and optoelectronic systems