Two-dimensional semiconductor photodetectors: from physical mechanisms to intelligent sensing system integration

Heterojunction photodetectors based on two-dimensional (2D) materials are leading the development of a new generation of high-performance smart optoelectronic systems by virtue of their tunable band structures, diverse photoresponse mechanisms, and excellent integration. Herein, we summarize the research progress of 2D heterojunction photodetectors from the basic response mechanisms to multi-field synergistic modulation and application integration. 2D semiconductor materials achieve efficient generation and separation of photogenerated carriers through multiple physical mechanisms, such as bandgap modulation, excitonic effects, etc. Furthermore, heterojunctions exhibit unique advantages in terms of band alignment, interfacial barrier modulation, and built-in electric field design, and combine nonlinear photovoltaic effects with multiphysics-field synergies to dramatically enhance their photoresponse efficiency and environmental stability. Furthermore, they are used in polarization imaging, infrared detection, low-light imaging, flexible wearable sensing, etc., and show broad prospects in self-powered detection, intelligent sensing, and neuromorphic optoelectronic fusion. Herein, we summarize the key breakthroughs and challenges of 2D heterojunctions in multimodal integration and intelligent optoelectronic detection, highlighting their potential advantages in low-power, highly integrated, and reconfigurable optoelectronic systems. With the continuous progress in materials and device design, 2D heterojunctions are expected to become the core foundation for future multifunctional optoelectronic information platforms and intelligent vision systems.