A self-powered WSe₂/GaSb vdW heterojunction photodetector enabling intelligent near-infrared vision and traffic-sign recognition

Self-powered photodetectors are indispensable for low-power optoelectronic systems such as edge sensing, optical communication, and machine vision. However, their development is severely hampered by interfacial defects that induce carrier leakage and nonradiative recombination. Here, we overcome this challenge by designing a WSe₂/GaSb van der Waals (vdW) heterojunction with favorable band alignment and a strong built-in electric field at the interface. The device delivers an ultralow dark current of ~2 pA at zero bias and a rectification ratio exceeding 10⁴, enabling zero-bias operation across 210-1000 nm. Under 880 nm illumination, it exhibits a responsivity of 331.5 mA W^-1, a specific detectivity of  Jones, an open-circuit voltage of 0.52 V, a maximum output power of 1.66 nW, and fast rise/fall times of 431/356 μs. Beyond device-level metrics, we demonstrate a closed “sensing-communication-computing” loop by realizing 8-bit ASCII optical communication and low-power near-infrared traffic sign recognition. Using U-Net reconstruction and YOLOv8n classification, the recognition accuracy is boosted from ~30% to ~80%, confirming its practical utility. This work provides an experimental and theoretical pathway toward next-generation self-powered, low-noise, intelligent vdW heterojunction photodetectors.