An Ultrasensitive Bi2O2Se/In2S3 Photodetector with Low Detection Limit and Fast Response toward High-Precision Unmanned Driving.

The machine vision utilized in unmanned driving systems must possess the ability to accurately perceive scenes under low-light illumination conditions. To achieve this, photodetectors with low detection limits and a fast response are essential. Current systems rely on avalanche diodes or lidars, which come with the drawbacks of increased energy consumption and complexity. Here, we present an ultrasensitive photodetector based on a two-dimensional (2D) Bi₂O₂Se/In₂S₃ heterostructure, incorporating a homotype unilateral depletion band design. This innovative architecture effectively modulates the transport of both free and photoexcited carriers, suppressing the dark current and facilitating the rapid and efficient separation of photocarriers. Owing to these features, this device exhibits a responsivity of 144 A/W, a specific detectivity of 1.2 × 10¹⁴ Jones, and a light on/off ratio of 1.1 × 10⁵. These metrics rank among the top values reported for state-of-the-art 2D devices. Moreover, this device also demonstrates a fast response time of 170/296 μs and a low noise equivalent power of 0.57 fW/Hz^1/2, attributes that endow it with ultraweak light imaging capabilities. Furthermore, we have successfully integrated this device into an unmanned driving system, providing a perspective on the design and fabrication of future optoelectronic devices.