PbS/CsPbBr₃ Heterojunction for Broadband Neuromorphic Vision Sensing

Neuromorphic light sensors with analogue-domain image processing capability hold promise for overcoming the energy efficiency limitations and latency of von Neumann architecture-based vision chips. Recently, metal halide perovskites, with strong light-matter interaction, long carrier diffusion length, and exceptional photoelectric conversion efficiencies, exhibit reconfigurable photoresponsivity due to their intrinsic ion migration effect, which is expected to advance the development of visual sensors. However, suffering from a large bandgap, it is challenging to achieve highly tunable responsivity simultaneously with a wide-spectrum response in perovskites, which will significantly enhance the image recognition accuracy through the machine learning algorithm. Herein, we demonstrate a broadband neuromorphic visual sensor from visible (Vis) to near-infrared (NIR) by coupling all-inorganic metal halide perovskites (CsPbBr₃) with narrow-bandgap lead sulfide (PbS). The PbS/CsPbBr₃ heterostructure is composed of high-quality single crystals of PbS and CsPbBr₃. Interestingly, the ion migration of CsPbBr₃ with the implementation of an electric field induces the energy band dynamic bending at the interface of the PbS/CsPbBr₃ heterojunction, leading to reversible, multilevel, and linearly tunable photoresponsivity. Furthermore, the reconfigurable and broadband photoresponse in the PbS/CsPbBr₃ heterojunction allows convolutional neuronal network processing for pattern recognition and edge enhancements from the Vis to the NIR waveband, suggesting the great potential of the PbS/CsPbBr₃ heterostructure in artificial intelligent vision sensing.