ABSTRACT Bionic vision systems employ spike‐based neural encoding—inspired by biological vision—to achieve high perceptual efficiency and adaptability. However, most current implementations commonly rely on carrier relaxation, charge trapping/detrapping, or ion migration processes along with peripheral circuits to emulate neural dynamics, which limit response speed, increase energy consumption, and hinder efficient device‐level spike encoding. Here, we demonstrate a bioinspired tunneling photodetector using an SnSe 2 /MLG/WS 2 junction, in which an electrically triggered switch from direct tunneling (DT) to Fowler–Nordheim tunneling (FNT) enables optical‐power‐dependent grayscale resolution and spiking‐encoded output within a single structure. By leveraging tunable tunneling transports for efficient photocarrier collection, the device achieves a responsivity of ≈233 A/W and a response time of ≈97 µs at 638 nm. We further demonstrate the device's capability for light‐intensity encoding and dynamic perception through grayscale image transmission. Specifically, spike signals encoded via the nonlinear photocurrent response allow a trained spiking neural network (SNN) to achieve 96.5% accuracy in grayscale letter recognition. Our results demonstrate that the tunable tunneling‐encoding strategy provides a practical pathway toward compact bionic visual sensors capable of grayscale imaging in neuromorphic vision front‐ends.
Fan et al. (Fri,) studied this question.