Light‐Induced Field‐Tunneling Synapses in Solution‐Processed Van Der Waals Heterostructures for Scalable, Retina‐Inspired Optical Sensing

ABSTRACT

Neuromorphic optical sensors that merge sensing and in‐pixel preprocessing within a single device are emerging as a key building block for next‐generation artificial vision. Here, we present a WSe ₂ /ZrO _2‐x van der Waals (vdW) heterostructure that realizes a light‐induced field‐tunneling synapse (LIFTS) for visual preprocessing. Exploiting the thin vdW heterostructure with the gate–drain overlap of a single‐gate transistor, two distinct operation modes can be reconfigured by simply adjusting the applied bias condition. In global gating mode, the device operates as a conventional p ‐type transistor with fast photo‐switching, whereas in local gating mode, it exhibits diode‐like rectification mediated by unique field‐tunneling carrier dynamics. Notably, this carrier dynamics enables intensity‐dependent photo‐synaptic operation—remaining inactive under dim light but activated under bright illumination, mimicking human photopic adaptation. At the pixel level, this intensity‐dependent photoresponse is spatially adaptive: dim regions retain a fast positive photoresponse, whereas bright regions activate the field‐tunneling pathway and trigger a negative post‐synaptic response, enabling selective suppression of saturated pixels at the point of detection. Building on this pixel‐level functionality, LIFTS arrays serve as scalable neuromorphic preprocessing layers that progressively recover visual features from glare‐saturated inputs, including realistic street scenes, via edge enhancement and bright‐region attenuation.