Amplitude-controllable event-driven organic photosensors based on ionic-mediated inhibition.

Next-generation artificial vision systems must integrate rapid temporal-contrast detection with dynamic sensory-gain modulation to prioritize task-relevant stimuli. Conventional semiconductor photosensors lack intrinsic mechanisms for spike generation with tunable amplitude, requiring complex multitransistor architectures and limiting efficiency. Here we report an event-driven organic photosensor that integrates temporal-contrast detection and amplitude modulation within a single active layer by coupling ionic and electronic transport in an organic mixed ionic-electronic conductor. In a bulk heterojunction with a non-fullerene acceptor, fast electron extraction generates excitatory photocurrent spikes, whereas ion-compensated hole accumulation in the organic mixed ionic-electronic conductor donor provides voltage-tunable inhibitory control over spike amplitude-functionally analogous to attentional gain modulation in biological vision. This enables in-sensor amplitude-temporal coding, preserving motion-relevant contrast in bias-weighted optical events and reducing redundant read-out. These results establish ionic-electronic coupling in organic mixed ionic-electronic conductors as a materials strategy for adaptive, low-power neuromorphic vision hardware.