Design concept and device structure of the amplitude-programmable event-driven organic photodetector.

A research team from Xi'an Jiaotong University (XJTU) has achieved a breakthrough in neuromorphic vision by developing amplitude-programmable, event-driven organic photosensors. Led by the State Key Laboratory for Mechanical Behavior of Materials, the team used molecular design of organic mixed ionic-electronic conductors (OMIECs) to integrate information weighting directly into the material's intrinsic photoresponse.

This innovation enables a single active layer to simultaneously perform event detection, amplitude modulation, and information weighting. By transforming the material from a passive signal carrier into an active information-processing unit, the research provides a novel materials-science pathway for efficient, adaptive neuromorphic vision.

The findings were published in Nature Materials under the title Amplitude-controllable event-driven organic photosensors based on ionic-mediated inhibition.

Professor Ma Wei's team proposed a novel ion-mediated inhibition mechanism and developed an ionic–electronic event-driven sensor (IEES). By blending the organic mixed ionic-electronic conductor PgBDT-T with the non-fullerene acceptor Y6 into a bulk heterojunction, the team coupled fast electron transport with slower ion motion within the same photosensitive layer.

When light changes, rapid electron extraction triggers a transient "excitatory" photocurrent. Concurrently, internalized anions compensate for slowly accumulating holes in PgBDT-T, progressively inhibiting subsequent photocurrents.

Applying an external voltage allows continuous adjustment of the ion feedback strength, enabling precise, real-time control over event pulse amplitude.

Adjustable pulse amplitudes are used for information encoding. Each event reflects both the intensity of illumination changes and the weight set by the pixel bias. This combines the low-redundancy advantage of event sensing with analog amplitude encoding, reducing processing overhead for low-power, adaptive neuromorphic visual systems.