All‐Organic Field‐Effect Phototransistors Based on Organic Polymer Semiconductors for High‐Performance Near‐Infrared Photodetection

Abstract Organic near‐infrared (NIR) phototransistors show great promise in applications such as night vision, medical imaging, and wearable electronics. Herein, The development of a high‐performance organic NIR phototransistor is reported by compositing diketopyrrolo‐pyrrole‐dithienylthieno[3,2‐b]thiophene (DPPDTT) and PY‐IT. The device exhibits broad‐spectrum absorption ranging from 400 to 1000 nm, along with low roughness and excellent continuity, which facilitate effective light absorption and charge transport. Electrical characterizations reveal that the composite transistor achieves an output current of 33.6 µA at a gate voltage of −60 V, representing a more than six‐fold increase compared to the pure DPPDTT‐based device, along with enhanced carrier mobility. Under an 800 nm NIR illumination, the phototransistor demonstrates outstanding optoelectronic performance, including a photoresponsivity ( R ) as high as 1.13 × 10 4 A W −1 , a specific detectivity ( D * ) of 4.13 × 10 12 Jones, and an external quantum efficiency ( EQE ) exceeding 10 6 %, outperforming most reported organic phototransistors. Notably, the device maintains significant photosensitivity even under weak light (1.2 µW cm − 2 ), with rise and fall times of 24.84 and 30.41 ms, respectively. Furthermore, their capabilities for NIR imaging have been successfully demonstrated by a customized shadow mask. This work provides an effective pathway for developing highly sensitive organic NIR photodetectors.