Organic Single-Crystal Transistor with Unique Photo Responses and Its Application as Light-Stimulated Synaptic Devices.

Tremendous progress has been achieved on organic transistor-based photodetectors; however, because of the nonpositive correlation relationship between the photo/dark current ratio (P) and the gate voltage, the claimed best P, R (photoresponsivity), and D* (detectivity) can hardly be obtained simultaneously at a given gate voltage, which severely compromises the device performance. Here, a light and voltage dually gated transistor based on an organic semiconducting single crystal of 2,6-dithienylanthracene (DTAnt) is developed. Attributing to its very low on/off ratio in the dark and the remarkable increment of mobilities under illumination, this phototransistor shows good performance with a P of 3.83 × 103, R of 1.32 A W-1, and D* of 1.94 × 1012 Jones achieved simultaneously at Vg = -100 V. Besides, the good reversibility and repeatability of its light-responsive behavior allows for the construction of an artificial photonic neuromorphic device with demonstrated synaptic functions, including excitatory postsynaptic current, short/long-term memory , and pair-pulse facilitation/depression.