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.