Polymer P-Insulator-N Optoelectronic Synaptic Transistor With Ultra-low Energy Consumption and Enhanced Light Response for Neuromorphic Applications

Developing ultra-low-power optoelectronic synaptic devices is of urgent necessity for artificial intelligence and brain-inspired devices. Here, a P-ins-N (p-type semiconductor, insulator, and n-type semiconductor) sandwich structure is proposed for an organic optoelectronic synaptic transistor. The p-type semiconductor is the hole-transport pathway for the photocurrent, and the n-type semiconductor acts as a floating-gate, while the insulator layer between them is employed to improve the photo-induced charge transfer and reduce charge recombination. The P-ins-N synaptic transistor not only has a low operating voltage (−3 V) and a high I_ON/I_OFF ratio (> 10⁴), but also exhibits enhanced photo-response performance. It can simulate various biological synaptic functions, such as excitatory postsynaptic current (EPSC) and paired-pulse facilitation (PPF). Moreover, the conversion from short-term memory (STM) to long-term memory (LTM) is achieved by changing the inputs of light pulses. The low energy consumption is 0.003 fJ, and the figure of merit R (R = E_C × V_G) is as low as 1 × 10⁻¹⁷ J·V. Meanwhile, it also has potential applications in simulating the regulatory effect of infrared light on wound healing and recognizing handwritten digits.