Gate-Tunable Synaptic Plasticity through Controlled Polarity of Charge Trapping in Fullerene Composites

Motivated by the biological neuromorphic system with high degree of connectivity to process huge amounts of information, transistor-based artificial synapses are expected to pave a way to overcome the von Neumann bottleneck for neuromorphic computing paradigm. Here, artificial flexible organic synaptic transistors capable of concurrently exhibiting signal transmission and learning functions are verified using C-60/poly(methyl methacrylate) (PM MA) hybrid layer for the first time. C-60, trapping sites are doped in PM MA by facile solution process to form the hybrid structure. The flexible synaptic transistor exhibits a memory window of 2.95 V, a current(on)/current(off) ratio greater than 10(3), program/erase endurance cycle over 500 times. In addition, comprehensive synaptic functions of biosynapse including the excitatory postsynaptic current with different duration time, pulse amplitudes and temperatures, paired-pulse facilitation/depression, potentiation and depression of the channel conductance modulation, transition from short-term potentiation to long-term potentiation, and repetitive learning processes are successfully emulated in this synaptic three terminal device. The realization of synaptic devices based on C-60 with low operation voltage and controlled polarity of charge trapping is an important step toward future neuromorphic computing using organic electronics.