Polymer bulk-heterojunction synaptic field-effect transistors with tunable decay constant

High-fidelity and high temporal precision synaptic propagation, which are mainly determined by the decay kinetics of synaptic currents, are crucial for neuromorphic computing that has emerged as a promising avenue towards building the next generation of intelligent computing systems. However, the precise control of the decay kinetics of synaptic currents in the fixed synaptic device has rarely been reported in the synaptic transistors. In this work, a type of synaptic field-effect transistors (SFETs) based on the polymer bulk p–n heterojunction (BHJ) was invented, in which decay constant was able to be well controlled. The essential functionalities of synapses, such as excitatory/inhibitory postsynaptic current (EPSC/IPSC) and paired-pulse facilitation (PPF), were successfully used in this artificial synaptic device. More importantly, small angle-neutron scattering (SANS) was used to elucidate the current decay mechanism of these devices, which was found to be significantly impacted by the aggregation and connectivity of n-type fullerene. This work provided a universal synaptic transistor device with tunable decay constant, shedding light on the future development of high-fidelity and high temporal precision synaptic propagation neuromorphic computing systems.