Surface-modified polydimethylsiloxane with soft-plasma as dielectric layer for flexible artificial synaptic transistors

The conductance of field-effect transistors (FETs) can be effectively stimulated by electrical or optical pulses, which could be potentially applied as artificial synapses. The combination of solution processable elastomers with polymer semiconductors has attracted extensive interest in all-polymer flexible synaptic electronics, due to the flexible and light weight property. In this work, a glow-discharge soft-plasma is utilized to treat the widely-used elastomer polydimethylsiloxane (PDMS) layer. Subsequently, the surface energy of PDMS is increased, from the contact angle of 100° to fully spread state and induce high charge trapping density (Δn, about 1.9 × 10¹² cm⁻² under 525 nm green light irradiation and positive gate-bias stress) on the surface. The PDMS surface are homogenously etched by soft plasma without damaging underneath materials, which can be used as dielectric layer in organic FETs. Thus, prepared organic FETs warrant quick charge transfer dynamics between PDMS surface and semiconductor layer. Upon which, flexible synaptic FETs are demonstrated, corresponding synaptic functions like excitatory postsynaptic current (EPSC), paired pulse facilitation (PPF), short-term plasticity (STP) are all realized. Furthermore, the handwritten digits with an accuracy of 86.2% are realized utilizing prepared synaptic devices.