Organic electronic synapses with pinched hystereses based on graphene quantum-dot nanocomposites

Organic electronic synapses (e-synapses) based on poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS)/ graphene quantum dot (GQD) nanocomposites are fabricated by using a solution method. Current–voltage (I–V) curves for the devices under dual positive bias voltage sweeps show that the conductance with a pinched hysteresis gradually increased with increasing applied voltage, and those for the devices under dual negative bias voltage sweeps gradually decreased with increasing applied voltage, indicative of the fingerprint of e-synapses. The current in the devices decreases with increasing concentration of GQDs in the active layer, and the devices fabricated utilizing the ratio of PEDOT:PSS to GQDs of 1:0.4 shows the best performance among the e-synapses. The carrier transport and operating mechanisms of the e-synapses are described on the basis of both the I–V results and the trapping and escape of electrons from the GQDs. NPG Asia Materials (2017) 9, e413; doi:10.1038/am.2017.133; published online 28 July 2017