Realization of artificial synapse and inverter based on oxide electric-double-layer transistor gated by a chitosan biopolymer electrolyte

Low-voltage transparent zinc oxide (ZnO) thin-film transistor with chitosan biopolymer electrolyte as a gate dielectric was fabricated at room temperature and characterized. Due to an electric-double-layer (EDL) effect near the chitosan/ZnO interface through mobile-proton migration, the transistor exhibits a good performance with a carrier mobility of 7.88 cm2 V-1 s-1, a threshold voltage of 1.0 V, an on-off current ratio of 5 ± 104, a subthreshold slope of 135 mV Dec-1, and an operating voltage of less than 3 V, respectively. Based on the EDL transistor, the excitatory post-synaptic current and paired-pulse facilitation (PPF) behavior of biological synapses are mimicked, and PPF index is related to the inter-spike interval of the paired pulse. Furthermore, the resistor-loaded inverter based on the transistor was built, showing a high voltage gain of ∼4 at a low supply voltage of 3 V, a small delay, a large noise margin and a low power consumption. The EDL transistor may find potential applications in portable electronics and synaptic electronics.