The current flowing through the device is controlled by the exchange of ions between an electrolyte and the OECT channel composed of an organic conductor or semiconductor.
OECTs consist of a semiconductor or even conductor thin-film (the channel), usually made of a conjugated polymer, which is in direct contact with an electrolyte.
When a voltage is applied to the gate, ions from the electrolyte are injected in the channel and change the electronic charge density, and hence the drain current.
However, some channel materials can hold the migrated ions even after removing the gate voltage enabling their use as memory devices.
When a positive voltage is applied to the gate, cations from the electrolyte are injected into the PEDOT:PSS channel, where they compensate the negative charge on the sulfonate anions.
In contrast, in OECTs, ions are injected into the channel and change the electronic charge density throughout its entire volume.
As a result of this bulk coupling between ionic and electronic charge, OECTs show a very high transconductance[8] along with an outstanding intrinsic gain.