Mixed ionic/electronic conduction in conducting polymers introduces new physics/chemistry and an
additional functionality in organic optoelectronic devices. The incorporation of an ionic species in a
conjugated polymer matrix results in the increase in electrical conductivity associated with the
electrochemical doping of the material. In recent years polymer light emitting electrochemical cells
(LECs) have been demonstrated. In such electrochemical optoelectronic devices, mobile ions facilitate
the efficient injection of electronic charge carriers creating ‘‘in situ’’ doping regions near the electrodes
and lead to efficient electroluminescence light emission. Here, we introduce the same concept of an LEC
in the organic field effect transistors (OFETs). The presence of both electronic and ionic charge carriers
in the active layers of OFETs brings high charge carrier mobility and light emission even using
symmetric source and drain metal electrodes