A fast organic field effect transistor (100), which operates at low voltages, is achieved by the introduction of an oligomeric or polymeric electrolyte (131) between the gate electrode (141) and the organic semiconductor layer (121), which electrolyte (131) has a dissociation constant of at least 10-8. Said organic semiconductor layer (121) is in contact with the source electrode (111) and the drain electrode (112) of the transistor. In operation a potential (152) applied to said gate electrode (141) controls the current A between said source electrode (111) and said drain electrode (112).