Organic Field Effect Transistor

A Field effect transistor (FET) operates as a capacitor where one plate is the gate electrode and the other a conducting channel between two ohmic contacts-the source and drain electrodes.The density of charge carriers in  the channel is modulated by the voltage applied to the second plate of capacitor i.e. the gate electrode.Without gate source bias, very little current flows between source and drain electrode and the transistor is in the off state.Application of gate source voltage causes charging at the dielectric surface and induces charge in the semiconducting layer yielding a significant increase in conductivity in the sample, turning it to the On state. Organic field effect transistors(OFETs) are similar to the Silicon field effect transistor, except the active layer (conducting) is of organic semiconductor material. OFETs can be operated in accumulation of charges in the channel with negative gate voltages.

OTFTs are based on multilayer structure whose electrical properties are affected by device structures, characteristics of different material layers and interface between them. Depending on the position of electrodes with respect to active semiconductor and dielectric layer, there are various device structures such as Bottom Gate Bottom Contact (BGBC), Bottom Gate-Top Contact (BGTC), Top Gate-Bottom Contact (TGBC) and Top Gate-Top Contact (TGTC).