Theory of organic field effect transistors

Field effect transistors with an organic material as active layer are at pr esent essentially used to determine the mobilities in these materials, Unti l now, in analysing the measured current characteristics, only the simplest (Shockley) model has been used which accounts neither for this type of thi n film transistor (TFT), which operates in depletion and accumulation, nor for the nature of the carriers, Starting from two-dimensional simulations f or the analogous silicon TFT, we have developed an analytical model for the TFT that accounts for several peculiarities of the current characteristics of this type of transistor. In addition, a first modification has been dev eloped which describes the situation when the charged states are polarons a nd bipolarons, as is the case in organic materials. Applications to publish ed experimental current characteristics show that a general reanalysis is n eeded. (C) 1998 John Wiley & Sons, Ltd.