Two ways in front of you:-

Creation of the device models based on measurements such as DC Characteristics and S- Parameters. or

Creation the models base on the physics of the device.

I enclose for you a list of publications that includes more than 80 papers covers the small signal and large signal models of  such devices using the two approaches and using these models for several applications (Amplifiers, Doublers, Triples, Oscillators).

good Luck.

Prof. S. El-Rabaie

Your answer was very helpful, thanks alot. But, I have to ask, is OFET modeling very different from conventional FET modeling? 

The approaches described earlier are general for modelling any devices, the organic and non organic ones they are under the same umberall. I enclose for you the title of one of the papers covers the creation of the Compact DC models of the OFT.

Compact DC Modeling of Organic Field-Effect Transistors: Review and Perspectives

published on IEEE electron devices 2014

If you are working on the military college (EGYPT), I can give you my book under the title"“Computer Aided Simulation and Optimization of Nonlinear Active Microwave Circuits”,  Published January 2000(10258/2000) . that will help you by the codes included to understand the topic.

my mobile number :-          01284985170

Dear Sir,

You can try to find literature of your interest at

www.freefullpdf.com

This is a powerful source of information.

Good luck