I am sorry; however, you question is not precise enough. You are asking on OFET parameters (threshold voltage, On/Off ratio), but this device has thethree electrode geometry. In other words, the OFET device has planar as well as vertical structure. In common case the source-drain represents the planar structure, while source-gate and drain-gate stand for vertical one. In should be noted that there are many observation of conductivity switching due to trapping (charge storage), dipole switching (e.g. ferroelectric), molecular switching (photoenhanced conformation chages), etc. However, these origin of these phenomena is related to the vertical direction (source-gate or drain-gate field) and the "reading" of the conductivity is done in planar direction by the drain-source current.

Generally speaking, in OFET device you can perform certain changes due to vertical field and these changes are influencing the lateral conductivity by the changes in charge concentration (e.g. trapping), changes in effective mobility (e.g. charge hopping between molecules due to conformation changes), and/or changes in local electric field (e.g. dipolar field).

Dear RAM , 

Can you describe the construction of your device in more details? From the conceptual point of view devices can be constructed vertically and laterally like the vertical mos transistor and the lateral mos transistors where the channel is vertical in the first structure and lateral in the second structure. There is also the vertical bipolar transistor and the lateral bipolar transistor where the stack of the three transistor layers is vertical or lateral. So, from the principle point of view devices can be made vertical or lateral according to the stacking of their constituting layers. Switching devices base on metal insulator metal devices can be stacked in a planar manner. In this case one has to control the distance between the two electrodes by the photolithography. In case of vertical stacking the active device thickness is controlled by the I-layer thickness.

This is the major difference.

wish you success