Photoinduced relaxation effects in three-terminal polymer based device structures

We examine the dynamics of relaxation of the excess current generated by photoexcitation in different structures. The excess current is introduced upon photoexciting the devices for a certain duration. The decay process of this current in polymer field effect transistors (FETs) upon switching off the excitation source can be appropriately modeled to a serial relaxation dynamics arising from a hierarchy of systems with increasing spatial separation of the photo-generated negative and positive charges. The results at different gate voltages are informative in terms of extracting the spatial distribution of the trapped carriers. These results are compared to decay rates in two-terminal planar structures and Schottky barrier modified two-terminal planar structures.