Submicrometer Polymer Field - Effect Transistor

Recent developments towards future polymer electronics are aimed at different applications as organic displays, complementary circuits, and all-polymer integrated circuits [1-3]. Basic devices are organic field-effect transistors (OFET, cross section in Figs.2 and 3) with an active layer made from an organic material. Until now the achieved performance of OFET's is not sufficient for envisaged low-end applications. Actually, for low-cost fabrication the active material must be a soluble conjugated polymer allowing for solution processing. The charge carrier mobility in the resulting layers is rather low. Highest values obtain so far are up to 0.1 cm2V-1s-1 for soluble regioregular poly(3-alkylthiophene) poly-(9,9-dioctylfluorene-bithiophene) and pentacene from soluble precursors, but often one gets values orders of magnitude lower (for comparison, in Silicon one has about 103 cm2V-1s-1). Considering that even for low-end applications a frequency above 100kHz and an operation voltage below 10V are needed, one is led to a rather restrictive requirement on the transistor channel length (this is the distance from source S to drain D in the schematic cross section of Fig.2). This connection is visualized in Fig.1. Here one can see, that e.g. for the mobility of Submicrometer Polymer Field-Effect Transistor