Electrical properties of doped and non-doped end-capped oligothiophenes in microcontacts

Summary form only given. The application of oligomers with well defined chain length as active molecular component in electronic and opto-electronic devices (FET´s, LED´s) has recently gained much attraction. The direct investigation of transport phenomena in this oligomer layers should profit by the development of micro- or nanostructured metal/organic/metal heterostructures. We have fabricated microstructures by electron beam lithography and dry etching process with distances in the submicron region between two gold contacts and used vacuum sublimated films of end-capped oligothiophene. Current/voltage measurements using undoped and iodine-doped films have been performed as a function of oligomer chain length n, (n=5..7), electrode distances and doping time. The logarithm of the conductivities depends on the inverse chain length and is strongly dependend on the doping time up to 15 days. The results of the experiments will be analyzed with respect to the different morphology of the films and compared with those on macroscopic films.