Microscopic and spectroscopic characterization of interfaces and dielectric layers for OFET devices

The functionality of organic devices is strongly influenced by their interfaces. We report on new microscopic methods for interface characterization of organic devices in operation mode. With photoemission electron microscopy (PEEM), a direct mapping of charge carrier density is possible. Microscopy in the scanning Kelvin force mode (SKPM) gives information about the local surface potential. In addition to lateral information, depth profiling of interface chemistry is important. As an example, we present a study of the electrode/dielectric layer interface, performed using photoelectron spectroscopy. This interface is of technological relevance for organic memories, based on organic field effect transistors (OFETs). The dielectric part is made of ferroelectric polymers like poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)). We compare aluminium/P(VDF‐TrFE) and PEDOT:PSS/P(VDF‐TrFE) interfaces (PEDOT:PSS is the conductive polymer poly(3,4‐ethylenedioxythiophene):polystyrenesulphonate). Finally we present memory elements consisting of metal ferroelectric insulator semiconductor (MFIS) and OFET structures. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)