  Mixed layers of copper-phthalocyanine (p-conductive) and fullerene
(n-conductive) are used for the fabrication of organic field-effect transistors
(OFETs) and inverters. Regarding the electrical characteristics of these
donor-acceptor blends they show ambipolar charge carrier transport, whereas
devices made from only one of the materials show unipolar behavior. Such mixed
films are model systems for ambipolar transport with adjustable field-effect
mobilities for electrons and holes. By variation of the mixing ratio it is
possible to balance the transport of both charge-carrier types. In this paper
we discuss the variation of mobility and threshold voltage with the mixing
ratio and demonstrate ambipolar inverters as a leadoff application. The gained
results were analyzed by simulations using an analytical model for ambipolar
transistors and subsequently compared to complementary inverters.
