Ambipolar Organic Field-Effect Transistor based on an Organic Heterostructure

Ambipolar charge injection and transport are a prerequisite for a light-emitting organic field-effect transistor (LE-OFET). Organic materials, however, typically show unipolar charge-carrier transport characteristics. Consequently, organic thin-film field-effect transistors based on a single material as active layer can typically either be operated as p- or as n-channel device. In this paper we show that by using a heterostructure with pentacene as hole-transport and N,N'-Ditridecylperylene-3,4,9,10- tetracarboxylic diimide (PTCDI-C(13)H(27)) as electron-transport material, ambipolar characteristics, i.e., simultaneous p- and n-channel formation, can be observed in a single device. An OFET structure is investigated in which electrons and holes are injected from Mg top and Au bottom contacts into the PTCDI-C(13)H(27) and pentacene layers, respectively. Our device exhibits electron and hole mobilities of 3×10**-3 cm**2/Vs and 1×10**-4 cm**2/Vs, respectively. This device architecture serves as a model structure for ambipolar field-effect transistors, which are a prerequisite for light-emitting field-effect transistors.