Ambipolar and Light-Emitting Organic Field-Effect Transistors (English shop)

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The goal of this thesis was the fabrication and characterization of a light-emitting ambipolar organic field-effect transistor (OFET). In the literature, light-emitting ambipolar field-effect transistors (FET) based on small molecules, which are of interest for novel electro-optical devices, have not yet been described. For the realization of such a light-emitting ambipolar OFET, three different strategies were pursued: Firstly, conventional single-layer OFETs were investigated in terms of their electroluminescent properties. Secondly, bilayer heterostructures based on an electron- and a hole-transport material were prepared. Thirdly, a novel concept based on coevaporated, i.e. mixed films consisting of an electron- and a hole-transport material, has been realized. Although the single-layer structures were light-emitting, the unipolar transport properties of the organic materials restrict light emission to a region close to one contact. In contrast, in bilayer heterostructures an ambipolar transport characteristics was measured, but no electroluminescence (EL) observed. Finally, with the novel concept of a coevaporated bulk heterostructure, EL in an ambipolar OFET could be observed for the first time.