Influence of self-assembled monolayer dielectrics on the morphology and performance of α,ω-dihexylquaterthiophene in thin film transistors

Three different ultrathin hybrid dielectrics based on self-assembled monolayers (SAMs) from phosphonic acid molecules were investigated on aluminum oxide. The impact of the underlying SAMs on the semiconductor morphology and transistor device performance was studied by reducing the film thickness of the subsequently deposited α,ω-dihexylquaterthiophene semiconductor to one monolayer and less. The nature of the SAM relates to the molecular orientation of submonolayer films, which is investigated by photoluminescence microscopy and atomic force microscopy. SAMs with high surface energy tend to induce a face-on growing of the semiconductor, whereas for SAMs with low surface energy an edge-on growth is favorable