Solution-processible small molecules have tremendous potential for providing both high charge carrier mobility and low cost processing. This study outlines a detailed microstructural study of the effect of substrate chemistry on fluorinated 5,11-bis(triethylsilyethynl) antradithiophene thin films and identifies the source of the edge-nucleated crystals believed to be the source of the high charge carrier mobility obtained for films made with chemically-modified electrodes. We find that crystals on chemically-modified electrodes predominantly form (001) oriented platelets while untreated surfaces form a fine mixture of (001) and (111) oriented crystals. For (001) oriented platelets, the (010) fast growth face and high charge transport direction lies in the plane of the film and allows extended growth from platelets nucleated near the electrode edge into the transistor channel. For short channel lengths, the high mobility growth fronts from adjacent electrodes bridge the channel gap, providing a high mobility pathway for charges across the channel.
Citation: Chemistry of Materials
Pub Type: Journals
Organic Electronics, Thin-film Transistors, Grazing-incidence X-ray Diffraction