Air-Stable Solution-Processed Thin-Thin Film Transistors with Hole Mobilities of 3.5 cm$^{2}$/Vs

We report on organic thin-film transistors fabricated on a novel soluble small molecule organic semiconductor difluoro bis(triethylgermyl) anthradithiophene. Fabrication techniques are all applicable at room temperature and ambient pressure, and include drop-casting, spin-coating, and spray deposition. Devices exhibit remarkable electronic properties, including charge carrier mobilities as high as 3.5 cm$^{2}$/Vs, on/off current ratios of 10$^{5}$, and good environmental and operational stability. Chemical treatment of the contact surface with self-assembled monolayers allows us great control of the crystalline order within the organic semiconductor layer. Because thin-film microstructure defects such as grain boundaries reduce the charge transport capabilities of the active layer, high quality single crystals are grown by physical vapor transport for comparison. By correlating the electrical properties with the structural data obtained from X-ray diffraction, we find that a good $\pi -\pi $ overlap is responsible for this superior electronic behavior.