Spontaneous aggregation of pentacene molecules and its influence on field effect mobility

The authors have found that pentacene molecules deposited on SiO2 substrates treated with self-assembled monolayers, such as hexamethyldisilazane or octadecyltrichlorosilane, aggregate spontaneously. In situ, real-time low-energy electron microscopy investigation of the morpho-logical changes in pentacene films deposited under ultrahigh vacuum reveals that the balance between pentacene film and substrate surface energies is an origin of this aggregation. With in situ atomic force microscopy - field effect transistor measurements, the authors demonstrate that field effect mobility is critically affected by this aggregation.