X-ray diffraction investigations of well-ordered sexithiophene films deposited on flexible substrates

Through optimizing deposition conditions such as substrate temperature and growth rate, well-ordered sexithiophene films were deposited on flexible substrates of insulating polyvinylpyrrolidone (PVP) and transparent conductive indium tin oxide (ITO). X-ray diffraction investigation showed that well-ordered sexithiophene films were deposited at substrate temperature of 90 °C and growth rate of 10 nm/min on PVP substrate with the main axis of sexithiophene molecules oriented parallel to the PVP surface and the crystallinity was declined with the decrease of substrate temperature. On ITO substrate, substrate temperature notably influenced the sexithiophene molecule orientation. There existed an inclined angle between the main axis of sexithiophene molecules and the ITO surface in the film deposited at room temperature. With the increase of substrate temperature, the main axis tended to parallel to the ITO surface and well-ordered sexithiophene film was deposited at 50 °C and 10 nm/min. Too slow or too rapid growth rate would lead to poor crystallinity of sexithiophene films on both PVP and ITO substrates.