Growth conditions effects on morphology and transport properties of an oligothiophene semiconductor

In this paper we report X-ray diffraction measurements and UV–visible spectra of thin film of 8T oligothiophene grown at two substrate temperatures 25 and 175 °C. We also report the scanning electron microscopy pictures of 8T films deposited at different temperatures (25, 120, 150 and 175 °C). These experimental results account for a different structural organization of organic molecules in the thin films. We also show that the increase of substrate temperature enhances the charge transport in 8T-based field-effect transistors. UV–visible spectroscopy shows that heating the substrate during 8T film deposition enhances the molecular order and leads to large crystallites. The last result is confirmed by scanning electron microscopy. Carrier mobility in 8T field-effect transistor increases rapidly when the substrate temperature exceeds 120 °C, up to a value of 0.33 cm2 V−1 s−1.