Abstract
Growth mechanism of bis(2-phenylethynyl) end-substituted oligothiophenes (diPhAc-nTs, n = 2, 3) based organic thin films deposited by high vacuum deposition on Si/SiO2 substrates have been investigated. Especially the influence of acetylenic (-C≡C-) vs. olefinic (-C=C-) spacers in thiophene-phenylene derivatives on the growth process was studied in details. While olefinic containing oligomers, distyryl-oligothiophenes (DSnTs) show a Stranski-Krastanov mechanism, dependence of thin film morphology on thickness and substrate temperature by atomic force miscrocopy (AFM) reveals a Volmer-Weber mechanism in diPhAc-nTs. These results underline the importance of molecular structure on growth mechanism and resulting thin film morphology for future electronic applications such as charge transport in organic thin film transistors (OTFTs).