Ultrathin films of functionalized oligomers with well-defined chain and conjugation lengths are of interest for organic electronic devices. Using the example of end-capped quinquethiophene vapor-deposited onto a Ag(111) surface, it is demonstrated that highly ordered monolayers of chemisorbed oligomers can be obtained in very large defect-free domains LEED and STM (see Figure) studies provide information about the geometric parameters molecular structure, and quality of the layers.