Mechanisms of the Adsorption and Self-Assembly of Molecules with Polarized Functional Groups on Insulating Surfaces

ABSTRACT: The adsorption and self-assembly of several pentahelicene molecules with polarized and rigid functional groups have been studied on the Suzuki (001) surface in ultrahigh vacuum by noncontact AFM and KPFM, with the assistance of DFT calculations. It is shown that the adsorption strongly depends not only on the functional groups but also on the ionic substrate lattice. In particular, the local dipole of the functional groups, the adsorption geometry with respect to the cation lattice, and the ionic structure of the surface play a dominant role with a considerably large impact on the self-assembly of the helicene molecules. The work provides a detailed insight into the interaction of functionalized molecules with ionic insulator surfaces and into self-assembly. Ordered organic thin films are believed to be important surface systems for a variety of applications, in particular, for conducting devices.1−3 For optimal properties, the films must be 2-D and well-ordered (crystalline),1 which is realized b