A two-dimensional superstructure of molecules with high electron affinity was successfully formed on Au(111), and it indicated wide band-gap n-type behavior. The molecule used was fluorinated fullerene (C60F36). Although there exist three isomers (C3, C1, and T) in our molecular source, scanning tunneling microscopy (STM) images and density functional theory (DFT) calculations suggested that the molecules in the well-ordered region consisted of only the C3isomer. Its LUMO distribution governs the adsorption orientation due to partial electron transfer from Au to the molecule. The intermolecular C-F…p electrostatic interactions determines the lateral orientation of C60F36 molecules.

[Ref] Shimizu et al., ACS Nano 6, 2679-2685 (2012).