Self-assembly of functionalized anthradithiophene on Au(111)

We utilize scanning tunneling microscopy (STM) to characterize the initial growth and crystallization of the high-performance, small organic molecule 2,8-difluoro-5,11-triethylsilylethynyl (diF TESADT) on Au(111). Two ordered structures are observed with diF TESADT backbone planes parallel to the substrate. Submolecular resolution imaging of the first monolayer ordered film regions realizes structures with close approach of fluorine-sulfur and fluorine-fluorine atoms of alternating molecules. These measurements provide evidence for the importance of non-covalent F-S and F-F interactions in driving 2D self-assembly. Scanning Tunneling Spectroscopy indicates a 2.4 eV transport gap which is insensitive to the local domain. Structures and growth are put in context of bulk measurements and device performance measurements.