Selective Cooperative Self-Assembly between an Organic Semiconductor and Native Adatoms on Cu(110)

We investigate molecular adsorption, film growth, and self-assembly for titanyl phthalocyanine (TiOPc) on Cu(110) in ultrahigh vacuum using low-temperature scanning tunneling microscopy (LT-STM). Three unique molecular adsorption configurations are identified, two of which are referred to as "O-down" and one as "O-up", each differing in the molecular registry with the surface. Even though disorder dominates film growth to coverages in excess of 1 monolayer in the native thin film, extended self-assembled 1D configuration-dependent nanoribbons form upon annealing of the film. The STM data reveal that the nanoribbons consist of "O-down" TiOPc and a Cu skeleton, anchoring cooperatively on the Cu(110) terraces. Agent-based simulations show that nanoribbons grow and elongate due to anisotropic adatom attachment rates along the two major surface directions. The study reveals the importance of molecule-adatom interactions for novel approaches toward nanostructuring organic semiconductor/metal interfaces.