Control of Two-Dimensional Ordering of F16CuPc on Bi/Ag(111): Effect of Interfacial Interactions

Abstract

In-situ low-temperature scanning tunneling microscopy, density functional theory (DFT) calculations, and molecular dynamics (MD) simulations have been used to systematically investigate the supramolecular assembly of copper hexadecafluorophthalocyanine (F16CuPc) on various Bi/Ag(111) surfaces, including metallic BiAg2 surface alloy, semimetal Bi-P × √3 overlayer and Bi(110) monolayer. We demonstrate that the molecular ordering of F16CuPc is strongly affected by the molecule−substrate interfacial interactions on different substrates and the intermolecular interactions. At the monolayer region (lst layer), F16CuPc molecules interact strongly with BiAg2 and form a quasi-hexagonal unit cell with two alternative “α” and “β” in-plane orientations to minimize the repulsive electrostatic forces between neighboring F16CuPc. In contrast, a highly ordered quadratic monolayer structure with the same in-plane orientation forms on both P × √3 overlayer and Bi(110) surface due to the relatively weak interfacial interact...