Probing the Properties of Quasi‐Isolated ClAlPc by Using Polycrystalline h‐BN on Pt(111) as a Testbed

Abstract

AbstractThe structural and electronic properties of chloro‐aluminum phthalocyanine (ClAlPc) molecules on insulating hexagonal boron nitride (h‐BN) monolayers (MLs) grown on Pt(111) surfaces are studied via scanning tunneling microscopy and spectroscopy (STM/STS) along with low energy electron diffraction in ultra‐high vacuum conditions. As a reference, the structural properties of the h‐BN/Pt(111) surface are studied, where various moiré patterns associated to different orientations of the h‐BN lattice with respect to the Pt(111) surface below are characterized, for the first time, at the atomic scale. Room temperature deposition of ClAlPc molecules on h‐BN/Pt(111) gives rise to the formation of mainly bilayer molecular structures, where the ClAlPc molecules adopt an alternating Cl‐up and Cl‐down stacking configuration. Upon annealing, bilayer molecular structures become islands comprising only a single layer of molecules adsorbed in a Cl‐up configuration. In the ML regime, the possible influence of the moiré pattern superstructure and the h‐BN lattice on the molecular ordering is also studied. Finally, the electronic properties of ClAlPc on h‐BN/Pt(111) are investigated through high‐resolution STM imaging of the frontier molecular orbitals and differential conductance plots. The results point toward a weak molecule–substrate interaction.