Black Phosphorus for Directed Molecular Assembly with Weak Electronic Coupling

Abstract

The combination of two-dimensional materials with organic molecules offers the possibility to obtain low dimensional hybrid materials with tailored properties. Black phosphorus is a monoelemental semiconducting material with a non-planar puckered atomic structure. Here, we study porphyrin molecules on black phosphorus and show that they self-assemble with an epitaxial relationship indicating that the molecule-surface interaction largely dominates the molecule-molecule interaction. The atomic structure of black phosphorus is found to be at the origin of the substrate driven self-assembly. Despite this strong interaction with molecules, the electronic coupling is found to be weak allowing the molecules to maintain the properties of their gas phase, which is the usual behaviour for van der Waals materials. Therefore, the combination of the peculiar puckered structure with the van der Waals nature of black phosphorus provides this material with the ability to interact strongly enough with adsorbed molecules to drive their assembly but weakly enough to keep their electronic properties intact.

Effect of bonding and antibonding character of electronic states on their tunneling spectra

“…3, which confirms the theoretical description given above. molecular orbital (LUMO) state is broader than the highest occupied molecular orbital (HOMO) state [14], which is distinctively different from what is observed on graphene [14,15]. This can be understood in a simple picture as a consequence of the asymmetric spatial extension of the B and AB states of BP.…”

“…4. The dI/dV spectrum of bulk BP around the Fermi level exhibits a 0.3-V gap corresponding to the gap of bulk BP [7,13,14]. Outside the gap, the dI/dV signal exhibits a stronger increase in the conduction band than in the valence band [Fig.…”