Interplay of local and global interfacial electronic structure of a strongly coupled dipolar organic semiconductor

Abstract

We investigate the consequences of strong electronic coupling at the organic semiconductor/metal interface in both the ground and excited state manifold for the case of chloro-boron subphthalocyanine on Cu(111). Using a combination of low-temperature scanning tunneling microscopy and ultraviolet photoelectron spectroscopy and angle-resolved two-photon photoemission, we are able to connect local electronic interactions at the interface with thin film structure despite complex growth in the submonolayer regime. We show that strong coupling leads to charge transfer from the surface to the molecule, and we are able to correlate this observation with the specific molecular adsorption geometry. Strong coupling further results in molecular excited state anion resonances and is responsible for autoionization of highly excited image potential states, relating to the heterogeneous electronic environment in these thin films. This study provides a step towards disentangling interfacial electronic interactions at complex organic/metal interfaces.