Unraveling orbital hybridization of triplet emitters at the metal-organic interface.

We have investigated the structural and electronic properties of phosphorescent planar platinum(II) complexes at the interface of Au(111) with submolecular resolution using combined scanning tunneling microscopy and spectroscopy as well as density functional theory. Our analysis shows that molecule-substrate coupling and lateral intermolecular interactions are weak. While the ligand orbitals remain essentially unchanged upon contact with the substrate, we found modified electronic behavior at the Pt atom due to local hybridization and charge transfer to the substrate. Thus, this novel class of phosphorescent molecules exhibits well-defined and tunable interaction with its local environment.