Hybrid states and charge transfer at a phthalocyanine heterojunction: MnPc(δ+)/F16CoPc(δ-)

Using photoelectron spectroscopy we demonstrate charge transfer at an interface between two well-known transition metal phthalocyanines, MnPc and F16CoPc, resulting in charged MnPc(δ+) and F16CoPc(δ-) species. Moreover, the transferred charge is substantially confined to the two transition metal centers. Density functional theory calculations reveal that a hybrid state is formed between the two types of phthalocyanines, which causes this charge transfer. For the hybrid state the Mn 3d(xz) interacts with the Co 3d(z2) orbital leading to a two-level system. As only the lower of the two hybrid states is occupied, the charge is directly transferred to the Co 3d(z2) orbital.