Interface charge transfer between metal phthalocyanine and fluorinated hexaazatrinaphthylene molecules

A typical donor/accepter (D/A) interface made of fluorinated hexaazatrinaphthylene (HATANA-F6) and metal phthalocyanine (MPc) molecules has been studied by photoelectron spectroscopy. Planar shape copper phthalocyanine (CuPc) and non-planar titanyl phthalocyanine (TiOPc) molecules show contrast behavior of D/A interface charge transfer (CT), though the electron affinity of HATANA-F6 is smaller than the ionization potential (IP) of both MPcs. While the CuPc/HATNA-F6 interface has no clue for the CT, the TiOPc/HATNA-F6 has an indication of interface CT-induced band bending. Not only the difference in IP but also molecular shape and interface geometry at D/A contact largely affect the characteristics of CT state formation.