Interaction at the F16CuPc/TiO2 Interface: A Photoemission and X-ray Absorption Study

The interfacial interaction and charge transfer dynamics between a F16CuPc molecular thin film and rutile TiO2(110) (1X1) surface have been studied by photoelectron spectroscopy (PES), near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, and resonant photoemission spectroscopy (RPES). The evolution of PES spectra as a function of F16CuPc film thickness shows strong coupling between the molecules and the TiO2 surface. Adsorbed molecules experience substrate mediated charge transfer. Electrons being pulled away from nitrogen atoms toward to carbon ring results in an opposite direction binding energy shift for C is and N Is. Moreover, the molecule gets deformed due to their strong interaction with the TiO2 surface. Ultrafast charge transfer from F16CuPc molecules to the TiO2 substrate takes place on the time scale of 10 fs due to their strong electronic coupling. The results pave the way for the design and realization of F16CuPc based electronic devices.