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) (1×1) 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 1s and N 1s. 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