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Accueil > Séminaires > Séminaires passés > Seminaires de 2012 > Energy level alignment and ultrafast electron dynamics at the pyridine/ZnO(10-10) interface

Dr. A. Julia Staehler (Fritz Haber Institute of the Max Planck Society, Berlin)

Energy level alignment and ultrafast electron dynamics at the pyridine/ZnO(10-10) interface

Mardi 13 Mars 2012 à 14h

Hybrids of inorganic and organic semiconductors may exhibit electronic and excitonic properties that go beyond the linear combination of each material’s properties with each other. At the interface, new states may form through hybridization of molecular orbitals with substrate states. We investigate the occupied and unoccupied electronic band structure and the ultrafast electron dynamics using femtosecond time-resolved two-photon photoemission (2PPE). Characterization of the pristine, ZnO(10-10) surface yields the absolute measurement of the valence and conduction band (CB) edge energies and significant surface band bending upon hydrogen termination that leads to a metallic surface. We furthermore directly monitor the hot electron relaxation in the bulk ZnO CB on femtosecond timescales and electron capture at the semiconductor surface (>100 ps). Adsorption of pyridine (C5H5N) leads to a massive reduction of the work function of the sample up to DF = - 2.7 eV which strongly affects the energy level alignment at the inorganic/organic interface.

This work is partially funded by the DFG through Sfb 951.