title: Chemical Interaction, Space-charge Layer and Molecule Charging Energy for a TiO2/TCNQ Interface.
abstract: Three driving forces control the energy level alignment between transition-metal oxides and organic materials: the chemical interaction between the two materials, the organic electronegativity and the possible space charge layer formed in the oxide. This is illustrated in this study by analyzing experimentally and theoretically a paradigmatic case, the TiO2(110) / TCNQ interface: due to the chemical interaction between the two materials, the organic electron affinity level is located below the Fermi energy of the n-doped TiO2. Then, one electron is transferred from the oxide to this level and a space charge layer is developed in the oxide inducing an important increase in the interface dipole and in the oxide work-function.
authors.affiliation: Dept. Surfaces, Coatings and Molecular Astrophysics, Institute of Materials Science of Madrid (ICMM-CSIC), Sor Juana Inés de la Cruz 3, E-28049 Madrid (Spain).
authors.forename: José I
authors.initials: JI
authors.lastname: Martínez
authors.affiliation: Dept. Condensed Matter Theoretical Physics and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, ES-28049 Madrid (Spain).
authors.forename: Fernando
authors.initials: F
authors.lastname: Flores
authors.affiliation: Dept. Condensed Matter Theoretical Physics and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, ES-28049 Madrid (Spain).
authors.forename: José
authors.initials: J
authors.lastname: Ortega
authors.affiliation: Dept. Physics and Astronomy, and Laboratory for Surface Modification, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8019 (USA).
authors.forename: Sylvie
authors.initials: S
authors.lastname: Rangan
authors.affiliation: Dept. Physics and Astronomy, and Laboratory for Surface Modification, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8019 (USA).
authors.forename: Charles
authors.initials: C
authors.lastname: Ruggieri
authors.affiliation: Dept. Physics and Astronomy, and Laboratory for Surface Modification, Rutgers, The State University of New Jersey, Piscataway, NJ 08854-8019 (USA).
authors.forename: Robert
authors.initials: R
authors.lastname: Bartynski
keywords: DFT; band bending; charging energy; space-charge layer; tcnq; titanium dioxide