title: Microscopic origin of the charge transfer in single crystals based on thiophene derivatives: A combined NEXAFS and density functional theory approach.
abstract: We have investigated the charge transfer mechanism in single crystals of DTBDT-TCNQ and DTBDT-F4TCNQ (where DTBDT is dithieno[2,3-d;2',3'-d'] benzo[1,2-b;4,5-b']dithiophene) using a combination of near-edge X-ray absorption spectroscopy (NEXAFS) and density functional theory calculations (DFT) including final state effects beyond the sudden state approximation. In particular, we find that a description that considers the partial screening of the electron-hole Coulomb correlation on a static level as well as the rearrangement of electronic density shows excellent agreement with experiment and allows to uncover the details of the charge transfer mechanism in DTBDT-TCNQ and DTBDT-F4 TCNQ, as well as a reinterpretation of previous NEXAFS data on pure TCNQ. Finally, we further show that almost the same quality of agreement between theoretical results and experiment is obtained by the much faster Z+1/2 approximation, where the core hole effects are simulated by replacing N or F with atomic number Z with the neighboring atom with atomic number Z+1/2.
authors.affiliation: Graduate School Materials Science in Mainz, 55128 Mainz, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Chernenkaya
authors.affiliation: Physikalisches Institut, Goethe-Universität, 60438 Frankfurt am Main, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Morherr
authors.affiliation: Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Backes
authors.affiliation: Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Popp
authors.affiliation: Physikalisches Institut, Goethe-Universität, 60438 Frankfurt am Main, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Witt
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
authors.forename: X
authors.initials: X
authors.lastname: Kozina
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
authors.forename: S A
authors.initials: SA
authors.lastname: Nepijko
authors.affiliation: Institut für Anorganische Chemie, Goethe-Universität, 60438 Frankfurt am Main, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Bolte
authors.affiliation: MAX-IV Laboratory, Lund University, 22100 Lund, Sweden.
authors.forename: K
authors.initials: K
authors.lastname: Medjanik
authors.affiliation: MAX-IV Laboratory, Lund University, 22100 Lund, Sweden.
authors.forename: G
authors.initials: G
authors.lastname: Öhrwall
authors.affiliation: Physikalisches Institut, Goethe-Universität, 60438 Frankfurt am Main, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Krellner
authors.affiliation: Max-Planck-Institut für Polymerforschung, 55021 Mainz, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Baumgarten
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
authors.forename: H J
authors.initials: HJ
authors.lastname: Elmers
authors.affiliation: Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Schönhense
authors.affiliation: Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany.
authors.forename: H O
authors.initials: HO
authors.lastname: Jeschke
authors.affiliation: Institut für Theoretische Physik, Goethe-Universität, 60438 Frankfurt am Main, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Valentí