title: Investigation of sodium insertion into tetracyanoquinodimethane (TCNQ): results for a TCNQ thin film obtained by a surface science approach.
abstract: In this contribution, we investigate the insertion of sodium into tetracyanoquinodimethane (TCNQ) and its effect on the electronic structure by means of a surface science experiment. We exposed a TCNQ thin film stepwise to sodium vapour and monitored the electronic structure by X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS). During the insertion experiment three stages were observed, which can be related to three different phases, predominantly consisting of TCNQ(0), TCNQ(1-) and TCNQ(2-). With increasing sodium content the Fermi level shifts upwards and new electronic states appear in the band gap. For phases with high sodium content the sodium diffusion seems to be inhibited which we attribute to closed diffusion pathways in the molecular structure of TCNQ(1-).
authors.affiliation: Department of Materials Science, Surface Science Division, Darmstadt University of Technology, Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Precht
authors.affiliation: Department of Materials Science, Surface Science Division, Darmstadt University of Technology, Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany and InnovationLab GmbH, Speyerer Str. 4, 69115 Heidelberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Stolz
authors.affiliation: Department of Materials Science, Surface Science Division, Darmstadt University of Technology, Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany and InnovationLab GmbH, Speyerer Str. 4, 69115 Heidelberg, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Mankel
authors.affiliation: Department of Materials Science, Surface Science Division, Darmstadt University of Technology, Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Mayer
authors.affiliation: Department of Materials Science, Surface Science Division, Darmstadt University of Technology, Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Jaegermann
authors.affiliation: Department of Materials Science, Surface Science Division, Darmstadt University of Technology, Jovanka-Bontschits-Str. 2, 64287 Darmstadt, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Hausbrand