title: Photoemission studies of polythiophene and polyphenyl films produced via surface polymerization by ion-assisted deposition.
abstract: Conducting polymer films are grown by mass-selected, hyperthermal thiophene ions coincident on a surface with a thermal beam of organic monomers of either alpha-terthiophene (3T) or p-terphenyl (3P) neutrals. Mass spectrometry and X-ray photoelectron spectroscopy previously verified polymerization of both 3T and 3P by 200 eV C(4)H(4)S(+) during surface polymerization by ion-assisted deposition (SPIAD). The electronic structure of these films are probed here by ultraviolet photoelectron spectroscopy (UPS) and polarized near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and compared with similar spectra of evaporated films. The conducting polymer films formed by SPIAD display new valence band features resulting from a reduction in both their band gap and barrier to hole injection, which are calculated from the occupied and unoccupied valence band states measured by UPS and NEXAFS. These changes in film electronic structure result from an increase in the electron conjugation length and other changes in film structure induced by SPIAD.
authors.affiliation: Department of Chemistry (m/c 111), University of Illinois at Chicago, Chicago, Illinois 60607-7061, USA.
authors.forename: Sanja
authors.initials: S
authors.lastname: Tepavcevic
authors.forename: Amanda T
authors.initials: AT
authors.lastname: Wroble
authors.forename: Mark
authors.initials: M
authors.lastname: Bissen
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Wallace
authors.forename: Yongsoo
authors.initials: Y
authors.lastname: Choi
authors.forename: Luke
authors.initials: L
authors.lastname: Hanley