Electronic delocalization in discotic liquid crystals: A joint experimental and theoretical study

Xavier Crispin*, Jérôme Cornil, Rainer Friedlein, Koji Kamiya Okudaira, Vincent Lemaur, Annica Crispin, Gaël Kestemont, Matthias Lehmann, Mats Fahlman, Roberto Lazzaroni, Yves Geerts, Göran Wendin, Nobuo Ueno, Jean-Luc Bredas, William R. Salaneck

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

132 Scopus citations

Abstract

Discotic liquid crystals emerge as very attractive materials for organic-based (opto)electronics as they allow efficient charge and energy transport along self-organized molecular columns. Here, angle-resolved photoelectron spectroscopy (ARUPS) is used to investigate the electronic structure and supramolecular organization of the discotic molecule, hexakis(hexylthio)diquinoxalino[2,3-a:2′,3′-c]phenazine, deposited on graphite. The ARUPS data reveal significant changes in the electronic properties when going from disordered to columnar phases, the main feature being a decrease in ionization potential by 1.8 eV following the appearance of new electronic states at low binding energy. This evolution is rationalized by quantum-chemical calculations performed on model stacks containing from two to six molecules, which illustrate the formation of a quasi-band structure with Bloch-like orbitals delocalized over several molecules in the column. The ARUPS data also point to an energy dispersion of the upper π-bands in the columns by some 1.1 eV, therefore highlighting the strongly delocalized nature of the π-electrons along the discotic stacks.

Original languageEnglish (US)
Pages (from-to)11889-11899
Number of pages11
JournalJournal of the American Chemical Society
Volume126
Issue number38
DOIs
StatePublished - Sep 29 2004

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

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