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 Brédas, William R. Salaneck

Research output: Contribution to journalArticlepeer-review

137 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
Externally publishedYes

ASJC Scopus subject areas

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

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