Electronic delocalization in discotic liquid crystals: A joint experimental and theoretical study
2004 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 126, no 38, 11889-11899 p.Article in journal (Refereed) Published
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.
Place, publisher, year, edition, pages
2004. Vol. 126, no 38, 11889-11899 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-22579DOI: 10.1021/ja048669jLocal ID: 1854OAI: oai:DiVA.org:liu-22579DiVA: diva2:242892