Extended space charge region and unoccupied molecular band formation in epitaxial tetrafluorotetracyanoquinodimethane films

• Verfasst von: Gerbert, David [VerfasserIn]
• Verfasst von: Maaß, Friedrich [VerfasserIn]
• Verfasst von: Tegeder, Petra [VerfasserIn]
• Titel: Extended space charge region and unoccupied molecular band formation in epitaxial tetrafluorotetracyanoquinodimethane films
• Verf.angabe: David Gerbert, Friedrich Maaß, and Petra Tegeder
• Umfang: 6 S.
• Fussnoten: Gesehen am 04.05.2018
• Titel Quelle: Enthalten in: The journal of physical chemistry <Washington, DC> / C
• Jahr Quelle: 2017
• Band/Heft Quelle: 121(2017), 29, S. 15696-15701
• ISSN Quelle: 1932-7455
• DOI: doi:10.1021/acs.jpcc.7b02939
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1572641142

Abstract

Generating well-defined molecular structures at inorganic/organic interfaces and within molecular films is fundamental for charge carrier transport and thus the performance of organic molecule-based (opto)electronic devices. Here we show by means of low-energy electron diffraction that tetrafluorotetracyanoquinodimethane (F4TCNQ) grows in an epitaxial fashion on the Au(111) surface, resulting in a unit cell which consists of one molecule. In this well-ordered crystalline films we found the formation of an extended space charge region and a dispersing unoccupied electronic molecular state using energy- and angle-resolved two-photon photoemission. The latter finding is a clear proof for band formation in the crystalline molecular structure. We suggest that the high electron affinity of F4TCNQ and a bandlike electron transport are responsible for the formation of the space charge region. Using F4TCNQ as a hole injection layer may open the opportunity to manipulate the hole injection barrier in a controlled way via variation of the F4TCNQ layer thickness.