Electronic properties of the polycrystalline tin dioxide interface with conjugated organic layers

• Published in: Surface science 2011-08, Vol.605 (15), p.1449-1453
• Main Authors: Komolov, A.S., Komolov, S.A., Lazneva, E.F., Gavrikov, A.A., Turiev, A.M.
• Format: Article
• Language: English
• Subjects: Amorphous thin films; Ceramic thin films; Charge transfer; Conjugated organic molecules; COPPER PHTHALOCYANINE; CRYSTAL STRUCTURE; DEPOSITION; Deposits; Electron-solid scattering and transmission-elastic; ELECTRONIC STRUCTURE; FERMI SURFACES; INTERFACES; Non-epitaxial thin film structures; ORGANIC COMPOUNDS; OXIDES; Surface electronic phenomena (work function surface potential, surface states, etc.); THIN FILMS; Tin dioxide; Tin oxides; Work functions
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/j.susc.2011.05.010

The results on the electronic structure of the unoccupied electronic states of the polycrystalline SnO 2 in the energy range from 5 eV to 25 eV above the Fermi level are presented. The modification of the electronic structure and of the surface potential upon deposition of the ultrathin films of copper phthalocyanine (CuPc) and of perylene tetracarboxylic acid dianhydride (PTCDA) film onto the SnO 2 surface were studied using the very low energy electron diffraction (VLEED) method and the total current spectroscopy (TCS) measurement scheme. A substantial attenuation of the TCS signal coming from the SnO 2 surface was observed upon formation of a 1.5–2 nm thick organic deposit layer while no new spectral features from the deposit were distinguishable. It was observed that the electronic structure typical for the organic films was formed within the organic deposit thickness range from 2 nm to 7 nm. The interfacial charge transfer was characterized by the formation of the polarization layer up to 5 nm thick in the organic films. The PTCDA deposition on SnO 2 was accompanied by the negative charge transfer onto the organic layer and to the 0.65 eV increase the surface work function. At the CuPc/SnO 2 interface, the negative charge was transferred to the SnO 2 surface and the overall surface work function decreased by 0.15 eV. ► DOUS of the polycrystalline SnO 2 surface was determined. ► Modifications of DOUS upon deposition of the conjugated organic films were observed. ► A polarization layer up to 5 nm thick is formed in the organic films.