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O: Fachverband Oberflächenphysik
O 27: Organic Electronics and Photovoltaics II (jointly with CPP, DS, HL)
O 27.6: Vortrag
Dienstag, 12. März 2013, 10:45–11:00, H32
Correlation of morphology and electronic properties of MoO3-doped CBP layers III: XPS and UPS study — •Maybritt Kühn1,4, Eric Mankel1,4, Daniela Donhauser2,4, Tobias Glaser3,4, Thomas Mayer1,4, and Wolfram Jaegermann1,4 — 1Technische Universität Darmstadt, Fachgebiet Materialwissenschaft — 2Technische Universität Braunschweig, Institut für Hochfrequenztechnik — 3Universität Heidelberg, Kirchhoff-Institut für Physik — 4InnovationLab GmbH, Heidelberg
Electro-chemical doping is a prerequisite to improve efficiency and conductivity of organic OLED materials. Here the p-type doping behavior of MoO3 is analyzed using photoelectron spectroscopy (XPS/UPS). The doped CBP layers were evaporated and analyzed under UHV conditions. Concerning the Fermi level shift three different regimes can be distinguished: At low doping concentrations (< 9 mol%) a rapid shift towards the HOMO level of CBP can be observed, becoming less strong and finally saturating at a maximum shift of 1 eV at a doping concentration of 45 mol%. The electron transfer from CBP to MoO3 leads to the formation of reduced MoO3. Determining the amount of these species we get information of the surface to volume ratio of the MoO3 clusters in dependence of the doping concentration. Also here three different regimes can be distinguished. The morphology and Fermi level shift regimes will be correlated discussing the dopant morphology as shown in Talk I. Finally the amount of transferred charges is calculated regarding the reduced MoO3 species and is compared with the number of cations determined by IR-spectroscopy (Talk II).