Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 38: [DS] Organic electronics and photovoltaics: electronic properties I (jointly with CPP, HL, O)
O 38.5: Vortrag
Mittwoch, 28. März 2012, 10:30–10:45, H 2032
IR spectroscopic investigation of the MoO3 doping efficiency in CBP — •Tobias Glaser1,4, Sven Tengeler1,4, Sebastian Beck1,4, Daniela Donhauser2,4, Bernd Lunkenheimer3,4, Andreas Köhn3,4, and Annemarie Pucci1,4 — 1Universität Heidelberg, Kirchhoff-Institut für Physik, INF 227, 69120 Heidelberg — 2Technische Universität Braunschweig, Institut für Hochfrequenztechnik, Schleinitzstraße 22, 38106 Braunschweig — 3Universität Mainz, Institut für Physikalische Chemie, Jakob-Welder-Weg 11, 55128 Mainz — 4InnovationLab GmbH, Speyerer Str. 4, 69115 Heidelberg
A major challenge towards high-efficiency and low-voltage organic electronic devices such as OLEDs is to overcome the low bulk conductivity of the organic films. P-type doping with transition-metal oxides like tungsten oxide and molybdenum oxide has proven to increase the charge carrier concentration in hole transporting materials. But the doping efficiency of only a few percent is rather low and the reason for the low efficiency is not fully understood yet. We investigated doping of the ambipolar charge transport material 4,4’-Bis(N-carbazolyl)-1,1’-biphenyl (CBP) with MoO3 using FTIR-spectroscopy in ultrahigh-vacuum. Comparison of the measured spectra of films with different MoO3-concentration to DFT-calculations reveals the amount of charge transfer from CBP to MoO3 but also shows that most of the CBP molecules are still in the neutral state. Also the impact of substrate temperature during the evaporation process is investigated.
Financial support by BMBF (project MESOMERIE) is gratefully acknowledged.