Regensburg 2013 – scientific programme
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DS: Fachverband Dünne Schichten
DS 15: Organic Electronics and Photovoltaics II (jointly with CPP, HL, O)
DS 15.10: Talk
Tuesday, March 12, 2013, 12:00–12:15, H32
Electronic interface properties of PCBM using photoelectron spectroscopy — •Julia Maibach1,2, Eric Mankel1,2, Thomas Mayer1,2, and Wolfram Jaegermann1,2 — 1Technische Universität Darmstadt, Fachbereich Materialwissenschaft — 2InnovationLab GmbH, Heidelberg
The electronic interface properties of wet processed organic materials are of current interest as many fabrication techniques for organic electronic devices are based on inks. Photoelectron spectroscopy (PES) has proven to be a powerful method to investigate the electronic structure at semiconductor contacts. Due to high surface sensitivity of PES, the interface is generally prepared step by step in UHV. For films deposited from solution we integrated a newly developed ultrasonic nebulizer unit to the UHV cluster-tool of the analytic competence center at the InnovationLab, Heidelberg. Dilute solutions of Phenyl-C61-butyric acid methyl ester (PCBM) in Chlorobenzene were used to deposit the material on ozone and polymer treated ITO as well as on gold to investigate the contact behavior of PCBM. With the nebulizer method layer thicknesses in the range of 10-20 Å can be achieved while repeated exposure to the nebulae increased step by step the emission intensities of the PCBM. Furthermore drop-casting of thicker layers has been performed allowing in combination the thickness dependent determination of the electronic properties. In case of PCBM on ozone treated ITO the HOMO spectra shift 0.4 eV to higher binding energy with increasing thickness, indicating the formation of a space charge region in PCBM due to electron transfer from ozone treated ITO.