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DS: Fachverband Dünne Schichten

DS 26: Organic Electronics and Photovoltaics (jointly with CPP, HL, O)

DS 26.12: Vortrag

Mittwoch, 13. März 2013, 18:45–19:00, H33

Improving the contact materials of organic electronic devices: Polymeric dipole layers vs. self assembling monolayers — •Janusz Schinke^1,2, Julian Heusser^3,2, Marc Hänsel^3,2, Julia Maibach^4,2, Wolgang Kowalsky^1,2, Michael Kröger^1,2, Eric Mankel^4,2, and Wolfram Jaegermann^4,2 — ¹TU Braunschweig, Institut für Hochfrequenztechnik — ²Innovation Lab GmbH — ³Universität Heidelberg, Kirchhoff-Institut für Physik — ⁴TU Darmstadt, Materials Science Institute, Surface Science Division

In organic electronic devices, charge injection at the contacts is crucial for high electrical performance. Most of these devices require at least one electrode with a sufficiently low work function (WF). Low-WF electrodes like alkaline earth metals are easily available; however, they are chemically very reactive and oxidize in ambient atmosphere. A smart way to overcome this problem is the use of molecular or polymeric dipole layers (PDLs). The use of PDLs to tune an electrodes work function can be advantageous over self assembled monolayers(SAMs) as the PDL concept can be applied to a wider range of electrode materials like ITO, Ag, Au or Al. We have used two different PDLs: branched polyethylenimine (PEI) and polyethyleneimine ethoxylate (PEIE). We studied the the properties of PDL treated substrates via AFM, ambient Kelvin probe and XPS/UPS. Both interlayers lower the metal substrate work function by approx. 1000meV. On ITO we reach absolute values of about 3.0eV which leads to strongly enhanced electron injection in model devices.