Regensburg 2013 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 65: Poster: Organic electronics and photovoltaics (CPP; jointly with HL, O)
HL 65.6: Poster
Mittwoch, 13. März 2013, 16:30–18:30, Poster C
Investigation of Polyethylenimine and Polyethylenimine-ethoxylated as electron injection layers in solution processed organic light-emitting diodes. — •Sebastian Stolz1,4, Ingo Ringle2, Eric Mankel3,4, Janusz Schinke4, Michaela Agari2, Gerardo Hernandez-Sosa1,4, Wolfram Jaegermann3,4, Uli Lemmer1, and Norman Mechau1,4 — 1Light Technology Institute, Karlsruhe Institute of Technology — 2Pre-development, Heidelberger Druckmaschinen AG — 3Materials Science Institute, Technische Universität Darmstadt — 4InnovationLab GmbH, Heidelberg
One obstacle for inexpensive solution processed organic light-emitting diodes (OLEDs) is the current use of low work-function metals like calcium or barium as cathode materials. These metals are highly reactive, which is why they cannot be easily solution processed but have to be prepared in UHV. In this work, we investigate two organic polymers, Polyethylenimine (PEI) and Polyethylenimine-ethoxylated (PEIE), which are known to reduce the work-function of various metals, for their applicability as electron injection layers. Therefore, both polymers are dissolved in 2-Methoxyethanol with varying concentrations and are then spin coated on top of Aluminum substrates. The concentration dependent change in work-function is determined by kelvin probe measurements and ultraviolet photoemission spectroscopy. Furthermore, OLEDs using PEI, or PEIE respectively, as electron injection layer are prepared by spin coating. Compared to reference devices with calcium as electron injection material, these OLEDs show comparable turn on voltages and luminance values of more than 50%.