Dresden 2020 – scientific programme
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DS: Fachverband Dünne Schichten
DS 30: Poster: Organic Thin Films and Thin Oxides
DS 30.5: Poster
Wednesday, March 18, 2020, 15:00–18:00, P1A
Analyzing the Influence of Doped Organic Semiconductor Interlayers on the Electronic Structure of Intrinsic Hole Transport Materials — •Markus Frericks1,2, Christof Pflumm3, Eric Mankel1,2, Thomas Mayer1, and Wolfram Jaegermann1,2 — 1Technische Universität Darmstadt, Darmstadt — 2InnovationLab GmbH, Heidelberg — 3Merck KGaA, Darmstadt
The electronic structure at the interfaces of layered electronic devices plays an important role in understanding and improving device properties. In organic light emitting diodes, often a doped layer is placed between the contact and the transport layer to improve the charge injection. While the interface towards the contact is widely studied, less focus is laid on the influence on the intrinsic transport layer. We examined layer systems of doped and undoped hole transport materials. To analyze the electronic structure of the organic semiconductors, photoelectron spectroscopy is used. The organic layers are stepwise deposited by thermal evaporation in an ultra-high vacuum system. In between each deposition step the sample is measured. This allows for the study of the energy level evolution with increasing distance from the interface. The rather difficult interpretation of these organic-organic interfaces is supported by computer modeling. It is found, that the Fermi level position in the intrinsic layer is strongly influenced by the doped layer below. It lies about 1 eV lower compared to a sample without doped layer.