Berlin 2015 – scientific programme
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DS: Fachverband Dünne Schichten
DS 1: Organic Electronics and Photovoltaics
DS 1.7: Talk
Monday, March 16, 2015, 11:00–11:15, H 2032
Investigation of charge transfer in organic semiconductors using infrared spectroscopy — •Tobias Glaser1,2, Sebastian Beck1,2, and Annemarie Pucci1,2,3 — 1Universität Heidelberg, Kirchhoff-Institut für Physik — 2InnovationLab GmbH, 69115 Heidelberg — 3Universität Heidelberg, Centre for Advanced Materials
Charge transfer in organic semiconductors is used in various ways to increase the performance of organic electronic devices. For example electrochemical doping is used to increase the conductivity in charge transport layers. Additionally, charge injection layers are used to decrease injection barriers between electrodes and organic transport layers. In both cases molecular charge transfer plays an important role, but the basic mechanisms are still subject of heated debate. Due to strong relaxation effects upon molecular charging, infrared (IR) spectroscopy is very well suited to investigate charge transfer in organic semiconductors. Neutral and charged molecules can be distinguished by their different specific vibrational features in spectra of doped layers as well as for interfaces. In this study we investigated charge transfer in thin layers of commonly known transport materials such as 4,4*-bis(N-carbazolyl)-1,1*-biphenyl (CBP) doped with inorganic and organic dopants such as MoO3 or F4TCNQ and at interfaces of organic semiconductors. By quantitative analysis of the experimental spectra the doping efficiency and the degree of charge transfer can be determined for the doped layers. Whereas, for interfacial charge transfer, the formation of a space charge region can be mapped. Financial support by BMBF (project MESOMERIE) is gratefully acknowledged.