Berlin 2012 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 44: Poster IV: Thin film photovoltaics; Organic electronics and photovoltaics (jointly with CPP, HL, O); Organic thin films; Trends in atomic layer deposition (Focused session)
DS 44.22: Poster
Freitag, 30. März 2012, 09:30–12:00, Poster E
IR spectroscopic studies on charge transfer in thin films of donor-acceptor complexes — •Sebastian Beck1,4, Diana Nanova2,4, Andreas Fuchs3,4, Christian Lennartz3,4, Tobias Glaser1,4, Michael Kröger2,4, and Annemarie Pucci1,4 — 1Universität Heidelberg, Kirchhoff-Institut für Physik, INF 227, 69120 Heidelberg — 2Technische Universität Braunschweig, Institut für Hochfrequenztechnik, Schleinitzstr. 22, 38106 Braunschweig — 3BASF SE, 67056 Ludwigshafen — 4InnovationLab GmbH, Speyerer Str. 4, 69115 Heidelberg
In the ongoing development of organic electronic devices, new materials with adjustable properties are needed in order to meet different specific requirements. Prototypical examples are the charge transfer complexes (CT complexes) with the acceptor 7,7,8,8-Tetracyanoquinodimethan (TCNQ). In this study, the degree of charge transfer in thin films of organic CT complexes of TCNQ which were deposited via thermal evaporation was determined with infrared spectroscopy. We demonstrate a linear relationship between the shift in the energy of the CN-stretching mode of TCNQ and the charge transfer in the CT complexes. The measured correlation very well agrees with DFT calculations. For Na-TCNQ we observe a splitting in the CN-stretching mode peak, which can be explained by the coupling of two modes and was confirmed by the calculations. In CT complexes with partial charge transfer the appearance of an electronic excitation is demonstrated.
Financial support by BMBF (project MESOMERIE) is gratefully acknowledged.