Dresden 2017 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 9: Organic Electronics and Photovoltaics II: Doping (joint session CPP/DS/HL, organized by CPP)
CPP 9.10: Talk
Monday, March 20, 2017, 17:45–18:00, ZEU 260
Molecular drift of p-type dopants in doped organic semiconductors driven by an external electric field and studied by spectroscopic IR-microscopy — •Sebastian Beck1,2, Vipilan Sivanesan1,2, Lars Müller2,3, Seon-Young Rhim1,2, Jakob Bernhardt1,2, and Annemarie Pucci1,2 — 1Universität Heidelberg, Kirchhoff-Institut für Physik — 2InnovationLab GmbH, Heidelberg — 3TU Braunschweig, Institut für Hochfrequenztechnik
A homogeneous dopant distribution is known to be important for efficient charge transfer (CT) in doped organic semiconductors as well as the functionality of organic electronic devices. Therefore, a lot of effort is made to control the molecular composition in devices throughout the deposition process. However, during device operation an unintentional movement of charged molecules such as dopants through the layers can occur and can reduce or even destroy device performance. To further improve the understanding of these effects the implementation of new analytical methods is advised. In this study, the motion of the p-type dopant Mo(tfdCO2Me)3 in highly regioregular P3HT induced by an external electric field was studied with spectroscopic IR-microscopy. The molecular drift was identified by measuring laterally resolved IR spectra of doped layers between two electrodes before and after applying a dc field of about 2 V/micron. An analysis of the changes of the vibrational modes of the dopant molecule as well as the spectral features of the charged P3HT chains enabled an estimate of the mobility of the dopant molecules. Our results are in agreement with electrical measurements and clarify underlying processes of device fatigue.