Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 65: Organic Photovoltaics and Electronics
O 65.10: Vortrag
Mittwoch, 9. März 2016, 17:45–18:00, H2
Controlling the electronic properties in liquid crystal conjugated small molecules for application in electronics — •Nadine Tchamba Yimga1, Holger Borchert1, Peer Kirsch3, Jürgen Parisi1, and Elizabeth von Hauff2 — 1Department of Physics, University of Oldenburg, Germany — 2Department of Physics and Astronomy, VU University Amsterdam, The Netherlands — 3Merck KGaA, Liquid Crystals R&D Chemistry, Germany
Organic semiconductors offer numerous advantages for electronics. However, carrier mobilities in organic semiconductors are generally orders of magnitude lower than in inorganic semiconductors. This is a major bottle neck for device efficiency. The electrical properties are additionally dependent on thin film morphology which is challenging to control in solution deposited films. We studied structure-function relationships in a novel liquid crystal molecule. The molecular films demonstrate phase changes from crystalline to nematic to isotropic phases at temperatures of 140 C, 165 C and 250 C, respectively. We demonstrate the influence of temperature on the structure of solution processed films with cross polarized microscope (CPM) and X-ray diffraction (XRD). Current-voltage measurements and impedance spectroscopy were performed on films annealed to temperatures above the crystalline - nematic phase change and subsequently cooled. The mobility increases from 10−4 cm2 V−1 s−1 to 10−3 cm2 V−1 s−1. We demonstrate that controlled structural manipulation of the film can be used to reduce electronic disorder. These results show the potential of liquid crystal conjugated materials in electronic applications.