Regensburg 2019 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Poster Session III

CPP 37.55: Poster

Mittwoch, 3. April 2019, 11:00–13:00, Poster B1

Investigation of the templating effect of graphene on organic molecular layers — •Max Reimer, Selina Olthof, and Klaus Meerholz — University of Cologne, Luxemburger Str. 116, Germany

Electrical and optical properties of many organic semiconducting molecules are highly anisotropic. Therefore these properties will depend on the packing and ordering motif when deposited as thin films. However, most of the time when such molecules are used in organic electronic devices the growth mode is rather amorphous. Being able to grow layers with an engineered order could dramatically improve their properties such as absorption, emission, and most importantly mobility [1]. In the past years, monolayer graphene has proven to be a useful templating material [2] for subsequent material growth. Using this approach and optimizing the preparation conditions we are able to achieve an ordered and oriented growth mode for merocyanine dyes; this versatile material class is highly interesting for the use in organic photovoltaics. Two in-situ methods, low energy electron diffraction (LEED) and ultraviolet photoelectron spectroscopy (UPS), allow us to observe the packing motif and the width of the energetic levels in the region of the highest occupied molecular orbital (HOMO) which is connected to the degree of order of the molecular layer. We further exploit atomic force microscopy (AFM) which provides information about the grain size of the formed crystalline regions. The optimized film growth allows us to improve the IV characteristic of basic organic devices containing these molecules. [1] Guillaume Schweicher et al., IJC 2014, 54, 595-620 [2] Ti Wang et al., Sci. Rep. 2016, 6, 28895