Dresden 2014 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 100: Graphene: Adsorption, Intercalation, Doping (organized by O)

TT 100.3: Talk

Thursday, April 3, 2014, 16:30–16:45, WIL C107

Wetting properties of parahexaphenyl on exfoliated graphene — •Markus Kratzer¹, Stefan Klima¹, Borislav Vasić¹, Aleksandar Matković², Marijana Milićević², Rados Gajić², and Christian Teichert¹ — ¹Institute of Physics, Montanuniversität Leoben,Franz Josef Straße 18, 8700 Leoben, Austria — ²Institute of Physics, University of Belgrade, Pregrevica 118 P.O. Box 68, 11080 Belgrade, Serbia

Graphene (Gr) bears potential to serve as transparent and flexible electrode material in organic electronics. Therefore, understanding of the growth of organic thin films on it is essential. Here, we investigated the growth morphology of films formed by the rodlike para-hexaphenyl (6P) molecule on Gr as a model system. As substrates exfoliated graphene transferred onto a silicon oxide support were used. Sub-monolayer amounts of 6P were deposited by means of hot-wall epitaxy between 333 K and 393K. The evolving film morphologies, investigated by atomic-force microscopy (AFM), exhibited a strong dependence on temperature and number of supporting Gr layers. At 333 K, needle like structures - which are known to be composed of flat lying molecules [1]- and islands composed of upright standing molecules coexist on the Gr. For the higher temperatures solely needles, forming networks, are found. The needles forming at 363 K exhibit an increasing dewetting with increasing number of Gr layers which is attributed to Gr layer dependent changes in surface energy, diffusion properties and preferential adsorption sites.

[1] C. Teichert et al. Appl. Phys. A 82 (2006) 665.