Dresden 2011 – scientific programme
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O: Fachverband Oberflächenphysik
O 29: Graphene I
O 29.7: Talk
Tuesday, March 15, 2011, 12:45–13:00, WIL B321
Single and double layer graphenes as ultra-barriers for fluorescent polymer films — •Philipp Lange1, Martin Dorn1, Nikolai Severin1, David A. Vanden Bout2, and Jürgen P. Rabe1 — 1Humboldt-Universität zu Berlin, Department of Physics, Germany — 2The University of Texas at Austin, Department of Biochemistry and Chemistry, USA
Graphene, with its combined high electrical conductivity, optical transparency and mechanical flexibility, offers great potential for electrodes in flexible organic optoelectronic devices. Since freely suspended graphene is also largely impermeable to gases, it could even serve as both transparent electrode and effective barrier to protect the device against the ubiquitous degradation by water and oxygen. However, in a working device graphene may be subject to structural degradation. Here we report on the chemical and structural stability of graphene in-situ on a conjugated polymer film. Fluorescence and scanning force microscopies were used to probe the degradation of the polymer protected from ambient by graphene. We detected individual permeable point defects in single layer graphene resulting from a rare event structural degradation. Double layer graphene in contrast is stable and protects the polymer most efficiently from degradation. We estimate an upper limit of the water and oxygen transmission rates through graphene in direct contact with the polymer film as low as 5x10−6 g m−2day−1 and 6x10−3 cm3m−2day−1, respectively, which is on the order of the technologically required transmission rates. This suggests that graphenes can function as both electrode and barrier layer in future devices.