Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 45: Nanomaterials - Nanospheres & Fibres

MM 45.1: Talk

Wednesday, March 13, 2013, 16:30–16:45, H26

Fabrication of transparent metal electrodes by nanosphere lithography — •Eser Metin Akinoglu, Anthony Morfa, and Michael Giersig — Freie Universität Berlin, Department of Physics, Berlin, Germany

Electrodes providing sufficient transparency and conductivity are important for high performance optoelectronic applications such as thin-film solar cells and light emitting diodes. Periodically perforated metal films provide a tunable basis to achieve high transparency while maintaining a low sheet resistance by simply changing the geometrical dimensions of the metal grid.

Nanosphere lithography is an inexpensive method to fabricate tunable transparent metal electrodes. This technique utilizes a self assembled and hexagonally close packed monolayer of colloidal polystyrene submicron particles as a lithography mask. Annealing and reactive ion etching in an oxygen plasma is used to modify the mask. Metal is then deposited and the resultant metal nanostructure shapes and dimensions are determined by the mask's negative image.

In this presentation we discuss results from transparent silver electrodes produced in this way. We demonstrate structural, electronic and optical properties of our gratings with SEM, AFM, four-point probe and optical measurements. Sheet resistances as low as 3 Ohm/Sq and an average transmissivity of 70% was achieved. Percent transmission values up to 82% are predicted by a simple geometric model promising competitiveness with transparent conductive oxides. Finally, these silver electrodes were incorporated into organic photovoltaic devices.