Berlin 2015 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 43: P8: Nanoparticles and Compsite Materials
CPP 43.21: Poster
Wednesday, March 18, 2015, 10:00–13:00, Poster A
Charge Storage in β-FeSi2 Nanoparticles — Jens Theis1, •Sebastian Küpper1, Robert Bywalez2, Hartmut Wiggers2, and Axel Lorke1 — 1Fakultät für Physik and CENIDE, Universität Duisburg-Essen — 2Institut für Verbrennung und Gasdynamik and CENIDE, Universität Duisburg-Essen
The increasing use of mobile electronics creates a steady demand for new energy storages with very high capacitance. Here we report on the observation of a surprisingly high specific capacitance of β-FeSi2 nanoparticle layers. The devices work without the need of a fluid phase, the charge storing material is abundant and cost effective, and the sample design is easy to fabricate. Lateral, interdigitated capacitor structures were fabricated on thermally grown silicon dioxide and covered by FeSi2 particles by drop or spin casting. The FeSi2-nanoparticles, with sizes in the range of 10-30 nm, were fabricated by gas phase synthesis in a hot wall reactor. Compared to the bare electrodes, the nanoparticle-coated samples exhibit a 3-4 orders of magnitude increased capacitance. Time-resolved current voltage measurements show that for short times (seconds to minutes), the material is capable of storing up to 1 As/g at voltages around 1 V. The devices are robust and exhibit long term stability under ambient conditions. The specific capacitance is strongly dependent on the air humidity. It is highest for a relative humidity of 95%, while for a relative humidity below 40% the capacitance is almost indistinguishable from a nanoparticle-free reference sample. An isotope effect can be observed by using heavy water vapour.