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O: Fachverband Oberflächenphysik
O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)
O 60.85: Poster
Wednesday, March 16, 2011, 17:30–21:00, P4
Calculation of up-conversion signal of Er3+ ions near gold nanospheres — •Florian Hallermann1, Stefan Fischer2, Jan Christoph Goldschmidt2, and Gero von Plessen1 — 1Institute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany — 2Fraunhofer Institute for Solar Energy Systems, Heidenhofstr. 2, 79110 Freiburg, Germany
In conventional silicon solar cells, photons with energies below the silicon band gap (1.12 eV) do not contribute to current generation. The near-infrared part of the solar spectrum could possibly be exploited by use of up-conversion processes. For example, electrons could be excited from the ground state to a final state via intermediate states through sequential absorption of infrared photons. Such electrons subsequently relax from the final state by emitting photons whose energy is high enough to be absorbed in the silicon.
In this work, we show on the basis of model calculations how the up-conversion signal of Er3+ ions can be enhanced using spherical gold nanoparticles. In the vicinity of the nanoparticles, the excitation rate of the ions is changed due to the near-field of the particles. These changes are computed using Mie theory and a rate equation system. In addition, also the relaxation times of all involved excited states of the ions are changed by the presence of metal nanoparticles. This is caused by a near-field induced energy transfer from the ions to the nanoparticles, which offer additional radiative and nonradiative decay channels. Here, we semi-analytically calculate the effects that these changes have on the up-conversion signal.