Dresden 2009 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 8: Glass I

DF 8.3: Vortrag

Dienstag, 24. März 2009, 10:40–11:00, WIL B321

Improving up-conversion efficiency of rare earth ions by metallic nanoparticles — •Stefan Wackerow¹, Marcel Dyrba¹, Stefan Schweizer^1,2, Gerhard Seifert¹, and Heinrich Graener¹ — ¹Martin Luther university Halle-Wittenberg, 06120 Halle (Saale), Germany — ²Fraunhofer Center for Silicon Photovoltaics, 06120 Halle (Saale), Germany

A potential way to increase silicon solar cell efficiency is frequency up-conversion of infrared sunlight which can be done by rare earth ions. A novel approach to enhance the up to now rather low up-conversion rates of rare earth ions in glasses is the inclusion of metallic nanoparticles in the glass. The nanoparticles may increase up-conversion efficiencies by the local near-field enhancement and interaction of the plasmon polaritons with rare earth energy levels.

We are therefore studying the co-doping of glasses with rare earth ions and metallic nanoparticles. Generation of silver nanoparticles in glasses is a two-step process. First, silver ions are brought into the glass by field-assisted ion exchange. Second, these glasses are heated in an hydrogen atmosphere, reducing the silver ions to atoms, which then form silver nanoparticles. This nanoparticle formation has been investigated in commercial rare-earth laser glasses, borate glasses and standard soda lime glass. In order to tune the resonance between plasmon polaritons and the rare earth energy levels, we also modified the nanoparticle shapes from spherical to ellipsoidal by irradiating the samples with intense femtosecond laser pulses.

All modified samples were analyzed by fluorescence measurements.