Dresden 2009 – wissenschaftliches Programm

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DF: Fachverband Dielektrische Festkörper

DF 8: Glass I

DF 8.1: Vortrag

Dienstag, 24. März 2009, 10:00–10:20, WIL B321

Upconversion in fluorozirconate based glass ceramics for high efficiency solar cells — •Bernd Ahrens^1,2, Bastian Henke², Paul T. Miclea^2,3, and Stefan Schweizer^2,3 — ¹Department of Physics, University of Paderborn, Warburger Str. 100, 33098 Paderborn, Germany — ²Fraunhofer Center for Silicon Photovoltaics, Walter-Hülse-Str. 1, 06120 Halle (Saale), Germany — ³Institute of Physics, Martin-Luther-University of Halle-Wittenberg, Heinrich-Damerow-Str. 4, 06120 Halle (Saale), Germany

Solar cells are unable to use the whole solar spectrum. In particular, sub bandgab photons cannot be absorbed. Materials, which convert in an upconversion process two or more sub bandgap photons into photons with an energy higher than the bandgap energy, are of great interest. Low-phonon energy glasses like fluorozirconate (FZ) glasses are desirable hosts for rare-earth ions such as Er, Ho, Nd, Pr, and Tm because they enable upconverted fluorescence that would be quenched in high-phonon energy glasses. FZ glasses additionally doped with trivalent neodymium and chlorine ions and subsequently annealed show enhanced upconverted fluorescence intensities compared to the as-made samples. The samples were annealed at temperatures up to 290^∘C to initiate the growth of BaCl₂ nanocrystals therein; the Nd³⁺ ion is incorporated in the glass as well as in the nanoparticles. The diameters of the nanocrystals are in the range from a few to several tens of nanometers. The development of glass ceramics doped with Er³⁺, whose optical properties make it a better choice for the application as an upconversion layer on silicon solar cells, is in progress.