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2010
Conference Paper
Titel
Rare-earth doped fluorozirconate-based glass ceramics for high efficiency solar cells: recent developments
Abstract
Transparent, rare-earth doped fluorozirconate-based glasses and glass ceramics are attractive systems as up- and down-converters to increase solar cell efficiency. For up-conversion applications, erbium-doped fluorozironate glasses have been investigated. 2-dimensional intensity mapping of the up-converted fluorescence yielded information on the homogeneity of the glass sample and the erbium distribution therein. Depth scan experiments showed that the focus position of the excitation laser beam plays a crucial role since saturation of the 2-photon upconversion occurs for high excitation power. For down-conversion applications, the efficiency of a silicon solar cell could be significantly increased in the ultraviolet spectral range by placing a europium-doped glass ceramic on top. High transparency is a key issue here to avoid scattering losses and to obtain high light output. Transmission spectra of fluorozirconate glasses, which were additionally doped with chlorine ions to initiate the growth of BaCl2 nanoparticles therein upon thermal annealing, show that the absorbance in the visible spectral range depends significantly on the annealing conditions.