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Efficiency of Thin Film Silicon Solar Cells with Spectral Down-Converter from Rare-Earth Ion Doped Thin Films
K. Baumgartner, B. Ahrens, O. Angelov, M. Sendova-Vassileva, D. Dimova-Malinovska, B. Holländer, S. Schweizer, R. Carius
Rare Earth, Thin Film Solar Cell, Down Conversion
Advanced Photovoltaics: New Concepts and Ultra-high Efficiency
Subtopic: New Materials, Cells and Modules
Event: 25th European Photovoltaic Solar Energy Conference and Exhibition / 5th World Conference on Photovoltaic Energy Conversion, 6-10 September 2010, Valencia, Spain
Session: 1CO.7.4
245 - 250
ISBN: 3-936338-26-4
Paper DOI: 10.4229/25thEUPVSEC2010-1CO.7.4
0,00 EUR
Document(s): paper


Solar cells with glass as cover or superstrate have a poor response in the blue and near UV spectral range due to absorption in the glass, the front contact layer and the doped layer. The efficiency of these solar cells can be improved by applying a spectral down-converter on top of the glass. Tb-doped SiO2 and Al2O3 films and a Tb-doped fluorozirconate glass were investigated for their suitability as a down-converter. Tb absorbs light in the spectral range from 250 to 380 nm and emits it in the spectral range between 400 and 630 nm, which transmits through the first layers and is efficiently absorbed by the active layer of the solar cell. Tb-doped SiO2 and Al2O3 films with concentrations between 0.04 and 14 at.% Tb were prepared by magnetron co-sputtering and afterwards annealed in order to enhance their conversion efficiency. The overall highest PL intensity was found for SiO2:Tb films with 2 at.% Tb annealed at 700 °C. These films were successfully integrated into amorphous thin film silicon solar cells and an average enhancement in the internal quantum efficiency of 3 % in the spectral range from 300 to 380 nm was observed, with a maximum gain of 33 % at 308 nm.