Progress on up- and down-converted fluorescence in rare-earth dopedfluorozirconate-based glass ceramics for high efficiency solar cells

摘要

Transparent glasses as up- or down-converters are attractive sysfems to increase the efficiency of solar cells. Er-doped fluorozirconate (FZ) glasses show an intense up-conversion upon excitation at 1540 nm. Transmission spectra show that the absorbance at 1540 nm grows linearly with the Er-doping level. In Eu-doped FZ glasses, Which were additionally doped with chlorine ions, the growth of BaCl_2 nanocrystals can be observed upon thermal annealing. For high annealing temperatures a phase change from hexagonal to orthorhombic phase BaCl_2 can be seen. Upon excitation in the ultrav io-let (UV) spectral range these glass ceramics emit an intense blue emission. A combination of a silicon solar cell and an Eu-doped FZ glass ceramic as a down-converting top layer shows an increase in the-short circuit current in the UV spectral range compared to a solar cell without a down-converting top layer.