Down‐Conversion in Rare‐Earth Doped Glasses and Glass Ceramics

Abstract

This chapter investigates down-converters based on rare earth (RE) ions in zirconium, barium, lanthanum, and aluminum (ZBLAN), glass ceramics and borate glasses. The down-conversion efficiency of europium and samarium is optimized for solar cells. An improvement of the quantum efficiency of the cells is demonstrated in the spectral region where the external quantum efficiency (EQE) of the cells is low. For silicon-based solar cells, improvement of the quantum efficiency is achieved by europium (Eu) ions. As the quantum efficiency of the silicon is high even at wavelengths below 400nm the gain by the enhanced EQE in the UV is spoiled by extra absorption from the glass. As the photon flux of the sun light is low in the spectral region where down-converters are appropriate it turns out to be extremely important to avoid all spurious losses in the remaining part of the spectrum