Neodymium‐doped fluorochlorozirconate glasses as an upconversion model system for high efficiency solar cells

Thermal processing of as‐made fluorozirconate glasses which were additionally doped with neodymium and chlorine ions leads to enhanced upconversion fluorescence intensities. The samples were annealed between 240 °C and 290 °C and the optimum value of upconversion intensity was found for the 270 °C sample. The development of glasses doped with Er, whose luminescence characteristics make it a better choice for application as an upconversion layer on silicon solar cells, is in progress. In addition, we present external quantum efficiency measurements of a silicon solar cell with a NaYF 4 :Er 3+ upconverter. We also show a theoretical analysis where erbium transitions can be enhanced selectively to increase upconversion efficiency. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)