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 degrees C and 290 degrees C and the optimum value of upconversion intensity was found for the 270 degrees 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 NaYF4:Er3+ upconverter. We also show a theoretical analysis where erbium transitions can be enhanced selectively to increase upconversion efficiency.