Ion exchange doping of solar cell coverglass for sunlight down-shifting

In this work, silicate glass slides were doped with silver or copper by ion exchange in molten salts in order to obtain luminescent sheets suitable as down-shifters to be used for covering and protecting solar cells. The samples were treated at different temperatures, in nitrate, sulfate and chloride salts, for different times. Post-exchange thermal treatments were performed on some of them in order to tailor the ion aggregation states and their luminescence features. Optical absorption and near ultraviolet-visible luminescence analyses were performed in order to test the suitability of the samples as down-shifters and, moreover, X-ray absorption near edge structure (XANES) analyses were performed on copper doped samples in order to better identify the oxidation states of the incoming ion as a function of the synthesis parameters. The performance of the best samples was tested by measuring the output power of a GaAs solar cell covered with the treated glass slides and illuminated with a solar simulator lamp.