Visible‐to‐UV/Violet Upconversion Dynamics in Er³⁺‐Doped Oxyfluoride Nanoscale Glass Ceramics

Visible‐to‐UV/violet upconversion luminescence is found and studied in oxyfluoride glass ceramics with Er³⁺ dopant concentrations of 3.5, 6.0, or 12.0 mol%, covering a broad pump‐power range. The glass ceramics with doping levels of 3.5 and 6.0 mol% show the strongest upconversion luminescence intensity when compared to both higher doping levels and the respective precursor glasses. A comprehensive analysis of the involved upconversion mechanisms is presented. These materials could be useful to enhance the efficiency of the water‐splitting systems by using UV/violet light upconverted from the green and red parts of the solar spectrum, which are an alternative to photovoltaic solar cells.