Ultrabright single-band red upconversion luminescence in highly transparent fluorosilicate glass ceramics containing KMnF perovskite nanocrystals.

With a specially designed composition, highly transparent Yb/Er-doped fluorosilicate glass ceramic (GC) containing KMnF perovskite nanocrystals (NCs) is obtained for the first time. The rare-earth ions are preferentially accumulated in regions embedded with KMnF NCs; as a result, a remarkably enhanced (by an order of magnitude) single-band red upconversion luminescence (UCL) is achieved. Absolute quantum efficiency of the red UCL, which cannot be measured in previous GCs owing to insufficiency, reaches as high as 0.10%±0.02% in the GC sample reported in this Letter. This value is even higher than that of the well-known multiband emitting β-NaYF:Er/Yb NCs and widely recognized GCs containing NaYF:Yb/ErNCs.