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Blue, Green, and Red Upconversion Emission from Lanthanide-Doped LuPO4 and YbPO4 Nanocrystals in a Transparent Colloidal Solution


  • We thank A. Kornowski and S. Bartholdi-Nawrath for the TEM investigations and Dr. K. Kömpe for measuring X-ray powder diffractograms. Part of this work was financially supported by the Swiss National Science Foundation.


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Light converter: The emission of visible light (Vis) upon excitation in the near-infrared (NIR) has been observed for the first time in a transparent solution. Excitation at 975 nm (marked red in the picture) of optically clear colloidal solutions of LuPO4:Yb3+, Tm3+, and YbPO4:Er3+ nanocrystals in chloroform leads to visible upconversion luminescence in the blue, green, or red spectral regions.