Monodisperse Silica‐Coated Polyvinylpyrrolidone/NaYF4 Nanocrystals with Multicolor Upconversion Fluorescence Emission

In full color: Ultrafine lanthanide-doped polyvinylpyrrolidone/NaYF4 nanocrystals with narrow size distribution were synthesized and found to disperse well in water and many organic solvents. Silica was coated onto the nanocrystals to form a uniform thin layer. Highly efficient upconversion fluorescence was observed from both uncoated and silica-coated PVP/NaYF4 nanocrystals doped with Yb/Er or Yb/Tm (see picture). Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z602975_s.pdf or from the author. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.