Fig. 2: Characterization of UCL-NCs.

TEM images of a PbS QDs, b core-shell-shell Nd sensitized Tm-UCNPs, c UCL-NCs and d mPEG-silane functionalized silica-coated UCL-NCs. Images of dark-field scanning TEM and corresponding EDS elemental mapping of (e, f) UCL-NCs and (g, h) UCL-NCs@SiO2. HR-TEM images of (i) PbS QDs, (j) core-shell-shell Nd sensitized Tm-UCNPs and (k) UCL-NCs. l Electron diffraction image of UCL-NCs.