Enhancing upconverted white light in Tm3+/Yb3+/Ho3+-doped GdVO4 nanocrystals via incorporation of Li+ ions.

The white light emission of Tm3+/Yb3+/Ho3+-doped GdVO4 nanocrystals, following excitation with near-infrared light (λexc = 980 nm), via a multiphoton upconversion process is presented. Upconverted blue emission from the Tm3+ ions as well as green/red emissions from the Ho3+ ions contributes to the observed white light. The calculated Commission internationale de l'éclairage (CIE) color coordinates were calculated to be x = 0.34; y = 0.32 and lie at the center of the white region. Furthermore, the intensity of the upconverted white light was enhanced by the incorporation of monovalent Li+ ions into the GdVO4 matrix. An explanation for this enhancement is proposed based on X-ray diffraction and fluorescence lifetime measurements.