Generation of white-light through frequency upconversion in praseodymium-ytterbium codoped nano-structured fluorogermanate glass

摘要

Praseodymium-ytterbium codoped fluorogermanate nano-structured phosphors for solid-state lighting were synthesized by thermal treatment of precursor glasses. Room temperature luminescence features of praseodymium-ytterbium ions incorporated into low-phonon-energy PbF_2 nanocrystals dispersed into the fluorogermanate glass matrix and excited with near-infrared light emitting diode laser was evaluated. The luminescence spectra exhibited predominant emissions in the 475-500, 520-530, and 600-650 nm regions. White-light emission was observed in ytterbium-sensitized praseodymium-doped phosphor excited at 980 nm. The dependence of the luminescence emisson intensity upon annealing temperature, and rare-earth concentrations was also evaluated. The results indicated that there exist an optimum annealing temperature and activator ion concentration in order to obtain efficient upconversion emission signals with CEE 1946 chromaticity coordinates within the white-light borderline region. Results indicate that the nanocomposite fluorogermanate glassy phosphor is a promissing novel contender for application in white-light solid-state display technology