Photo-induced luminescence degradation in Ce, Yb co-doped yttrium aluminum garnet phosphors

Photon-induced luminescence degradation of Ce, Yb co-doped yttrium aluminum garnet phosphors with different Yb concentrations under 457 nm irradiation is studied for the first time, to the best of our knowledge. The degradation behavior is more significant in nano-phosphors prepared via the solgel method, compared with bulkier samples prepared via solid-state reaction. Photoluminescence intensity of ${\mathrm{Ce}}^{3+}$ ions experiences a drop after initial illumination, due to photoionization of ${\mathrm{Ce}}^{3+}$ ions, whereas the down-converted luminescence of ${\mathrm{Yb}}^{3+}$ ions remains relatively stable. Co-doping ${\mathrm{Yb}}^{3+}$ contributes to the luminescence drop of ${\mathrm{Ce}}^{3+}$ with the excessive ${\mathrm{Yb}}^{3+}$ ions serving as additional electron traps. The results are in support of a charge transfer process.