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 Ce ions experiences a drop after initial illumination, due to photoionization of Ce ions, whereas the down-converted luminescence of Yb ions remains relatively stable. Co-doping Yb contributes to the luminescence drop of Ce with the excessive Yb ions serving as additional electron traps. The results are in support of a charge transfer process.