The luminescence spectra and energy transfer from Ce3+/Tb3+ to Yb3+ in Ca3(BO3)2

Ce3+, Yb3+ and Tb3+ singly doped and Ce3+-Yb3+, Tb3+-Yb3+ codoped Ca3(BO3)2 phosphors were prepared by a solid state reaction method. The photoluminescence excitation and emission spectra at room temperature were investigated. The emissions of Yb3+ ion are at around 1000 nm, matching well with the optimal response of Si-based solar cells. When codoped with Ce3+ or Tb3+ ion, the absorption is greatly broadened in the ultraviolet-visible region. Energy transfer from Ce3+/Tb3+ to Yb3+ was investigated, the cooperative energy transfer process is proposed.